猕猴桃果实淀粉代谢研究进展

Advance in starch metabolism research of kiwifruit

猕猴桃为国际重要水果种类,已成为我国精准扶贫、乡村振兴的“金果果”。淀粉作为植物光合作用固定碳形成的主要碳水化合物,在植物的整个生长发育过程中具有重要作用。猕猴桃果实属于淀粉积累型水果,在临近商业采收时淀粉积累达到峰值,然后随着果实软化成熟淀粉降解为糖,果实甜度增高,风味品质形成。同时,猕猴桃属于呼吸跃变型果实,具有生理后熟属性,采后易软化,不耐贮藏。淀粉作为细胞内容物对维持细胞膨压,支持果实硬度起着重要作用。随着猕猴桃基因组的测序完成,猕猴桃果实淀粉代谢分子研究取得新的进展,尤其是淀粉降解方面,但是目前对猕猴桃果实淀粉代谢进展的整理与归纳还鲜有报道。因此,从猕猴桃果实淀粉的理化性质、植物淀粉代谢途径以及猕猴桃果实淀粉代谢分子机制三个方面展开,并结合淀粉与猕猴桃果实风味品质、成熟软化的关系,对猕猴桃果实淀粉研究现状与进展进行综述,为以后创制优质高淀粉耐贮藏猕猴桃新材料或选育新品种,以及建立即食供应的快速后熟技术体系提供理论支撑。

Kiwifruit(Actinidia chinensis Planch.)is well known as“the king of fruit”and deeply loved by consumers at home and abroad because of its unique flavor and being rich in a variety of vitamins,dietary fiber,mineral elements and other nutrients.As the rapid development of kiwifruit industry in China,kiwifruit has become“Golden fruit”of the targeted poverty alleviation and rural revitalization.Starch,as the main carbohydrate derived from carbon with plant photosynthesis,plays an important role in plant whole growth and development.The kwifruit belongs to the starch-accumulating fruit,and the photosynthetic products are accumulated and converted into starch during the fruit growth and develop-ment close to the commercial harvest.The starch in kiwifruit is present in the form of particles,which increase from 3-4μm to 10-12μm during the fruit growth and then decrease to 6-8μm with maturity and then disappeared finally when fruit ripens.The starch accumulation is strongly similar among differ-ent cultivars or germplasm,but the starch content differs at same stages of fruit growth and develop-ment.Initially,there is little starch accumulation in the early stages of fruit development,and starch starts to accumulate only after the increase of the cell volume and weight and reaches to the peak close to the commercial harvest,accounting for 40%of the dry matter of the fruit.At this time,80%of the starch in the pericarp is mainly amylopectin.During storage period after harvesting,the starch is degrad-ed into sugar with fruit softening and ripening,leading to the increase of sweetness with about 10%of sugar content and the formation of fruit flavour.In higher plants,the starch metabolism involves starch starch synthesis pathway and molecular regulation mechanism should be deeply strengthened,which is of great significance for creating new varieties or new germplasm with high content of starch and high quality,and controlling fruit softening and ripening to provide ready-to-eat kiwifruit.