Reconsideration of S-genotype Assignments, and Discovery of a New Allele Based on S-RNase PCR-RFLPs in Japanese Pear Cultivars

概要

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The S-genotype assignments in the Japanese pear cultivars, 'Akaho', 'Tanzawa', 'Kimizukawase', 'Choju', 'Ichiharawase' and 'Meigetsu' previously determined by pollination tests have raised some doubt recently. These cultivars were analyzed by S-RNase based PCR-RFLP, and their S-genotype assignments reconsidered. The assignment based on the PCR-RFLP system was in agreement with that determined previously by pollination tests in six cultivars, 'Chojuro', 'Doitsu', 'Kikusui', 'Kosui', 'Taihaku' and 'Yakumo', confirming the applicability of the system. 'Akaho', 'Tanzawa', 'Kimizukawase' and 'Choju' were analyzed and assigned as S_3S_5, S_4S_5, S_1S_5 and S_1S_5, respectively. Two of these cultivars, 'Akaho' and 'Tanzawa', were also confirmed by our pollination tests. In three cultivars, 'Ichiharawase', 'Meigetsu' and 'Heiwa' ('Nijisseiki' × 'Ichiharawase'), a new S-RNase fragment with a size and digestion pattern distinct from those of S_1 to S_7-RNases of Japanese pear was amplified. The deduced amino acid sequence in the hypervariable region of this S-RNase was quite different from those of S_1 to S_7-RNases. We, therefore, assigned this S-RNase as S_8-RNase, and identified the S-genotypes of 'Ichiharawase', 'Meigetsu' and 'Heiwa' as S_1S_8, S_1S_8 and S_4S_8, respectively.
日本育種学会の論文