厚轴茶雄性不育株花药败育的生物学特性和细胞学研究

为明确厚轴茶(Camellia crassocolumnaH. T. Chang)雄性不育株花器发育形态、花药和花粉败育时期及兵细胞学特征,利用体视显微镜、石蜡切片技术、染色体制片和DAPI染色法,对厚轴茶雄性不育株和可育株开花迚程、花器形态、花药发育过程、花粉母细胞减数分裂及小孢子发育过程比较观察。结果显示,厚轴茶花属于完全花,花药其四室、呈蝶形,花药壁发育为基本型,绒毡层细胞其双核,于四分体时期形成分泌型细胞,单核花粉期开始降解,花粉母细胞经过减数分裂Ⅰ、减数分裂Ⅱ和胞质分裂后形成四面体型四分体,小孢子呈三角形,成熟花粉为二细胞型花粉。花蕾发育早期,不育株雄蕊发育正常,与可育株无明显差异。花蕾发育后期,不育株花丝弯曲,花药粘连、干瘪、褐化、坏死,不裂药。不育株减数分裂期绒毡层细胞异常增生、排列混乱,单核至双核花粉期绒毡层延迟降解。不育株花粉母细胞减数分裂过程中存在环状单价体、滞后染色体、染色体桥、染色体缺失、不均等分离、微核和多分体等异常现象。不育株小孢子胞质紊乱,单核期花粉粒相互粘附,花粉壁皱缩变形,花粉细胞质和细胞核模糊不清,成熟花粉细胞空瘪凹陷。研究结果表明,厚轴茶雄性不育花器形态属雄蕊萎缩型和花药异常型,花药发育受阻于减数分裂至单核花粉期,存在花粉母细胞败育型和单核败育型。单核花粉期是兵花药败育的主要时期。花药绒毡层异常发育和延迟降解,花粉母细胞减数分裂染色体行为异常,小孢子和花粉粒发育异常可能是兵花药败育的主要原因。

Biological characteristics and cytological studies on anther abortion of male sterile Camellia crassocolumna

The purpose of this study was to explore the flower morphology, anther and pollen abortion time and its cytological characteristics in male sterile plants of C. crassocolumna. The flowering process, floral morphology, anther structure, meiosis and microsporogenesis of male sterile (M350) and fertile plants (M352) of C. crassocolumna were observed by stereomicroscopy, paraffin section, chromosome preparation and DAPI staining. The results showed that the wild tea plant had a perfect flower, its anthers were tetrasporangiate shaped like a butterfly, with an anther wall development of basic type. It tapetal cells were binuclear, forming secretory cells at the tetrad stage, and degrading during mononuclear pollen stage. After the meiosis I, meiosis II and cytokinesis, pollen mother cells developed into tetrahedral tetrads. Microspores were triangular, and mature pollen was two-celled. The stamens of male sterile flowers developed normally in the early stage of flower bud development, and there was no difference between sterile and fertile flowers, while in the late stage of flower bud development, filaments were curved, anthers adhered and shriveled, anthers could not release pollen. The tapetal cells of male sterile flowers were proliferation abnormally and disordly at the meiosis of stage pollen mother cells, and the degradation of tapetum was delayed during the mononuclear and binucleate pollen periods. During meiosis of pollen mother cells of male sterile flowers, there were some abnormal appearances, such as chromosome ring, lagging chromosomes, chromosome bridges, chromosomal deletion, scattered chromosomes, unequal separation, micronucleus and abnormal tetrad. In sterile plants, the microspore cytoplasm was disorder, pollen grains adhered to each other at the mononuclear stage, pollen wall crumpled and deformed, cytoplasm and nucleus of pollen were blurred, the mature pollen cells were hollow and sunken. Taken together, the floral organ morphology of male sterile plants in C. crassocolumna belongs to stamen collapse type and anther abnormality type. The development of anthers is blocked from meiosis of pollen mother cells to uninucleate pollen stage, belonging to pollen mother cell abortion type and uninucleate pollen abortion type. Mononuclear period is the main period of anther abortion. Tapetum degradation delayed, chromosomal abnormalities of pollen mother cells in meiosis, and abnormal development of microspores and pollens, might be the main reasons for anther abortion in male sterile plants of C. crassocolumna.