菠萝蜜果实糖苷酶和多聚半乳糖醛酸酶的活性变化

【目的】研究菠萝蜜果实成熟软化的机制和干、湿苞菠萝蜜质地差异形成的机理,为菠萝蜜育种提供理论基础。【方法】以不同基因型的干苞和湿苞菠萝蜜为材料,以对硝基苯β-D-吡喃半乳糖苷和对硝基苯α-D-吡喃甘露糖苷为底物测定果实成熟软化过程中β-半乳糖苷酶（β-Gal）、α-甘露糖苷酶（α-Man）,以多聚半乳糖醛酸为底物测定多聚半乳糖醛酸酶（PG）的活性变化。【结果】水溶性和盐溶性的β-半乳糖苷酶活性在两个湿苞菠萝蜜基因型中均表现先上升后下降的趋势,分别在采后2d和采后当天达到最高值,其中,水溶性酶的活性水平分别先上升42.3%、52.8%随后下降22.8%、52.6%,盐溶性酶的活性先上升27.6%、67.7%后下降10.5%、35.4%;水溶性多聚半乳糖醛酸酶活性在两个湿苞菠萝蜜基因型中均表现出直线上升的趋势,酶活性水平增加75.0%、147.3%,而在两个干苞菠萝蜜基因型中则略有增加（增加40.9%）或变化不大;盐溶性的多聚半乳糖醛酸酶和水溶及盐溶性α-甘露糖苷酶在不同基因型的干苞和湿苞菠萝蜜果实中呈现不同的变化趋势。【结论】水溶性和盐溶性β-半乳糖苷酶、水溶性多聚半乳糖醛酸酶在湿苞和干苞菠萝蜜类型间表现出完全不同的变化趋势,而在湿苞或干苞基因型内表现出相同的变化趋势,它们与干湿苞菠萝蜜果实的质地差异形成有关。

Activity of glycosidase and polygalacturonase in jackfruit fruit

Objective The present experiment was conducted to study the mechanism of fruit ripening and softening of jackfruit as well as the difference in fruit ripening and softening of soft flesh and hard flesh jackfruit so as to provide references for jackfruit breeding. Method Using different genotypes of soft and hard flesh jackfruit, the activities of galactosidase, man-nosidase and polygalacturonase were investigated during ripening of fruit. ResultDuring ripening of two genotypes of soft flesh jackfruit, the activities of water soluble and salt soluble galactosidase increased first and then decreased, with the maxi-mum appeared on the second day and the first day of harvest. The activity of water soluble β-Gal increased by 42.3%-52.8% and then decreased by 22.8%-52.6%. The activity of salt soluble β-Gal increased by 27.6%-67.7% and then decreased by 10.5%-35.4%. While during ripening of two genotypes of hard flesh jackfruit, the activities of water soluble and salt soluble β-Gal rarely changed. The activity of water soluble polygalacturonase increased by 75.0%-147.3% during ripening of two soft flesh jackfruit genotypes, while increased little （40.9%） or changed little during ripening of two hard flesh jackfruit genotypes. The activities of salt soluble polygalacturonase, water soluble and salt soluble mannosidase changed differently in two genotypes of soft flesh jackfruit and two genotypes of hard flesh jackfruit. Conclusion The activities of water and salt soluble β-Gal and water soluble polygalacturonase changed differently in fruit softening of hard flesh and soft flesh jackruit while similarly in fruit softening of genotypes of hard flesh or soft flesh jackfruit. Therefore, they were supposed to be related with the different fruit texture developing of soft and hard flesh jackfruit.