Sugarcane represents an important renewable source among biofuel crops with high capability to assimilate carbon among the C4 plants. Limited availability of freshwater renders this crop uneconomical, warranting the necessity for the development of varieties with higher water use efficiency and tolerant to water deficiency stress. Sugarcane variety cv. Co740 was subjected to varied levels of water deficiency stress to isolate transcripts differentially expressed to the imposed stress. The leaf relative water content was used as a measure to estimate the stress response. PCR-based cDNA suppression subtractive hybridization technique was applied to construct forward subtracted library for differentially expressed genes under stress. Dot blot-selected 158 clones showing elevated response were sequenced, of which 62% resembled similarity with known functional genes, 12% with hypo-

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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.

Sugarcane (Saccharum officinarum L.) is one of the most important field crops grown in the tropics and sub-tropics. More than half of the world's sugar is derived from sugar cane. Conventional methods have greatly contributed to crop improvement; however limitations such as complex genome, narrow genetic base, poor fertility, susceptibility to biotic and abiotic stresses and long duration to breed elite cultivars still impose a challenge. Sugarcane, thus, is a suitable candidate for application of biotechnology and genetic engineering tools. In this direction, in vitro culture systems and related biotechnologies have been developed as novel strategies for sugarcane improvement. Studies have been conducted towards employing in vitro culture combined with radiation/chemical induced mutagenesis for mutant isolation. Advancements in genomics tools have paved the way for a detailed understanding of the mechanism underlying biotic and abiotic stress responses. The potential of the current genomics programs, aimed at elucidating the structure, function, and interactions of the sugarcane genes, will revolutionize the application of biotechnology to crop improvement. Genetically modified sugarcane with increased resistance to agronomic traits including biotic and abiotic stresses, yield and juice could become useful in breeding for better varieties. This review outlines some of the biotechnological developments that are in place and tailored to address important issues related to sugarcane improvement.

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.