Characteristic Evaluation Of Parthenocarpic Eggplant And Expression Analysis Of Parthenocarpic Related Genes

Eggplant (Solarium melongena L.) is warm required vegetable. In flowering stage low temperature often induced bad pollination and fertitization, induced flower and fruit drop, and reduced income. The low temperature and weak light tolerance varieties are in urgent need in production. Parthenocarpy can conquer flower and fruit drop caused by low temperature, enhance the ability of fruit setting, increase yield, improve fruit qualities and decrease culture cost. The experiment researched the expression effects and its molecular genetic mechanism.The parthenocarpic eggplant cultivars were used in this study. This experiment studied the expreesion effects of parthenocarpic cultivars in winter greenhouse, spring greenhouse and spring field, the influence of pollen viability and different pollination methods to the parhenocarpic fruit formation and development. Furthermore, the cDNA-AFLP technology was used to compare and analyze the defferential expression of parthenocarpic cultivars and unparthnocarpic cultivars fruit. The main results were summed as follows:1. The parthenocapic lines D-55, D-56 and D-62 are temperature sensitive type. The expression of parthenocarpic gene is contolled by temperature, and the parthenocarpic gene can completely express at the average daily lowest temperature 12.8℃.2. Compared with unparthenocarpic cultivars, the parthenocarpic cultivars can tolerant low temperatures and weak light. Though the experiments of winter greenhouse, spring greenhouse and early field, the result showed that parthenocarpic cultivar and its F1 hybridization hold higher ratio of fruit setting under natural pollination, obtain higher yield, revealed adaptabilities for low temperature and weak light, and yield increasing potential. The parthenocapic cultivars can be used for new varieties breeding for low temperature resistance and create new germplasm.3. The parthenocarpic characteristic of the parthenocarpic lines have no significant relationship with pollen viability. Though analysis the influence of flowering temperature and culture temperature to pollen viability, the pollen of both parthenocarpic cultivars and unparthenocarpic cultivars have certain viability at the average daily lowest temperature 16.1℃. At the culture temperature 18℃the ratio of pollen germination is lower, it is 1.88～7.29%, and there is no significant differenc among cultivars. Through analysis pollen viability, ratio of fruit setting and ratio of parthenocarpy in low temperature, it revealed that there is no significant correlation between pollen viability and parthenocarpy. Parthenocarpy is not reduced by the decreasing of pollen viability. The formation of parthenocarpy fruit may have no relation with pollen viabity.4.The experiment for screening pollen germination medium and culture temperature showed that the germination of eggplant pollen need a certain amount sugar and boric acid, but if the concentration is too high it will hold back germination. The best culture medium is 0.5% agar + 5% sugar + 10mg·L-11 boric acid. it have the highest germination rate. The impacts of florescence temperature, culture temperature and their interaction to pollen germination are very significant. The ratio of germination is the lowest in low temperature, and when the culture temperature is 25℃, the germination rate greatly increased.5. The three treatments of natural pollination, controlled pollination and stigma treatment have no influence on parthenocarpic fruit growth and development. The speed of fruit development with stigma treatment was very accordant to the fruit with natural pollination. The parthenocarpic fruit can set and develop normally without pollination and fertilization, the result showed that the hormone for fruit growth and development of tested parthenocarpic cultivars isn't dependent on the development of seeds. The controlled pollination can help fruit setting and developing of unparthenocarpy cultivars.6. cDNA-AFLP approach was used to detect differently expressed genes in ovary and fruit between parthenocarpy and unparthenocarpy cultivars under low temperature and suitable temperature. 120 pairs of primer were used for selective amplification. 92 TDFs were selected for the differential expression in different cultivar or stage. Among 92 TDFs, 14TDFs may related to parthenocarpy, 4 TDFs were cloned and sequenced, and expression patterns of 2 TDFs were conformed by RT-PCR approach. Compared with the publicly available databases, the 4 sequenced TDFs presented some significant similarity with the gene of putative senescence-associated protein, Lycopersicon esculentum maturing fruit gene, the gene of Solanum lycopersicum cDNA sequence, Phaseoleae environmental sample clone 18S ribosomalRNA gene. These genes may affect the structure and synthesis of ribosome, and influence the synthesis of maturing and senescence-associated protein, thus influence the seeds formation and fruit enlargement.