Li Zichao, Mu Ping, Li Chunping, Zhang Hongliang, Li Zhikang, Gao Yongming, Wang Xiangkun
Key Lab of Crop Genomics and Genetic Improvement, Ministry of Agriculture, Beijing Key Lab of Crop Genetic Improvement, China Agricultural University, Beijing, 100094, China.
Theor Appl Genet. 2005 May;110(7):1244-52. doi: 10.1007/s00122-005-1958-z. Epub 2005 Mar 12.
To genetically dissect drought resistance associated with japonica upland rice, we evaluated a doubled haploid (DH) population from a cross between two japonica cultivars for seven root traits under three different growing conditions (upland, lowland and upland in PVC pipe). The traits included basal root thickness (BRT), total root number (RN), maximum root length (MRL), root fresh weight (RFW), root dry weight (RDW), ratio of root fresh weight to shoot fresh weight (RFW/SFW) and ratio of root dry weight to shoot dry weight (RDW/SDW). The BRT was significantly correlated with the index of drought resistance, which was defined as the ratio of yield under the stress of the upland condition to that under the normal lowland condition. A complete genetic linkage map with 165 molecular markers covering 1,535 cM was constructed. Seven additive quantitative trait loci (QTLs) and 15 pairs of epistatic loci for BRT and RN were identified under upland and lowland conditions, and 12 additive QTLs and 17 pairs of epistatic QTLs for BRT, RN, MRL, RFW, RFW/SFW and RDW/SDW were identified under the PVC pipe condition. Four additive QTLs and one pair of epistatic QTLs controlling IDR were also found. These QTLs individually explained up to 25.6% of the phenotypic variance. QTL x environment (Q x E) interactions were detected for all root traits, and the contributions of these interactions ranged from 1.1% to 19.9%. Five co-localized QTLs controlling RFW and RDW, RFW/SFW, RDW/SDW and IDR, BRT and RN, RN, MRL and IDR were found. Four types of QTLs governing BRT and RN were classified by their detection in the upland and lowland conditions. Some common QTLs for root traits across different backgrounds were also revealed. These co-localized QTLs and common QTLs will facilitate marker-assisted selection for root traits in rice breeding programs.
为了从基因层面剖析与粳型旱稻相关的抗旱性，我们评估了两个粳稻品种杂交产生的加倍单倍体（DH）群体在三种不同生长条件下（旱地、水田和PVC管中的旱地）的七个根系性状。这些性状包括基部根粗（BRT）、总根数（RN）、最大根长（MRL）、根鲜重（RFW）、根干重（RDW）、根鲜重与地上部鲜重之比（RFW/SFW）以及根干重与地上部干重之比（RDW/SDW）。基部根粗与抗旱指数显著相关，抗旱指数定义为旱地胁迫条件下的产量与正常水田条件下产量的比值。构建了一张包含165个分子标记、覆盖1535 cM的完整遗传连锁图谱。在旱地和水田条件下，鉴定出7个控制基部根粗和总根数的加性数量性状位点（QTL）以及15对上位性位点；在PVC管条件下，鉴定出12个控制基部根粗、总根数、最大根长、根鲜重、根鲜重与地上部鲜重之比以及根干重与地上部干重之比的加性QTL和17对上位性QTL。还发现了4个控制抗旱指数的加性QTL和1对上位性QTL。这些QTL分别解释了高达25.6%的表型变异。检测到所有根系性状均存在QTL与环境（Q×E）互作，这些互作的贡献率在1.1%至19.9%之间。发现了5个共定位QTL，分别控制根鲜重和根干重、根鲜重与地上部鲜重之比、根干重与地上部干重之比以及抗旱指数，基部根粗和总根数，总根数、最大根长和抗旱指数。根据在旱地和水田条件下的检测情况，将控制基部根粗和总根数的QTL分为4种类型。还揭示了不同背景下一些根系性状的共同QTL。这些共定位QTL和共同QTL将有助于在水稻育种计划中对根系性状进行标记辅助选择。
