Plant acclimation to environmental stress: a critical appraisal

Being a prime source of food, agriculture sustains almost all life-forms on the Earth. However, apart from natural calamities, a range of man-made activities are causing significant increase in environmental stresses for plant growth. Adverse conditions, in turn, restrict crop plants to reach their full genetic potential of producing high yield (Anjum et al., 2014). Also, agriculture is under pressure to accelerate crop-yield to feed rapidly increasing world-population that is projected to stabilize at around 9.2 billion toward the year 2050 (Singh, 2012). Thus, a clear understanding of the strategies for sustainably improving crop-health, development and productivity under adverse conditions is timely and imperative. With the major aim of achieving plant-environmental stress-acclimation, discussions are focused in the 17 chapters of the entitled above edited book mainly on two major tools: (a) genetically engineering stress-responsive genes, and (b) sustainable agriculture practices. Under the categorized above first tool, the strategy of employing DREB-like proteins, homeobox genes, APETALA2 gene-family, and G-proteins for overcoming environmental-stresses and increasing crop-yield under adverse conditions. Notably, exhaustive studies on the potential role of the dehydration-responsive element-binding proteins (DREB2)-like proteins and their interaction with abscisic acid particularly during seed-germination/seedling-growth, may give us an insight in plant developmental processes and stress-adaptation/tolerance-mechanisms. A gradual rise in atmospheric temperature is going to be a major challenge for crop research in near future. To this end, exhaustive molecular genetic studies were recommended for both understanding and getting more insights into thermo-sensing-mechanisms in thermal-stressed crops. Nevertheless, development of several functional tools like molecular maps, express sequence tags (ESTs), and understanding the mechanism of transgenes expression in chloroplasts particularly in important bioenergy crops can help in the minimization of the rapidly increasing marginal lands, the contributions. Transcription factors (TFs) represent master-switches controlling several target stress-responsive genes and are considered most important for regulation of gene expression. Stress-tolerance in plants can be engineered through getting insights into homeobox-TFs and APETALA2/ethylene response element-binding protein (AP2/EREBP) in abiotic/biotic stress responses and their potential use as target genes. However, a detailed functional analysis of homeobox and AP2 TFs is required to identify novel pathways and better understand underlying molecular mechanisms. Regulation of stress related pathways, including reactive oxygen species-production, stomatal regulation and processes related to plant water relations can be modulated by G-proteins and related machinery. G-proteins were suggested herein as the key proteins for overcoming environmental stresses and increasing crop yield. Elucidation of different non-genetic or epigenetic