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MYB transcription factors play vital role in various biotic and abiotic defense responses. A differentially expressed, stress-responsive, R2-R3-type, MYB-like transcription factor-associated EST (MYB18) from drought and salt SSH libraries was identified. A full-length DNA sequence of a MYB gene, namely SoMYB18, was isolated from sugarcane var. Co740. SoMYB18 encodes for an ORF of 1284 bp having 427 amino acids with 47.43 kDa theoretical protein size MYB protein. The phylogenetic characterization of the deduced amino acid sequence showed similarity with monocot MYB proteins. SoMYB18 is a member of the R2R3-MYB subfamily, containing two MYB DNA-binding domains (R2, R3) and a SANT/MYB DNA-binding domain. The SoMYB18 gene was transferred into tobacco, and stable transgenic plants expressing SoMYB18 were evaluated for salt, drought and cold tolerance. Compared to un-transformed tobacco plants, SoMYB18-expressing plants exhibited notably improved tolerances to salt and drought stress. The SOD and CAT activities were considerably elevated in transgenic plants, as well as proline accumulation and chlorophyll content were considerably high and lipid peroxidation was reduced relative to un-transformed plants during salt stress. These results indicated that this sugarcane R2R3-MYB transcription factor plays key role in regulating stress responses and may be implicated in the activation of salt-related genes, being useful in improving the salt stress tolerance in crops.

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Sugarcane yellow leaf virus (SCYLV) is a distinct member of the Polerovirus genus of the Luteoviridae family. SCYLV is the major limitation to sugarcane production worldwide and presently occurring in most of the sugarcane growing countries. SCYLV having high genetic diversity within the species and presently ten genotypes are known to occur based on the complete genome sequence information. SCYLV is present in almost all the states of India where sugarcane is grown. Virion comprises of 180 coat protein units and are 24-29 nm in diameter. The genome of SCYLV is a monopartite and comprised of single-stranded (ss) positive-sense (+) linear RNA of about 6 kb in size. Virus genome consists of six open reading frames (ORFs) that are expressed by sub-genomic RNAs. The SCYLV is phloem-limited and transmitted by sugarcane aphid Melanaphis sacchari in a circulative and non-propagative manner. The other aphid species namely, Ceratovacuna lanigera, Rhopalosiphum rufiabdominalis, and R. maidis also been reported to transmit the virus. The virus is not transmitted mechanically, therefore, its transmission by M. sacchari has been studied in different countries. SCYLV has a limited natural host range and mainly infect sugarcane (Sachharum hybrid), grain sorghum (Sorghum bicolor), and Columbus grass (Sorghum almum). Recent insights in the protein-protein interactions of Polerovirus through protein interaction reporter (PIR) technology enable us to understand viral encoded proteins during virus replication, assembly, plant defence mechanism, short and long-distance travel of the virus. This review presents the recent understandings on virus biology, diagnosis, genetic diversity, virus-vector and host-virus interactions and conventional and next generation management approaches.

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Efforts were carried out to isolate vegetative insecticidal protein genes from local isolates of Bacillus thuringiensis. The study focused on vip1/vip2 binary toxin, considering its insecticidal potential against coleopteran and hemipteran pests. Thirty nine B. thuringiensis local strains and one standard reference strain (HD 1) were screened for the presence of vip1/vip2 gene by using a PCR approach. Among 39 isolates only four isolates (PDKV-08, PDKV-27, PDKV-28 and NCIM-5112) showed the presence of the desired gene. SDS-PAGE screened profiling of the isolates showed the presence of 95 kDa and 50 kDa protein which confirmed our PCR study. For further characterization, the vip1/vip2 gene was cloned from the PDKV-08 isolate by using the pJET1 cloning vector. Sequence homologous analysis confirms the presence of the vip1/vip2 gene. A further BLAST analysis also revealed that the isolated vip1/vip2 gene is highly conserved and showed a maximum of 88% sequence homology with existing vip1/vip2 genes. Insect toxicological potential was also elucidated by performing bioassays of PDKV-08 supernatant proteins against the coleopteran store grain pest, Sitophilus zeamais. The results from a bioassay revealed 60% mortality.

MYB transcription factors are one of the most important mediators for the survival of plants under multiple stress responses. In the present study, EaMYB18, encoding a single R3 repeat MYB DNA binding domain was isolated from stress-tolerant wild relative species of sugarcane Erianthus arundinaceus. In silico analysis of 948 bp coding mRNA sequence of EaMYB18 exhibited the presence of four exons and three introns. Further, the EaMYB18 gene was transformed in tobacco and its stable inheritance was confirmed through antibiotic resistance screening, PCR amplification and Southern hybridization blotting. Results of the estimation of MDA, proline, total chlorophyll and antioxidant activities of EaMYB18 transgenic tobacco lines exhibited least oxidative damage under drought and cold stress over the untransformed ones, the over-expression of EaMYB18 has improved drought and cold stress tolerance ability in tobacco. The comparative physiological and biochemical analysis of transgenic tobacco plants overexpressing SoMYB18, SsMYB18 and EaMYB18, revealed that the EaMYB18 and SsMYB18 transgenic plants demonstrated effective tolerance to drought and cold stresses, while SoMYB18 showed improved tolerance to salt stress alone. Amongst these three genes, EaMYB18 displayed the highest potential for drought and cold stress tolerances as compared to SoMYB18 and SsMYB18 genes.

This work provides a thorough understanding about the function ofcis-acting elements regarding drought, salt, cold and wounding stress.