Expression Pattern of in Vitro Organogenesis-Associated Genes as Transcriptional Marker in Indian Sandalwood (Santalum Album L.)

Abstract

Indian sandalwood (Santalum album L.) is an expensive wood that requires reproducible method for mass propagation to ensure sustainable use. Organogenesis employs different combinations of the medium;. its suitability is decided based on the explant’s morphological changes. Early prediction of organogenesis in the explant helps reduce the combinations thereby saving time and resources. We initially developed an efficient protocol for the direct and indirect organogenesis (up to shooting development phase) of sandalwood in the present investigation. Woody Plant Media (WPM) supplemented with various concentrations of 6-Bezylaminopurine (BAP) and 1-Naphthaleneacetic acid (NAA) were tested for direct organogenesis, while different treatments consisting of various levels of 2,4-dichlorophenoxyacetic acid (2,4-D), NAA, BAP, Adenine sulphate (ADS), glycine and potassium nitrate were tested for indirect organogenesis.Three stages of leaf development were selected viz., the leaf just after inoculation in WPM media, initial stage of callus formation from leaf and shoot formation for expression pattern analysis. The targeted genes were Alternative oxidase (ao), Late embryogenesis abundant (lea), Cytochrome P450 (cyt-p450), ABC transporter (abct), and Serine-threonine phosphatase (stp) which are associated with in vitro organogenesis. The expression patterns were evaluated to identify a transcription marker. During the initial stages of organogenesis, ao, cyt-p450 and abct showed no/little change in expression in thedirect pathway but up-regulation of ao and abct and downregulation of cyt-p450 were observed in the indirect pathway. Expression of lea was increased up to 70-fold during direct and dropped to half during indirect organogenesis.