Cereal rye and its wild forms are important sources of genetic diversity for wheat breeding due to their resistances to biotic and abiotic stresses. Secale strictum subsp. anatolicum (Boiss.) K. Hammer (SSA) is a weedy relative of cultivated rye, S. cereale. Meiotic chromosome pairing in F-1 hybrids of SSA and S. cereale reveals strong genomic affinity between the two genomes. A study of the transferability of S. cereale sequence-based markers to SSA and hexaploid triticale demonstrated their applicability for tracing SSA chromatin in wheat. The transferability of the markers was over 80% from homoeologous groups 1, 2, and 3, and greater than 70% from groups 4 to 7. This study focused on the generation and molecular and cytogenetic characterization of wheat-SSA alien derivatives. Twelve were identified using combinations of non-denaturing fluorescence in situ hybridization (ND-FISH), genomic in situ hybridization (GISH), and molecular marker analysis. All SSA chromosomes, except 3R(a) and 6R(a), were transferred to wheat either in the form of monosomic additions (MA), mono-telosomic additions (MtA), double-mono-telosomic additions (dMtA), or double-monosomic additions (dMA). The germplasm developed in this study will help to enhance the genetic base of wheat and facilitate molecular breeding of wheat and triticale.

Sequence-based markers have added a new dimension in the efficiency of identifying alien introgressions in wheat. Expressed sequence tag-sequence tagged sites (EST-STS) markers have proved useful in tracing alien chromatin. In this study, we report the development of Thinopyrum bessarabicum- and Secale anatolicum-specific EST-STS markers and their application in tracing respective alien chromatin introgressions in wheat. The parental lines, Chinese Spring (CS), ISR991.1 (CS/Th. bessarabicum amphidiploid), and ISR1049.2 (CS/Secale anatolicum amphidiploid), were used as core experimental materials. Using comparative analysis of RNA-Seq data, 10 903 and 10 660 candidate sequences specific to Th. bessarabicum and S. anatolicum, respectively, were assembled and identified. To validate the genome specificity of these candidate sequences, 68 and 64 EST-STS markers were developed from randomly selected candidate sequences of Th. bessarabicum and S. anatolicum, respectively, and tested on sets of alien addition lines. Fifty-five and 53 markers for Th. bessarabicum and S. anatolicum chromatin, respectively, were assigned to chromosomal location(s), covering all seven chromosomes. Approximately 83% of S. anatolicum-specific markers were transferable to S. cereale. The genome-specific candidate sequences identified and the EST-STS markers developed will be valuable resources for exploitation of Th. bessarabicum and Secale species diversity in wheat and triticale breeding.

A variety of Thinopyrum bessarabicum introgressions in both hexaploid and tetraploid wheats were generated and characterized by molecular cytogenetic analysis. Six wheat-J genome recombinants were identified with ND-FISH and GISH. Diploid wheatgrass, Thinopyrum bessarabicum (2n = 2x = 14, EbEb or JbJb or JJ), is a well-known alien source of salinity tolerance and disease resistance for wheat improvement. The true genetic potential and effect of such introgressions into wheat can be best studied in chromosomal addition or substitution lines. Here, we report the generation and characterization of various categories of Th. bessarabicum derivatives in both hexaploid and tetraploid cultivated wheats. Sequential non-denaturing fluorescence in situ hybridization (ND-FISH) and genomic in situ hybridization (GISH) are robust techniques to visualize the size of alien introgressions and breakpoints. We identified a complete set of monosomic addition lines into both bread wheat and durum wheat, except for 7J in durum wheat, by sequential ND-FISH and GISH. We also characterized alien derivatives belonging to various classes including mono-telosomic additions, disomic additions, monosomic substitutions, double monosomic substitutions, monosomic substitution–monosomic additions, double monosomic additions, and multiple monosomic additions into both bread and durum wheats. In addition, various wheat-Th. bessarabicum recombinant chromosomes were also detected in six alien derivatives. These wheat-Th. bessarabicum derivatives will provide useful cytogenetic resources for improvement of both hexaploid and tetraploid wheats.

