| Budget Amount *help |
¥15,000,000 (Direct Cost: ¥15,000,000)
Fiscal Year 2004: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 2003: ¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2002: ¥9,200,000 (Direct Cost: ¥9,200,000)
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| Research Abstract |
Differences of the internal feedback regulation in ethylene biosynthesis between climacteric and nonclimacteric fruits were investigated.
Several MADS-box genes were cloned from banana and melon in climacteric fruits, and grape and cucumber in nonclimacteric fruits. Constitutive expression of these genes throughout growth and ripening was observed in both climacteric and nonclimacteric fruits.
From these MADS-box genes, VvmadsRIN-like gene from grape berries was introduced into rin tomato, a mutant with non-ripening feature by break of LeMADS-RIN gene. VvmadsRIN-like complimented LeMADS-RIN and the transformed rin tomato fruit showed normal ripening phenomena. From wild-type tomatoes, a novel ethylene signaling gene, LeEIL4, was isolated.
The softening characteristics and the role of ethylene in the softening process were investigated in three types of pear fruit. In climacteric fruit, ‘La France' softened dramaticall with ethylene production, while ‘Yali' showed no significant changes in flesh firmness and texture during ripening despite of large amount of ethylene production. ‘Nijisseiki', a nonclimacteric fruit, did not show detectable decrease in flesh firmness. These difference in fruit softening correlated well with endo-polygalacturonase gene expression. PC-PG1 and PC-PG2 were expressed in ‘La France' fruit during ripening, while, only PC-PG2 did in ‘Nijisseiki', and neither of PC-PG1 or PC-PG2 did in ‘Yali'.
Alterations in cell wall polysaccharides during ripening were investigated using fig fruit. Even though quantitative and qualitative changes in cell wall polysaccharides occurred during fruit ripening, qualitative variations occurred in the pectic polymers but not in the hemicellulosic polymers.
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