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.
Saccharum spontaneum, a wild relative of sugarcane, is highly tolerant to drought and salinity. The exploitation of germplasm resources for salinity tolerance is a major thrust area in India. In this study, we utilized suppression subtractive hybridization (SSH) followed by sequencing for the identification of upregulated transcripts during salinity stress in S. spontaneum clones coming from different geographical regions of India. Our sequencing of the SSH library revealed that 95% of the transformants contained inserts of size 200–1500 bp. We have identified 314 differentially expressed transcripts in the salinity‐treated samples after subtraction, which were subsequently validated by quantitative real‐time polymerase chain reaction. Functional annotation and pathway analysis revealed that the upregulated transcripts were a result of protein modifications, stress, and hormone signaling along with cell wall development and lignification. The prominently upregulated transcripts included UDP glucose dehydrogenase, cellulose synthase, ribulose, cellulose synthase COBRA, leucine‐rich protein, NAC domain protein, pectin esterase, ABA‐responsive element binding factor 1, and heat stress protein. Our results is a step forward the understanding of the molecular response of S. spontaneum under salinity stress, which will lead to the identification of genes and transcription factors as novel targets for salinity tolerance in 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 NADPbinding 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.
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