| Budget Amount *help |
¥3,890,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥390,000)
Fiscal Year 2007: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2006: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
To identify genes correlated to self-incompatibility(S-genes)of wild type sweet potato(Ipomoea trifida), genomic sequences of S-locus from S1, 53, S10, S29 self-incompatible lines and Sc, the self-compatible line, were isolated and sequenced.
By the expression analysis and sequence polymorphism, several S-gene candidates were identified ; AB1 to AB4 as male S-gene candidates and SE1 to SE2 and SEA as female S-gene candidates. Among these genes, AB2, A83, SE2 and SEA were found from all analyzed S-locus sequence. In the Sc S-haplotype, however, some mutations were observed in the promoter sequence and gene itself in some of the S-gene candidates. These mutations may contribute the Sc-haplotype as self-compatible.
To determine spatial and temporal expression of these four S-gene candidates, in situ hybridization analyses were carried out. In situ analyses indicated that all of the male part S-candidate genes were expressed in the tapetum at early developmental stage, and all of the female
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part S-candidate genes were expressed in the papilla cells of stigma at mature stage. These results indicated that all S-candidate genes share a necessary and sufficient condition for S-genes.
Comparison between the genomic sequences of five S-haplotypes indicated that the existence of a regions which have highly sequence polymorphisms, designated as S-locus diversed regions(SDRs). Within this SDRs, three S-candidate genes were located, which are AB2, AB3 and SEA, therefore, these gene products might play key roles in the self-incompatibility reaction.
Furthermore, comparison of the length of the SDRs from self-incompatible lines indicated that SDR length is longest in the most dominant S-haplotype and is shortest in the most recessive line, and the order of the SDR length is consistent with the dominance-recessive hierarchy of the self-incompatibility. In the dominance line have additional sequence to recessive line, such as transposon-like sequences, repetitive sequences, and fragments of organelle genome-like sequences. From this observation, it was considered that the lines at the higher hierarchy in the self-incompatibility of Ipomoea trifida was developed from recessive line. Less
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