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Chitinases are essential enzymes in crustaceans that play an important role in the molting cycle and digestion of chitin. Based on the present study, the chitinase encoding cDNA of Penaeus mergueinsis with a length of 1440 bp containing 467 amino acids was sequenced by PCR and then its phylogenetic and bioinformatics analysis was performed. The new sequence was registered in the gene bank with the accessition number MT250539 and the molecular weight of the protein resulting from this sequence was predicted to be 51.84 KDa and the theoretical isoelectric point of 4.79. Comparison of amino acid sequences among penaeid chitinases showed the highest identification (about 97 to 92%) with P. mondon chi-3, F. chinensis, P. vannamei and P. japonicus chi-3, respectively. Phylogenetic studies showed that chitinase in the present study belongs to group 3 chitinases. Revealed protein pattern analyzes showed that chitinase from P. mergueinsis contained the catalytic domain Glyco-18 at position 2-347, a chitin-binding site of pritrophin A at position 403-456, a disulfide bridge formed by two cysteines at position 436-421 is a chitin-binding domain type 2, active site (¹¹7FDGLDMDWE¹²⁵), a proline / threonine-rich region at positions 376-412, and a putative N-glycosylation site at position 427-424 (NTSG). The present study shows that the P. mergueinsis sequence contains active chitinase motifs similar to previously sequenced chitinases, and in the case of cloning, expression and purification probably has functional and structural features similar to the enzymes of the above species.

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Pigeonpea (Cajanus cajan (L) Millsp.) is a drought tolerant legume widely grown in the arid and semi-arid tropics of the world which possesses a deep and extensive root system that succors a number of important physiological and metabolic functions to cope with drought. Application of available functional genomics approaches to improve productivity under water deficit requires a better understanding of the mechanisms involved during pigeonpea’s response to water deficit stress. In order to identify the genes associated with water deficit in pigeonpea, Suppression Subtractive Hybridization cDNA library was constructed from polyethylene glycol-induced water deficit young root tissues from pigeonpea and 157 high quality ESTs were generated by sequencing of 300 random clones which resulted in 95 unigenes comprising 37 contigs and 58 singlets. The cluster analysis of ESTs revealed that the majority of the genes had significant similarity with known proteins available in the databases along with unique and hypothetical/uncharacterized proteins. These differential ESTs were characterized and genes relevant to the specific physiological processes were identified. Northern blot analysis revealed the up regulation of ornithine aminotransferase, cyclophilin, DREB and peroxidase. The differentially expressed sequences are conceived to serve as a potential source of stress inducible genes of the water deficit transcriptome and hence may provide useful information to understand the molecular mechanism of water deficit management in legumes. 

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Drought sensitivity is considered as a major concern for chickpea (C. arietinum) seed production. Determination of drought adaptation mechanisms is an essential constituent of this crop breeding programs. With this purpose, the present research was conducted to distinguish the molecular basis of chickpea drought tolerance using cDNA-AFLP approach. The expression profile was compared between drought tolerant (ICCV2 and FLIP9855C) and susceptible lines (ILC3279) of chickpea under three drought treatments including well-watered, intermediate, and severe stress; where soil water content was kept at 85–90%, 55–60%, and 25–30% of Field capacity, respectively. Totally, 295 transcript-derived fragments (TDFs) were visualized. Among the differentially expressed TDFs, 72 TDFs were sequenced. Sequenced cDNAs were categorized in different functional groups involved in macromolecules metabolism, cellular transport, signal transduction, transcriptional regulation, cell division and energy production. Based on the results, ribosomal protein S8, mitochondrial chaperone, proteases, hydrolases, UDP -glucuronic acid decarboylase, 2-hydroxyisoflavanone dehydratase, NADPH dehydrogenase, chloride channels, calmodulin, ABC transporter, histone deacetylase and factors involved in chloroplast division were among genes that were affected by drought stress. Similarity search in data base showed that cell wall elasticity, isoflavonoids, maintenance of structure and function of proteins through increase in expression of mitochondrial chaperones, programed cell death, and remobilization of storage material from leaves to seeds were among mechanisms that distinguished differences between drought tolerant and drought susceptible lines.