| Rice is one of the most important food crops in the world and the endosperm is an important part of rice seeds.The development of endosperm influences the rice yield and rice quality directly.Therefore,the study of regulation mechanism of rice endosperm development is very important.In recent years,we found that imprinting genes were very important for Arabidopsis development,while role of imprinting genes in rice endosperm development was not well understood.At the same time,studies have shown that transcription factors are widely involved in rice endosperm development.This project focuses on a potential imprinting gene OsbZIP76 and try to explore its role in the process of rice endosperm development.The results are as followed:1.Previous studies showed that the maternal allele of OsbZIP76 is predominately expressed in the endosperm of rice,we try to validate it in four different cross combinations.However,we found that in the hybrid endosperm of Wufeng/Yu6,the allele of Yu6 is predominantly expressed regardless of the direction of crossing.In the Dongxiang/Rongfeng and Dongxiang/Yu6 wild rice crosses it suggested that OsbZIP76 is a maternally expressed gene.The results suggested that the imprinting status of OsbZIP76 is varied among strains or varieties.2.In subcellular localization analysis,we found that OsbZIP76 was expressed in the nucleus of tobacco epidermal cells.This was consistent with that OsbZIP76 is predicted as a transcriptional factor,but yeast two-hybrid experiment suggested that OsbZIP76 alone does not have the transcriptional activation activity.3.qRT-PCR results showed that OsbZIP76 was highly activated at 3 DAF,and its expression reached to the peak at 10 DAF.Furthermore,in situ hybridization experiment indicated that the OsbZIP76 transcripts was also accumulated in the pericarp cells at the early-developed caryopsis.4.The sectioning results suggested that the timing of cellularization and starch accumulation was promoted in the osbizp76 and RNAi plants in comparison to the wild-type at 3DAF to 5DAF.These findings suggested that disruption of OsbZIP76 led to precocious cellularization in rice endosperm.5.Most of the transgenic lines showed comparable plant height and tiller numbers as the wild-type.However,the seed thickness and 1,000-grain weight of the osbzip76 mutants were significantly reduced in comparison to that of the wild-type.6.we identified two nuclear factor Y(NF-Y)family members,OsNF-YB1,was able to interact with OsbZIP76 in yeast.Split luciferase(LUC)assay and BiFC assay verified the interactions between OsbZIP76 and OsNF-YB1/9.The results will provide a foundation for endosperm development and new ideas for rice quality improvement. |
