QTL Mapping Of Leaf Chlorophyll Content In Y-Liang-You 2

Optimizing leaf chlorophyll content can improve canopy photosynthetic efficiency.The third phase super-rice cultivar Y-Liang-You 2(YLY2)is a two-line hybrid rice from crossing of its male parent,Yuan-Hui 2(YH2)and its female parent Y58 S.Both YLY2 and its male parent YH2 have low leaf chlorophyll content.In order to identify key genes controlling chlorophyll content of YLY2.In this study,YH2 and Y58 S were used as parents to create a recombinant inbred line(RIL)group containing 276 strains by single-particle transfer method.And then,a high-density genetic map of this population by genome re-sequencing was obtained.QTL mapping of leaf chlorophyll content was performed based on leaf SPAD value measured at different growth and development stages for many years,which provided a reference for identifying key genes controlling chlorophyll content in YLY2 leaves.The main results were as the followings:(1)Fifteen QTLs that potentially control leaf SPAD value of chlorophyll content were identified in this study.Most of them were negative additive effects.Nine of them are located at similar loci with previous reports,and the others are reported here for the first time.This indicated that the effective QTLs affecting chlorophyll content in the RIL population mainly came from the female parent Y58 S.(2)From 2015 to 2018,lots of negatively additive effect QTLs affecting chlorophyll content were detected in the vicinity of chromosome 4 marker Block46264 and Block46306,and its phenotypic variation explanation reached more than 10%,which was the major QTL that influenced the chlorophyll content of the RIL population.(3)From 2016 to 2018,a lot of negatively additive effect QTLs affecting chlorophyll content were detected in the vicinity of chromosome 5 marker Block51355,and its phenotypic variation explanation reached more than 5%.This interval also has an effect on chlorophyll content of the RIL population.(4)The QTLs affecting chlorophyll content were not the same in different years and different growth stages,which indicated that the genetic regulation affecting rice chlorophyll content is complex and highly susceptible to environmental factors.