QTL Analysis For Aluminum Tolerance In Rice (Oryza Sativa L.)

Aluminum (Al) toxicity is a primary factor limiting the crop production in acid soils. The difference in A1 tolerance was observed among rice varieties. In this study, Al tolerance was assessed on the basis of relative root elongation (RRE). A total of 188 rice varieties collected in our laboratory were screened for A1 tolerance. Based on the screening results, an F2 mapping population containing 188 individuals was developed from a cross between the A1 tolerant japonica cultivar Yangnuo 6 Hao and the sensitive indica cultivar Shuangzhuzhan. Four QTLs(qRRE1-4) responsible for Al tolerance were identified and the major QTL (qRRE4) was successfully dissected to a single Mendelian factor in an F3 population for fine-mapping of qRRE4. The main results are summarized as follows:(1) In the screening for Al tolerance in 188 rice varieties, nine Al-tolerant rice varieties and six Al-sensitive rice varieties were determined.(2) A F2 population of 188 individuals derived from a cross between Yangnuo 6 Hao and Shuangzhuzhan was constructed. The distribution of Al tolerance (referred to as RRE) was found continuous in this population, which indicated that Al tolerance was controlled by quantitative trait loci (QTL).(3) A genetic linkage map containing 146 SSR and InDel markers were constructed, which spanned 1889.1 cM, and the average distance of an interval between two loci was 12.9 cM.(4) Four QTLs controlling Al tolerance were detected on chromosome 1 (qRREl),5 (qRRE2) and 10(qRRE3, qRRE4) respectively, the phenotypic variations explained were ranged from 2.7% to 11%. Yangnuo 6 Hao contributed favorable alleles for the qRRE2, while Shuangzhuzhan contributed favorable alleles for the other three QTLs. From this four QTLs, qRRE3 and qRRE4 are new QTLs and have higher effect value. An F3 population segregating for qRE4 as a single Mendelian factor was constructed and fine-mapping of qRRE4 is underway.