Potato is the 4th largest staple food in the world currently. As a high biomass crop, potato harbors excellent potential to produce energy-rich compounds such as triacylglycerol as a valuable co-product. We have previously reported that transgenic potato tubers overexpressing WRINKLED1, DIACYLGLYCEROL ACYLTRANSFERASE 1, and OLEOSIN genes produced considerable levels of triacylglycerol. In this study, the same genetic engineering strategy was employed on potato leaves. The overexpression of Arabidopsis thaliana WRINKED1 under the transcriptional control of a senescence-inducible promoter together with Arabidopsis thaliana DIACYLGLYCEROL ACYLTRANSFERASE 1 and Sesamum indicum OLEOSIN driven by the Cauliflower Mosaic Virus 35S promoter and small subunit of Rubisco promoter respectively, resulted in an approximately 30- fold enhancement of triacylglycerols in the senescent transgenic potato leaves compared to the wild type. The increase of triacylglycerol in the transgenic potato leaves was accompanied by perturbations of carbohydrate accumulation, apparent in a reduction in starch content and increased total soluble sugars, as well as changes of polar membrane lipids at different developmental stages. Microscopic and biochemical analysis further indicated that triacylglycerols and lipid droplets could not be produced in chloroplasts, despite the increase and enlargement of plastoglobuli at the senescent stage. Possibly enhanced accumulation of fatty acid phytyl esters in the plastoglobuli were reflected in transgenic potato leaves relative to wild type. It is likely that the plastoglobuli may have hijacked some of the carbon as the result of WRINKED1 expression, which could be a potential factor restricting the effective accumulation of triacylglycerols in potato leaves. Increased lipid production was also observed in potato tubers, which may have affected the tuberization to a certain extent. The expression of transgenes in potato leaf not only altered the carbon partitioning in the photosynthetic source tissue, but also the underground sink organs which highly relies on the leaves in development and energy deposition.

Thinopyrum species are potential sources of disease resistance for wheat. Thinopyrum bessarabicum is a well-known source of salt tolerance, but there are very few reports of rust resistance being transferred from this species to wheat. Here, we report wheat-Th. bessarabicum–derived stem rust and stripe rust–resistant doubled haploid (DH) lines and characterized using molecular markers and cytogenetic analyses. We used sequential non-denaturing fluorescence in situ hybridization (ND-FISH) and genomic in situ hybridization (GISH) to determine their genomic compositions. Cytological results were validated by molecular analysis using genome-specific PCR markers. These lines were either alien additions, partial diploids, or partial amphidiploids. Line DH9 was a disomic addition line carrying chromosome 4Jb whereas DH1 was a double disomic addition line for chromosomes 6Jb and 7Jb. Lines DH7 and DH8 were partial diploids that were cytologically unstable due to having ph1ph1 genotype. DH7 also had a pair of T6BL-6JbL.6JbS translocated chromosomes and was monosomic for a T5DS-5JbS.5JbL translocation. The size of the translocated alien segment in chromosome T5DS-5JbS.5JbL was L+(0–0.42)S, whereas the size of wheat chromatin in chromosome T6BL-6JbL.6JbS was S+(0–0.85)L. Lines DH5 (2n = 50) and DH11 (2n = 54) were partial amphidiploids with eight and 12 Th. bessarabicum chromosomes, respectively. Lines DH7, DH8, and DH11 expressed an intermediate level of resistance to stem rust with infection types (ITs) varying from 1+2 to 23-, whereas they were immune or near-immune (IT 0 to 0) to stripe rust. Comparison of the rust reactions, genome compositions, and molecular markers of the DH lines along with their parents indicated that the Thinopyrum chromosome conferring resistance to both rusts was 2Jb.

Xanthophylls are a class of carotenoids that are important micronutrients for humans. They are often found esterified with fatty acids in fruits, vegetables, and certain grains, including bread wheat (Triticum aestivum). Esterification promotes the sequestration and accumulation of carotenoids, thereby enhancing stability, particularly in tissues such as in harvested wheat grain. Here, we report on a plant xanthophyll acyltransferase (XAT) that is both necessary and sufficient for xanthophyll esterification in bread wheat grain. XAT contains a canonical Gly-Asp-Ser-Leu (GDSL) motif and is encoded by a member of the GDSL esterase/lipase gene family. Genetic evidence from allelic variants of wheat and transgenic rice (Oryza sativa) calli demonstrated that XAT catalyzes the formation of xanthophyll esters. XAT has broad substrate specificity and can esterify lutein, β-cryptoxanthin, and zeaxanthin using multiple acyl donors, yet it has a preference for triacylglycerides, indicating that the enzyme acts via transesterification. A conserved amino acid, Ser-37, is required for activity. Despite xanthophylls being synthesized in plastids, XAT accumulated in the apoplast. Based on analysis of substrate preferences and xanthophyll ester formation in vitro and in vivo using xanthophyll-accumulating rice callus, we propose that disintegration of the cellular structure during wheat grain desiccation facilitates access to lutein-promoting transesterification.

