Plant Genome Mapping Laboratory, University of Georgia, Athens, Georgia 30602, USA.
G3 (Bethesda). 2013 Jan;3(1):101-8. doi: 10.1534/g3.112.004499. Epub 2013 Jan 1.
We describe a recombinant inbred line (RIL) population of 161 F5 genotypes for the widest euploid cross that can be made to cultivated sorghum (Sorghum bicolor) using conventional techniques, S. bicolor × Sorghum propinquum, that segregates for many traits related to plant architecture, growth and development, reproduction, and life history. The genetic map of the S. bicolor × S. propinquum RILs contains 141 loci on 10 linkage groups collectively spanning 773.1 cM. Although the genetic map has DNA marker density well-suited to quantitative trait loci mapping and samples most of the genome, our previous observations that sorghum pericentromeric heterochromatin is recalcitrant to recombination is highlighted by the finding that the vast majority of recombination in sorghum is concentrated in small regions of euchromatin that are distal to most chromosomes. The advancement of the RIL population in an environment to which the S. bicolor parent was well adapted (indeed bred for) but the S. propinquum parent was not largely eliminated an allele for short-day flowering that confounded many other traits, for example, permitting us to map new quantitative trait loci for flowering that previously eluded detection. Additional recombination that has accrued in the development of this RIL population also may have improved resolution of apices of heterozygote excess, accounting for their greater abundance in the F5 than the F2 generation. The S. bicolor × S. propinquum RIL population offers advantages over early-generation populations that will shed new light on genetic, environmental, and physiological/biochemical factors that regulate plant growth and development.
我们描述了一个由 161 个 F5 基因型组成的重组近交系（RIL）群体，这是使用传统技术可以进行的最广泛的整倍体杂交，杂交亲本是栽培高粱（Sorghum bicolor）和近缘高粱（Sorghum propinquum），该杂交种在植物结构、生长发育、繁殖和生活史等许多与植物相关的性状上发生分离。S. bicolor × S. propinquum RILs 的遗传图谱包含 10 个连锁群上的 141 个位点，共涵盖 773.1cM。尽管遗传图谱具有非常适合数量性状基因座作图的 DNA 标记密度，并涵盖了大部分基因组，但我们之前观察到高粱着丝粒异染色质对重组具有抗性，这一发现突显了这一点，即高粱中的绝大多数重组集中在远离大多数染色体的小区域内的常染色质上。该 RIL 群体在一个环境中得到了推进，该环境对 S. bicolor 亲本非常适应（实际上是为其选育的），但 S. propinquum 亲本却不适应，这主要消除了一个短日照开花的等位基因，该等位基因使许多其他性状变得复杂，例如，使我们能够定位到以前无法检测到的新的开花数量性状基因座。在该 RIL 群体的发展过程中积累的额外重组也可能提高了杂合子过剩尖端的分辨率，这解释了它们在 F5 代比 F2 代中更为丰富的原因。S. bicolor × S. propinquum RIL 群体相对于早期群体具有优势，将为研究遗传、环境和生理/生化因素对植物生长和发育的调控提供新的线索。
