水稻籽粒镉积累QTL定位及候选基因分析

水稻(Oryza sativa)是全世界重要的经济作物之一, 稻田镉(Cd)污染和镉积累问题严重威胁世界水稻的产量和品质以及人类健康, 如何降低水稻中镉积累已成为热点问题。以籼稻品种华占(HZ)为父本、粳稻品种热研2号(Nekken2)为母本, 连续自交多代后得到120个重组自交系群体, 对其镉积累进行检测和分析, 同时利用遗传图谱进行QTL作图。结果共检测到7个QTLs, 分别位于水稻第2、3、9和12号染色体上, 其中1个LOD值高达4.97。对这些QTL区间内与耐金属离子胁迫相关的候选基因进行定量分析, 发现LOC_Os02g50240、LOC_Os02g52780、LOC_Os09g31200、LOC_Os09g35030和LOC_Os09g37949这5个基因在双亲间的表达量差异显著, 结合亲本对不同金属离子的浓度积累数据, 推测LOC_ Os02g50240、LOC_Os09g31200及LOC_Os09g35030的高表达可能极大地提高了水稻对镉离子的吸收和胁迫耐受能力。通过QTL挖掘和分析, 发现这些基因与水稻籽粒的镉积累有关, 可能影响水稻耐镉胁迫的能力。研究结果为进一步筛选和培育耐镉胁迫的水稻品种创造了条件, 为阐明水稻镉积累的分子调控机制奠定了基础。

QTL Mapping of Candidate Genes Involved in Cd Accumulation in Rice Grain

Rice is one of the world’s most important crops, but cadmium (Cd) pollution and Cd accumulation in rice fields pose a serious threat to its yield and quality as well as to human health. How to reduce Cd accumulation in rice has become a major concern. In this study, a japonica rice variety Nekken2 was used as the maternal parent, and an indica rice variety HZ was used as the paternal parent. After F₁ generation was obtained by cross-breeding, successive selfings were performed for 120 recombinant inbred lines (RILs) population as the QTL mapping populations. We measured the Cd content in rice grains of each line at the maturity stage. Meanwhile, QTL mapping was performed using genetic map. As a result, a total of 7 QTLs were detected, which were located on chromosome 2, 3, 9, and 12 of rice, with the highest LOD score of 4.97. The qRT-PCR analysis on the candidate genes involved in metal ion stress resistance in these QTL regions showed that the expression level of LOC_Os02g50240, LOC_Os02g52780, LOC_Os09g31200, LOC_Os09g35030 and LOC_Os09g37949 was significantly different from the parents. Combined with the data of concentration of different metal ions in the parents, we speculated that the high expression of LOC_Os02g50240, LOC_Os09g31200 and LOC_Os09g35030 might greatly improve the absorption and tolerance of rice to Cd ion stress. And these genes may be related to the accumulation of Cd in rice grains, and may affect the ability of rice to tolerate Cd stress, which could help for further breeding and screening for rice varieties to tolerate Cd stress, and exploring the molecular regulation mechanism of Cd accumulation in rice.