Zhao Mingzhu, Wang Yuanzheng, He Na, Pang Xiu, Wang Lili, Ma Zuobin, Tang Zhiqiang, Gao Hong, Zhang Liying, Fu Liang, Wang Changhua, Liu Jingang, Zheng Wenjing
Institute of Rice Research, Liaoning Academy of Agricultural Sciences, Shenyang, 110000, China.
Institute of Crop Research, Liaoning Academy of Agricultural Sciences, Shenyang, 110161, China.
Rice (N Y). 2022 Nov 28;15(1):60. doi: 10.1186/s12284-022-00606-z.
Grain length (GL) that is directly associated with appearance quality is a key target of selection in rice breeding. Although abundant quantitative trait locus (QTL) associated with GL have been identified, it was still relatively weak to identify QTL for GL from japonica genetic background, as the shortage of japonica germplasms with long grains. We performed QTLs analysis for GL using a recombinant inbred lines (RILs) population derived from the cross between japonica variety GY8 (short grains) and LX1 (long grains) in four environments.
A total of 197 RILs were genotyped with 285 polymorphic SNP markers. Three QTLs qGL5.3, qGL6.1 and qGL11 were detected to control GL by individual environmental analyses and multi-environment joint analysis. Of these, a major-effect and stable QTL qGL6.1 was identified to be a novel QTL, and its LX1 allele had a positive effect on GL. For fine-mapping qGL6.1, a BCF population consisting of 2,487 individuals was developed from a backcross between GY8 and R176, one line with long grain. Eight key informative recombinants were identified by nine kompetitive allele specific PCR (KASP) markers. By analyzing key recombinants, the qGL6.1 locus was narrowed down to a 40.41 kb genomic interval on chromosome 6. One candidate gene LOC_Os06g43304.1 encoding cytochrome P450 (CYP71D55) was finally selected based on the difference in the transcriptional expression and variations in its upstream and downstream region.
Three QTLs qGL5.3, qGL6.1 and qGL11 were identified to control grain length in rice. One novel QTL qGL6.1 was fine mapped within 40.41 kb region, and LOC_Os06g43304.1 encoding cytochrome P450 (CYP71D55) may be its candidate gene. We propose that the further cloning of the qGL6.1 will facilitate improving appearance quality in japonica varieties.
粒长（GL）与外观品质直接相关，是水稻育种选择的关键目标。尽管已鉴定出大量与粒长相关的数量性状基因座（QTL），但由于长粒粳稻种质资源匮乏，从粳稻遗传背景中鉴定粒长QTL仍相对困难。我们利用粳稻品种GY8（短粒）和LX1（长粒）杂交衍生的重组自交系（RIL）群体，在四个环境中对粒长进行了QTL分析。
用285个多态性SNP标记对197个RIL进行了基因分型。通过单环境分析和多环境联合分析，检测到3个控制粒长的QTL，即qGL5.3、qGL6.1和qGL11。其中，一个主效且稳定的QTL qGL6.1被鉴定为新的QTL，其LX1等位基因对粒长有正向作用。为了精细定位qGL6.1，通过GY8与长粒品系R176回交构建了一个由2487个单株组成的BCF群体。利用9个竞争性等位基因特异性PCR（KASP）标记鉴定出8个关键信息重组株。通过对关键重组株的分析，将qGL6.1基因座定位到第6染色体上一个40.41 kb的基因组区间。基于转录表达差异及其上下游区域的变异，最终筛选出一个编码细胞色素P450（CYP71D55）的候选基因LOC_Os06g43304.1。
鉴定出3个控制水稻粒长的QTL，即qGL5.3、qGL6.1和qGL11。一个新的QTL qGL6.1被精细定位在40.41 kb区域内，编码细胞色素P450（CYP71D55）的LOC_Os06g43304.1可能是其候选基因。我们认为进一步克隆qGL6.1将有助于改善粳稻品种的外观品质。
