Fine mapping and candidate gene analysis ofqRN5a, a novel QTL promoting root number in rice under low potassium
Fine mapping and candidate gene analysis ofqRN5a, a novel QTL promoting root number in rice under low potassium
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低钾水稻根数QTL qRN5a精细定位及候选基因分析
DOI：
10.1007/s00122-020-03692-z
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发表时间：
2020-10-01
影响因子：
5.4
通讯作者：
Wu, Weixun
中科院分区：
文献类型：
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作者：
Islam, Anowerul;Zhang, Yingxin;Wu, Weixun
qRN5a是水稻低钾条件下增加根系数量的新QTL，定位于5号染色体48.8 kb的区域，loc_os05g27980是最有可能的候选基因。钾(K)是植物生长发育所必需的一种矿质营养素，但水稻耐低钾（LK）的分子机制尚不清楚。本研究在中恢9308 （ZH9308）遗传背景中携带谢青早b片段的染色体片段代换系CSSL35中，发现了LK下根数（RN）的数量性状位点qrn5。在LK胁迫下，CSSL35在苗期比ZH9308长出了更多的根，qrn5a最初位于1023 kb的基因组区域内。本研究为了解qrn5a的分子基础，构建了CSSL35与ZH9308杂交获得的F-2:3（BC5F2:3）大群体进行精细定位。高分辨率连锁分析将qrn5的范围缩小到48.8 kb，标记为A99和A139。结果表明，其中3个基因（Os05g0346700、LOC_Os05g27980和loc_os05g28000）在亲本间存在非同义单核苷酸多态性。表达分析表明loc_os05g27980是LK下RN的正调控基因，是qrn5a最有可能的候选基因。loc_os05g27980编码一个含有LATERAL organs BOUNDARIES domain的蛋白。此外，我们发现在LK条件下，qrn5a促进根组织中osiaa23的表达并抑制oshak5的表达，从而促进CSSL35的根起始。需要进一步研究oshak5in水稻，以阐明不同K（+）浓度下根系构型变化的基础。qRN5ais有用的分子标记辅助选择与改善根架构开发一个理想株型水稻缺K。
Key message qRN5a, a novel QTL for increasing root number under low K in rice, was fine mapped to a 48.8-kb region on chromosome 5, andLOC_Os05g27980is the most likely candidate gene. Potassium (K) is a mineral nutrient essential for plant growth and development, but the molecular mechanism for low-K (LK) tolerance in rice remains poorly understood. In our previous study, the quantitative trait locus (QTL)qRN5afor root number (RN) under LK was identified in the chromosome segment substitution line CSSL35 carrying segments from XieqingzaoB in the genetic background of Zhonghui9308 (ZH9308). CSSL35 developed more roots than ZH9308 under LK at the seedling stage, andqRN5awas initially located within a 1,023-kb genomic region. In this study, to understand the molecular basis ofqRN5a, a large F-2:3(BC5F2:3) population obtained from crossing CSSL35 and ZH9308 was constructed for fine mapping. High-resolution linkage analysis narrowed downqRN5ato a 48.8-kb interval flanked by markers A99 and A139. Seven putative candidate genes were annotated in the delimited region, and three genes (Os05g0346700,LOC_Os05g27980, andLOC_Os05g28000) had nonsynonymous single-nucleotide polymorphisms in the coding sequence between the two parents. Expression analysis suggests thatLOC_Os05g27980, which encodes a LATERAL ORGAN BOUNDARIES domain-containing protein, is a positive regulator of RN under LK and is the most likely candidate gene forqRN5a. Moreover, we found thatqRN5apromotes expression of OsIAA23and repressesOsHAK5expression in root tissues to promote root initiation in CSSL35 under LK conditions. Additional investigations onOsHAK5in rice are needed to elucidate the basis of changing root architecture under different K(+)concentrations.qRN5ais useful for marker-assisted selection to develop an ideotype with improved root architecture in rice under K deficiency.