利用双向回交导入系定位水稻苗期耐亚铁毒和锌毒的QTL

Mapping of QTL for Iron and Zinc Toxicity Tolerance at Seedling Stage Using a Set of Reciprocal Introgression Lines of Rice

铁和锌是水稻生长必需的微量元素,但在低洼或酸性土壤中,过量的二价铁和锌对水稻生长具毒害作用,最终造成生物量和产量下降。为探讨水稻苗期耐亚铁毒、锌毒的遗传机制,利用优质粳稻品种Lemont和高产籼稻品种特青为亲本构建的高代双向回交导入系和308个在染色体上均匀分布的SNP标记剖析耐亚铁毒、锌毒相关的QTL。从双向导入系共检测到42个影响耐亚铁毒、锌毒相关性状如苗高、苗干重、根干重以及胁迫与对照相对值的QTL,多数位点增强亚铁毒、锌毒抗性的有利等位基因来自Lemont。其中同时在2个背景下表达的QTL有4个,占定位QTL总数的9.52%,说明大多数QTL的表达具有明显的遗传背景效应。同一遗传背景下同时影响耐亚铁毒和锌毒的QTL有9个,其中QSdw5在2个背景中均被检测到,其效应大小和方向一致,说明水稻苗期耐亚铁毒、锌毒之间存在遗传重叠位点。因此,通过分子标记辅助选择从Lemont中导入或聚合有利的遗传重叠区域,可以提高特青对亚铁毒、锌毒的抗性水平。

Ferrum and zinc are essential microelements for rice.However,rice growing in lowland or acid soil is easily subjected to ferrous iron and zinc toxicities which harm plant growth and finally result in deduction of biomass and yield in production.The aim of this study was to identify quantitative trait locus（QTL）underlying ferrous iron toxicity tolerance（FTT）and zinc toxicity tolerance（ZTT）of rice using a reciprocal advanced backcross introgression lines,which was derived from the cross between Lemont（japonica）and Teqing（indica）,and 308 evenly distributed single nucleotide polymorphism（SNP）markers developed from the two parents.A total of 42 putative QTLs affecting shoot height（SH）,shoot dry weight（SDW）,and root dry weight（RDW）under control and stress conditions and for the relative value of the stress to the control were detected,the alleles at most loci improving the tolerance of ferrous and zinc toxicities were from Lemont.Among them,only four QTLs（9.5%）were detected under the two backgrounds,indicating the expression of most QTLs is specific to genetic background.Nine QTLs were detected from the same genetic background affecting the tolerance of both ferrous and zinc toxicities,in which QSdw5 was expressed under the two backgrounds with the same direction and similar quantity of gene additive effect,suggesting that there is a genetic overlap between FTT and ZTT at seedling stage in rice.It is likely,therefore,to improve Teqing＇s FTT and ZTT by introgressing and pyramiding Lemont favorable alleles at the overlapping QTLs via marker-assisted selection.