Atlg65030, A Wd40-repeat Protein, Regulates Seed Mass And Size In Arabidopsis

WD40-repeat proteins mediate interaction between protein and protein via conserved DWD motif in Eukaryotes. Both in animals and Arabidopsis, it has been reported WD40-repeat proteins acted as substrate receptors for DDB1-CUL4-ROC1 based E3 ubiquitin ligases. Recent studies in plants regarding the function of WD40-repeat proteins are scarce, while the role they played in the signal transduction, cell circle regulation, RNA modification, etc. have been reported previously.Male sterility has been applied in agricultural production widely. Over dozens of years, it has been the subject of intense research only at cellular level. With the increasing number of genes male sterility related, not only the research regarding its molecular mechanism has been driven deeply but also the application of heterosis has been promoted for a further step.Our work has identified a novel mutant of WD40-repeat protein gene which produces a heavier and larger phenotype along with weaker vegetative growth, compared with wild type. We targeted the gene to the first chromosome 65030 of Arabidopsis via TAIL-PCR. Bioinformatic analysis demonstrated its role as a member of WD40-repeat protein family which contained a highly conserved DWD motif. Subcellular location of atlg65030 manifested that atlg65030 was a nuclear-localized protein. Semi-quantitative RT-PCR analysis showed that atlg65030 expressed preferentially in the floral during the late development period. Over expression of atlg65030 caused smaller seed phenotype. while anti expression line can not be obtained. Moreover. we still observed that compared with wild type. atlg65030 generated less siliques and seeds. To investigate the mechanism leading to this phenotypes. we generated seeds with atlg65030 mutant as maternal by crossing wild type as paternal, vice versa. The atlg65030 mutant can not be obtained by former hybridization while the mutant can be obtained by latter test partially. The result indicated the development of male gamete was interrupted. The segregation ratio of T1 and T2 mutant did not comply with typical mendelian inheritance, which indicated the male gamete aborted partially. To research the principle deeply, we stained the pollen with DAB, DAPI, TTC, KI-I2 respectively. We find the problem occurring in nucleus and to explore the exact aberrant period, the pollen was stained by Ehrlich's hematoxylin. The normal modality of meiosis in different periods can be observed by Olympus light microscope and the notion that mitosis has been abnormal can be deduced.Above all, the work elucidated that WD40-repeat protein gene atlg65030 influenced the development of pollen by the regulation of cell division, which leaded to the abortion of male gamete ultimately. The living seeds became larger due to the more nutrition. The work not only promoted the research of pollen developmental mechanism but also revealed huge agricultural application value of male sterility mutant and larger size phenotype.