Analysis of EIN2 gene expression in Petunia (Petunia×hybrida) and study of its regulatory role in ethylene signaling pathway

The plant hormone ethylene regulates a variety of processes، such as growth، seed germination، flower initiation، organ abscission، adventitious root formation، leaf expansion، fruit ripening، and petal senescence after fertilization. Flower senescence is one of the developmental processes in which ethylene plays a key role. The climacteric rise of endogenous ethylene in these flowers has been shown to play a regulatory role in the events leading to death of some of the floral organs. In recent studies، loss-of-function ETHYLENE INSENSITIVE2 (EIN2) mutation showed ethylene insensitivity which indicated an essential role of EIN2 in ethylene signaling. As the EIN2 gene، a positive regulator، plays a central role in ethylene signal transduction، we characterized its expression pattern in Petunia. The results showed that EIN2 transcript was present in all of tissues، with highest levels in style/stigma and ovary opened petunia flowers. Also، expression analysis was carried out to evaluate the effects of pollination، glucose، ABA، ACC on ethylene biosynthesis and signaling in petunia flower. The results indicate that glucose may play an important role in ethylene-associated regulation of flower senescence. These results demonstrate that NtEIN2 mediates ethylene signals in wide range of physiological processes and also cross-talk with other hormones like ABA in environmental stresses.