Abiotic stresses collectively are responsible for crop losses worldwide. Among these, drought and salinity are the most destructive. Different strategies have been proposed for management of these stresses. Being a complex trait, conventional breeding approaches have resulted in less success. Biotechnology has emerged as an additional and novel tool for deciphering the mechanism behind these stresses. The role of compatible solutes in abiotic stress tolerance has been studied extensively. Osmotic adjustment, at the physiological level, is an adaptive mechanism involved in drought or salinity tolerance, which permits the maintenance of turgor under conditions of water deficit, as it can counteract the effects of a rapid decline in leaf water potential. Increasing evidence from a series of in vivo and in vitro studies of the physiology, biochemistry, genetics, and molecular biology of plants suggest strongly that Glycine Betaine (GB) performs an important function in plants subjected to environmental stresses. It plays an adaptive role in mediating osmotic adjustment and protecting the sub-cellular structures in stressed plants, protection of the transcriptional and translational machineries and intervention as a molecular chaperone in the refolding of enzymes. Many important crops like rice do not accumulate glycinebetaine under stress conditions. Both the exogenous application of GB and the genetically engineered biosynthesis of GB in such crops is a promising strategy to increase stress tolerance. In this review we will discuss the importance of GB for abiotic stress tolerance in plants. Further, strategies like exogenic application and transgenic development of plants accumulating GB will be also be discussed. Work done on exogenic application and genetically engineered biosynthesis of GB will be listed and its advantages and limitations will be described.

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The automation of sequencing technologies, flooding in the knowledge of plant-pathogen interactions and advancements in bioinformatics provide tools leading to better knowledge not only of the genome of plant pathogens or microorganism beneficial to plants but also of ways of incorporating genes from microbes into plants as microbial-derived resistance. The identification of various microorganism genes playing key role during pathogensis and the dissection of the signal transduction components of the hypersensitive response and systemic acquired resistance pathways have greatly increased the diversity of options available for tailoring fungus resistant crops. The genetically engineered plants carrying these genes showed spontaneous activation of different defense mechanisms, leading the plant in an elevated state of defense. This 'defense mode' greatly enhances the plant's ability to quickly react to a pathogen invasion and more successfully overcome the infection. The aim of this review is to highlight the dynamic use of genes of microorganisms in enhancing crop tolernace towards fungal intruders by examining the most relevant research in this field.

Study on genetic variability, character association and path analysis was carried out with sixty chrysan-themum genotypes keeping in mind of their applicability in future crop improvement programmes. High phenotypic and genotypic coefficient of variation were found for the character such as number of flower per plant, number of branches per plant, number of primary branches, number of secondary branches, plant spread and plant height. High heritability coupled with high expected genetic advance was observed for number of flower per plant, number of secondary branches and branches per plant. In general, genotypic correlation coefficients were found to be higher than the phenotypic correlations for most of the characters. Number of flowers per plant showed highly positive significant correlation at both genotypic and phenotypic level with plant spread (0.977,0.974), number of primary branches (0.952,0,828), number of branches per plant (0.956, 0.950), number of flower per spray (0.932, 0.821) and number of secondary branches (0.770, 0.744). Path analysis revealed that plant spread, number of primary branch-es, number of flower per spray and number of branches per plant had highest positive and direct effects on number of flowers per plant at genotypic and phenotypic levels. Thus, the useful cultivars can be used as parents in hybridization programme to obtain admirable progenies