Abstract: Rice is one of the most important food crops in the world. At present, there is a problem of heavy metal pollution in agricultural land, but the tolerance of rice to heavy metals such as cadmium (Cd) is low, which affects the yield and quality of rice. Mapping quantitative trait loci (QTLs) related to Cd tolerance in rice is of great significance for guiding the breeding of Cd tolerance in rice. To explore Cd stress related genes, 124 backcross recombinant inbred ines (BILs) derived from Japonica rice 02428 and Indica rice Changhui 891 were used as materials to analyze the root length and bud length of rice at germination stage, and to locate QTLs related to Cd stress at germination period. The results showed that the root length and bud length of 02428 and Changhui 891 were significantly inhibited under Cd stress (P<0.01), and the inhibition of Cd on root length was stronger than that of bud length. Five QTLs related to Cd stress were detected by QTL analysis: qCdBL3, qCdRL7, qCdBL8.1, qCdBL8.2 and qCdBL9, which were located on chromosome 3, 7, 8, 8 and 9 of rice, respectively, with a contribution rate of 6.45%~19.46%. Among them, qCdBL3, qCdBL8.1, qCdBL8.2 and qCdBL9 were related to bud length, and qCdRL7 was related to root length. At the same time, two  QTLs affecting root length and bud length were detected under control conditions (aqueous solution): qCKBL8 and qCKRL4, which were located on chromosome 8 and 4, respectively, with the contribution rates of 10.53% and 1089%. Comparison showed that QTLs controlling root length or bud length of rice in germination stage were different between control and Cd treatment, which indicated that the genetic mechanism controlling root length and bud length of rice under Cd stress might be different from that under non-Cd stress. The results provided a reference for cloning Cd-tolerant genes and breeding new Cd-tolerant rice varieties.

Key words: rice, cadmium stress, germination period, QTLs

摘要： 水稻是世界上最主要的粮食作物之一，目前农用耕地存在土壤重金属污染的问题，而水稻对镉（Cd）等重金属的耐受性较低，进而使水稻产量和质量受到影响。定位稻种耐Cd胁迫相关数量性状基因座(quantitative trait loci, QTLs)，对于指导水稻耐Cd育种具有重要意义。为发掘Cd胁迫相关基因，以粳稻02428和籼稻昌恢891衍生的124个回交重组自交系群体（backcross recombinant inbred ines，BILs）为材料，对水稻萌芽期的根长、芽长进行了分析，并对萌芽期与Cd胁迫相关的QTLs进行了定位分析。结果显示：Cd胁迫处理下，02428和昌恢891根长和芽长均受到显著抑制（P＜0.01），其中Cd对根长的抑制强于芽长；QTL分析共检测到5个萌芽期与Cd胁迫相关的QTLs：qCdBL3、qCdRL7、qCdBL8.1、qCdBL8.2和qCdBL9分别位于水稻第3、7、8、8和9号染色体上，贡献率为6.45%~19.46%。其中，qCdBL3、qCdBL8.1、qCdBL8.2和qCdBL9与芽长相关，qCdRL7与根长相关。同时，检测到2个在对照条件下（水溶液）影响根长和芽长的QTLs：qCKBL8、qCKRL4，分别位于第8和4号染色体上，贡献率为10.53%和10.89%。比较显示，对照和Cd处理条件下控制水稻萌芽期根长或芽长的QTLs均不相同，说明Cd胁迫条件下，控制水稻根长和芽长的遗传机制可能不同于非Cd胁迫条件。研究结果为耐Cd基因的克隆和耐Cd水稻新品种的选育提供了参考。

关键词: 水稻, 镉胁迫, 萌芽期, QTL