Survival of plants in response to salinity stress is typically related to Na+ toxicity, but little is known about how heterologous high-affinity potassium transporter (HKT) may help alleviate salt-induced damages in potato (Solanum tuberosum L.). In this study, we used the Arabidopsis thaliana high-affinity potassium transporter gene (AtHKT1) to enhance the capacity of potato plants to tolerate salinity stress by decreasing Na+ content and improving K+/Na+ ratio in plant leaves, while maintaining osmotic balance. Seven AtHKT1 transformed potato lines (namely T1, T2, T3, T5, T11, T13 and T15) were compared with non-transgenic control plant at molecule and whole-plant levels. The lines T3 and T13 had the highest AtHKT1 expression with the tolerance index (an quantitative assessment) being 6.8 times that of the control. At 30 days under 100 and 150 mmol L− 1 NaCl stress treatments, the T3 and T13 lines had least reductions in net photosynthetic rate, stomatal conductance and transpiration rate among the seven lines, leading to the increased water use efficiency and decreased yield loss. We conclude that the constitutive overexpression of AtHKT1 reduces Na+ accumulation in potato leaves and promotes the K+/Na+ homeostasis that minimizes osmotic imbalance, maintains photosynthesis and stomatal conductance, and increases plant productivity.

In China, potato is a kind of foreign crop lacking germplasm resource, especially the varieties grown in arid and semi-arid areas. Therefore, it is an effective way to rich the germplasm resource by introducing potatoes abroad. In this study, the Shannon-Wiener's diversity index and comprehensive score (F-value) were used to investigate the genetic diversity of 119 intro-duced potato clones from Peru International Potato Center about 10 phenotypic traits (emergence rate, plant height, stem diameter, leaf area, growth period, tuber number per plant, yield per plant, commodity rate, dry matter content and tuber length-width ratio). The genetic diversity of growth period was the most abundant among these phenotypic traits in 119 potato clones. Stem diameter, leaf area, growth period, tuber number per plant, yield per plant, commodity rate, dry matter content and tuber length-width ratio had significant effects on comprehensive value of phenotypic traits, and could be used to evaluate the potato germplasm resources on the drought farming. The F-value was significantly correlated with the economic characters (yield per plant, commodity rate and dry matter content), which can be used as the main evaluation index of potato germplasm resources. CIP393228.67 and CIP385561.124 in arid area and CIP304350.95, CIP392797.22, and CIP388615.22 in semi-arid area showed high and stable yield characteristics. These 119 introduced potato clones are rich in genetic diversity with good comprehensive evaluation, they could effectively complement potato germplasm resources and be beneficial to potato breeding in China.

The status of K + is important for plant health. However, little is known about if high-affinity potassium transporter HKTs may help K + retention under salt stress. Here, we determined the effect of Arabidopsis thaliana transporter gene ( AtHKT1 ) on the K + status, Na + -induced toxicity, and salt tolerance in tobacco ( Nicotiana tabacum L.). Six AtHKT1 transformed tobacco lines (T1, T2, … T6) were contrasted with a non-transgenic plantlet at the whole-plant and molecule levels. AtHKT1 gene was expressed in the xylems of stem, root and leaf vein in the transgenic tobacco, with the line T3 having highest expression. At Day 15, in the 200 mmol L −1 NaCl stress treatment, the transgenic plants remained a healthy K + status, while the control plants decreased K + content by 70% and Na + contents in leaves and stems were 1.7 times that in the transgenic line. The AtHKT1 expression enhanced the activities of SOD, CAT and POD, raised chlorophyll and soluble sugar contents and root activity, and decreased MDA and proline contents and electrolyte leakage destruction. The constitutive over-expression of AtHKT1 that helps maintain a healthy K + status while reducing Na + toxicity may serve as a possible mechanism in maximizing productivity of tobacco under salt stress.