Triacylglycerol is a major component of vegetable oil in seeds and fruits of many plants, but its production in vegetative tissues is rather limited. It would be intriguing and important to explore any possibility to expand current oil production platforms, for example from the plant vegetative tissues. By expressing a suite of transgenes involved in the triacylglycerol biosynthesis, we have previously observed substantial accumulation of triacylglycerol in tobacco (Nicotiana tabacum) leaf and potato (Solanum tuberosum) tuber. In this study, simultaneous RNA interference (RNAi) downregulation of ADP-glucose pyrophosphorylase (AGPase) and Sugar-dependent1 (SDP1), was able to increase the accumulation of triacylglycerol and other lipids in both wild type potato and the previously generated high oil potato line 69. Particularly, a 16-fold enhancement of triacylglycerol production was observed in the mature transgenic tubers derived from the wild type potato, and a two-fold increase in triacylglycerol was observed in the high oil potato line 69, accounting for about 7% of tuber dry weight, which is the highest triacylglycerol accumulation ever reported in potato. In addition to the alterations of lipid content and fatty acid composition, sugar accumulation, starch content of the RNAi potato lines in both tuber and leaf tissues were also substantially changed, as well as the tuber starch properties. Microscopic analysis further revealed variation of lipid droplet distribution and starch granule morphology in the mature transgenic tubers compared to their parent lines. This study reflects that the carbon partitioning between lipid and starch in both leaves and non-photosynthetic tuber tissues, respectively, are highly orchestrated in potato, and it is promising to convert low-energy starch to storage lipids via genetic manipulation of the carbon metabolism pathways.

Emmer wheat (Triticum dicoccon Schrank) is a potential source of new genetic diversity for the improvement of hexaploid bread wheat. Emmer wheat was crossed and backcrossed to bread wheat and 480 doubled haploids (DHs) were produced from BC1F1 plants with hexaploid appearance derived from 19 crossses. These DHs were screened under well-watered conditions (E1) in 2013 to identify high-yielding materials with similar phenology. One-hundred and eighty seven DH lines selected on this basis, 4 commercial bread wheat cultivars and 9 bread wheat parents were then evaluated in extensive field experiments under two contrasting moisture regimes in north-western NSW in 2014 and 2015. A significant range in the water-use-efficiency of grain production (WUEGrain) was observed among the emmer derivatives. Of these, 8 hexaploid lines developed from 8 different emmer wheat parents had significantly improved intrinsic water-use-efficiency (WUEintr) and instantaneous water-use-efficiency (WUEi) compared to their bread wheat recurrent parents. Accurate and large scale field-based phenotyping was effective in identifying emmer wheat derived lines with superior performance to their hexaploid bread wheat recurrent parents under moisture stress.

到2030年,全球植物油需求量预计将翻番.然而目前的植物油生产平台,包括油棕和温带油籽却难以满足如此的增幅.因此,探索新型植物油来源对弥补未来的植物油的短缺变得越来越重要.植物油的主要形式是三酰甘油(TAG),最近通过基因工程在植物营养组织中生产TAG引起了人们极大的兴趣.多学科的"组学"研究也愈发提高了我们对植物脂质生物化学和代谢的理解.鉴于此,生物化学途径鉴定及对脂肪酸生物合成、脂质组装和转换关键的基因的注释已得到有效更新.近年来,通过对TAG生物合成涉及的关键基因和调节因子的遗传操作,高生物量植物营养组织和油籽中TAG的积累得到了前所未有的迅速发展.本文总结了目前从单基因操作到旨在增加高生物量植物组织中TAG积累的多基因叠加基因工程策略,讨论了可能有助于进一步缓解食用油和生物柴油潜在短缺的植物油生产的新方向和建议.

