Poster: Root Biology

Abs # 531: QTL analyses indicate that multiple genetic factors control Al-tolerance in Arabidopsis thaliana.

Presenter:	Kobayashi, Yuriko , g4113007@guedu.cc.gifu-u.ac.jp.
Authors	Kobayashi, Yuriko  (A)   Sekiya, Kayoko  (A)   Hara, Tetsuo  (A)   Koyama, Hiroyuki  (A)
Affiliations:	(A): Lab of Plant Cell Tech. Faculty of Agriculture. Gifu Univ.

It has been widely accepted that plants have two types of aluminum tolerant mechanisms, namely internal aluminum tolerance and aluminum exclusion, but molecular mechanisms have not been fully elucidated. Genetic approaches would be useful to identify genes link to each Al-tolerant mechanism. For example, mutant studies of Arabidopsis suggest that several genes would be linked to Al-tolerance of this plant species. To determine whether other genes control Al-tolerance of this plant, QTL analyses may be useful. Single factor QTL and epistasis for A. thaliana aluminum tolerance were analyzed using a recombinant inbred (RI) population of 100 lines derived from a cross between Ler and Col. Root growth of the RI population was determined in hydroponics using solutions containing 0 or 4 EM of AlCl₃ and a series of nutrients, except Pi, at pH 5.0. Aluminum (Al) tolerance was defined as relative root length [RRL (%)], and the RI lines ranged from 22.6-97.4% with a broad sense heritability of 0.99. Using the composite interval mapping method, two significant single factor QTLs (P<0.05) were detected by RRL on chromosomes 1 and 4, where the Col allele showed positive and negative effects on the Al-tolerance. These QTLs could explain about 42.5% of the total variation of Al-tolerance among the RI population. On the other hand, five epistatic loci pairs were identified by the complete pair-wise search method. No single factor QTL and epistatic loci pairs were shared by both the root length in the control and the RRL, suggesting that the loci identified by the RRL would be specific for Al-treatment and controlling Al-tolerance among the RI population. Mapping positions of almost of QTLs and epistasis are not related with previously reported mapping positions by mutants.