Ectopic expression of SsMYB18, a novel MYB transcription factor from Saccharum spontaneum augments salt and cold tolerance in tobacco, Suger Tech:

Abstract

MYB transcription factors play imperative role in developmental and numerous defense processes in plants. In this study, functional characterization of SsMYB18, a single-repeat MYB transcription factor isolated from Saccharum spontaneum, a stress-tolerant wild relative species of sugarcane is reported. SsMYB18 gDNA is 1470 bp in length with an open reading frame of 1074 bp having four introns and five exons, encoding 357 amino acids. The deduced amino acid sequence showed similarities to MYB proteins reported in other plants, including the conserved MYB-binding domain. SsMYB18 is a new member of the MYB transcription factor subfamily. The SsMYB18 gene was transferred in to Nicotiana tabacum by Agrobacterium-mediated transformation. Subsequent screening through PCR and southern, transgenic tobacco lines harboring SsMYB18 were identified and assessed for drought, salt and cold tolerance. Compared to non-transformed tobacco host plants, SsMYB18 overexpressing plants demonstrated appreciably augmented tolerances to salt, cold and drought stresses. In these transgenic lines, the activities of antioxidant enzymes (SOD, POX and CAT) were notably increased virtually to non-transformed ones. The MDA content was less, and levels of chlorophyll and proline were also markedly high in SsMYB18 overexpressed plants than that of non-transformants. The results suggested that transgenic tobacco plants constitutively expressing the single-repeat SsMYB18 transcription factor showed high tolerance to salt and cold, while moderate to drought stresses as compared to controls. Besides SsMYB18 transgenic tobacco plants showed advantage over its homolog SoMYB18 by having additional high tolerance to cold stress rather than only to salt stress