Functional Analysis of PH-START1 in Regulating Arabidopsis thaliana Seed Development
FENG Jia-Jia ,SUN Dan-Dan, WANG Qian, GAO Meng-Zhu, ZHANG Hao, WANG Feng-Ru *, DONG Jin-Gao*
Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology/College of Life Science, Hebei Agricultural University, Baoding 071001, China
Abstract Seed development is directly related to crop yield and quality, although several genes that can regulate seed development have been reported in the literature, the molecular mechanism of seed development has not yet established a complete regulatory network. In order to identify the main genes regulating seed development and improve the control network of seed development, the gene PH-START1 (pleckstrin homolgy - the lipid/sterol-binding St AR-related lipid transfer protein domains 1) was identified that can regulate seed development in Arabidopsis thaliana, over-expression of PH-START1 in Arabidopsis reduced the seed yield by 61.7% and the grain weight by 80%, which indicated that PH-START1 was the main gene regulated seed development. The function of the gene in regulating the development of seed was determined by analyzing the growth, seed setting rate and grain weight of the transgenic plants with functional loss and gaining. By observing the development of seed embryo and endosperm, the specific process of gene regulation of seed development was clarified. By analyzing the tissue location of the target gene, the expression pattern was clarified. The wild-type seeds were arranged neatly and tightly and the pods were full under the microscope. The PH-START1 T-DNA insertion mutant, the PH-START1, was arranged neatly, occupying the entire inner space of the siliques, with a single silique producing 55 seeds, with a 117% seed yield. However, the seeds of PH-START1 transgene OE-1 in A. thaliana were sparse and scattered, with only 18 seeds in a single silique, and only 38.30% of the seed setting rate. Further analysis showed that PH-START1 also affected the structure of the seeds. The endosperm cells of the seeds after over-expression of PH-START1 decreased obviously, and the aleurone layer cells were arranged in disorder and embryo development was blocked. In order to deepen the mechanism of PH-START1, the expression pattern of PH-START1 was analyzed. The results showed that PH-START1 was the most expressed in seed, and was mainly distributed at the base and top of style with the growth time. In stamens, the expression in filament and anther increased with the increase of development time, and was concentrated in pollen grains. This study identified that the PH-START1 was a main gene that regulates seed development, and clarified its specific process and expression patterns that affected seed development. This result provide a theoretical basis for improving seed development regulatory molecular network and modern molecular breeding.
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