Antimicrobial Snakin-1 peptide is also involved in GA signaling Pathway

ALMASIA, NATALIA INÉS; NARHIRÑAK, VANESA; HOPP H. ESTEBAN; DEL VAS, MARIANA; VAZQUEZ-ROVERE, CECILIA

Congreso; XLVI REUNIÓN ANUAL DE SAIB; 2010

Snakin-1 (StSN1) is an antimicrobial peptide isolated from S.tuberosum that was shown to be active against fungal and bacterial pathogens in vitro and in vivo. Recently, we suggested that StSN1 has a dual function in defense and development. Other members of its family (snakin/GASA) have already been implied in diverse processes such as cell division/elongation, transition to flowering and signaling pathways. In addition, it has been demonstrated that most GASA genes are transcriptionally up-regulated by gibberellic acid (GA) and upon the analysis of transgenic lines harboring SN1 promoter region fused to GUS reporter gene we demonstrated that in potato SN1 promoter was induced after GA treatments. We have previously obtained potato transgenic lines overexpressing or silencing StSN1 gene and in this work they were further characterized. Even when overexpressing lines did not show remarkable phenotypic differences from wild type, silenced plants exhibited altered leaf morphology, internode elongation, flowering timing, tuberization, plant growth and development. Since their dwarf phenotype was rescued by exogenous GA3, it suggests that they are defective in GA biosynthesis. qRTPCR confirmed that GA 20-oxidase is down-regulated and consequently the contents of bioactive GAs could be decreased. Our results suggest that StSN1 is involved in the GA signaling pathway.that was shown to be active against fungal and bacterial pathogens in vitro and in vivo. Recently, we suggested that StSN1 has a dual function in defense and development. Other members of its family (snakin/GASA) have already been implied in diverse processes such as cell division/elongation, transition to flowering and signaling pathways. In addition, it has been demonstrated that most GASA genes are transcriptionally up-regulated by gibberellic acid (GA) and upon the analysis of transgenic lines harboring SN1 promoter region fused to GUS reporter gene we demonstrated that in potato SN1 promoter was induced after GA treatments. We have previously obtained potato transgenic lines overexpressing or silencing StSN1 gene and in this work they were further characterized. Even when overexpressing lines did not show remarkable phenotypic differences from wild type, silenced plants exhibited altered leaf morphology, internode elongation, flowering timing, tuberization, plant growth and development. Since their dwarf phenotype was rescued by exogenous GA3, it suggests that they are defective in GA biosynthesis. qRTPCR confirmed that GA 20-oxidase is down-regulated and consequently the contents of bioactive GAs could be decreased. Our results suggest that StSN1 is involved in the GA signaling pathway.