Study On Apomixis Mechanism And Evaluation Of Resources In Eulaliopsis Binata

As an alternative way to sexual reproduction, apomixis was considered to be an important subject in development biology and aroused widely concentration from biologists and plant breeders for fixation of heterosis. Identification of more available apomictic resources and reveal of the mechanism in apomixis development would help to understand the genetic control of plant reproduction without fertilization and contribute to fixation of heterosis in breeding practice.In this study, nine populations of dragon grass (Eulaliopsis binata (Rotz) C.E Hubbard) from four provinces were collected for evaluation of genetic diversity within single apomictic population and among different populations by using RAPD and AFLP molecular markers. Embryological investigations were conducted to observe the female gametophyte formation and embryo development. Apomixis was evaluated based on comparison of seed setting rates between treatments of pollination with emasculation, bagging and removal of stigma. Meanwhile, the features of pollen adherence to stigma and germination process were also observed during pollination. The chromosome numbers and ploidy of E. binata were examined by counting chromosome numbers in root tip cells and relative ploidy was also checked in embryo and endosperm of mature seeds by scanning with flow cytometry. The main results are listed as follows.1) RAPD and AFLP analysis revealed that diversity existed in different populations of E. binata. Based on molecular markers and morphological observation and cellulose content, the nine populations from four provinces were classified into 4 types: Slender-leaf biotype (Hubei) Dark-green-leaf biotype (Guangxi), Red-haulm biotype (Shangxi) and Wide-leaf biotype (Henan and Shanxi). Among different populations from same place, little variance was examined. No variance was identified within the Slender-leaf type and Wide-leaf type even by AFLP markers, but relatively high variance was found in the Red-haulm type..2) The embryological investigation indicated that the development pattern of embryo sac was gametophytic apospory. In the early stage of ovule development, a few of the nucellus cells developed into aposporous initial cells, which differentiated into two forms of mature embryo sac: a) one form (67.6% of total embryo sacs investigated) of the mature...