The canopy-air temperature difference can reflect the physiological adaptability of plants under drought stress. In this study, drought tolerant varieties Jizhangshu 8 and Longshu 10, drought sensitive varieties Atlantic and Shepody, and ten potato clones with different drought tolerance levels from Peru International Potato Center were used to measure plant phenotypic traits (plant height, leaf area, leaf fresh weight, normalized difference vegetation index), photosynthetic indexes (photosynthetic rate, stomatal conduc-tance, transpiration rate, chlorophyll content) and the canopy-air temperature difference, and evaluated the drought tolerance under semi-arid and semi-humid environments. The canopy-air temperature difference, transpiration rate and stomatal conductance were most sensitive to drought stress. The canopy-air temperature difference was significantly different among different potato varieties (clones) under semi-arid and semi-humid environments. The drought tolerance coefficient of canopy-air temperature difference showed significantly positive correlations with drought tolerance coefficients of plant phenotypic characters and photosynthetic in-dexes. The canopy-air temperature difference is an effective indicator to evaluate potato drought tolerance by using infrared ther-mometers, which could provide a theoretical basis for the research of potato drought tolerance breeding.

Canopy interception is one of the most important processes in an ecosystem, but it is still neglected when assessing evapotranspiration (ET) partitioning in apple orchards on the Loess Plateau in China. To explore the importance of canopy interception, we monitored two neighbouring apple orchards on the Loess Plateau in China, one 8-year-old and the other 18-years old at the start of the study, from May to September for four consecutive years (2013-2016). We measured parameters of canopy interception (I) including precipitation, throughfall, stemflow, leaf area index, transpiration (T), and soil evaporation (S) to quantify ET. The importance of canopy interception was then assessed by comparing the relationship between water supply (precipitation) and water demand (ET), calculated with and without considering canopy interception (T + S and T + S + I, respectively). Tree age clearly influenced canopy interception, as estimates of annual canopy interception during the study years in the younger and older orchards amounted to 22.2-29.4 mm and 26.8-39.9 mm, respectively. Daily incident rainfall and rainfall intensity in both orchards were significantly positively correlated with daily canopy interception in each year. The relationship between annual precipitation and annual ET (calculated with and without consideration of canopy interception) in the younger orchard differed during 2015 and 2016. Ignoring canopy interception would result in underestimation of annual ET in both apple orchards and hence incorrect evaluation of the relationship between water supply and water demand, particularly for the younger orchard during 2015 and 2016. Thus, for a complete understanding of water consumption in apple orchards in this and similar regions, canopy interception should not be ignored when assessing ET partitioning.

Light is a major environmental factor that affects metabolic pathways and stimulates the production of secondary metabolites in potato. However, adaptive changes in potato metabolic pathways and physiological functions triggered by light are partly explained by gene expression changes. Regulation of secondary metabolic pathways in potato has been extensively studied at transcriptional level, but little is known about the mechanisms of post-transcriptional regulation by miRNAs. To identify light-responsive miRNAs/mRNAs and construct putative metabolism pathways regulated by the miRNA–mRNA pairs, an integrated omics (sRNAome and transcriptome) analysis was performed to potato under light stimulus. A total of 31 and 48 miRNAs were identified to be differentially expressed in the leaves and tubers, respectively. Among the DEGs, 1353 genes in the leaves and 1841 genes in the tubers were upregulated, while 1595 genes in the leaves and 897 genes in the tubers were downregulated by light. Mapman enrichment analyses showed that genes related to MVA pathway, alkaloids-like, phenylpropanoids, flavonoids, and carotenoids metabolism were significantly upregulated, while genes associated with major CHO metabolism were repressed in the leaves and tubers. Integrated miRNA and mRNA profiles revealed that light-responsive miRNAs are important regulators in alkaloids metabolism, UMP salvage, lipid biosynthesis, and cellulose catabolism. Moreover, several miRNAs may participate in glycoalkaloids metabolism via JA signaling pathway, UDP-glucose biosynthesis and hydroxylation reaction. This study provides a global view of miRNA and mRNA expression profiles in potato response to light, our results suggest that miRNAs might play important roles in secondary metabolic pathways, especially in glycoalkaloid biosynthesis. The findings will enlighten us on the genetic regulation of secondary metabolite pathways and pave the way for future application of genetically engineered potato.

