小立碗藓RNase H1s的功能研究

	小立碗藓RNase H1s的功能研究; Research on the function of RNase H1s in Physcomitrium patens
	陈思霖
导师	吴建强
摘要	RNase H1 is a class of ribonucleases with non-sequence specificity, which widely present in prokaryotes and eukaryotes. RNase H1s were reported to play crucial roles in RNA processing, DNA replication, DNA damage repair, and the maintenance of genomic stability. However, previous studies of plant RNase H1s were mainly focused on the higher vascular plant Arabidopsis thaliana. The function of RNase H1 in early land plants and the roles it played in plant terrestrial evolution are still unknown. As a representative of early land plants, Physcomitrium patens has evolved developmental regulation and hormone signaling pathways which are similar to the vascular plants. Thus, further investigation of the function and molecular regulation mechanisms of PpRNH1s is important for illustrating the origin and adaptive evolution of land plant. In our study, we investigated the function of RNase H1s in P. patens. The main results and conclusions of this study are summarized as follows: 1. P. patens harbors two RNase H1 proteins, PpRNH1A and PpRNH1B, possessing a conserved RNase H domain with catalytic function. 2. Structural and phylogenetic analysis revealed that PpRNH1s and AtRNH1s are evolutionarily conserved, whereas specific differentiations exist between these two RNase H1 families. The differences were found in many aspects including the number of homologous genes, the structure of sequences, and the subcellular localization. 1) Comparing to A. thaliana, the mitochondrial-localized RNase H1 has not evolved in the early landing P. patens. 2) Interspecific specificity is existed between the DNA: RNA hybrid binding domain of PpRNH1s and AtRNH1s. Moreover, no chloroplast or mitochondrial targeting sequence was found in PpRNH1s. 3) PpRNH1A is localized in both nucleus and cytosol, unlike AtRNH1A which is only present in the nucleus. 3. The expressions of PpRNH1s are highly tissue-specific at different developmental stages, and the expression patterns between PpRNH1A and PpRNH1B were significantly different. At the stage of vegetative growth, the expression of PpRNH1A is widespread in gametophyte. After the plants transform to reproductive growth, PpRNH1A is highly expressed at the seta of sporangia. In contrast to PpRNH1A, the expression of PpRNH1B is highly tissue-specific, and the abundance is much lower at all stages during the development. It only expresses in tissues with high meristematic activity, such as the tip cells of protonema, new leaves, axillary buds, and the bottom of sporangia.
	2021-11
文献类型	学位论文
条目标识符	http://ir.kib.ac.cn/handle/151853/74607
专题	昆明植物所硕博研究生毕业学位论文
推荐引用方式 GB/T 7714	陈思霖. 小立碗藓RNase H1s的功能研究, Research on the function of RNase H1s in Physcomitrium patens[D],2021.

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