淹水和干旱条件下水稻根系形成的QTLs及候选基因分析

为了研究不同水分条件下组成型根系性状和适应性根系性状的遗传机制，利用由IR64／Azucena发展的双单倍体（DH）群体分析了淹水和干旱条件下水稻幼苗种子根长（SRL）、不定根数（ARN）、总根干重（RW）及其对应的相对参数（干旱和淹水条件下根系性状的比值）的QTLs。淹水与干旱条件下检测到一个共同的种子根长QTL和一个共同的总根干重QTL。同时对前人发表的遗传群体定位的根系性状QTLs进行比较分析，检测到几个共同的根系性状QTLs。对与细胞伸长、分裂相关的候选基因进行了定位，其中4个细胞壁相关的ESTs（OsEXP2，OsEXP4，EXT和Xet）被定位在与不同水分条件下检测出的根系性状QTLs的相同区间。

QTLs and Candidate Genes for Rice Root Growth Under Flooding and Upland Conditions

To investigate the genetic factors underlying constitutive and adaptive root growth under different water-supply condi-tions, a double haploid (DH) population, derived from a cross between lowland rice variety IR64 and upland rice variety Azucena, with 284 molecular markers was used in cylindrical pot experiments. Several QTLs for seminal root length (SRL), adventitious root number (ARN) and total root dry weight (RW) respectively, under both flooding and upland conditions were detected. Two identi-cal QTLs for SRL and RW were found under flooding and upland conditions. The relative parameters defined as the ratio of pa-rameters under the two water-supply conditions were also used for QTL analysis. A comparative analysis among different genetic populations was performed for the QTLs for root traits and several consistent QTLs for root traits across genetic backgrounds were detected. Candidate genes for cell expansion and elongation were used for comparative mapping with the detected QTLs. Four cell wall-related expressed sequence tags (ESTs) for OsEXP2, OsEXP4, EXT and Xet were mapped on the intervals carrying the QTLs for root traits.