Plant responses to drought, salinity and extreme temperatures: towards genetic engineering for stress tolerance

Abstract

Abiotic stresses, such as drought, salinity, extreme temperatures, chemical toxicity and oxidative stress are serious threats to agriculture and the natural status of the environment. Increased salinization of arable land is expected to have devastating global effects, resulting in 30% land loss within the next 25 years, and up to 50% by the year 2050. Therefore, breeding for drought and salinity stress tolerance in crop plants (for food supply) and in forest trees (a central component of the global ecosystem) should be given high research priority in plant biotechnology programs. Molecular control mechanisms for abiotic stress tolerance are based on the activation and regulation of specific stress-related genes. These genes are involved in the whole sequence of stress responses, such as signaling, transcriptional control, protection of membranes and proteins, and free-radical and toxic-compound scavenging. Recently, research into the molecular mechanisms of stress responses has started to bear fruit and, in parallel, genetic modification of stress tolerance has also shown promising results that may ultimately apply to agriculturally and ecologically important plants. The present review summarizes the recent advances in elucidating stress-response mechanisms and their biotechnological applications. Emphasis is placed on transgenic plants that have been engineered based on different stress-response mechanisms. The review examines the following aspects: regulatory controls, metabolite engineering, ion transport, antioxidants and detoxification, late embryogenesis abundant (LEA) and heat-shock proteins.

Genetic approaches towards overcoming water deficit in plants - special emphasis on LEAs

“…They have also been discovered in the prokaryotes (Stacy and Aalen, 1998) , 2000). The LEA proteins confer increased resistance to osmotic or freeze stress when introduced into yeast and also improved water deficit tolerance in the transformants (Wang et al, 2003, also see Table 1). Structural information in both hydrated and dry states is known in a group 3 LEA-like protein (AavLEA1) from Aphelenchus avenae provides new insights in to the molecular mechanism especially under stress conditions (Goyal et al, 2003).…”

The mutual responses of higher plants to environment: Physiological and microbiological aspects

“…However, it has to be considered that stress always occurs as a complex of various interacting environmental factors that contribute in varying degrees to the overall stressed phenotype [72,73,[97][98][99][100][101][102][103][104][105][106][107][108][109]. Consequently, plants usually respond to a unique complex of growth conditions [13,16,77,78,117,[124][125][126]. Abiotic and biotic stress factors have some common signal and responding pathways in plants and thereby can be utilized potentially by cross-signaling [14,93,118,119].…”

Relationship between water use efficiency (WUE) and production of different wheat genotypes at soil water deficit

“…Many advances in relation to this hot topic, including molecular mechanism of anti-drought and corresponding molecular breeding have taken place [28,33,34,39,44,47,50,53,[55][56]63,[72][73][74][75]78]. Although the obtained transgenic crops (mainly, wheat) by different types of gene technology all exhibit drought resistance to some extent, they have many shortfalls related to agronomical performance and/or development [47,49,53,62,66,68,74]. These results imply that systemical, deeper, and comprehensive understanding of physiological mechanism of crops under drought stresses is not enough to manipulate the physiological regulatory mechanism and take advantage of full this potential for productivity, whose study is the bridge between molecular machinery of drought and anti-drought agriculture, because the performance of genetic potential of crops is expressed by physiological realization in fields [1,2,8,10,53,54].…”