ABSTRACT

Drought is a major constraint in rainfed rice production and root architectural traits are important breeding targets for improving productivity under drought stress. A set of chromosome segment substitution lines (KDML105-CSSLs) and KDML105 were grown in the wet season at two sites (Rice Gene Discovery (RGD) and Ubon Ratchatani Rice Research Center (URRC)) in Thailand under well-watered (WW) and drought stress (DS) treatments. RGD is characterized by having a heavy clay soil type while URRC’s soil has a high percentage of sand and characterized by infertility. Root architecture traits varied within the population at both sites and exhibited plasticity in response to drought as affected by location by water regime interaction. Lateral root density increased by 77% with drought at RGD but decreased by 18% at URRC. The proportion of nodal roots that elongated more vertically increased under drought stress by 21%, at RGD. Root number per tiller was negatively associated with tiller number and biomass at RGD under drought, while lateral root density was negatively associated with biomass under drought at URRC. Eight QTL were identified for the number of nodal roots per tiller, lateral root density, and nodal root growth angle. Several candidate genes were identified by annotating the genes within the QTL regions. Our study presented genetic insights into root architectural traits with potential use in rice breeding programs for drought tolerance.

摘要

干旱是雨育水稻生产的主要制约因素，根系结构特征是在干旱胁迫下提高生产力的重要育种目标。一组染色体片段替代品系（KDML105-CSSLs）和 KDML105 在泰国的两个地点（水稻基因发现（RGD）和乌汶水稻研究中心（URRC））在湿润季节（WW）和干旱胁迫 (DS) 处理。RGD 的特点是具有重粘土类型，而 URRC 的土壤具有高比例的沙子和不育的特点。根系结构特征在两个地点的种群中各不相同，并且在响应干旱时表现出可塑性，因为受水情相互作用的位置影响。RGD 的侧根密度随着干旱增加了 77%，但在 URRC 减少了 18%。在 RGD 下，在干旱胁迫下垂直伸长更多的节根的比例增加了 21%。在干旱条件下，RGD 每分蘖的根数与分蘖数和生物量呈负相关，而侧根密度与 URRC 干旱下的生物量呈负相关。每个分蘖的节根数、侧根密度和节根生长角共鉴定了8个QTL。通过对 QTL 区域内的基因进行注释，确定了几个候选基因。我们的研究提供了对根系结构特征的遗传见解，在水稻耐旱育种计划中具有潜在用途。而侧根密度与 URRC 干旱下的生物量呈负相关。每个分蘖的节根数、侧根密度和节根生长角共鉴定了8个QTL。通过对 QTL 区域内的基因进行注释，确定了几个候选基因。我们的研究提供了对根系结构特征的遗传见解，在水稻耐旱育种计划中具有潜在用途。而侧根密度与 URRC 干旱下的生物量呈负相关。每个分蘖的节根数、侧根密度和节根生长角共鉴定了8个QTL。通过对 QTL 区域内的基因进行注释，确定了几个候选基因。我们的研究提供了对根系结构特征的遗传见解，在水稻耐旱育种计划中具有潜在用途。