Abstract
The panicle apical abortion (PAA) causes severe yield losses in rice production, but details about its development and molecular basis remain elusive. Here, we detected PAA quantitative trait loci (QTLs) in three environments using a set of chromosome segment substitution lines (CSSLs) that was constructed with indica Changhui121 as the recurrent parent and japonica Koshihikari as the donor parent. First, we identified a novel major effector quantitative trait locus, qPAA7, and selected a severe PAA line, CSSL176, which had the highest PAA rate among CSSLs having Koshihikari segments at this locus. Next, an F2 population was constructed from a cross between CSS176 and CH121. Using F2 to make recombinantion analysis, qPAA7 was mapped to an 73.8-kb interval in chromosome 7. Among nine candidate genes within this interval, there isn’t any known genes affecting PAA. According to the gene annotation, gene expression profile and alignment of genomic DNA, LOC_Os07g41220 and LOC_Os07g41280 were predicted as putative candidate genes of qPAA7. Our study provides a foundation for cloning and functional characterization of the target gene from this locus.
Highlights
Rice is the staple food of half of the world’s population
panicle apical abortion (PAA) often occurs in agricultural production, reducing the total spikelet number per panicle, and causing great yield loss
Elucidating the genetic mechanism of PAA is helpful for preventing yield loss due to PAA in rice and for cultivating new rice varieties with “ideal” plant architectures and high yields
Summary
A high, stable yield of rice has always been one of the most important goals pursued by breeders. The rice yield is mainly determined by the number of panicles per unit area, grain number per panicle and 1,000-grain weight (Xing and Zhang, 2010). Increasing the grain number per panicle is a prior goal of many rice breeders in high-yield breeding. The panicle architecture, which is characterized by its size and branching pattern, determines the number of spikelets, and number of grains per panicle (Sakamoto and Matsuoka, 2004). Large panicle with more branches and spikelets have been preferred in breeding programs for new rice types with higher yield. Understanding the molecular genetic mechanisms of panicle development and identification of superior alleles for large panicles are of great interest to both plant biologists and plant breeders
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