‘ファースト’雄性不稔突然変異体 (T -4) を種子親とした軟果皮中玉トマトF(1) 系統 (MS-II) の特性

Breeding for a soft pericarp in medium-sized tomato fruit was conducted by crossing the male sterile mutant (T-4) of the large-fruited 'First' and a small-fruited pure line with a soft pericarp (S). Pericarp characteristics of the F(1) hybrid (named MS-II) were compared with the parents and two similar medium-fruited tomato cultivars, 'Red ore' and 'Frutica'. Pericarp firmness in MS-II was lower as compared with that of both T-4 and S. Differences in pericarp firmness among MS-II, 'Red ore' and 'Frutica' were dependent on truss. In the first truss, MS-II developed fruits with a softer pericarp than 'Red ore', but with a firmer pericarp than 'Frutica'. In the second and third trusses, pericarp firmness of the fruit in MS-II tended to be lower than those of the other two cultivars. The thickness of the exocarp cuticle in MS-II was lower than that in 'Red ore', but was no different to that in 'Frutica'. Thus genotypic differences in pericarp firmness among MS-II, 'Red ore' and 'Frutica' seem to be derived from differences in the degree of cutin development in the epidermal perimeter. A thinner cuticle can explain pericarp softness in the fruits above the second truss in MS-II.

薄皮果柔の中玉トマト品種育成を目的とし，‘ファースト’花粉非崩壊型雄性不稔系統 (T-4) を種子親，果皮の軟らかい小果固定系統 (S) を花粉親とするF(1)雑種 (MS-II) の特性について，両親系統および既存の中玉F(1)品種‘レッドオーレ’，‘フルティカ’のそれと比較した．両親系統と比較したところ，MS-IIの果実硬度は花粉親である軟果皮Sと同等となり，果皮硬度はSよりも低い値となった．3段摘心栽培において，MS-IIの果実硬度は第1段では2品種と差は無かったが，上位果房ほど両品種よりも低くなる傾向を示した．果皮硬度は，第1果房では‘レッドオーレ’よりも低く，‘フルティカ’よりも高かったが，上位果房ほど両品種よりも低い値となる傾向を示した．MS-IIの外果皮におけるクチクラ厚を測定したところ，‘フルティカ’と同等となり，‘レッドオーレ’よりも低かった．また，MS-IIのクチクラ層の発達程度が2品種よりも低いことが観察され，MS-IIの果皮硬度が2品種よりも低い傾向を示すのは，外果皮におけるクチクラ層の発達程度が低いためと推測された．

原著論文 (Original paper)