Quantitative Trait Loci and Candidate Gene Identification for Chlorophyll Content in RIL Rice Population under Drought Conditions

Rice (Oryza sativa) is the staple food for more than half of the world population. Rice needs 2-3 times more water compared to other crops. Drought condition is one of the limited factor in rice production. Recombinant inbred line population derived from a cross between rice genotype tropical japonica Kaybonnet and indica ZHE733 named K/Z RIL population was used to identify candidate genes for chlorophyll content related to grain yield under drought condition. Chlorophyll content in the flag leaf of the rice plant is related to the grain yield since chlorophyll plays an important role in the photosynthesis. The K/Z RIL population was screened in the field at Fayetteville, Arkansas, USA by controlled drought stress treatment at the reproductive stage (R3), and the effect of drought stress was quantify by measuring chlorophyll content, flag leaf characteristics, and grain yield. Quantitative trait loci (QTL) analysis was performed with a set of 4133 single nucleotide polymorphism (SNP) markers by using QTL IciMapping software version 4.2.53. Candidate genes within the QTL regions were identified by using the MSU Rice Genome Annotation Project database release 7.0 as the reference. A total of eleven QTLs and forty-three candidate genes were identified for chlorophyll content related to the grain yield under drought condition. Most of the candidate genes involve in biological processes, molecular functions, and cell components. By understanding the genetic complexity of the chlorophyll content, this research provides information to develop drought-resistant rice varieties with greater productivity under drought stress condition.