La Borde Niegel, Rajewski John, Dweikat Ismail
Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE, United States.
Front Genet. 2023 Mar 15;14:1129460. doi: 10.3389/fgene.2023.1129460. eCollection 2023.
Sorghum (Sorghum bicolor L.) a drought tolerant staple crop for half a billion people in Africa and Asia, an important source of animal feed throughout the world and a biofuel feedstock of growing importanceorghum's originated from tropical regions rendering the crop to be cold sensitive. Low temperature stresses such as chilling and frost greatly affect the agronomic performance of sorghum and limit its geographical distribution, posing a major problem in temperate environments when sorghum is planted early. Understanding the genetic basis of wide adaptability and of sorghum would facilitate molecular breeding programs and studies of other C4 crops. The objective of this study is to conduct quantitative trait loci analysis using genotying by sequencing for early seed germination and seedling cold tolerance in two sorghum recombinant inbred lines populations. To accomplish that, we used two populations of recombinant inbred lines (RIL) developed from crosses between cold-tolerant (CT19, ICSV700) and cold-sensitive (TX430, M81E) parents. The derived RIL populations were evaluated for single nucleotide polymorphism (SNP) using genotype-by-sequencing (GBS) in the field and under controlled environments for their response to chilling stress. Linkage maps were constructed with 464 and 875 SNPs for the CT19 X TX430 (C) and ICSV700 X M81 E (C) populations respectively. Using quantitative trait loci (QTL) mapping, we identified QTL conferring tolerance to chilling tolerance at the seedling stage. A total of 16 and 39 total QTL were identified in the C and C populations, respectively. Two major QTL were identified in the C population, and three major QTL were mapped in the C population. Comparisons between the two populations and with previously identified QTL show a high degree of similarity in QTL locations. Given the amount of co-localization of QTL across traits and the direction of allelic effect supports that these regions have a pleiotropic effect. These QTL regions were also identified to be highly enriched for genes encoding chilling stress and hormonal response genes. This identified QTL can be useful in developing tools for molecular breeding of sorghums with improved low-temperature germinability.
高粱（Sorghum bicolor L.）是非洲和亚洲5亿人的耐旱主粮作物，是全球重要的动物饲料来源，也是一种越来越重要的生物燃料原料。高粱原产于热带地区，因此对寒冷敏感。低温胁迫如冷害和霜冻会极大地影响高粱的农艺性能并限制其地理分布，在温带环境中早播高粱时会造成重大问题。了解高粱广泛适应性的遗传基础将有助于分子育种计划以及其他C4作物的研究。本研究的目的是利用测序基因分型对两个高粱重组自交系群体的早期种子萌发和幼苗耐冷性进行数量性状位点分析。为实现这一目标，我们使用了由耐寒（CT19、ICSV700）和冷敏感（TX430、M81E）亲本杂交产生的两个重组自交系（RIL）群体。对衍生的RIL群体在田间和控制环境下进行测序基因分型（GBS）以评估其对冷胁迫的单核苷酸多态性（SNP）。分别为CT19×TX430（C）和ICSV700×M81E（C）群体构建了含有464个和875个SNP的连锁图谱。通过数量性状位点（QTL）定位，我们在幼苗期鉴定出了赋予耐冷性的QTL。在C和C群体中分别总共鉴定出16个和39个QTL。在C群体中鉴定出两个主要QTL，在C群体中定位到三个主要QTL。两个群体之间以及与先前鉴定的QTL的比较表明QTL位置具有高度相似性。鉴于跨性状QTL的共定位数量和等位基因效应方向支持这些区域具有多效性。这些QTL区域还被鉴定为高度富集编码冷胁迫和激素反应基因的基因。这些鉴定出的QTL可用于开发具有改善的低温发芽能力的高粱分子育种工具。
