Pleiotropism of the Photoperiod-Insensitive Allele of Hd1 on Heading Date, Plant Height and Yield Traits in Rice

Zhen-Hua Zhang,Kai Wang,Shi-Hua Cheng,Jie-Yun Zhuang,Ye-Yang Fan,Liang Guo,Yu-Jun Zhu,Wengui Yan

doi:10.1371/journal.pone.0052538

Abstract

Five populations segregated in isogenic backgrounds and three sets of near isogenic lines (NILs) overlapping in a 362.3-kb region covering heading date gene Hd1 were developed from the indica rice cross Zhenshan97 (ZS97)/Milyang 46 (MY46). They were used to analyze the effects of Hd1 on heading date, plant height and yield traits. In a background of the parental mixtures, the photoperiod-sensitive allele derived from ZS97 functioned in promoting and delaying flowering in the natural short-day and long-day conditions, respectively. In the background of ZS97, no response to the photoperiod was observed, whereas the photoperiod-insensitive allele derived from MY46 functioned in delaying flowering, increasing plant height, and enhancing grain productivity. The additive effects estimated in two NIL sets were 6.14 and 6.14 d for heading date, 4.46 and 5.55 cm for plant height, 10.82 and 11.54 for the number of spikelets per panicle, 6.82 and 8.00 for the number of grains per panicle, and 2.16 and 2.23 g for grain yield per plant, which explained 94.1% and 96.3%, 70.5% and 84.8%, 52.4% and 55.2%, 28.9% and 39.2%, and 36.5% and 26.9% of the phenotypic variances, respectively. Since the photoperiod-insensitive allele of Hd1 confers a long vegetative phase, it is a good candidate for breeding rice varieties with high yielding potential for low latitudes.

Highlights

Heading date (HD) is the most crucial factor determining the regional and seasonal adaptation of rice (Oryza sativa L.)
In a previous study using populations derived from a residual heterozygote identified from a recombinant inbred population of the indica rice cross Zhenshan 97 (ZS97)/Milyang 46 (MY46), we found that a 1.90-Mb genomic region covering Hd1 had significant effects on heading date and yield traits [14]
Many regions covering QTLs for HD exhibits significant effects on plant height (PH) and yield traits in primary mapping, the pleiotropism has only been confirmed for Ghd7 and DTH8/ Ghd8

Summary

Introduction

Heading date (HD) is the most crucial factor determining the regional and seasonal adaptation of rice (Oryza sativa L.). This trait is decided by basic vegetative phase (BVP), photoperiod sensitivity (PS) and temperature sensitivity (TS), among which PS plays the leading role as shown in molecular studies of quantitative trait loci (QTLs) underlying natural variation of flowering in rice. At the Hd1 locus, the photoperiod-sensitive allele (PS allele) confers a short BVP and the non-sensitive allele (non-PS allele) confers a long BVP. At the Ehd locus, the dominant allele Ef1 confers a short BVP and the recessive alleles ef and ef-h confer long BVP [10]

Methods

Results

Conclusion