Global demand for vegetable oil is anticipated to double by 2030. The current vegetable oil production platforms, including oil palm and temperate oilseeds, are unlikely to produce such an expansion. Therefore, the exploration of novel vegetable oil sources has become increasingly important in order to make up this future vegetable oil shortfall. Triacylglycerol (TAG), as the dominant form of vegetable oil, has recently attracted immense interest in terms of being produced in plant vegetative tissues via genetic engineering technologies. Multidiscipline-based “-omics” studies are increasingly enhancing our understanding of plant lipid biochemistry and metabolism. As a result, the identification of biochemical pathways and the annotation of key genes contributing to fatty acid biosynthesis and to lipid assembly and turnover have been effectively updated. In recent years, there has been a rapid development in the genetic enhancement of TAG accumulation in high-biomass plant vegetative tissues and oilseeds through the genetic manipulation of the key genes and regulators involved in TAG biosynthesis. In this review, current genetic engineering strategies ranging from single-gene manipulation to multigene stacking aimed at increasing plant biomass TAG accumulation are summarized. New directions and suggestions for plant oil production that may help to further alleviate the potential shortage of edible oil and biodiesel are discussed.

The introduction of kikuyu (Cenchrus clandestinus (Hochst. ex Chiov.) Morrone) into Australia in 1918 has seen it become established and adapted to several geographic regions in a wide range of ecologies and environmental situations. After it naturalised to local conditions, researchers and farmers recognised the value of kikuyu in marginal and previously unproductive sites, where forage quality and quantity made this species popular with dairy farmers and pastoralists. Its versatility and prostrate, mat-forming characteristics also led to the adoption of kikuyu by local governments, homeowners and sporting organisations in urban environments as turf. Kikuyu has the ability to alleviate soil contamination and remediate soils, thus enhancing the use of previously unproductive land. However, the aggressive growth habit of the species, considered a problem in certain regions of the world, has led to a noxious weed classification in some states of the USA. This review includes information on expected changes to world agricultural and urban environments and the potential expanded role of kikuyu. The origin of kikuyu grass, genetic variability, tolerances to soil salinity and drought, and potential for genetic improvement are also discussed.

Wheat grain proteins responses to mixing and thermal treatment were investigated using Mixolab-dough analysis systems with flour from two cultivars, Ventura-26 (normal amylose content) and Ventura-19 (reduced amylose content). Size exclusion high performance liquid chromatography (SE-HPLC) and two-dimensional gel electrophoresis (2-DGE) analysis revealed that, stress associated and metabolic proteins largely interacted with dough matrix of Ventura-26 after 26min (56°C); gliadins, avenin-like b proteins, LMW-GSs, and partial globulins showed stronger interactions within the dough matrix of Ventura-26 at 32min/C3 (80°C), thereafter, however, stronger protein interactions were observed within the dough matrix of Ventura-19 at 38min/C4 (85°C) and 43min (80°C). Thirty-seven proteins associated with changes in dough matrix due to reduced amylose content were identified by mass spectrometry and mainly annotated to the chromosome group 1, 4, and 6. The findings provide new entry points for modifying final product attributes.

