Wheat is one of the most important food crops in the world, and grain number per spike (GNS) is one of the most important factors affecting wheat grain yield. Therefore, identifying genes controlling GNS is important for wheat production. However, wheat is an allohexaploid species and has a highly complex genome, and the isolation of wheat genes is challenging. In this study, we identified a candidate gene, TraesCS4B02G047100 (TaRLK-4B), associated with GNS using both quantitative trait locus (QTL) mapping and genome-wide association study (GWAS) based on RNA-Seq. We obtained three homozygous mutant lines, bb-1, bb-2 and bb-3, using the CRISPR/Cas9 gene editing system. Compared with Fielder (wild type, WT), the three mutant lines exhibited significant reductions in GNS, total spikelets per spike (TSS) and spike length (SL). These results indicated that TaRLK-4B positively regulates GNS and its related traits TSS and SL. The TaRLK-4B gene contains two exons and one intron and belongs to the largest subfamily of LRR-RLKs. We performed RNA-Seq analysis using spikes from the WT and bb-2 mutant line at the tillering stage. A total of 1,193 differentially expressed genes (DEGs) were identified, including previously cloned TaSPL17 homologous genes in the three subgenomes and their orthologous gene OsIPA1 (OsSPL14) in rice. Combining RNA-Seq data of TaRLK-4B and DAP-Seq data of the TaSPL17-7D, we identified 136 overlapping genes which are likely downstream targets of TaSPL17-7D. Therefore, we hypothesized that TaRLK-4B represents a novel putative component of the TaSPL17-centered regulatory network. In addition, haplotype analysis revealed that Haplotype 2 (Hap2) is a favorable haplotype for increasing GNS, but the thousand-grain weight (TGW) was not significantly different between Haplotype 1 (Hap1) and Hap2.

The objective of this study was to identify and confirm a candidate gene for wheat grain number per spike (GNS), and investigate its molecular mechanisms. Quantitative trait locus (QTL) mapping and genome-wide association study (GWAS) identified that the TraesCS4B02G044100, annotated as a glabrous enhancer-binding protein-like (TaGeBPL-4B), is a candidate gene of the GNS. Knockout and overexpression studies showed that TaGeBPL-4B participates in the positive regulation of the GNS by modulating spikelet development. The RNA-seq and DAP-seq analyses revealed that TraesCS5B02G120800, which encodes an amino acid permease (TaAAP-5B), is a direct downstream target gene of TaGeBPL-4B. We further confirmed this regulation by yeast one-hybrid (Y1H), dual-luciferase reporter assay (Dual-Luc) and electrophoretic mobility shift assays (EMSA). TaGeBPL-4B activates the expression of TaAAP-5B and modulates amino acid contents, which possibly influence wheat spike development and GNS

Wheat (Triticum aestivum L.) is a vital staple crop globally, with its grain microelement content playing a crucial role in human nutrition and health. In this study, the concentrations of eight essential microelements (micronutrients and toxic elements): iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), selenium (Se), chromium (Cr), cadmium (Cd), and arsenic (As), were quantified in 272 wheat varieties using inductively coupled plasma mass spectrometry (ICP-MS) under three different environments. A genome-wide association study (GWAS) was conducted using 176,357 molecular markers, comprising 163,223 single-nucleotide polymorphisms (SNPs) and 13,134 insertion-deletion (InDels) variants, identified through RNA sequencing. A total of 196 significant markers associated with microelement content traits were identified across 21 chromosomes in various environments. Of these, 14 significant markers consistently appeared across environments, forming 13 QTLs and linking to 45 candidate genes. Among these, 29 genes were homologs of known genes in Arabidopsis and rice, while 16 were novel candidates. Haplotype analysis indicated significant phenotypic variation in microelement accumulation, with TraesCS6A02G204300Hap2 notably enhancing iron content. This study provides valuable insights into the genetic architecture of microelement accumulation in wheat grains and introduces novel genetic resources for breeding wheat varieties aimed at improving micronutrient content and ensuring food safety.

Reducing plant height (PH) is one of the core contents of the “Green Revolution”, which began in the 1960s in wheat. A number of 27 reduced-height (Rht) genes have been identified and a great number of quantitative trait loci (QTLs) for PH have been mapped on all 21 chromosomes. Nonetheless, only several genes regulated PH have been cloned. In this study, we found the interval of QTL QPh-1B included an EST-SSR marker swes1079. According to the sequence of swes1079, we cloned the TaOSCA1.4 gene. We developed a CAPS marker to analyze the variation across a natural population. The result showed that the PH was significantly different between the two haplotypes of TaOSCA1.4–1B under most of the 12 environments and the average values of irrigation and rainfed conditions. This result further demonstrated that TaOSCA1.4 was associated with PH. Then, we validated the TaOSCA1.4 via RNAi technology. The average PHs of the wild-type (WT), RNAi lines 1 (Ri-1) and 2 (Ri-2) were 94.6, 83.6 and 79.2 cm, respectively, with significant differences between the WT and Ri-1 and Ri-2. This result indicated that the TaOSCA1.4 gene controls PH. TaOSCA1.4 is a constitutively expressed gene and its protein localizes to the cell membrane. TaOSCA1.4 gene is a member of the OSCA gene family, which regulates intracellular Ca2+ concentration. We hypothesized that knock down mutants of TaOSCA1.4 gene reduced regulatory ability of Ca2+, thus reducing the PH. Furthermore, the cell lengths of the knock down mutants are not significantly different than that of WT. We speculate that TaOSCA1.4 gene is not directly associated with gibberellin (GA), which should be a novel mechanism for a wheat Rht gene.

