玉米花粉无性系分化能力的变化和染色体数目的不稳定性

胚性细胞在胚性细胞团、胚状体和再生植株的根部均可以发生。在胚性细胞团表面产生的胚性细胞发育成新的胚性细胞团,在胚性细胞团内部产生的胚性细胞形成许多细胞分裂中心,由这些分裂中心进一步发育成新的胚性细胞团。新的胚性细胞团即可以保持分化能力,也可能丧失分化能力。胚性细胞发育成胚状体的过程与玉米合子胚的形成基本相似。成熟胚状体具有胚芽、胚根、盾片等结构。无性系胚性细胞团具有染色体数目不同的细胞壤嵌存在的特性。由胚性细胞团中的胚性细胞发育成的胚状体,其整倍体细胞占优势,而在丧失正常分化能力的细胞团中,非整倍体细胞占优势。

VARIATION OF DIFFERENTIATION CAPACITY OF MAIZE POLLEN CLONES AND INSTABILITY OF CHROMOSOME NUMBER

Initiation of embryogonic colls occurs in embryogenic aggrogates, embryoids and roots of regonerated plants. Respectively, the embryogenic cells from the surface of the embryogeonic aggrogates develop into new embryogenic aggrogates and the inner embryogonic cells evolve a lot of centers of sogme ntationwhich also give rise to new aggrogates. The now aggrogates may either maintain differentiation capacity or lose it, The morphogonesis from embryenic cell to embryoid is mainly similar to that of Maize zygotic embryo. The mature embryoids possess a plumule, a radicle and a scutellum. The embryogenic aggregates of clones are characterized by mosaicism of different cells in chromosome number. Euploid cells are predominant in the embryoids from embryogenic cells ocourring in the embryogenic aggregates and anouploid cells are predominant in the aggregates lost normal differentiation capacity.