Physiological and molecular responses for long term salinity stress in common fig (Ficus carica L.)

Salinity stress in increasingly becoming a major challenge in current and expanding agricultural ecosystems. Unlike temporal abiotic stresses, plants are usually exposed to salinity stress for an entire lifespan. Therefore, a long term effect (10 weeks) of continuous salinity exposure was investigated for three common fig landraces (Zraki, Mwazi, and Khdari). Both relative water content and chlorophyll content decreased with elevated salinity stress, while stem length barely changed. The most prominent decline was observed in root biomass. The data would align common fig to moderately tolerant threshold slop with a C-50 range of 100 to 150 mM NaCl. A high and significant correlation was evident between root biomass and chlorophyll content (85%). Concurrently, differential expression of putative salinity responsive genes in common fig were determined; signal peptide peptidase-like 2B (FcSPPL2B), dehydration responsive element binding protein (FcDREB), calcineurin B-like protein (CBL)-CBL-interacting serine/threonine-protein kinase 11 (FcCIPK11), sorbitol dehydrogenase (FcSORD) and dehydrin (FcDHN). The data were discussed for each gene in respect of its potential role in salinity stress mitigation. The combined physiological and molecular data would conclude Zraki as the most salinity tolerant genotype. The major implication of the data emphasizes the tremendous genotype by environment (salinity stress) interaction in common fig.