QTLs and epistasis for aluminum tolerance in rice (Oryza sativa L.) at different seedling stages |
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Authors: | P Wu C Y Liao B Hu K K Yi W Z Jin J J Ni C He |
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Institution: | (1) Department of Biological Science, College of Life Science, Zhejiang University, Hua Jia Chi Campus, Hangzhou, 310029, China e-mail: Pwu@zjau.edu.cn Fax: 0086-571-6971323, CN |
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Abstract: | To investigate the genetic background for aluminum (Al) tolerance in rice, a recombinant inbred (RI) population, derived from
a cross between an Al-sensitive lowland indica rice variety IR1552 and an Al-tolerant upland japonica rice variety Azucena, was used in culture solution. A molecular linkage map, together with 104 amplified fragment length
polymorphism (AFLP) markers and 103 restriction fragment length polymorphism (RFLP) markers, was constructed to map quantitative
trait loci (QTLs) and epistatic loci for Al tolerance based on the segregation for relative root length (RRL) in the population.
RRL was measured after stress for 2 and 4 weeks at a concentration of 1mM of Al3+ and a control with a pH 4.0, respectively. Two QTLs were detected at both the 2nd and the 4th weeks on chromosomes 1 and
12 from unconditional mapping, while the QTL on chromosome 1 was only detected at the 2nd stress week from conditional mapping.
The effect of the QTL on chromosome 12 was increased with an increase of the stress period from 2 to 4 weeks. The QTL on chromosome
1 was expressed only at the earlier stress, but its contribution to tolerance was prolonged during growth. At least one different
QTL was detected at the different stress periods. Mean comparisons between marker genotypic classes indicated that the positive
alleles at the QTLs were from the Al-tolerant upland rice Azucena. An important heterozygous non-allelic interaction on Al
tolerance was found. The results indicated that tolerance in the younger seedlings was predominantly controlled by an additive
effect, while an epistatic effect was more important to the tolerance in older seedlings; additionally the detected QTLs may
be multiple allelic loci for Al tolerance and phosphorus-uptake efficiency, or for Al and Fe2+ tolerance.
Received: 29 July 1999 / Accepted: 13 October 1999 |
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Keywords: | Oryza sativa L AFLP markers RFLP markers Aluminum tolerance QTLs Epistasis |
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