A Maize Early Responsive to Dehydration Gene, ZmERD4, Provides Enhanced Drought and Salt Tolerance in Arabidopsis

Early responsive to dehydration (ERD) genes could be rapidly induced to respond to dehydration and to various other abiotic stresses. Here, we report on an ERD gene (ZmERD4) from maize cloned by rapid amplification of complementary DNA (cDNA) ends. The ZmERD4 cDNA had a total length of 2,536 bp with an open reading frame of 2,196 bp, 5'-untranslated region (UTR) of 48 bp, and 3'-UTR of 292 bp. The gene encoded a predicted polypeptide of 732 amino acids. The ZmERD4 protein shared a high amino acid sequence similarity with ERD4 of Oryza sativa and Arabidopsis thaliana. A reverse-transcription polymerase chain reaction analysis revealed that ZmERD4 was constitutively expressed in different tissues. RNA gel blot showed that ZmERD4 could be induced by both drought and salt stress and also responded to abscisic acid treatment, but it was not induced by low temperature (4A degrees C). Transgenic Arabidopsis plants constitutively expressing the ZmERD4 gene under the control of the 35S cauliflower mosaic virus 35S promoter exhibited slightly smaller-sized leaves under normal growing conditions. Moreover, 35S::ZmERD4 transgenic plants displayed enhanced tolerance to water deficit and high salinity when compared to wild-type plants. Altogether, these findings suggested that ZmERD4 played an important role in early stages of plant adaptation to stress conditions and might be useful in improving plant tolerance to abiotic stress.