Recent interest in mesophyll conductance (gm) has revealed a dynamic leaf trait that significantly limits photosynthetic rate and influences leaf water-use efficiency (Flexas et al., 2008, 2013; Douthe et al., 2011; Evans & von Caemmerer, 2013). Traditional methods of estimating gm are slow, technically challenging and error-prone (Warren, 2006; Evans, 2009), but the recent development of online stable carbon isotope discrimination (∆13CA) measurement systems coupled to leaf gas exchange have removed some of these measurement problems (Barbour et al., 2007, 2010; Tazoe et al., 2009). Taking advantage of relatively rapid gm measurements available with online ∆13CA, we explored the genetic control of gm within a wheat mapping population and were able to identify a quantitative trait locus (QTL) responsible for 9% of variation in gm. This preliminary study demonstrates that we can now investigate the genetic control of gm, and that further study across multiple mapping populations and growth environments is warranted to confirm the QTL and identify the gene(s). After CO2 has diffused through stomatal pores and into the leaf intercellular air space, it must also diffuse through the cell walls, through the plasma membrane, the cytosol and finally the chloroplast envelope before it can be fixed by RuBisco (Evans et al., 2009). The inverse of combined resistances to CO2 diffusion from the intercellular air space to the sites of fixation is termed mesophyll conductance (gm). There has been considerable recent research in gm, revealing that gm is a significant limitation to photosynthesis (Warren et al., 2003; Niinemets et al., 2009), responds to environmental conditions (Flexas et al., 2007; Warren, 2008; Douthe et al., 2011; Evans & von Caemmerer, 2013; von Caemmerer & Evans, 2015), is variable between genotypes of the same species (Barbour et al., 2010; Gu et al., 2012; Jahan et al., 2014) and contributes to leaf water-use efficiency (Flexas et al., 2013). Leaves with high surface area of chloroplasts exposed to the intercellular air space tend to have higher gm (Evans & von Caemmerer, 1996; Tomás et al., 2013) and leaves with thick cell walls tend to have lower gm (Tomás et al., 2013), and gm has also been found to vary in plants with altered expression of aquaporin (Uehlein et al., 2003, 2008; Hanba et al., 2004). This aquaporin relationship provides a potential mechanism for the observed rapid response of gm to environmental conditions (Tazoe et al., 2011). However, very little is known about genetic control of gm, despite a growing number of studies highlighting the contribution of gm to traits of agronomic importance like photosynthesis and water-use efficiency. Gu et al. (2012) investigated leaf gas exchange in 11 rice introgression lines using a multiple regression analysis, and found that under well-watered conditions variation in gm explained a significant proportion of variation in photosynthetic rate. There have been no studies to date that have directly tested the genetic control of gm in any species. Hence, our study aimed to demonstrate that the current tools allow the assessment of the genetic control of gm in wheat. Six replicate plants of 150 Cranbrook/Halberd doubled haploid (DH) lines of the common wheat (Triticum aestivum L.) mapping population and the two parental lines were grown for 5 wk in controlled environment rooms. The temperature inside the growth rooms was set at 25°C during the 14 h light period, and 17°C in the dark. Relative humidity was maintained at 75–80% and photosynthetically active radiation was 600 μmol m−2 s−1 at the upper leaves. Seeds were planted in 8 l pots with potting mix amended with slow-release fertilizer (Osmocote Exact, Scotts, Sydney, NSW, Australia). Plants were thinned to two per pot at week three. Gas exchange measurements could be made on a maximum of 30 plants each day, so planting was staggered in time to allow all plants to be measured at the same days after planting and developmental stage. Measurements on the 912 plants took 6 wk. A coupled leaf gas exchange/∆13CA measurement system was used to measure photosynthetic rate (A), stomatal conductance (gs), leaf intrinsic water-use efficiency (A/gs) and gm. Two Li6400xt photosynthesis systems (Li-Cor Inc., Lincoln, NE, USA) fitted with 6 cm2 leaf chambers and red–blue light sources were connected to a tunable diode laser absorption spectrometer (TDLAS, model TGA100A, Campbell Scientific Inc., Logan, UT, USA) as described by Barbour et al. (2007, 2010). The CO2 mole fraction inside the leaf cuvette was controlled at 400 μmol mol−1, leaf temperature at 25°C, and irradiance at 2000 μmol m−2 s−1 for all leaves. Relative humidity was not controlled, and varied between leaves from 72% to 80% (leaf-to-air vapour pressure difference, VPd, varied between 0.63 and 0.92 kPa). Two of the youngest, fully expanded leaves from each plant were placed side-by-side in the leaf cuvette and remained in the cuvette until gas exchange and isotope compositions stabilized (20–40 min). Mesophyll conductance was estimated from gas exchange and ∆13CA as described by Barbour et al. (2010), but including ternary effects (Farquhar & Cernusak, 2012). Assumptions were required to apply the equations; we assumed that isotope fractionation during carboxylation was 29‰, fractionation during photorespiration was 16.2‰, fractionation during dissolution and diffusion through water was 1.8‰, fractionation during day respiration was −3‰, the rate of day respiration at 25°C was 2.2 μmol m−2 s−1 (Jahan et al., 2014) and the CO2 compensation point in the absence of day respiration was 37.5 μmol mol−1. An analysis of variance (ANOVA) in Genstat, 16th edn (VSN International Ltd, London, UK) revealed a significant effect of the time of day at which measurements were made (a general linear decline in gs and gm over the course of the day, a slight increase in A and an increase in A/gs), so time of measurement was treated as a covariate and means of gas exchange parameters were adjusted accordingly. The covariate-adjusted means were very similar to numerical means for A and gs (mostly < 5% change), but changed more for gm (up to a 44% change, and a 14% change on average). A genetic map with 1325 loci for the population is described in Lehmensiek et al. (2005). The composite interval mapping function in QTL Cartographer 2.5 (Wang et al., 2007) was used, carrying out 1000 permutations with 2 cM steps at P = 0.01 to detect QTL. Among the doubled haploid lines, photosynthetic rate and stomatal conductance varied from 22.4 to 35.3 μmol m−2 s−1 and 0.50 to 1.30 mol m−2 s−1, with means of 29.4 μmol m−2 s−1 and 0.79 mol m−2 s−1, respectively (Fig. 1). The two parental lines, Cranbrook and Halberd, had A of 29.1 ± 2.2 and 25.4 ± 0.7 μmol m−2 s−1 and gs of 0.62 ± 0.08 and 0.81 ± 0.07 mol m−2 s−1, respectively (mean ± standard error (SE), n = 6). These values for gas exchange in wheat are high (cf. Fischer et al., 1998), but consistent with nonlimiting growth conditions, and high light, low VPd measurement conditions (Jahan et al., 2014). Mesophyll conductance varied three-fold, 0.27–0.94 mol m−2 s−1 bar−1, with a mean of 0.55 mol m−2 s−1 bar−1. The two parental lines, Cranbrook and Halberd, had gm of 0.71 ± 0.13 and 0.44 ± 0.07 mol m−2 s−1 bar−1, respectively (mean ± SE, n = 6). Cranbrook had significantly higher leaf intrinsic water-use efficiency than Halberd (P = 0.009) due to both higher A and lower gs (Fig. 1). This cultivar ranking is the same as the ranking of these two cultivars for water-use efficiency estimated from leaf carbon isotope discrimination (∆13Cl) in field trials over multiple seasons and sites (Rebetzke et al., 2008). This ranking differs from that reported by Jahan et al. (2014) due to a reversal in ranking of gs and gm between genotypes. The reason for the difference in genotype rankings for gs and gm between experiments may relate to differences in leaf age, and measurement light and VPd between the two experiments (younger leaves were measured at a lower VPd and higher light in the current experiment). Both gs and gm are known to respond to short-term changes in environmental conditions (Flexas et al., 2008). Mesophyll conductance was positively, but not closely, related to photosynthetic rate across the genotypes (gm = 0.024A − 0.08, R = 0.36, P < 0.0001; data not shown), but was unrelated to stomatal conductance (P > 0.05). The observation that stomatal conductance and mesophyll conductance are not correlated is important because the most useful combination of traits for improving water-use efficiency while maintaining productivity would be high gm, to allow high A, but low gs (Barbour et al., 2010). Of course, leaf intrinsic water-use efficiency would need to scale to grain water-use efficiency, a link that remains unclear (Rebetzke et al., 2013). In this study, gm was positively, but again not strongly, related to leaf-intrinsic water-use efficiency (gm = 0.011A/gs − 0.18, R = 0.42, P < 0.0001; data not shown). That is, variability in gm explained 18% of observed variability in A/gs. All else being equal (i.e. if gm varied but gs and photosynthetic capacity did not), we would expect a positive relationship between A/gs and gm due to increased chloroplastic CO2 concentration allowing increased A at higher gm. Positive relationships between gm and A/gs have been observed for a number of species (Flexas et al., 2013). QTL analysis revealed a region on the long arm of chromosome 2A containing a QTL for gm with a limit of detection (LOD) score of 3.07, which explained 9% of variation in gm within the population (Table 1). This is the first report of a QTL for gm in any species. While this level of genetic control is not strong, and comes from a single mapping population grown in a single (controlled) environment, the result is statistically significant and important for a complex trait such as gm. The molecular marker of interest, PSR540, is in the same region as marker wmc170. Marker wmc170 lies close to a gene for sodium exclusion in a salt-tolerant genotype of durum wheat (Munns et al., 2003), a gene later identified as HKT1;4 (Huang et al., 2006). The active HKT1;4 allele is not present in modern wheat. The broad region of interest on chromosome 2A has synteny to rice chromosome 4 (Gale & Devos, 1998). Based on this synteny, Forrest & Bhave (2010) identified copies of a number of wheat aquaporin genes within this region through in silico mapping. These genes are of particular interest because aquaporin are thought to transport CO2 through membranes (Hanba et al., 2004; Uehlein et al., 2008). Carbon dioxide must cross the plasma membrane and chloroplast envelope to reach the chloroplast stroma, so it is possible that aquaporin within the plasma membrane could influence gm (sensu Uehlein et al., 2008). Many wheat aquaporin have been localized to the plasma membrane (Forrest & Bhave, 2008), including those mapped to chromosome 2 (e.g. TaPIP2;3, TaTIP3;2 and TaTIP2;1). The in silico map of Forrest & Bhave (2010) does not predict specific locations of genes on chromosomes, so a molecular genetic study seems warranted to confirm the gene location, identity and function. Setting aside the exciting result of the first QTL for gm, it is also pleasing that this study identified three QTL for leaf intrinsic water-use efficiency, on 3B, 5A and 7A. The QTL on 3B coincides with a QTL for carbon isotope discrimination as recorded in whole leaf tissue (∆13Cl) identified for this mapping population by Rebetzke et al. (2008). The linked marker, P40/M54-7, identified here is in the same location as markers glk683 and wm1-1A found in the Rebetzke et al. (2008) study. Leaf carbon isotope discrimination (∆13Cl) has been extensively used as a proxy for water-use efficiency, particularly in wheat (Farquhar & Richards, 1984; Condon et al., 1987), because both ∆13Cl and A/gs depend on the control of CO2 and H2O diffusion through stomata. This study provides further support for carbon isotope discrimination theory and evidence of the underlying genetic control of ∆13Cl in wheat. Here we report the first hints of genetic control of mesophyll conductance. Relatively rapid gm measurement techniques combined with recently developed molecular genetic tools provide the opportunity to understand genetic control of gm in plants and improve the likelihood of using this trait to improve crop productivity and water-use efficiency. We note that, although not used here, combined measurements of leaf gas exchange and chlorophyll fluorescence using the ‘variable J’ method developed by Di Marco et al. (1990) and Harley et al. (1992) will also give rapid measurements of gm (although typically over a smaller leaf area and with considerable sensitivity to errors in the estimation of the CO2 compensation point in the absence of day respiration, Pons et al., 2009, than the ∆13CA technique). We trust that this preliminary study will prompt further studies on the topic using multiple mapping populations grown in a range of environmental conditions. This research was supported by the Grains Research and Development Corporation (US00056) and the Australian Research Council through a Future Fellowship to MMB (FT0992063). S. Ryazanova and W. Lin are thanked for technical support and Dr R. Munns for valuable discussion.

