Identification Of Parthenocarpy Related ESTs In Eggplant(Solanum Melongena L.) Using Suppression Subtraction Hybridization

In flowering stage, low temperature often induce poor pollination and fertilization, flower and fruit drop, and result in fields decreasing in green house. Parthenocarpy can avoid flower and fruit drop caused by low temperature, improve the ability of fruit setting and fruit quality, increase yield and decrease costs. So isolation of parthenocarpy related genes has good significance for guiding parthenocarpic eggplant breeding, cultivating seedless, low-temparature resistant eggplant cutivars.This experiment studied parthenocarpy related ESTs with parthenocarpic eggplant D-10 ovary cDNA serving as tester and non-parthenocarpic eggplant 03-2 ovary cDNA as driver. Real-time PCR was used to detect differentially expressed genes in the first fruit at flowring day, after flowring 7 days and 20 days. A 500bp fragment of auxin growth promotor protein gene was obtained by 3'-RACE and its sequence analysis was finished. The main results were summed as follows:1. A forward and a reverse suppression subtraction hybridization (SSH) cDNA library with 472 and 124 positive clones were constructed respectively. 384 expressed sequence tags (ESTs) were obtained. 121 ESTs were highly homologous with known proteins and 136 ESTs could be new genes.2. We identified the homologous between ESTs obtained from SSH and GeneBank using Blast program.The homologous genes are as follows:Fruit growth related genes including auxin growth promoter protein and expansin protein encoding genes ; Flower development genes including MADS-box and zine finger encoding genes; Signal transduction genes including MAPKK and WRKY transcription factor encoding genes.3. Five parthenocarpy related ESTs were obtained, including two MADS-box family, one auxin growth promoter protein, one expansin protein, one cytochrome P450 NADPH-reductase and one MAPKK family.4. Auxin Growth Promotor Protein Gene's expression pattern in parthenocarpic and non-parthenocarpic eggplant are different. Its expression patten in parthenocarpic eggplant is high-low-higher and no expression, increasing continuously in non-parthenocarpic eggplant. Expression of this gene in parthenocarpic eggplant is higher than that of non-parthenocarpic eggplant. Auxin Growth Promotor Protein Gene is closely related with expression of auxin synthesis gene.5. MADS-box SEPALLATA3 Gene's expression patten in parthenocarpic and non-parthenocarpic eggplant are different. It's expression patten in parthenocarpic eggplant is high-low-higher and no expression, increasing continuously in non-parthenocarpic eggplant. MADS-box SEPALLATA3 Gene probably induce parthenocarpy in eggplant.6. 3'-RACE-PCR was used to obtain a Auxin Growth Promotor Protein gene's 3'-sequence. The total length was 771 bp, with a 3' polyA structure. Its amino acid identity is 94% with a tomato putative auxin growth promotor protein, with a conservative domain named GDP-fucose protein O-fucosyltransferase.