| Budget Amount *help |
¥20,410,000 (Direct Cost: ¥15,700,000、Indirect Cost: ¥4,710,000)
Fiscal Year 2010: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2009: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2008: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2007: ¥7,280,000 (Direct Cost: ¥5,600,000、Indirect Cost: ¥1,680,000)
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| Research Abstract |
Reproductive barriers are important for the maintenance of species identity. We discovered a reproductive barrier via hybrid breakdown among the progeny of a cross between the japonica rice cultivar Koshihikari and the indica rice cultivar Habataki. Genetic analysis indicated that the hybrid breakdown is regulated by the interaction of two recessive genes: hbd2 in Habataki and hbd3 in Koshihikari. Linkage mapping showed that hbd2 is located near the 100 cM region of chromosome 2 in Habataki, whereas hbd3 is located near the 60 cM region of chromosome 11 in Koshihikari. Fine mapping of hbd2 resulted in the identification of the causal gene as casein kinase I (CKI1). Further analysis revealed that hbd2-CKI1 allele gains its deleterious function that causes the weakness phenotype by a change of one amino acid. As for the other gene, hbd3 was mapped to the NBS-LRR gene cluster region. It is the most common class of R-gene that triggers the immune signal in response to pathogen attack. Expression analysis of pathogen response marker genes suggested that weakness phenotype in this hybrid breakdown can be attributed to an autoimmune response. This finding provides a new insight in understanding the molecular and evolutionary mechanisms establishing reproductive barriers in plants.
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