The main objective of this research was to add genotyping information to previous phenotyping findings of Pakistani guava for the purposes of selective breeding. Inter-primer binding site (iPBS) and microsatellite (SSR) markers were used to assess the molecular variation and genetic structure of 51 promising Pakistani guava (Psidium guajava L.) genotypes which were then compared with 19 others from different geographical regions across the world. PCR of 6 iPBS primers (dominant markers) produced a total of 97 bands (96.63 % polymorphic) ranging from 100 to 2800 bp and the mean PIC for primers ranged from 0.1687 to 0.3522. The mean unbiased expected heterozygosity (0.183), Shannon's information index (0.275) and average fixation index (Fst or inbreeding) (0.925) indicated a high level of inbreeding among the accessions tested. Multi-locus DNA fingerprints using 18 SSR loci unambiguously differentiated all accessions and demonstrated an absence of duplicated samples. Diversity analysis revealed a total of 172 alleles (from 124 to 553 bp) ranging from 2 to 17 with a mean value of 9.56 alleles per locus. The mean unbiased expected heterozygosity (0.091), Shannon's information index (0.130) and mean inbreeding coefficient (0.854) also indicated a high level of inbreeding among the accessions. Ordination and cluster analysis from both iPBS and SSR markers showed that the genetic relationships between all accessions could be separated into geographic origin, specifically Pakistan, Mexico, Hawaii and India. Guava accessions cultivated in Pakistan and wild guava germplasm are highly divergent and possess abundant genetic diversity. The iPBS PCR-based genome fingerprinting technology used in this study is low-cost and provides an effective alternative in differentiating accessions of guava and their related species or genera.

