Advancing Harvest Index in Winter Wheat in High Biomass Backgrounds through Genomics Enabled Breeding

小麦是全球三大主要粮食作物之一，年产量超过7亿吨。到2050年，全球小麦需求将增长到9亿吨，为了实现这一目标，产量必须在目前1%的年增长率基础上每年增加1.6%。提高生物量的研究，特别是通过提高小麦光合作用的方法，可能会带来一些产量增加，但这不太可能有助于实现产量目标，除非产生的额外生物量是“有用的生物量”，即谷物。收获指数(HI，谷物干物质(DM)产量/地上DM)是衡量有用生物量与非有用生物量之比的指标，是产量的关键组成部分。对于冬小麦，HI值很少超过0.55，而且自1990年代S以来没有显著增加，尽管理论上的上限高达0.65。更好地了解HI的遗传基础将有助于HI在较高生物量品种中的改良和稳定表达，从而导致遗传产量潜力的阶段性变化。有大量证据表明，产量潜力是一个库容量受限的性状，其中碳积累受籽粒库容量的限制。因此，提高每平方米籽粒数是提高现代冬小麦HI和产量潜力的重要途径。结实效率是衡量开花时每单位穗干重的籽粒数，也是另一个特别值得关注的性状。该项目与KWS UK Ltd的Ed Byrne和Jacob Lage博士合作，将对KWS UK的精英冬小麦双单倍体品系进行表型鉴定，包括籽粒产量、HI、千粒重和每平方米籽粒；以及籽粒分配和光合作用性状，包括穗和茎节间干物质分配指数、结果效率(开花期每穗粒数对穗干物质干物质分配指数)、冠层NDVI和叶片叶绿素含量(SPAD)。该小组(150条线)代表了整个KWS计划的分层抽样，将进行基因分型。标记-性状分析将通过GWAS进行，以确定可用于育种计划的籽粒分割性状标记，以选择高HI、高生物量的基因型。还将筛选(100个系)包括BBSRC Breders‘s Toolkit小组中的合成来源和地方品种来源的更广泛的种质，并进行标记-性状分析，以更好地了解潜在基因座的范围。。KWS小组中的籽粒分配的遗传和生理基础将通过对DH品系的子集进行RNAseq实验，并结合孕穗期的穗激素浓度分析来进一步研究。

Wheat is one of the three major staple cereal crops globally, with excess of 700m tonnes produced per year. Global demand for wheat is set to grow to 900m tonnes by 2050, and in order to meet that target, yields must increase by 1.6% per year, up from current annual increases of 1%. Research to improve biomass, particularly through the avenue of enhancing wheat photosynthesis may generate some yield increases, however this is unlikely to help hit yield targets unless the additional biomass generated is "useful biomass", or grain. Harvest index, (HI, grain dry matter (DM) yield / aboveground DM) is a measure of the ratio of useful biomass to non-useful biomass, and is a key component of yield. For winter wheat, HI values rarely exceed 0.55, and have not increased significantly since the 1990's, despite a theoretical limit as high as 0.65. A better understanding of the genetic basis of HI would allow for the improvement and stable expression of HI in higher biomass varieties, leading to a step change in genetic yield potential. There is significant evidence that yield potential is a sink limited trait, where carbon accumulation is limited by grain sink strength. Therefore improving grains per m2 is an important avenue for increasing the HI and yield potential of modern winter wheat. Fruiting efficiency is a measure of the number of grains set per unit of spike dry weight as anthesis, and is another trait of particular interest. This project is in collaboration with Drs Ed Byrne and Jacob Lage at KWS UK Ltd and will phenotype an association panel of elite KWS UK winter wheat doubled-haploid lines for grain yield, HI, 1000 grain weight and grains per m2; and grain partitioning and photosynthetic traits, including spike and stem-internode dry matter partitioning indices, fruiting efficiency (grains per unto spike DM at anthesis), canopy NDVI and leaf chlorophyll content (SPAD). The panel (150 lines), representing a stratified sampling across the KWS programme, will be genotyped. Marker-trait analysis will be performed via GWAS to identify markers for grain partitioning traits that can be used in breeding programs to select for high HI, high biomass genotypes.Wider germplasm including synthetic-derived and landrace-derived lines in the BBSRC Breders' Toolkit panel will also be screened (100 lines) and marker-trait analysis carried out to gain a better understanding of the range of potential loci. . The genetic and physiological basis of grain partitioning in the KWS panel will be investigated further with an RNAseq experiment on a subset of DH lines, in conjunction with spike hormone concentration analysis at booting.