Pollen tube guidance in flowering plants: the interplay between male and female gametophytes

【作者】 杨维才；

【机构】 中国科学院遗传与发育生物学研究所；

【摘要】 During evolution, novel reproductive structures and mechanisms have evolved to adapt to terrestrial land environment in plants. In angiosperms, such evolutionary development is manifested by the flower, multicellular gametophyte, double fertilization, loss of sperm motility, and siphonogamy in which the immotile sperm was delivered to the egg by a pollen tube produced by the male gametophyte(pollen), a process named pollen tube guidance(PTG). Previous studies suggested that PTG requires the intimate interactions between the pollen tube and maternal tissue of the pistil and the female gametophyte respectively. Through genetic screen, we isolated a number of Arabidopsis mutants that disrupt PTG processes. CCG, a central cell-specifically expressed gene, is required for the female gametophyte to attract the pollen tube. CCG encodes a nuclear protein that regulates the expression of a number genes important for PTG via CBP1 which interacts with RNA polymerase II, the Mediator complex and AGL transcription factors in the central cells and also LURE1 expression in the synergids indirectly. POD1, a pollen tube-expressed gene, is required for the male gametophyte to respond to the female signals. POD1 encodes an ER protein that interact specifically with CRT3 which is implicated to control the folding of LRR-RLKs. These findings suggest that there might be a chaprone complex to monitor the folding of the LRR-RLK proteins in the ER. Recently, two LRR-RLK complexes were identified as LURE1 receptor in Arabidopsis. Further progresses on the elucidation of PTG mechanisms will be discussed.更多还原

【Abstract】 During evolution, novel reproductive structures and mechanisms have evolved to adapt to terrestrial land environment in plants. In angiosperms, such evolutionary development is manifested by the flower, multicellular gametophyte, double fertilization, loss of sperm motility, and siphonogamy in which the immotile sperm was delivered to the egg by a pollen tube produced by the male gametophyte(pollen), a process named pollen tube guidance(PTG). Previous studies suggested that PTG requires the intimate interactions between the pollen tube and maternal tissue of the pistil and the female gametophyte respectively. Through genetic screen, we isolated a number of Arabidopsis mutants that disrupt PTG processes. CCG, a central cell-specifically expressed gene, is required for the female gametophyte to attract the pollen tube. CCG encodes a nuclear protein that regulates the expression of a number genes important for PTG via CBP1 which interacts with RNA polymerase II, the Mediator complex and AGL transcription factors in the central cells and also LURE1 expression in the synergids indirectly. POD1, a pollen tube-expressed gene, is required for the male gametophyte to respond to the female signals. POD1 encodes an ER protein that interact specifically with CRT3 which is implicated to control the folding of LRR-RLKs. These findings suggest that there might be a chaprone complex to monitor the folding of the LRR-RLK proteins in the ER. Recently, two LRR-RLK complexes were identified as LURE1 receptor in Arabidopsis. Further progresses on the elucidation of PTG mechanisms will be discussed.更多还原