Functional Analysis Of Chromatin Remodeler CHR729 In Rice

Chromatin remodeling factors utilize the energy from ATP hydrolysis to drive conformation changes of chromatin, thus affecting gene expression. Chromatin remodeling is well studied in yeast and animal systems, but in plants, particularly rice, the function of most chromatin remodeling factors remain largely unknown. CHD3-type chromatin remodeling factor CHR729 plays crucial roles in rice growth and development, whose gene mutation results in a subset of growth defects in rice. However, the detailed mechanism is still elusive. Here we tried to investigate the role of CHR729 in phytohormone dynamics, and to obtain over-expression and complementation lines of CHR729 for further studies. The major results are as listed as follows.1. We studied the expression pattern of CHR729 and found relative higher expression in leaf and callus. CHR729 could be induced by PEG and ABA, and repressed by light. CHR729 expression is regulated by DNA methylation and histone acetylation.2. Endogenous contents of auxin, abscisic acid and jasmonic acid decreased in chr729 mutant in both shoot of seedling and flag leaf at mature stage, and genes involved in auxin biosynthesis are down-regulated in chr729 mutant.3. Cell length in mature tissue decreased in longitudinal resin section of chr729 stem, while cell length in intercalary meristem unaffected. Many cytokinin oxidase/dehydrogenase genes were up-regulated in chr729 seedling, with a relative high enrichment of histone variant H2A.Z at some gene loci, suggesting that CHR729 regulates gene expression by modulating H2A.Z deposition.4. We obtained complementation line of chr729 and observed the phenotypic restoration of adaxial albino leaves. We also got over-expression line of CHR729, backcrossed mutant, and some double mutants, which would be useful in further studies.