Effect Of Endogenous IAA On Calyx Shedding Of ’Dangshansuli’Pear Fruitlet And Establishment Of The EST Library

’Dangshansuli’pear was a leading cultivar with big fruit size, juicy, sweet and crisp flesh in China. Its mature fruit exhibited two different shapes, i.e. calyx-shedding fruit and calyx-perpetual fruit. The russet always formed in calyx lobe of the calyx-perpetual fruit, and there were more sclereids in flesh, that had influenced outer appearance and inner quality of the fruit and decreased its economic benefit in market. When some chemical agents were applied by floral spray, such as flusilazole and paclobutrazol, the rate of calyx-perpetual fruit decreased, but unreasonable application of some chemical agents easily led to toxins residue and did not meet the qualification of pollution-free fruits. So it was a useful way to find out the key genes dominated on the calyx shedding by the method of biotechnology to provide a theoretical basis for the trait improving.A way of floral spray was used in experimental design in this essay, a way of enzyme linked immunosorbent assay was used to measure the content of endogenous IAA and endogenous GA, a method of field survey was to census the rate of calyx shedding and calyx setting, a method of standard curve was used to measure the activity of I AA oxidase, a way of Realtime PCR was used to observe the relative expression quantity, and the establishment of SSH library and the bioinformatic analysis were used to find out related genes.The main results were as follows:1.The calyx of ’Dangshansuli’ fruitlets began to shed on the10th day after full bloom.2.The key period when endogenous IAA and endogenous GA regulated the development of calyx was between10days and20days after full bloom. Also, high concentration of endogenous IAA and endogenous GA was one of the key factors resulting in calyx setting.3.The content of endogenous GA of ’Dangshansuli’ fruitlets increased after floral spray of GA3as well as the content of endogenous IAA. After floral spray of PP333. however, the content of endogenous IAA of ’Dangshansuli’ fruitlets decreased.4.The rate of calyx shedding was remarkably improved after the floral spray of PP333, while the rate of calyx shedding was remarkably reduced after the floral spray of GA3. 5.Low activity of IAA oxidase was one of the factors leading to calyx setting. We could make the calyx of ’Dangshansuli’ fruitlets shed by increasing the activity of IAA oxidase.6.Low expression quantity of ARP gene was one of the factors leading to calyx setting. We could make the calyx of ’Dangshansuli’ fruitlets shed by increasing the expression quantity of ARP gene7.Both3-isopropylmalate dehydrogenase and N-acyl-L-amino acid amidohydrolase participated in the related metabolic pathways of calyx developing, and it was presumed that the two kinds of enzymes might be the important related enzymes in the metabolic pathways of calyx developing during the period of ’Dangshansuli’fruitlet.