In wheat, a series of dwarf and semi-dwarf plant varieties have been developed and utilized worldwide since the 1960s and caused the ‘Green Revolution’. To date, 25 reduced-height (Rht) genes have been identified, but only several genes for plant height (PH) have been isolated previously. In this study, we identified a candidate gene, ATP-dependent DNA helicase (TaDHL-7B), for PH via QTL mapping and genome-wide association study (GWAS) methods. We knocked out this gene using the CRISPR/Cas9 system in variety ‘Fielder’. Two homozygous mutant genotypes, AAbbDD (−5 bp) and AAbbDD (−1 bp), were obtained in the T2 generation. The PH values of AAbbDD (−5 bp) and AAbbDD (−1 bp) were significantly reduced compared with the wild-type (WT, ‘Fielder’), indicating that TaDHL-7B is a novel Rht gene that controls the PH. This is the first time that a PH gene of wheat has been isolated with a non-hormone pathway, providing a new insight into the genetic control of PH. The TaDHL gene reduced the PH without a yield penalty. It could be used to improve the lodging resistance and yield in wheat breeding programs.

株高作为小麦重要的农艺性状之一,受遗传因子和外部环境共同影响,但遗传因子是最为主要的决定因素.小麦株高性状受到多基因调控,其数量性状位点广泛分布在小麦21条染色体上,目前已开发多个直接应用于育种辅助选择的株高相关的分子标记.目前,国内外学者围绕株高形成的遗传因素、基因定位与克隆、基因调控机理、分子标记辅助育种选择等进行了大量研究,并取得了重要的研究进展.本文综述了小麦株高的构成因素,阐述了小麦株高形成相关基因的遗传定位、克隆及其等位变异的挖掘和在小麦辅助育种中的利用,并展望了小麦株高下一步研究的前景.

In two growing seasons of wheat (2015-2017), we conducted a field trial with Taishan 28 in Tai'an Academy of Agricultural Science Feicheng experimental base, Tai'an City, Shandong Province. There were four irrigation levels of 150 (A1), 300 (A2), 450 (A3), and 600 (A4) m3·hm-2, and four nitrogen application levels of 90 (B1), 135 (B2), 180 (B3), and 225 (B4) kg·hm-2. We examined the effects of the combination effects of irrigation and nitrogen on dry matter accumulation and transport, nitrogen accumulation and transport, water consumption and utilization, photosynthetic characteristics, wheat grain yield and yield components of wheat. The results showed that dry matter accumulation, nitrogen accumulation, vegetative organs production, storage and the transportation volume to grains of the dry matter and nitrogen, and dry matter and nitrogen accumulation of grain in the mature stage of wheat all reached the maximum in A3B3 treatment, which were significantly different from other treatments. Under all the nitrogen treatments, soil water consumption in the 60-200 cm soil layer was A3>A4>A2>A1. Water use efficiency and nitrogen use efficiency in A3B3 treatment were higher than that under A3B4, A4B3 and A4B4. The net photosynthetic rate, stomatal conductance and transpiration rate of flag leaves from 7 to 28 days after flowe-ring were all significantly higher in A3B3 treatment, which was conducive to the photosynthetic synthesis of carbohydrates in wheat. The interaction effect of water and nitrogen addition significantly affected grain yield and yield components. Wheat yield was the highest in A3B3 treatment which reached at 9400 kg·hm-2. In conclusion, the treatment with irrigation of 450 m3·hm-2 and nitrogen of 180 kg·hm-2 could significantly improve dry matter and nitrogen accumulation, and promote transportation volume of the dry matter and nitrogen to grain. Compared with the high water and nitrogen treatment, it could effectively increase water use efficiency and nitrogen use efficiency, enhance photosynthetic capacity of flag leaf, produce more carbohydrate, and increase grain yield.

为了获得与小麦产量性状关联的分子标记,筛选相关标记的等位变异,以128份黄淮麦区小麦品种(系)为材料,在4个环境下鉴定产量性状,并选用在小麦全基因组21条染色体上的64个SSR、27个EST-SSR和47个功能标记检测所有材料的基因型.91个SSR和EST-SSR标记共检测到315个等位变异,单个引物检测到2～7个等位变异,平均3.5个;47个功能标记共检测到107个等位变异,单个引物检测到2～5个等位变异,平均2.3个.关联分析表明,49个位点与4个环境的产量性状及其均值显著关联(P≤0.005),其中38个位点在2个或以上环境或均值下被重复验证,16个位点与2个或以上性状相关联.对相对稳定的等位变异作进一步分析,发掘了一批与产量性状相关的优异等位变异,如降低株高的等位变异Ax2 *-null和UMN19*-A362,增加穗长的等位变异barc21-A220,增加可育小穗数的等位变异gpw2111-A156,增加总小穗数的等位变异swes65-A120,增加穗数的等位变异VRN-A1*-A 1068,增加穗粒数的等位变异cfdS-A215和增加千粒重的等位变异wmc626-A 170.研究结果对利用分子标记辅助选择进行小麦产量性状的遗传改良具有一定的指导意义.