Abiotic stresses such as extremes of temperature and pH, high salinity and drought, comprise some of the major factors causing extensive losses to crop production worldwide. Understanding how plants respond and adapt at cellular and molecular levels to continuous environmental changes is a pre-requisite for the generation of resistant or tolerant plants to abiotic stresses. In this review we aimed to present the recent advances on mechanisms of downstream plant responses to abiotic stresses and the use of stress-related genes in the development of genetically engineered crops.

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Cassava (Manihot esculenta Crantz) is one of the most important tropical crops showing tolerance to abiotic stress and adaptations to a wide range of environmental conditions. Here, we aimed to isolate and characterize the full-length cDNA and genomic sequences of a cassava translationally controlled tumor protein gene (MeTCTP), and evaluate its potential role in response to salt stress. The MeTCTP full-length cDNA sequence encodes for a deduced protein with 168 amino acid residues, with theoretical isoelectric point and molecular weight of 4.53 and 19 kDa, respectively, containing two putative signatures of TCTP family and one site for myristoylation. The MeTCTP genomic sequence includes four introns and five exons within a 1,643 bp coding region, and a 264 bp partial promoter sequence containing several putative cis-acting regulatory elements, among them, two putative GT-1 motifs, which may be related to response to sodium chloride (NaCl) and pathogen infection. Semi-quantitative RT-PCR assays showed that MeTCTP transcripts were higher in roots than leaves, and were significantly increased in detached leaves treated with NaCl. Furthermore, the recombinant MeTCTP conferred a protective function against salt stress in bacterial cells. We report for the first time the molecular cloning and characterization of a cassava TCTP with potential role in salt-stress response. Since salinity is one the most important abiotic factors affecting the production of crops worldwide, the MeTCTP gene could be a candidate gene for generation of salt tolerant crops.

Plant cystatins, also called phytocystatins, constitute a family of specific cysteine protease inhibitors found in several monocots and dicots, where they can be involved in the regulation of several endogenous processes and in defense against pests and pathogens, as well as in response to abiotic stress. In this mini-review we aimed to present isolated and characterized phytocystatins with potential use in control of plant disease caused by fungi.