Insights into stress responsiveness of MusaANS promoter- an anthocyanidin synthase gene from banana

Biotic and/or abiotic stressors dampen crop productivity and affect sustainability worldwide. To address these challenges, it is crucial to associate the desired stress-responsive genes with specific stress-inducible promoters for developing plant varieties with broad-spectrum stress tolerance. In this study, the promoter region of the anthocyanidin synthase (ANS) gene from banana was thoroughly analysed, and its tissue-specific expression, in response to various environmental insults was delineated. Comprehensive analyses such as transcript abundance-based expression profiling and evaluation of ProANS-GUS activity in transgenic lines was performed and the expression patterns thus obtained were corroborated with the presence of corresponding cis-elements in the promoter region. Transcription of the ANS gene was strongly altered by the imposition of environmental stresses or signaling molecules. MusaANS transcripts in banana were significantly suppressed by exposure to high salinity, salicylic acid or abscisic acid, while its expression was stimulated by methyl jasmonate as well as drought. In P_MusaANS-GUS transformed tobacco lines, P_MusaANS activity was mainly observed in the vascular tissue under control conditions. Drought, salinity, MeJA, salicylic acid and ABA strongly activated P_MusaANS whereas, ethephon suppressed its activity. Thorough scrutiny of P_MusaANS showed the presence of a diverse array of stress and phytochemical response-associated cis-elements, such as ARR1AT (cytokinin), ACGTATERD1 (drought), DPBFCOREDCDC3 (ABA), ABREOSRAB21 (ABA), ASF1MOTIFCAMV (salicylic acid), ERELEE4 (ethylene) and BIHD1OS (pathogen response). Based on the results, P_MusaANS is differentially activated under stress and hence is an excellent stress-inducible candidate promoter for producing resilient transgenic crop varieties.