杨树2n花粉花粉管生长缓慢的细胞学机理

利用2n 花粉与单倍性雌配子杂交是杨树三倍体选育的一条重要途径，实现了花粉染色体加倍带来的倍性效应与杂交产生的杂种优势的结合。在2n花粉利用时，由于2n花粉与单倍性花粉难以分离纯化，授粉时存在单倍性花粉竞争，2n花粉的花粉管生长缓慢而致使三倍体得率低。但2n花粉的花粉管生长缓慢的细胞学机理至今仍不清楚。本研究围绕杨树2n花粉花粉管生长缓慢的科学问题，以天然2n花粉高产的毛白杨为研究材料，在研究单倍性花粉、天然2n花粉以及人工诱导2n花粉三种类型花粉在离体萌发条件下萌发率和花粉管生长速率差异的基础上，研究其花粉管超微结构、微丝骨架的排列方式与动态组装调控、Ca2+浓度剃度及分布、胞吞胞吐作用等对花粉管极性生长的影响，进而揭示2n花粉花粉管生长缓慢的细胞学机制，并采取适宜的技术措施，提高杨树三倍体得率。

Triploid poplars play important roles in landscape cultivation, ecological protection and the production of lumber and pulp in China. It is one of vital methods to obtain triploids using 2n pollen crossing normal female gamete, which combined the ploidy effect with heterozygosity. There existes competition between 2n pollen grains and normal pollen grains as 2n pollen can not be screened from mixed pollen. However, pollen tubes slowly grow on stigma when pollinated with mixed pollen grains resulting in a lower frequency of triploid due to their poor competition. However, little is known about the cytological mechanism of slow polar growth of pollen tube in 2n pollen. In this study, we focused on the polar growth of 2n pollen during fertilization. Based on the investigation of germination rates of normal pollen, natural 2n pollen and induced 2n pollen and calculation of growth rates of their pollen tubes in vitro, the effects of ultrastructural observation, actin microfilament, Calcium signals and its distribution, the Endo/ Exocytosis to polar growth of pollen tube will be conducted to reveal the cytological mechanism of poor competition of 2n pollen during fertilization using natural 2n pollen producers of Populus tomentosa as materials. All results will provide a theoretical platform for triploid breeding of poplar.