The Function Of Qi Gene In Arabidopsis Growth And Development

Arabidopsis thaliana is a model plant which is commonly used in plant research for many years.Nevertheless,there are still a few genes are not known to function in Arabidopsis.In this study,we identified a gene,namely Qi,with only one copy in Arabidopsis.e-FP Browser data show that Qi is expressed in various Arabidopsis tissues.Qi is highly expressed in seeds,leaves and flowers,especially in several stages of seed embryogenesis and germination,suggesting that Qi has a key role in seed development and embryogenesis.So we carried out experiments to explore the function of Qi in Arabidopsis.In order to study Qi function,we firstly obtained one T-DNA insertion mutant of Qi and named it as qi-2.The mutant showed some phenotypes,such as abnormal embryo,short primary root and albino leaf.We then constructed p35S:Qi and pQi:Qi-GUS vectors,and transformed p35S:Qi into qi-2+/-and pQi:Qi-GUS into wild-type(WT)plants.The role of Oi in primary root,leaf,seed and embryo development in Arabidopsis was studied.The expression pattern of Qi was detected using transgenic plants expressing promoter GUS fusion constructs.The conclusions of this study are as follows:1.Genetic analysis showed that there were only WT and heterozygous plants,indicating that the homozygous mutant was lethal.We could rescue homozygous mutant through in vitro culture.2.The primary root length of qi-2-/-was significantly shorter than that of WT plants,and the number of cortex cells in the root meristem was significantly lower than that of WT plants.Moreover,vascular development was abnormal in qi-2-/-mutants.These results indicate that Qi is involved in the primary root development in Arabidopsis.3.We observed abino leaves in qi-2-/-the chlorophyll content was examined.The chlorophyll content of qi-2-/-was lower than that of WT plants.Trypan blue staining showed cell death in qi-2-/-.In addition,the supplement of sucrose in medium could not rescue abino leaves into green leaves of qi-2-/-.4.It was observed that seeds lethality in qi-2+/-mutants,and abnormal embryos appeared in various embryo developmental stages.These results indicate that Qi is involved in Arabidopsis seed development and embryogenesis.5.There was no significant difference of growth between the transgenic qi-2-/-plants expressing p35S:Qi and WT,and the expression of Qi in transgenic plants was significantly increased.6.There was no abnormal cell death was observed in transgenic qi-2-/-plants expressing p35S:Qi.7.The content of chlorophyll-b in transgenic qi-2-/-plants expressing p35S:Qi was slightly higher than that of WT,and chlorophyll-a was not significantly different from that of WT.8.The number of cortex cells in the root meristem of transgenic qi-2-/-plants expressing p35S:Qi was consistent with that of WT,and the protoxylem developed normally.9.The transgenic qi-2-/-plants expressing p35S:Qi has a normal seed development.10.The embryogenesis of transgenic qi-2-/-plants expressing p35S:Oi was similar to that of WT.11.Qi is expressed in the root meristem,vasculature,leaves,as well as in the stomata,flower and embryo.In summary,we investigated the role of Qi in Arabidopsis growth and development.Phenotypic analysis reveals that Qi is involved in root and vascular development.Qi also plays a key role in Arabidopsis chloroplast.In addition,Qi is crucial in seed development and embryogenesis.The gene expression profile of Qi also shows that Qi is expressed in various tissues and organs of Arabidopsis.