Since 2005, a serious emerging disease called fairway patch has occurred on the fairways, tees and green surrounds of a number of golf courses in New South Wales, Queensland, Victoria and Western Australia. It occurs most commonly on couch or bermudagrass (Cynodon dactylon) but has also been found on kikuyu (Pennisetum clandestinum) fairways at one golf course in Sydney. The disease begins as small patches (5–10 cm diam.) of yellow to tan-coloured grass. The patches enlarge into tan-coloured rings up to 1 m in diameter, which often coalesce to form unsightly brown networks of dead and dying grass. The patches are present all the year round but are most pronounced from late spring to late autumn. Fungal isolation from diseased roots and pathogenicity tests have proven that a slow-growing (ca. 2 mm/day on PDA at 25 °C), dark, septate, non-sporulating fungus is the cause of fairway patch. Phylogenetic analysis of the pathogen’s rDNA ITS and partial 28S sequences has shown that it is a new taxon and is described as Phialocephala bamuru P.T.W. Wong & C. Dong sp. nov. It belongs to a heterogeneous clade that includes Phialocephala, Acephala, Vibrissea, Phaeomollisia and Mollisia spp., but, as it is phylogenetically closest to Phialocephala spp. (94–95 % ITS affinities), it has been described as a Phialocephala species although it has not been shown to produce spores in culture. Research is continuing to study the biology and ecology of this ectotrophic root-infecting fungal pathogen and develop practical strategies to manage the disease.

