Study On Gynogenesis Induction In Tomato(Solanum Lycopersicum L.)

A reliable method for production of tomato haploids would have particular significance for tomatobreeding, especially with regard to the development of molecular markers, genetic map construction,gene mapping, and gene cloning. In vitro androgenesis and gynogenesis are two approaches often usedin plant haploid induction. The androgenesis approach include anther and microspore culture in vitro.Ideal result was not obtained though anther and microspore cultures have been widely studied for40years. The gynogenesis approach includes the non-fertilized ovaries and ovules culture in vitro. Theresearch about gynogenesis was limited contrast to androgenesis in tomato. Based on predecessors’work, in this study the ovaries, ovules and protoplasts of embryo sacs from the hybrids ‘Zhongza101’and ‘Zhongza105’ were cultured in vitro, in order to determine the potential for haploid induction via invitro gynogenesis in tomato. The main results were as follows:1. The flower bud stage of development suitable for ovule culture was optimized. External featuresof bud as sampling criteria indicated that buds having a sepal separation ranging from0to3mm inlength are suitable for ovule culture. The buds have a length of7-10mm and bloom after4-6days.2. An efficient method of ovule isolation was established in this study, allowing100–150ovules tobe isolated from one ovary.3. In the culture of tomato unfertilized ovules, the embryo sac cells were induced to divide, tens ofthousands calli and five ovule generated plants were obtained.4. Histological research was carried out to identify the origin of tomato ovule regenerated plants.The results indicated that embryo sacs cells were induced to divide from the chalazal end of ovule andseparated from ovule wall cells. The production of cell clump in embryo sac proved the possibility ofgynogenesis via ovule culture in vitro. Subsequently, the cell clumps ceased growth and ovule wall celldivided to form callus and generate plants.5. In order to eliminate the hindering effect of integument on embryo sac cells, the protoplasts ofembryo sacs were prepared and cultured. The results showed that the protoplasts of embryo sacs becamebigger and gradually formed different appearance of tissue.