SummaryOsmotin is a plant PR-5 protein. It has a broad spectrum of antifungal activity, yet also exhibits speci®city for certain fungal targets. The structural bases for this speci®city remain unknown. We show here that full sensitivity of Saccharomyces cerevisiae cells to the PR-5 protein osmotin is dependent on the function of MNN2, MNN4 and MNN6. MNN2 is an a-1,2-mannosyltransferase catalyzing the addition of the ®rst mannose to the branches on the poly l,6-mannose backbone of the outer chain of cell wall Nlinked mannans. MNN4 and MNN6 are required for the transfer of mannosylphosphate to cell wall mannans. Null mnn2, mnn4 or mnn6 mutants lack phosphomannans and are defective in binding osmotin to the fungal cell wall. Both antimannoprotein antibody and the cationic dye alcian blue protect cells against osmotin cytotoxicity. MNN1 is an a-1,3-mannosyltransferase that adds the terminal mannose to the outer chain branches of N-linked mannan, masking mannosylphosphate. Null mnn1 cells exhibit enhanced osmotin binding and sensitivity. Several cell wall mannoproteins can bind to immobilized osmotin, suggesting that their polysaccharide constituent determines osmotin binding. Our results demonstrating a causal relationship between cell surface phosphomannan and the susceptibility of a yeast strain to osmotin suggest that cell surface polysaccharides of invading pathogens control target speci®city of plant PR-5 proteins.

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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Characterization of genetic diversity by employing molecular tools is a prerequisite in developing strategies for conservation and utilization of poultry genetic resources. We assessed genetic variation within and between six Indian chicken populations (Naked Neck, White Silkies, Commercial Layer and Broiler, Giriraja and Desi) using nine microsatellite markers. Seven loci were polymorphic in all populations, with the number of alleles varying from -to ,1 per locus and ..+ to 2.0 per population. Average heterozygosity and gene diversity in the populations were *.02 and *.00, respectively. Some populations and loci deviated from Hardy-Weinberg equilibrium. Except Naked Neck, none of other populations was in genotypic disequilibrium for a single pairwise locus combination. F-statistics indicated that populations are genetically structured, ῌ2/ῌ of the total genetic variation being due to genetic di#erentiation within the populations. Estimates of Latter's FST and Nei's DS genetic distances revealed relatively close genetic similarity between Naked Neck and Giriraja, while White Silkies was the most distant. An estimated divergence time between Naked Neck and Giriraja was over+** years, with a comparatively longer (over ./* years) period of separation between Giriraja and White Silkies. We suggest that there is an essential room left for genetic improvement of Indian native breeds and commercial stocks.

The sugarcane (Saccharum officinarum) stress-related MYB transcription factor gene, ScMYBAS1, demonstrated induced response to water deficit and salt stress in our previous study. To elucidate its stress tolerance mechanism at the transcriptional level, we isolated and characterized the promoter (PScMYBAS1, 1,033 bp) flanking the 5' ScMYBAS1 coding region from the sugarcane genome. A series of PScMYBAS1 deletion derivatives from the transcription start site (-56, -152, -303, -442, -613, -777, -843, -1,033) was fused to the uidA reporter gene (GUS) and each deletion construct was analyzed by Agrobacterium-mediated transient transformation in tobacco leaves subjected to dehydration, salinity, cold, wounding, gibberellic acid (GA), salicylic acid (SA), and methyl jasmonic acid (MeJA). Deletion analysis of the promoter, PScMYBAS1, suggested that the 303-bp promoter region was required for basal expression. Promoter fragments, 777 bp or longer showed ~twofold to ~fourfold increased induction of GUS in response to abiotic stress (dehydration, salt, cold, wounding) and hormone (SA, MeJA) treatments. These findings further our understanding of the regulation of ScMYBAS1 expression and provide a new stress-inducible promoter system in transgenic plants.

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Genetic improvement of sugarcane variety CoC 671 was carried out through somaclonal variation. The somaclones were obtained by developing callus on 0.8M EMS and 13.57M 2-4.D containing medium. All the 310 regenerated plants were hardened in green house and planted in field for preliminary selection. On the basis of biometric and biochemical parameters 17 somaclones were evaluated in rod row trial and then for smut resistance supplementing with smut inoculum and detection by PCR.The somaclonal variants TC 906 was resistant and TC 922 was moderately resistant to smut. Somaclone TC 922 (2.17 kg, 165 t/ha, 3.34 cm) and TC 906 (2.07 kg, 144.11 t/ha, 3.25 cm) were superior in single cane weight, cane yield and cane diameter over their donor CoC 671 (1.72 kg, 128 t/ha, 2.74 cm). The morphological variations viz. stem colour, internodal alignment, internodal waxiness and leaf width were distinct and stable. The present study reports beneficial traits of the somaclones derived from CoC 671 and their field performance, especially for smut resistance and yield traits and early maturity.

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