Investigation of the response to salinity of transgenic potato plants overexpressing the transcription factor StERF94

Salinity is one of the most important constraints threatening the cultivation of potato plants (Solanum tuberosum L.). Itaffects plant growth and leads to significant yield loss. Consequently, it is important to improve the tolerance of potatoplants to salinity. In this context, we investigated the involvement of a potato ethylene responsive factor (StERF94) in plantresponse to salinity, since our previous genome-wide analysis showed that it may be related to biotic and abiotic stressresponse. ERF proteins belong to a large family of transcription factors that participate in plant response to abiotic stresses.We have previously identified the StERF94 gene which shows increased expression in potato plants submitted to salttreatment. In this study, transgenic potato plants overexpressing StERF94 were produced and submitted to salt treatment(100 mM NaCl) in vitro and under greenhouse culture conditions. StERF94 transgenic lines showed lower decrease of stemelongation under salt treatment in comparison to non-transgenic wild-type plants. Moreover, these plants showed a lowlevel of H2O2 and Malondialdehyde content, and an increase in catalase and GPX (Gluthation peroxidase) activitiescompared to non-transgenic plants. In a second step, enhanced expression of some target genes for example CuZn-SOD,DHN25 (Dehydrin) and ERD (Early Responsive to Dehydration) was noted in the StERF94 transgenic plants, submitted tosalt treatment. The StERF94 factor was also involved in the activation of osmoprotectant synthesis. Taken together, all thesedata suggest that overexpression of the StERF94 transcription factor increases the tolerance of potato plants to salinity byimproving plant growth, osmoprotectant synthesis and antioxidant activityleading to low oxidative stress damage.

Expression analysis of bZIP transcription factor encoding genes in response to water deficit stress in rice.

In plants, basic region/leucine zipper motif (bZIP) transcription factors regulate several developmental processes and activate genes in response to biotic and abiotic stresses. Role of stress responsive bZIP transcription factors was studied in paddy in relation to different stages of development and water deficit stress (WDS) in a drought tolerant cultivar N22 and susceptible IR 64. Further, relative water content (RWC), membrane stability index (MSI) and abscisic acid (ABA) content were measured as indices of WDS at different stages of development and levels of stress. Expression of stress responsive bZIP transcription factors was directly correlated to developmental stage and WDS and indirectly to RWC, MSI and ABA content.

Cloning and characterization of a water deficit stress responsive transcription factor gene from Oryza sativa L.

Understanding the biochemical and molecular basis of drought mechanism in rice is important as drought is one of the major causes affecting rice crop adversely. A 1017 bp gene sequence encoding AP2/ERF family TF was isolated from Oryza sativa sp. Indica cv N22 encoding a protein of 338 amino acid residues, with a molecular weight of 36.58 kDa, and no intron in the ORF. The gene was named as AP2/ERF-N22(2) different from the drought responsive gene AP2/ERF-N22 that we reported earlier. AP2/ERF-N22(2) has entirely different characteristics from that of AP2/ERF-N22. It has a single AP2 domain of 55 amino acid residues and a cluster of acidic amino acid residues at the C-terminal region, which could function as a trans-activation domain. Presence of NLS indicates that it is a nuclear localized transcription factor encoding gene. It falls in group VI L, sharing characteristic similarities. Arabidopsis members of group VI L have been shown to be involved in response to cytokinin under drought stress.