メロンつる割病菌(Fusarium oxysporum f.sp melonis)レース1,2y抵抗性台木品種'どうだい1号'育成過程における抵抗性選抜効果とその抵抗性機作(育種・遺伝資源)  [in Japanese] Selection Effectiveness and Mechanism of Expression in Fusarium oxysporum f.sp. melonis Race 1,2y Resistance in a Breeding Process of Rootstock Cultivar 'Dodai No.1'(Breeding & Germplasm Resource)  [in Japanese]

メロンつる割病菌レース1,2y抵抗性台木品種'どうだい1号'の育成過程において親品種とF_6世代までの分離系統についてレース1,2y抵抗性の世代間比較を行った.この結果,F_2世代の選抜による抵抗性の顕著な増加と,F_3からF_5世代に至る間での抵抗性の漸増が認められた.これらの選抜効果は,'どうだい1号'の両親である'メロン中間母本農1号'と,シロウリの'東京早生(丸葉)'の持つ相加的抵抗性遺伝子の集積によると考えられ,その発現機作は,根端部分におけるレース1,2y菌糸の感染率の低下と,根端部分に侵入した菌糸の伸長の抑制によることが明らかとなった.また,このことは異なる遺伝的背景を有するメロン品種においても同様であった.

A rootstock cultivar of melon (Cucumis melo L.) 'Dodai No. 1', which shows remarkable quantitative resistance to race 1,2y of Fusarium oxysporum f.sp. melonis. was developed from a cross between 'Melon Parental Line 1' ((var. reticulatus Naud. × var. makuwa Makino) × var. reticulatus Naud.) and Tokyo-wase (maruba)' (var. conomon Makino). To clarify the selection effectiveness of resistance, both parents, F_1 line ('Melon Parental Line 1' × 'Tokyo-wase (maruba)'), F_2 line and F_3-F_6 lines were evaluated for resistance by inoculation with F. oxysporum f.sp. melonis race 1,2y. Resistance was remarkably improved from F_2 to F_3, and moderately improved from F_4 to F_6. These findings indicate that F. oxysporum f.sp. melonis race 1,2y resistance is controlled by several additive genes derived from both parents. Observation using KOH-aniline blue technique for fluorescent staining of fungi demonstrated that the infection rate and extension of hyphae were suppressed in resistant cultivars and lines. These findings imply that the mechanisms in expression of additive genes are related to suppression of entrance and extension of F. oxysporum f.sp. melonis race 1,2y hyphae. Furthermore, it seemed that these mechanisms are common among C. melo cultivars that have different genetic backgrounds.