StMYBA1 from potato tuber was transformed into tobacco (Nicotiana tabacum) with the CaMV 35S promoter to investigate whether it can regulate anthocyanin biosynthesis in tobacco plants. As a result, anthocyanin accumulation was induced by overexpressing StMYBA1 in all tissues of transgenic tobacco lines. Several anthocyanin biosynthetic genes were highly expressed in leaves and roots of transgenic lines. In particular, the bHLH transcriptional partners NtAN1a and NtAN1b, especially NtAN1b, were up-regulated significantly in leaves and roots of StMYBA1-overexpressing tobacco. These results demonstrate that endogenous bHLH partners can be stimulated by overexpressing exogenous gene StMYBA1 in tobacco, and the elevated expression levels of bHLH partners are essential for anthocyanin production in plant tissues. Applying the dark conditions to the tobacco plants overexpressing StMYBA1 transiently, can down-regulate the expression levels of biosynthetic pathway genes and bHLH TFs, and subsequently reduce anthocyanin accumulation. We suggest that StMYBA1 can positively regulate anthocyanin biosynthesis in tobacco, and light is required for its function on anthocyanin accumulation.

Background: The SnRKs (sucrose non-fermenting 1 related protein kinase) are a gene family coding for Ser/Thr protein kinases and play important roles in linking the tolerance and metabolic responses of plants to abiotic stresses. To date, no genome-wide characterization of the sucrose non-ferment 1 related protein kinase 2 (SnRK2) subfamily has been conducted in potato (Solanum tuberosum L.).Results: In this study, eight StSnRK2 genes (StSnRK2.1-StSnRK2.8) were identified in the genome of the potato (Solanum tuberosum L.) cultivar 'Longshu 3', with similar characteristics to SnRK2 from other plant species in gene structure, motif distribution and secondary structures. The C-terminal regions were highly divergent among StSnRK2s, while they all carried the similar Ser/Thr protein kinase domain. The fluorescence of GFP fused with StSnRK2.1, StSnRK2.2, StSnRK2.6, StSnRK2.7 and StSnRK2.8 was detected in the nucleus and cytoplasm of onion epidermal cells with StSnRK2.3 and StSnRK2.4 mainly associated to the nucleus while StSnRK2.5 to subcellular organelles. Expression level analysis by qRT-PCR showed that StSnRK2.1, 2.2, 2.5 and 2.6 were more than 1 fold higher in the root than in the leaf, tuber and stem tissues. The expressions of StSnRK2.3, 2.7, and 2.8 were at least 1. 5 folds higher in the leaf and stem than in the root, but lower in the tuber. The expression of StSnRK2.4 was also significantly (P < 0.05) higher in leaf, stem, and tuber than in the root. From the perspective of the relative expressions of StSnRK2 genes in potato, ABA treatment had a different effect from NaCl and PEG treatments.Conclusion: In the present study, we identified and characterized eight SnRK2s in the potato genome. The eight StSnRK2s exhibit similar gene structure and secondary structures in potato to the SnRK2s found in other plant species. The relative expression of eight genes varied among various tissues (roots, leaves, tubers, and stems) and abiotic stresses (ABA, NaCl and PEG-6000) with the prolongation of treatments. This study provides valuable information for the future functional dissection of potato SnRK2 genes in stress signal transduction, plant growth and development.

Ridge-furrow with plastic mulching (RFPM) has been commonly used in the production of field crops, but it is unknown whether this practice would affect soil quality attributes. Field experiments were conducted to determine the effects of RFPM on potato tuber yield and soil quality under semi-arid conditions. Six different planting patterns (i.e., various ridges and furrows were in combination with plastic mulching) were compared in randomized complete block with three replicates. It was consistent in the two years of study that the completely mulched with ridge planting significantly increased soil available N, available P, available K, and soil organic matter (SOM) content, and decreased the numbers of fungi in the 0-20cm soil, compared to the control (flat plots with no ridge and no mulching). Also, ridge planting increased the numbers of aerobic azotobacter, nitrifying bacteria and ammonifying bacteria and decreased anaerobic azotobacter and denitrifying bacteria compared to furrow planting. In addition, the completely mulched with ridge planting increased hydrogen peroxidase, alkaline phosphatase, and urease (UR) activities in the soil. The enhanced enzymatic activities in the soil were largely attributable to decreased soil evaporation and increased soil temperature due to the use of black plastic on the soil surface. Therefore, ridge planting with plastic mulching can be considered to be one of the best approaches in the improvement of potato productivity, whereas, at the same time, maintaining or enhancing soil health in semiarid areas.

