Genetic control of root architectural traits in KDML105 chromosome segment substitution lines under well-watered and drought stress conditions

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 wellwatered (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.

Rice (Oryza sativa L.) breeding for a combination of shallow and deep root traits derived from lowland × upland for alternate wetting and drying systems

“…7A-B). Ruangsiri et al (2021) reported that the proportion of nodal roots that were more elongated vertically increased under drought stress by 21%, while the RDR under AWD in the present study increased by 6% (Fig 7D ).…”

Response of Southeast Asian rice root architecture and anatomy phenotypes to drought stress

“…(2022) reported crown root number to be correlated with growth and productivity under vegetative stage drought stress in the rice Global MAGIC population under dry direct-seeded conditions. Ruangsiri et al. (2021) found that crown root number was reduced in KDML 105 chromosome segment substitution lines when planted in clay soil, but an increase in crown root number was found in the same population when planted in sandy soil condition.…”

Photosynthetic Plasticity and Stomata Adjustment in Chromosome Segment Substitution Lines of Rice Cultivar KDML105 under Drought Stress

“…Ten KDML105-CSSLs showing tolerance under drought stress in field conditions were selected for this experiment. The KDML105-CSS lines were developed using the backcross breeding method with marker-assisted selection [ 22 , 23 ]. The seeds were obtained from the Innovative Plant Biotechnology and Precision Agriculture (APBT).…”

“…This area often faces drought stress during the cultivation season leading to a loss in productivity. To understand the mechanism of drought tolerance, chromosome segment substitution lines (CSSL) of KDML105 carrying quantitative loci (QTL) associated with drought stress located on chromosomes 1, 3, 4, 8, and 9 were developed [ 21 , 22 ]. Photosynthesis, gas exchange and stomatal morphology and behavior are responses related to drought tolerance.…”