The Selection Of Longer Shelf-Life Strains Of Cucumis Melo L. CV Hetao Transformed With An Antisense ACC Oxidase Gene

Melon (Cucumis melo L.) belongs to the Cucurbitaceae family,and is an annual herbaceous rambler,which has aboundantly nutritious fruit,special flavour,and suitable fragrance and sweet hence liked by people and listed in one of the biggest yield fruits in the world.China,half total area and yield of melon in the world,is the biggest country in producing melon. This research used a good regional melon (Cucumis melon L. cv Hetao) variety in He Tao area in the west Inner Mongolia. Hetao melon is typically climacteric fruit and attains the maturity appearing the high peak of breathe soonly during the postharvest period,that leads to softening and rotting of fruit flesh. The one of main purpose of the Hetao melon breeding is to improve the storage of the Hetao melon. Our laboratory had transferred the antisense ACC oxidase gene into Hetao melon by pollen-tube pathway. We had gained the transgenic melon strains. In this paper,from April,2005 to August, 2007,the transgenic Hetao melon of T₆,T₇ and T₈ generation had been selected by self pollination. Genetic stability,agronomical characters,fruit characters,seed characters,physiological and biochemical characters of T₈ generation transgenic melon were studied in postharvest storage period. The results and discussion as follows:1. We had gained the longer shelf-life of T₈ generation of transgenic melon stable strains(L1, L2 and L3) by selection of 3 generations. The storage experience of transgenic melon and non-transgenic melon indicated that transgenic melon L1, L2 and L3 strains of unrotted fruits rate maintained 100% at 10 day, the non-transgenic melon of unrotted fruits rate is 13-16% at 10 day, but transgenic melon L1, L2 and L3 strains of unrotted fruits rate still maintained 100% at 25 day, 45th day of unrotted fruits rate also above 83%.2. PCR analysis of T₈ generation of transgenic Hetao melon indicated that the antisense ACC oxidase gene had been integrated into the receptor Hetao melon genome.3. The agronomic characters investigation of T₈ generation of transgenic Hetao melon indicated that there were no significant differences between transgenic strains(L1, L2 and L3) and non-transgenic plants in agronomical characters.4. The fruit characters investigation of T₈ generation of transgenic Hetao melon indicated that there were significant differences in storage period and fruit weight between transgenic strains(L1, L2 and L3) and non-transgenic plants,others have no significant differences in fruit characters of different strains5. The seed characters investigation of T₈ generation of transgenic Hetao melon indicated that there were no significant differences between transgenic strains(L1, L2 and L3) and non-transgenic plants in seed characters.6. The loss rate of weight of transgenic melon was lower than non-transgenic melon during storage. Change on firmness and refractive suger content of transgenic melon was less significant deviation during storage period. The refractive suger contents of transgenic melon L1 and L2 strains were more than non-transgenic melon. The ethylene content of transgenic melon was only 4% of non-transgenic melon. The change of ACC content of transgenic melon was less marked during storage period. The ACC oxidase activity has maintained the low level.7. According to the analysis of fruit quality, the quality differences of transgenic melon and non-transgenic melon are not obvious at 9 days. The fruit remained high quality at 45 days after postharvest. The fruit edible quality has not been affected.