Inorganic pyrophosphate (PPi) is an enzyme involved in sugar metabolism in potato tubers. In our previous study, we isolated an inorganic pyrophosphatase (PPase) gene from potato and obtained the transgenic potato plants transformed with the sense and antisense PPase genes respectively. In the present experiment, the physiological indexes, tuber dormancy, and sprouting characteristics of the transgenic potatoes were analyzed and evaluated. The result showed that the PPase activity and the inorganic phosphate content of tubers were lower in the antisense transgenic plant lines but were higher in the sense transgenic plant lines, compared with wild-type tubers. Soluble sugars, such as glucose, fructose and sucrose increased in transgenic plants that had overexpression of the sense PPase gene, but decreased in the antisense transgenic plant lines, compared with wild-type tubers. Tuber sprouting time of the antisense transgenic plants were delayed for 2 and 3 weeks and reached the 100 % sprouting rate only after 14 and 16 weeks storage compared with the wild-type when tubers are stored under 25 and 4 °C, respectively. In contrast, tuber sprouting time of the sense transgenic plants was earlier by approximately 2 weeks than that of wild-type tubers under these storage temperatures.

Salinity and drought are two severe abiotic stresses that affect plant growth and decrease food production worldwide. Compared to the field plants, test-tube plantlets could be more direct and fast to investigate the mechanism of stress adaptation. In the present study, the ultrastructural and physiological differences of potato (Solanum tuberosum L. c.v. "Longshu No. 3'') plantlets in response to the gradient saline (0, 25, 50, 100, and 200 mM NaCl) and the modeling drought stresses with polyethylene glycol (PEG) at the concentrations of 0, 2, 4, 6, and 8 % were analyzed. The results show that the severe salt (200 mM NaCl) and the modeling drought stresses (8 % PEG) inhibited the plantlet growth. There are considerable differences in their ultrastructural alteration under salt and modeling drought adaptation: PEG caused the increase in the number of stacked chloroplast, plastoglobuli, and starch; NaCl induced the decrease in the number of chloroplast and plastoglobuli. Moreover, plantlet has higher free proline content, less malondialdehyde (MDA) content, and higher activities of catalase (CAT) and superoxide dismutase (SOD) under the gradient NaCl treatments than the gradient PEG treatments. The results of this study will provide theoretical and practical insights into characterizing the ultrastructural and physiological differences of plants adapting to various stressful environments.

Plant microRNAs are important endogenous gene regulators which regulate gene expression at post-transcriptional level. Previous studies have identified that miR169 family members regulated the NF-YA transcription factors which have been implicated in plant development and stress responses. At present, reported potato genome sequence data offered an opportunity for global insights into the molecular mechanisms of the miR169/NF-YA modules in potato. In this work, 4 novel stu-miR169 family members were predicted in potato based on potato genome sequence data. miRNA target prediction showed that mature stu-miR169 sequences have a bite sit on the 5 of StNF-YA genes in potato, and three of them were validated by RNA ligase-mediated 5′RACE (5′ RLM-RACE) assay. The result from investigation of the expression patterns of mature stu-miR169 and their predicted target genes also showed that mature stu-miR169 was down-regulated in response to the drought stress. There were some targeted StNF-YA genes that exhibited a negative expression pattern with mature stu-miR169 during the different periods of drought-treated samples. Taken together, the decreased expression of stu-miR169 might drive over-expression of NF-YA family members, they are related to resistances against drought stress.

In potato (Solanum tuberosum L.), R2R3 MYBs are involved in the regulation of anthocyanin biosynthesis. We examined sequences of these MYBs in cultivated potatoes, which are more complex than diploid potato due to ploidy and heterozygosity. We found amino acid variants in the C-terminus of the MYB StAN1, termed R0, R1, and R3, due to the presence of a repeated 10-amino acid motif. These variant MYBs showed some expression in both white and pigmented tubers. We found several new alleles or gene family members of R2R3 MYBs,StMYBA1 and StMYB113, which were also expressed in white potato tubers. From functional analysis in tobacco, we showed that the presence of a C-terminal 10-amino acid motif is optimal for activating anthocyanin accumulation. Engineering a motif back into a MYB lacking this sequence enhanced its activating ability. Versions of StMYBA1 and StMYB113 can also activate anthocyanin accumulation in tobacco leaves, with the exception of StMYB113-3, which has a partial R2R3 domain. We isolated five family members of potato StbHLH1, and one StJAF13, to test their ability to interact with MYB variants. The results showed that two alleles of StbHLH1 from white skin and red skin are non-functional, while three other StbHLH1s have different co-regulating abilities, and need to be activated by StJAF13. Combined with expression analysis in potato tuber, results suggest that StbHLH1 and StJAF13a re key co-regulators of anthocyanin biosynthesis, while the transcripts of MYB variants StAN1,StMYBA1, and StMYB113 are well expressed, even in the absence of pigmentation.

