Natural variation reveals that OsFLA2 controls flag leaf angle in rice
(Oryza sativa L.)
Abstract
Flag leaf angle (FLA) is an important outcrossing trait affecting the
hybrid seed production in rice (Oryza sativa L.). Natural variation of
FLA has been reported in rice, but the molecular basis for this
variation is largely unknown. Here we investigated the phenotypic values
of FLA in 353 rice natural accessions in six environments, which
indicated rich phenotypic variation. We performed a genome-wide
association study on FLA using 1.3 million single nucleotide
polymorphism (SNPs). A total of 37 SNPs were identified significantly
associated with FLA, of which 27 were located in previously reported
QTLs/Genes and 10 were novel. We identified two causal gene loci for
FLA, OsFLA6 and OsFLA2; OsFLA6 was co-localized with the gene OsLIC. In
addition, the accessions with large and small FLA values have
corresponding high and low OsFLA6 expression. We also confirmed that the
allele OsFLA2TT increased the FLA compared with that of the isogenic
line carrying allele OsSYL2CC by transgenic complementation experiment.
The allele frequencies of OsFLA6GG and OsFLA2TT decreased gradually with
an increase in latitude in the Northern Hemisphere. Our results should
facilitate the improvement of FLA of parents of hybrid rice.