Abiotic Stress. In: Hirano H, Sano Y, Hirai A, Sasaki T, editors. Rice Biology in the Genomics Era. Berlin: Springer Berlin Heidelberg; 2008. pp. 337-55. [DOI: 10.1007/978-3-540-74250-0_25]

Low temperature tolerance in plants: Changes at the protein level

Low temperature (LT) is one of several important environmental stresses influencing plant performance and distribution. Adaptation to LT is a highly dynamic stress-response phenomenon and involves complex cross-talk between different regulatory levels. Although plants differ in their sensitivity to LT, in temperate species low nonfreezing temperatures cause noticeable alterations in various biochemical and physiological processes that can potentially improve freezing tolerance. This adaptation is associated with changes in the expression pattern of genes and their protein products. Proteins are the major players in most cellular events and are directly involved in plant LT responses, thereby proteome analysis could help uncover additional novel proteins associated with LT tolerance. Proteomics is recommended as an appropriate strategy for complementing transcriptome level changes and characterizing translational and post-translational regulations. In this review, we considered alterations in the expression and accumulation of proteins in response to LT stress in the three major cereal crops produced worldwide (wheat, barley, and rice). LT stress down-regulates many photosynthesis-related proteins. On the contrary, pathways/protein sets that are up-regulated by LT include carbohydrate metabolism (ATP formation), ROS scavenging, redox adjustment, cell wall remodelling, cytoskeletal rearrangements, cryoprotection, defence/detoxification. These modifications are common adaptation reactions also observed in the plant model Arabidopsis, thus representing key potential biomarkers and critical intervention points for improving LT tolerance of crop plants in cold regions with short summers. We believe that an assessment of the proteome within a broad time frame and during the different phenological stages may disclose the molecular mechanisms related to the developmental regulation of LT tolerance and facilitate the progress of genetically engineered stress-resistant plant varieties.

Recent advances in polyamine metabolism and abiotic stress tolerance

Global warming is an alarming problem in agriculture and its effect on yield loss has been estimated to be five per cent for every degree centigrade rise in temperature. Plants exhibit multiple mechanisms like optimizing signaling pathway, involvement of secondary messengers, production of biomolecules specifically in response to stress, modulation of various metabolic networks in accordance with stress, and so forth, in order to overcome abiotic stress factors. Many structural genes and networks of pathway were identified and reported in plant systems for abiotic stress tolerance. One such crucial metabolic pathway that is involved in normal physiological function and also gets modulated during stress to impart tolerance is polyamine metabolic pathway. Besides the role of structural genes, it is also important to know the mechanism by which these structural genes are regulated during stress. Present review highlights polyamine biosynthesis, catabolism, and its role in abiotic stress tolerance with special reference to plant systems. Additionally, a system based approach is discussed as a potential strategy to dissect the existing variation in crop species in unraveling the interacting regulatory components/genetic determinants related to PAs mediated abiotic stress tolerance.