To explore the relationship between potato (Solanum tuberosum )different genetic traits and its re-sponse to water stress,we analyzed the genetic diversity of test materials by the methods of SSR,studied the content variation of peroxidase (POD and CAT)activity and soluble protein of different potato varieties under water stresses by processing potato transplanting seedling for PEG-6000 simulated water stress and natural wa-ter stress method.The results showed that the genetic similarity coefficient (GS)at 0.700 level,44 potato ma-terials can be divided into five types,most breed clustered together,explaining the genetic basis of testing vari-eties is still relatively narrow.Through a GGE-biplot comprehensive analysis of soluble protein,POD and CAT variation,44 selected materials were divided into 6 groups.Comparative analysis of genetic diversity analysis and physiological results found that there were no obvious consistency between them,namely the species differences in genetic traits can’t react their drought resistance performance difference directly.But two stress modes with high consistency on studying the characteristics of varieties of drought resistance.This research provides the reference for further drought resistance research.

Planting patterns have distinctive effects on the soil micro-ecological environment and soil quality. To explore the effects of film mulch ridge-furrow (FMRF) cropping on soil microbial properties and potato yield, a study was conducted in 2013 and 2014 in a continuously cropped field under nonfilm-mulched flat plot (CK), half-mulched flat plot (T1), fully mulched ridge cropping (T2), fully mulched furrow cropping (T3), half-mulched ridge cropping (T4) and half-mulched furrow cropping (T5) planting patterns. Our results indicate that T3 increased the average bacteria/fungi (B/F) ratio by 253% compared to CK. On average, half-mulched ridge cropping increased the bacteria population and aerobic Azotobacter by 9 and 19%, respectively, compared with CK. On average, T3 had the greatest inhibitory effect on fungi populations. Half-mulched furrow cropping had the most anaerobic Azotobacter and nitrifying bacteria. The study showed that FMRF increased soil bacteria, especially Azotobacter but reduced fungi and actinomycetes. Treatment T2 gave the greatest potato yield, followed by T4, whereas the greatest biomass yield was recorded in T4. Full-mulch furrow cropping methods produced the greatest nutrient use efficiency. The findings of this study enhance our understanding of soil microbe and plant responses to plastic mulch and planting patterns under semi-arid conditions.

甘肃省中部沿黄灌区是全国重要的加工型马铃薯生产基地,然而因集约化生产带来的连作障碍问题已经严重影响到当地马铃薯种植业的健康发展。结合田间试验和相关的室内分析,从马铃薯块茎产量和品质、植株生理特征和土壤真菌群落结构等角度,初步评估土壤灭菌和生物有机肥联用（Ammonia Disinfection plus Bio-organic Fertilizer Regulation,ABR）对马铃薯连作障碍的防控效果。同对照相比,ABR处理的块茎产量和商品薯率分别显著增加约71.1%—152.1%和39.2%—53.3%,但块茎化学品质变化不大。ABR处理叶绿素含量和根系活力较CK均显著增加,而叶片和根系丙二醛含量显著下降。PCR-DGGE分析发现,ABR处理显著影响了马铃薯连作土壤的真菌群落结构,表现为真菌群落的多样性指数较CK相比显著下降。ABR处理还有效抑制了土传病害的滋生,植株发病率和收获后的病薯率较CK分别显著下降约67.2%—82.2%和69.1%—70.5%。采用Real-time PCR评估连作土壤中3种优势致病真菌的数量变化,显示ABR处理下立枯丝核菌、茄病镰刀菌和接骨木镰刀菌的数量在生育期内较CK均有不同程度的下降。综合来看,土壤灭菌和生物有机肥联用技术在防控甘肃省中部沿黄灌区马铃薯连作障碍上具有较大的应用潜力,而对土传病害的抑制和微生物群落结构的改善是其主要的作用机理。

