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.

Screening and Molecular Identification of New Microbial Strains for Production of Enzymes of Biotechnological Interest

ABSTRACT: This research focused on isolation, identification and characterization of new strains of fungi and bacteria, which were able to produce extracellular xylanase, mannanase, pectinase and α-amylase. Fungi isolates were identified on the basis of analyses of 18S gene sequencing and internal transcribed spacer region. The closest phylogenetic neighbors according to 18S gene sequence and ITS region data for the two isolates M1 and SE were Aspergillus fumigatus and Aspergillus sydowii, respectively. I4 was identified as Bacillus mojavensis on the basis of the 16S rRNA gene sequencing and biochemical properties. The enzyme production was evaluated by cultivating the isolated microorganisms in liquid-state bioprocess using wheat bran as carbon source. Two fungi (M1, and SE) and one bacterium (I4) strains were found to be xylanase producer, and several were proven to be outstanding producers of microbial xylanase. The strains producing xylanase secreted variable amounts of starch-debranching enzymes and produced low level β-mannan-degrading enzyme systems. The bacterium strain was found to be capable of producing pectinolytic enzymes on wheat bran at high level. Some of the strains have good potential for use as sources of important industrial enzymes.