Review of the studies on the accumulation mechanisms of sugar and organic acids in Eriobotrya japonica fruit

Sugar and acid content and sugar/acid ratio are the important indexes for fruit quality.Sugars not only determine fruit sweetness,but also provide raw materials for synthesis of pigment,amino acids,vitamins and other nutrients and aromatic substances.Fruit acids and sugar form sugar/acid ratio,which decides fruit flavor.Meanwhile,fruit organic acids provide respiratory substrates for the synthesis of other essential substances.Sugar/acid ratio is one of the most important determiner for fruit quality.Sugar and organic acid metabolism processes are extremely complicated,the two pathways are closely connected.Understanding towards sugar and acid accumulation mechanism would provide important theoretical basis for cultivation and breeding.This article reviews the recent research advances on loquat(Eriobotrya japonica) sugar acid metabolism,physiology,molecular biology,and cultivation,etc,which will be helpful for related areas.Combining the authors’ research experience,the possible researching focuses on future loquat sugar and acid metabolic and regulation mechanism are proposed: further clarify the molecular mechanism of cultivation measures and environment factors on the fruit sugar and acid metabolism;ascertain the fruit sugar and acid transporting mechanisms;regulate fruit sugar and acid composition by genetic engineering technology;clarify the interaction mechanism of sugar accumulation and acid accumulation.