In this study,the detoxification potato plantlets plants of ‘Longshu No.3’were cultivated under PEG-4000(0,2%,4%,6% and 8% PEG)and gradient saline stress (0,25,50,100 and 200 mmol·L NaCl)respectively.The root growth and the ultrastructure of mesophyll cell were observed two weeks lat-er.The physiological and biochemical indices were measured to provided the theoretical basis for screening salt-tolerant and drought-resistant potato germplasm.The results showed that:with the increase of exter-nal PEG-4000 or NaCl concentration,(1)the total of root length,root volume and root number were de-creased.With extension of time the decrease was obvious.This decline in salt stress obviously greater than that in drought stress,explained that roots were sensitive to salt stress;(2)potato plantlet cell wall obvi-ously thickened and plasmolysis,plastoglobuli markedly increased,numerous vesicles,chloroplasts gradu-ally damaged to a complete disorganization;(3)potato plantlet plants leaf proline content significantly in-creased,the activities of catalase (CAT)and superoxide dismutase (SOD)and malondialdehyde (MDA) content significantly increased,while chlorophyll content decreased.In conclusion,the PEG-4000 simula-ted drought and salt stress could cause serious damage of plant chloroplast structure and chlorophyll con-tent significantly decreased.The more stress and the more serious damage.Simultaneously,drought and salt stress also induced that potato plantlet leaf proline content and the activities of catalase (CAT)and su-peroxide dismutase (SOD)significantly increased and alleviated the drought and high salt stress injury.

This optimized approach provides both a computational tool and a library construction protocol, which can maximize the number of genomic sequence reads that uniformly cover a plant genome and minimize the number of sequence reads representing chloroplast DNA and rRNA genes. One can implement the developed computational tool to feasibly design their own RAD-seq experiment to achieve expected coverage of sequence variant markers for large plant populations using information of the genome sequence and ideally, though not necessarily, information of the sequence polymorphism distribution in the genome.

蔗糖非酵解相关蛋白激酶家族2(Sucrose Non-Fermenting Related protein Kinases 2,SnRK2)是一类植物中高度保守的蛋白激酶,也是植物响应干旱、盐碱等导致渗透性胁迫的主要调控原件.本研究以马铃薯品种‘陇薯3号’为材料,观察试管苗在0、25、50、100、200 mmol/L NaCl 2周、4周和6周盐胁迫下和0、2％、4％、6％、8％ PEG 2周、4周和6周干旱胁迫下马铃薯地上部分组织中StSnRK2基因的表达模式.结果显示,盐和干旱胁迫下马铃薯StSnRK2基因表达模式不尽相同:在盐胁迫下StSnRK2.4和StSnRK2.6表达均上调;干旱胁迫下StSnRK2.3的表达量上升,而且随PEG浓度的增加StSnRK2.3表达量也随之增高;同一基因在不同胁迫处理下表达趋势也有差异,StSnRK2.5基因在盐胁迫下表达下调,在干旱胁迫下StSnRK2.5基因表达量高于对照;不同胁迫处理下基因的表达与生理指标的相关性也不同,盐胁迫下,StSnRK2.6基因与CAT和SOD活性呈极显著正相关,与气孔面积呈显著负相关,干旱胁迫下,StSnRK2.6基因的表达量与脯氨酸含量呈显著正相关.本文通过研究不同渗透胁迫条件下StSnRK2基因的表达模式,进一步解析了马铃薯对盐及干旱胁迫响应的机理,可为马铃薯抗逆品种的选育提供依据.

Local main cultivar of Xindapingwas used to investigate the effect of removing film on tuber yield,quality and water movement of potato under whole film mulched cultivation. The results indicated that the tuber yield,yield components and quality of potato were improved for film removing on 75 days after planting. Compared with covering film during the whole growth period( T5),tuber yield in treatments of film removing on 60 days after planting( T1),film removing on 75 days after planting( T2),90 days after planting( T3),and 105 days after planting( T4) were increased by 4%,28%,26%,and 10%,respectively. The tuber yield in treatment T2 was the highest. The quality of tuber was improved by removing film. Compared with T5,T1,and T2 treatments,T3 and T4 significantly increased the soluble sugar,soluble protein,amino acid,Vc and starch content,while decreased the content of organic acid. Generally,T2 was the better treatment in increasing both the yield and quality of film mulched potato.