Transcriptional regulation of annexins in Indian Mustard, Brassica juncea and detoxification of ROS in transgenic tobacco plants constitutively expressing AnnBj1.

Annexins in plants constitute a multigene family and there is growing evidence for their involvement in response to various stress treatments. We have cloned and characterized six different annexin genes from mustard. The transcript regulation of these genes was studied in treatments with various signaling molecules, osmotic stress, oxidative stress conditions and wounding. All these annexins were found to be reponsive to Abscisic acid (ABA). Two genes (AnnBj1 and AnnBj3) were found to respond to most of the stress conditions, which suggest their possible role in cross-talk in multiple signaling pathways. Wound response signal methyl jasmonate (mJA) caused rapid and high expression of AnnBj4. We extended our previous study and showed that transgenic tobacco plants heterologously expressing AnnBj1 evidenced mannitol induced ROS detoxification. These results suggest Brassica annexins may have potential role in alleviating abiotic stress, which should be characterized by in vivo function based studies through silencing by RNAi or overexpression in transgenic plants.