TILLING is widely used in plant functional genomics. Mutagenesis and SNP detection is combined to allow for the isolation of mutations in genes of interest. It can also be used as a plant breeding tool, whereby variation in known or candidate genes of interest to breeding programs is generated. Here we describe a simple low-cost TILLING procedure.

Segregating F(3) families, derived from a cross between oat cultivar Swan and the putative single gene line PC68, were used to determine the association of seed storage protein loci and resistance gene analogues (RGAs) with the crown rust resistance gene Pc68. SDS-PAGE analysis detected three avenin loci, AveX, AveY, and AveZ, closely linked to Pc68. Their diagnostic alleles are linked in coupling to Pc68 and were also detected in three additional lines carrying Pc68. Another protein locus was linked in repulsion to Pc68. In complementary studies, three wheat RGA clones (W2, W4, and W10) detected restriction fragment length polymorphisms (RFLPs) between homozygous resistant and homozygous susceptible F(3) DNA bulks. Four oat homologues of W2 were cloned and sequenced. RFLPs detected with two of them were mapped using F(3) and F(4) populations. Clone 18 detected a locus, Orga2, linked in repulsion to Pc68. Clone 22 detected several RFLPs including Orga1 (the closest locus to Pc68) and three RGA loci (Orga22-2, Orga22-3, and Orga22-4) loosely linked to Pc68. The diagnostic RFLPs linked in coupling to Pc68 were detected by clone 22 in three additional oat lines carrying Pc68 and have potential utility in investigating and improving crown rust resistance of oat.

Starch was isolated from seven varieties of field peas (Pisumsativum L.) and characterised using a combination of physical, chemical and functional tests. The total starch content of the peas ranged between 34% and 42.7% of dry matter, and the amylose content of the starch was between 35% and 38%. Average particle diameter of the seven starches varied between 21.4 and 26.1μm. All of the pea starches gave a typical C-type X-ray diffraction pattern, with relative crystallinity ranging between 36% and 55% and the proportion of B-type crystallites between 3.8% and 30.4%. Although there were only small differences between the starches in amylose content, they displayed significant variability in functional properties, including swelling power, pasting characteristics, thermal transition temperatures in the differential scanning calorimeter, and in susceptibility to invitro attack by α-amylase. The results indicate the importance of structural characteristics of starch molecules, particularly amylopectin, as determinants of the properties of native starch granules.

The large genome and polyploidy of wheat (Triticum aestivum L.) makes it difficult to identify desirable genetic changes based on phenotypic screening due to gene redundancy. Forward genetics is, therefore, more difficult in wheat than in diploid plants. A modified TILLING (Targeting Induced Local Lesions IN Genomes) method including the harvest of five heads per M1 plant, storage of M2 seeds, using unlabeled primers and agarose gels for mutation detection, and crossing of useful mutants for desired grain quality was explored in this report. A soft wheat cultivar, QAL2000, and a hard wheat cultivar, Ventura, were mutagenized with ethyl methanesulfonate (EMS). Screening of the waxy genes Wx‐A1 and Wx‐D1 in 2348 EMS‐treated M2 plants allowed identification of 121 mutants, including silent, missense, and knockout (truncation) mutations. A complete waxy wheat was successfully bred in 18 mo by crossing two truncation mutants (Wx‐A1‐truncation and Wx‐D1‐truncation; Wx‐B1 is naturally null in both mutants). Screening of two puroindoline genes (Pina and Pinb) in QAL2000 identified 19 mutants. A hard grain variant of a soft cultivar was identified due to a mutation in Pinb caused by a premature stop codon. Background mutations were observed and further self‐fertilization or crossing with a wild type was performed to eliminate deleterious mutations. With the rapid accumulation of wheat genomics information, many potential target genes of interest can be screened for mutations in these TILLING populations.