Arabidopsis zinc finger proteins AtC3H49/AtTZF3 and AtC3H20/AtTZF2 are involved in ABA and JA responses.

There are 68 CCCH zinc finger protein genes in the Arabidopsis genome. However, only a few of them have been characerized functionally. In this paper, we report the function of two Arabidopsis CCCH zinc finger proteins AtC3H49/AtTZF3 and AtC3H20/AtTZF2. To investigate their functions, we examined their expression patterns and analyzed their overexpression and knockout(KO)/RNA interference (RNAi) phenotypes. Both AtC3H49/AtTZF3 and AtC3H20/AtTZF2 genes were expressed in various vegetative tissues and in flowers, and their encoded proteins were localized in the cytoplasm. Overexpression of AtC3H49/AtTZF3 or AtC3H20/AtTZF2 conferred ABA hypersensitivity, reduced transpiration and enhanced drought tolerance. Their overexpression also altered the plant growth pattern. The transgenic plants grew slowly during the early stage of growth, but their growth rates were accelerated at later stages, and mature plants were larger than the wild-type plants. Moreover, the transgenic plants displayed delayed senescence and enhanced longevity. Subsequent experiments showed that jasmonic acid (JA)-induced senescence was also delayed. Microarray and quantitative reverse transcription-PCR analyses indicated that the expression of a number of genes involved in JA, ABA and biotic/abiotic stress responses was altered in the transgenic lines. Recombinant AtC3H49/AtTZF3 and AtC3H20/AtTZF2 proteins displayed RNase activity in vitro, suggesting that they may be involved in mRNA turnover process. The knockout/RNAi lines of AtC3H49/AtTZF3 and AtC3H20/AtTZF2 exhibited weak phenotypes, presumably because of their functional redundancy.