The Embryonic Development And Genetic Mechanism Research Of Apomixis Malus 'Rolalty'

As an important way of the reproduction,apomixis,sexual and asexual reproduction are known as three main reproductive ways in nature.Apomixis can overcome disadventages in asexual reproduction,keep the fine properties of the female parent and reduce the negative impact of the vegetative propagation,so that has the great value in agriculture.There are a great many plants of Malus with the apomixis ability.While all of them are facultative apomixes,most chromosome are polyploidy at the same time.Though we have a knowledge of apomixes research,we still remain unclear about its genetic mechanism and molecular mechanism as a result of complex condition and involved multiple reaction.Royalty(Rosaecea.Malus)is the typical and important germplasm resources in crabapple.It not only has deep red color leaves and laid colored flowers,fruit,but also has the excellent characteristics such as disease resistance,drought resistance.It's a specie with ornamental value in north China.In this research,we made Royalty as the materials to explore the embryonic development and molecular genetic mechanisms by designing hybridization pollination experiment and using molecular biology methods.The main research results are as follows:(1)The Royalty has the ability of facultative apomixes and higher production rate.Because when removed its stamen bagging the flowers,it could produce fruits.The seeds in fruit are in fertile.(2)The anther has been mature when flower is at bud stage.While with the development of flower,the anther didn't crack.A lot of pollen grains were in pollen sac,while only a small amount of pollen released.(3)By scanning electron microscopy and paraffin section,we found most of the Royalty pollen were abnormal.(4)We observed that the pollen has the normal activity and low generation rate by experiment.(5)The Royalty has two embryo sac developmental patterns.When in sexual reproduction,the embryo sac mother cell meiosis to produce embryo sac.While it mitosis to produce embryo sac directly in apomixes way.(6)Although still not fully clear about apomixis mechanism,we had found four genes APK?EFalpha?FIE?MSI1 which were related to apomixes.They all expressed 'high-low-high' in ovary at blooming stages,opposite with 'Flame'.