Transgenic approaches for abiotic stress tolerance in plants: retrospect and prospects

Abstract

Abiotic stresses including drought are serious threats to the sustainability of crop yields accounting for more crop productivity losses than any other factor in rainfed agriculture. Success in breeding for better adapted varieties to abiotic stresses depend upon the concerted efforts by various research domains including plant and cell physiology, molecular biology, genetics, and breeding. Use of modern molecular biology tools for elucidating the control mechanisms of abiotic stress tolerance, and for engineering stress tolerant crops is based on the expression of specific stress-related genes. Hence, genetic engineering for developing stress tolerant plants, based on the introgression of genes that are known to be involved in stress response and putative tolerance, might prove to be a faster track towards improving crop varieties. Far beyond the initial attempts to insert "single-action" genes, engineering of the regulatory machinery involving transcription factors has emerged as a new tool now for controlling the expression of many stress-responsive genes. Nevertheless, the task of generating transgenic cultivars is not only limited to the success in the transformation process, but also proper incorporation of the stress tolerance. Evaluation of the transgenic plants under stress conditions, and understanding the physiological effect of the inserted genes at the whole plant level remain as major challenges to overcome. This review focuses on the recent progress in using transgenic technology for the improvement of abiotic stress tolerance in plants. This includes discussion on the evaluation of abiotic stress response and the protocols for testing the transgenic plants for their tolerance under close-to-field conditions.

Modification of reactive oxygen species scavenging capacity of chloroplasts through plastid transformation

“…Inevitably, therefore, ROS scavenging capacity has been long recognised as a target for genetic engineering (Foyer et al 1994;Allen 1995;Bhatnagar-Mathur et al 2008), and over-expression of genes encoding enzymic components of these defences has been explored in a number of studies. The most intensively studied has been the over-expression of SOD.…”

Rhizosphere bacteria containing 1-aminocyclopropane-1- carboxylate deaminase increase growth and photosynthesis of pea plants under salt stress by limiting Na+ accumulation

“…Unfortunately, transgenic approaches and molecular breeding programs for improving crop tolerance to salt stress have generally not brought promising results in farmers' fields (Wang et al 2003;Bhatnagar-Mathur et al 2008;James et al 2008) with some notable exceptions (Munns et al 2006). Therefore, alternative approaches such as the use of soil micro-organisms such as mycorrhizal fungi and plant growthpromoting rhizobacteria (PGPR) may be exploited (Dodd and Pérez-Alfocea 2012).…”

Improvement of drought tolerance in white clover (Trifolium repens) by transgenic expression of a transcription factor gene WXP1

“…Drought is one of the most adverse environmental factors that affect plant growth and production (Bhatnagar-Mathur et al 2008). Plants have many characteristics that are adaptive to environments.…”