title: Genetic analysis of flag leaf size and candidate genes determination of a major QTL for flag leaf width in rice.
abstract: BACKGROUND
  Flag leaf is the most essential organ for photosynthesis in rice and its size plays an important role in rice breeding for ideal plant-type. Flag leaf size affect photosynthesis to a certain extent, thereby influencing rice production. Several genes controlling leaf size and shape have been identified with mutants. Although a number of quantitative trait loci (QTLs) for leaf size and shape have been detected on 12 chromosomes with different populations of rice, few of them were cloned.
  
  
  RESULTS
  The pair-wise correlation analysis was conducted on length, width and length-width ratio of the flag leaf, and yield per plant in the core recombinant inbred lines of Liang-You-Pei-Jiu (LYP9) developed in Hainan and Hangzhou. There were significant correlations among the three flag leaf size and shape traits. Interestingly, a positive correlation was found between flag leaf width and yield per plant. Based on the high-resolution linkage map we constructed before, 43 QTLs were detected for three flag leaf size and shape traits and yield per plant, among which 31 QTLs were unreported so far. Seven QTLs were identified common in two environments. And qFLW7.2, a new major QTL for flag leaf width, was fine mapped within 27.1 kb region on chromosome 7. Both qFLW7.2 and qPY7 were located in the interval of 45.30 ~ 53.34 cM on chromosome 7, which coincided with the relationship between yield per plant (PY) and flag leaf width (FLW).
  
  
  CONCLUSIONS
  qFLW7.2, which explained 14% of the phenotypic variation, increased flag leaf width with 93-11 allele. Two candidate genes were selected based on sequence variation and expression difference between two parents, which facilitated further QTL cloning and molecular breeding in super rice.
authors.affiliation: State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Tiyuchang Road 359, Hangzhou, 310006, China, zhang_596955105@126.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhang
authors.forename: Weijun
authors.initials: W
authors.lastname: Ye
authors.forename: Deyong
authors.initials: D
authors.lastname: Ren
authors.forename: Peng
authors.initials: P
authors.lastname: Tian
authors.forename: Youlin
authors.initials: Y
authors.lastname: Peng
authors.forename: Yang
authors.initials: Y
authors.lastname: Gao
authors.forename: Banpu
authors.initials: B
authors.lastname: Ruan
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Guangheng
authors.initials: G
authors.lastname: Zhang
authors.forename: Longbiao
authors.initials: L
authors.lastname: Guo
authors.forename: Qian
authors.initials: Q
authors.lastname: Qian
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Gao