Abstract: During ripening, fruits undergo complicated developmental changes with varying physiological and biochemical activities that affect color, flavor, and texture. In tomato, these changes include accumulation of ethylene, the red pigment lycopene and the cell wall hydrolase, polygalacturonase (PG). Recently, genes of PG, pectin esterase (PE), ACC synthetase, ACC oxidase, and ethylene syshetase etc. from tomato, banana, carica papaya, peach and mango have been cloned. In this report, a large tomato expressed sequence tag (EST) dataset (152 635 in total) from 27 different EST libraries was analyzed to gain insights into digital gene expressions of two fruit ripening related genes SlPEL and SlAPL in tomato. Their expression profiles were detected using semi-quantitative RT-PCR assays and real-time RT-PCR assays in tomato (cv. Meiweiyingtao) during fruit development and ripening. SlPEL expression increased in the fruit at 12 days after pollination, and reached the small peak 4-6 days later and the larger peak at 28 days after pollination; then dropped to the level of the small peak until red ripening stage. As SlPEL, SlAPL expression was also induced by the fruit ripening. But SlAPL expressed two weeks later than SlPEL. SlPEL expression achieved the small peak at 28-32 days after pollination and the large peak at 39 days after pollination; and kept the higher levels until red ripening stage. The results confirmed that the digital gene expression using different EST libraries is an effective way to check the research value genes.

Key words: Solanum lycopersicum, Pectate lyase, APETALA 2 Like, Expression Analysis