Biology Faculty Articles


Identification of QTLs and Candidate Loci Associated with Drought-related Traits of the K/Z RIL Rice Population

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Background: Rice is the main staple food for the global population and drought is one of the limited factor in rice production. In this research, progeny of a cross between an adapted U.S. rice cultivars with a tropical japonica and an indica rice genotype, were screened for drought resistant (DR) traits to identify DR loci, that would be useful for breeding U.S. rice cultivars for a water saving agricultural system.

Results: A recombinat inbred line (RIL) population, generated from selfed progeny of the cross between the drought resistant tropical japonica U.S. cultivar Kaybonnet and an indica drought sensitive cultivar ZHE733, was chosen for quantitative trait locus (QTLs) analysis of drought-resistance related traits. The DR traits were quantified by measuring different parameters of morphological traits, grain yield components and root architectural traits. K/Z RIL population of 198 lines were screened in the field at Fayetteville (AR), by giving controlled drought stress (DS) and well-watered (WW) treatment at the reproductive stage, consequently for three years and the effects of DS were quantify by measuring morphological traits and grain yield components. The effect of abscisic acid (ABA) sensitivity screen on parents and 198 lines at the V3 stage in culture media was quantified by measuring root architectural traits. QTL analysis was performed with a set of 4133 single nucleotide polymorphism (SNP) markers by using QTL IciMapping software version 4.2.53. A total of 41 QTLs and 184 candidate genes within the DR-QTL regions were identified for drought related traits. The potential candidate genes were validated by RT-qPCR of parental lines. The results of candidate DR genes revealed that the gene expression of 15 candidate DR genes with known annotations, and two candidate DR genes with unknown annotations within the DR-QTL regions were up-regulated in the drought resistant parent (Kaybonnet) compared to the drought sensitive parent (ZHE733) under DS conditions.

Conclusions: In this study, we detected 41 QTLs and 184 candidate genes within the DR-QTL regions, and most of the candidate genes were up-regulated in Kaybonnet as the drought resistant parent. The findings of this research provide important information to develop drought-resistant rice varieties with greater productivity under DS conditions.



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