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

小麦是全球三大主要谷物作物之一，每年产量超过7亿吨。到2050年，全球小麦需求将增长至9亿吨，为了实现这一目标，产量必须每年增长1.6%，高于目前的1%。提高生物量的研究，特别是通过增强小麦光合作用的途径，可能会增加一些产量，但这不太可能有助于达到产量目标，除非产生的额外生物量是“有用的生物量”或谷物。收获指数（HI，谷物干物质（DM）产量/地上DM）是有用生物量与无用生物量之比的量度，并且是产量的关键组成部分。对于冬小麦，HI值很少超过0.55，并且自20世纪90年代以来没有显著增加，尽管理论极限高达0.65。更好地理解HI的遗传基础将允许HI在更高生物量品种中的改进和稳定表达，从而导致遗传产量潜力的阶跃变化。有显著的证据表明，产量潜力是一个库限制性状，其中碳积累受到谷物库强度的限制。因此，提高每平方米粒数是提高现代冬小麦HI和产量潜力的重要途径。结果效率是每单位穗干重作为开花期的谷粒数的量度，并且是另一个特别感兴趣的性状。该项目与KWS UK Ltd的艾德伯恩博士和雅各布拉格博士合作，将对一组优良的KWS UK冬小麦双单倍体品系进行表型分析，以测定其籽粒产量、HI、1000粒重和每平方米籽粒数;籽粒分配和光合特性，包括穗和茎-节间干物质分配指数，结实效率（开花期穗粒数DM）、冠层NDVI和叶片叶绿素含量（SPAD）。将对代表KWS项目分层抽样的样本组（150行）进行基因分型。将通过GWAS进行标记-性状分析，以鉴定可用于育种计划以选择高HI、高生物量基因型的谷粒分配性状的标记。还将筛选BBSRC Breders' Toolkit面板中更广泛的种质，包括合成衍生和地方品种衍生的品系（100个品系），并进行标记-性状分析，以更好地了解潜在基因座的范围。. KWS面板中的谷粒分配的遗传和生理基础将通过对DH系的子集的RNAseq实验结合孕穗时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.