Gene expression studies of Saccharum spontaneum, a wild relative of sugarcane in response to salinity stress.

The study is aimed to assess the morphological, physiological, and molecular responses of seven Saccharum spontaneum clones for salinity stress. These clones (IND-07-1462, IND-07-1465, IND-07-1470, IND-07-1471, IND 16-1761, IND 16-1762, and IND 16-1763) were subjected to salinity stress at two different concentrations of electrical conductivity 6 and 8 ds/m after 60 days of planting. All seven genotypes showed a decrease in relative water content and nitrate reductase activity with an increase in severity of salt stress. The effect was more pronounced in IND-07-1471, while IND-16-1762 exhibited only a minimum drop. Similarly we observed an increase in proline content and lipid peroxidation activity for the genotype IND-07-1471, while IND-16-1762 showed minimum increase. Molecular profiling of genes/transcription factors like salt overly sensitive, responsive to abscissic acid, dirigent, myeloblastosis, ethylene responsive factor associated with salinity stress tolerance showed 19-, 18-, 17-, 10-, and 9-fold increased expression at 8 ds/m of salinity stress, respectively, in IND-16-1762 showed. Based on the evidences obtained from expression profiling, we have cloned the conserved regions of RAB and SOS1 genes. The domain of SOS and RAB was identified as a regulatory subunit of cAMP-dependent protein kinases which is involved in a signaling pathway.

Isolation, cloning and expression analysis of cinnamyl alcohol dehydrogenase (CAD) involved in phenylpropanoid pathway of Erianthus arundinaceus, a wild relative of sugarcane.

In this study we have cloned and characterized cinnamyl alcohol dehydrogenase (CAD) involved in phenylpropanoid pathway which can be utilized for biomass modification for improved saccharification efficiency. The full length gene CAD is of 4 kb containing four exons and three introns, among which the exon 1 and 2 of 88 and 116 bp were conserved with sorghum and Miscanthus CADs. The coding region of CAD was identified with 1098 bp open reading frame (ORF), for 365 amino acids. In the PROSITE analysis, a zinc-containing alcohol dehydrogenase signature (GHEVVGEVVEVGPEV) and an NADP-binding domain motif (GLGGLG) was identified, while the motif analysis showed unique signature sequence of "LEPYLA" at 258-264 aa which was absent in the CAD sequences of other crops. This sequence information on CAD from Erianthus a bioenergy crop might be useful for subsequent research on lignin engineering for improved biomass conversion and for unravelling the impact of lignin on cell wall mechanics.