Altendorf Kayla R, Larson Steven R, DeHaan Lee R, Crain Jared, Neyhart Jeff, Dorn Kevin M, Anderson James A
USDA-ARS, Forage Seed and Cereal Research Unit, Irrigated Agriculture Research and Extension Center, Prosser, WA 99350, USA.
The Land Institute, Salina, KS 67401, USA.
G3 (Bethesda). 2021 Apr 23;11(3). doi: 10.1093/g3journal/jkab025.
Intermediate wheatgrass (Thinopyrum intermedium) is an outcrossing, cool season grass species currently undergoing direct domestication as a perennial grain crop. Though many traits are selection targets, understanding the genetic architecture of those important for local adaptation may accelerate the domestication process. Nested association mapping (NAM) has proven useful in dissecting the genetic control of agronomic traits many crop species, but its utility in primarily outcrossing, perennial species has yet to be demonstrated. Here, we introduce an intermediate wheatgrass NAM population developed by crossing ten phenotypically divergent donor parents to an adapted common parent in a reciprocal manner, yielding 1,168 F1 progeny from 10 families. Using genotyping by sequencing, we identified 8,003 SNP markers and developed a population-specific consensus genetic map with 3,144 markers across 21 linkage groups. Using both genomewide association mapping and linkage mapping combined across and within families, we characterized the genetic control of flowering time. In the analysis of two measures of maturity across four separate environments, we detected as many as 75 significant QTL, many of which correspond to the same regions in both analysis methods across 11 chromosomes. The results demonstrate a complex genetic control that is variable across years, locations, traits, and within families. The methods were effective at detecting previously identified QTL, as well as new QTL that align closely to the well-characterized flowering time orthologs from barley, including Ppd-H1 and Constans. Our results demonstrate the utility of the NAM population for understanding the genetic control of flowering time and its potential for application to other traits of interest.
中间偃麦草（Thinopyrum intermedium）是一种异花授粉的冷季型禾本科植物，目前正作为一种多年生谷物作物进行直接驯化。尽管许多性状都是选择目标，但了解那些对当地适应性重要的性状的遗传结构可能会加速驯化进程。巢式关联作图（NAM）已被证明在剖析许多作物物种农艺性状的遗传控制方面很有用，但它在主要进行异花授粉的多年生物种中的效用尚未得到证实。在这里，我们介绍了一个中间偃麦草NAM群体，该群体是通过将十个表型不同的供体亲本与一个适应性普通亲本进行正反交培育而成，从10个家系中获得了1168个F1后代。通过测序进行基因分型，我们鉴定出8003个单核苷酸多态性（SNP）标记，并构建了一个群体特异性的一致性遗传图谱，该图谱包含21个连锁群上的3144个标记。通过全基因组关联作图和家系间及家系内的连锁作图相结合，我们对开花时间的遗传控制进行了表征。在对四个不同环境下的两个成熟度指标进行分析时，我们检测到多达75个显著的数量性状位点（QTL），其中许多在两种分析方法中都对应于11条染色体上的相同区域。结果表明开花时间的遗传控制很复杂，并且在年份、地点、性状以及家系内部都存在差异。这些方法有效地检测到了先前鉴定的QTL，以及与大麦中已充分表征的开花时间直系同源基因（包括Ppd-H1和CONSTANS）紧密对齐的新QTL。我们的结果证明了NAM群体在理解开花时间遗传控制方面的效用及其应用于其他感兴趣性状的潜力。
