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Living organisms alter their gene-expression patterns to withstand stressful conditions. Drought, salinity, heat and chilling are potent abiotic stresses causing an alteration in gene expression. Among these, high temperature stress stimulates Heat Shock Transcription Factors (HSF) which activate heat shock promoters, thus turning on the heat shock genes. Heat shock proteins are, therefore, products of heat shock genes and are classified as per their molecular weight, including small heat shock proteins (sHsps). Hsps are chaperones playing an important role in stress tolerance. These consist of a conserved domain, flanked by N- and C-terminal regions termed the alphacrystallin domain (ACD), and are widely distributed in living beings. Their role as chaperones is to help the other proteins in protein-folding and prevent irreversible protein aggregation. The conserved domains in sHsps are essential for heat-stress tolerance and for their molecular chaperone activity, enabling plant survival under increasing temperatures, leading to adaptations needed for coping with extremes climatic conditions. The present study focusses on identification of ACDs in the whole-genome of Solanum lycopersicum. A multinational consortium, International Tomato Annotation Group (ITAG), funded in part by the EU-SOL Project, provides annotation of the whole genome of S. lycopersicumavailable in the public domain. We used several in silico methods for exploring alpha-crystallin domains in all the chromosomes of S. lycopersicum. Surprisingly, these ACDs were found to be present in all the chromosomes excepting Chromosome 4; these are highly conserved in sHsps and are related to heat tolerance.

Abiotic stress often causes a series of morphological, physiological, biochemical and molecular changes that affect plant growth, development and productivity. To cope with abiotic stresses, it is necessary to understand plant responses to stresses that disturb homeostatic equilibrium at the cellular and molecular level. Genomic information on Capsicum annuum has been explored to identify microsatellite markers associated with abiotic stress tolerance and assign them to cognate functional groups related to specific stress responses. Several in silico methods have been used to identify simple sequence repeats associated with stress responsive gene candidates in Capsicum annuum. In this study, a microsatellite marker has been identified in Capsicum annuum associated with Nucleoside Diphosphate Kinase (NDK) having multiple environmental stress tolerance (oxidative, high temperature and salt stress) and which is also highly conserved in crops of Solanaceae. These are house-keeping enzymes that maintain intracellular levels of all nucleoside triphosphates (NTP) with the exception of adenosine triphosphate (ATP). These are also involved in phytochrome A response, UV-B signaling, auxin responses and oxidative stress signaling.

Drought and heat contribute to much of the yield decline in agricultural lands all over the world. The basic physiological responses developed against drought and heat stress overlie each other, as; both these stresses eventually lead to dehydration of the cell and to osmotic imbalance. To cope with abiotic stresses, it is necessary to understand plant responses to stresses that disturb homeostatic equilibrium at the cellular and molecular level. Although there has been remarkable progress in this with development of microarray-based expression profiling methods (together with genomic sequence data), understanding on ways to employ these data to engineer plants with improved stresstolerance is still at a nascent stage. However, these data can be used for discovering genes, functional microsatellites and regulatory elements using in silico methods. In this context, single nucleotide repeat marker sequences have been identified which is associated with small heat-shock protein sequence (sHSP) for heat tolerance in Capsicum annuum. These sHSP sequences have some structural features in common; its characteristic is that it is homologous and highly conserved. These sequences have been analyzed for molecular evolutionary conservedness in solanaceaeous crops and have been found to have a single nucleotide repeat sequence and a highly conserved sHSP sequence.