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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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