Overexpression Of A Cotton GA 20-oxidase Gene (GhGA20ox1) And Its Effects On Tomato Fruit Development

Gibberellins (GAs) are important plant hormones, involved in various developmental and physiological processes of plants. GA 20-oxidase is the key regulatory enzyme in the GA biosynthesis and metabolism pathway. To study the GA functions in the development of cotton fiber, a GA 20-oxidase gene GhGA20oxl was clone from the cotton fibers. To reveal the GA functions in fiber development, it is important to elucidate the function of the GhGA20oxl gene in the GA biosynthesis pathway.Tomato (Lycopersicum esculentum) is one of the most popular vegetable fruit crops in the world because of its special nutritive value. Additionally, tomato serves as a good model plant for other species whose fruit are also a fleshy berry in plant molecular biology research. It was demonstrated that GA play an important role in the fruit development. It is valuable to study the relationship of GA and its synthases to the fruit development, which may provide new strategy to engineer the productivity and quality of tomato.In the present paper, GhGA20oxl gene cloned from cotton fiber was introduced into tobacco and tomato plants. Phenotypes, gene expression and GA concentrations of transgenic plants were further analyzed. The main results were as followings:1. GhGA20ox1 gene was transformed into tobacco (Nicotiana benthamiana). 26 kanamycin resistant and GUS positive plantlets were obtained. RT-PCR results showed that GhGA20oxl gene was transcripted in the transgenic lines. The transgenic tobacco plants overexpressing GhGA20ox1 gene showed typical GA-overproduction phenotypes, such as elongated petioles, flowers, fruit stalks and hypocotyls, reduced leaf size, fruit size and reproductivity, and lighter green leaves. These observations suggested that GhGA20oxl gene promoted GA biosynthesis in transgenic tobacco plants. 2. GhGA20ox1 gene was introduced into tomato. 62 kanamycine resistant and GUS positive...