벼의 융단층과 화분모 세포의 발달에 관한 연구

Abstract

Pollen mother cells and tapetum development is fundamental for male gametogenesis. The former is the fundamental for male- gametophyte and the latter is the basis of the sporogenous tissue for supporting the gamete. Here I report a rice gene, DEFECTIVE TAPETUM AND MEIOCYTES 1 (DTM1), which controls the early stages of that development. First, T-DNA insertion mutations gave rise to abnormal tapetal formation. Cellular organelles, especially the ER, were underdeveloped, which led to hampered differentiation and degeneration of the tapetum. Because this gene encodes for endoplasmic reticulum (ER) membrane protein, I propose that DTM1 is an essential ER component that is needed for development of that organelle. In addition, the development of pollen mother cells was arrested at the early stages of meiotic prophase І. It is also thought by the same token, not due to indirect effects from undeveloped tapetum. Secondly, RNA in-situ hybridization analyses showed that DTM1 transcripts were most abundant in tapetal cells at Stages 6 and 7, and moderately in the pollen mother cells and meiocytes. Transcripts of UDT1, which functions in tapetum development during early meiosis, were reduced in dtm1 anthers, as were those of PAIR1, which is involved in chromosome-pairing and synapsis during meiosis. However, expression of MSP1 and MEL1, which function in anther wall specification and germ cell division, respectively, was not altered in the dtm1 mutant. Moreover, transcripts of DTM1 were reduced in msp1 mutant anthers, but not in udt1 and pair1 mutants. These results, together with their mutant phenotypes, suggest that DTM1 plays important roles in ER membrane during early tapetum development, functioning after MSP1 and before UDT1, and also in meiocyte development, after MEL1 and before PAIR1.