Molecular Bases of Plant Adaptation to Abiotic Stress and Approaches to Enhance Tolerance to Hostile Environments

Abstract

Abiotic stress has become the greatest threat to global food production and security, particularly in developing countries. Progress in increasing yield and its stability under adverse conditions through a direct selection has been hampered by the low heritability of yield, especially under drought. A better knowledge of the molecular and genetic basis of the mechanisms promoting tolerance to abiotic stress will enhance our capacity to more appropriately manipulate the genes limiting crop yield under hostile environments. This review describes and critically analyses the major advances in our understanding of the complex mechanisms underlying the adaptive response of the plant to abiotic stress, starting with the perception of the stress at the cellular level, its transduction through a cascade of signalling molecules and ending with the induction of genes whose products mitigate the harmful effects of the stress. Molecular markers and the ‘omics’ platforms (e.g., transcriptomics, proteomics, metabolomics etc.) offer unprecedented opportunities to identify and clone the genes governing plant adaptation to environmental stress and limiting yield under such conditions. The dissection of the genetic basis of quantitative traits into their single components, the so‐called QTLs (quantitative trait loci), allows us to deploy marker‐assisted selection (MAS) for enhancing crop performance under adverse conditions. Additional opportunities are also offered by genetic engineering, particularly through the expression of transcription factors regulating a suite of genes whose product is crucial to mitigate the effects of stress. Although the applicative results so far achieved with non‐conventional approaches have been limited, their integration with conventional breeding methodologies and other interdisciplinary approaches will greatly enhance our capacity to more effectively tailor crop genome to withstand harsh environmental conditions and to improve their sustainability under marginal conditions.

Recent Advances in the Genetic Transformation of Coffee

“…The most promising approach of genetic engineering for drought tolerance includes the use of functional or regulatory genes as well as the transfer of transcription factors. In recent years, plants tolerant to high temperature and water stress have been the subject of intense research [ 119 – 121 ]. For achieving drought tolerance, genes that have been targeted include those encoding enzymes involved in detoxification or osmotic response metabolism, enzymes active in signalling, proteins involved in the transport of metabolites, and regulating the plant energy status [ 119 – 121 ].…”

“…In recent years, plants tolerant to high temperature and water stress have been the subject of intense research [ 119 – 121 ]. For achieving drought tolerance, genes that have been targeted include those encoding enzymes involved in detoxification or osmotic response metabolism, enzymes active in signalling, proteins involved in the transport of metabolites, and regulating the plant energy status [ 119 – 121 ]. The dissection of molecular mechanisms related to signal transduction and transcriptional regulation might help in engineering drought tolerance in coffee.…”

Breeding for abiotic stresses for sustainable agriculture

“…The transgenic approaches and some of the many experiments designed to study the expression of stressrelated genes have been reviewed by Coraggio & Tuberosa (2004) and Bajaj & Mohanty (2005). The majority of transgenes used for stress tolerance are transcription factors that upregulate or downregulate the expression of other genes.…”

Overexpression of Osmyb4 enhances compatible solute accumulation and increases stress tolerance of Arabidopsis thaliana

“…Plants respond and adapt to abiotic stresses through various physiological and biochemical changes, including the expression of stress‐specific genes (Bracale and Coraggio 2003, Bray 1997, Coraggio and Tuberosa 2004, Shinozaki and Yamaguchi‐Shinozaki 1997).…”