Stress-tolerant Wild Plants: a Source of Knowledge and Biotechnological Tools for the Genetic Improvement of Stress Tolerance in Crop Plants

Abstract

Over the next few decades we must boost crop productivity if we are to feed a growing world population, which will reach more than 9×10 9 people by 2050; and we should do it in the frame of a sustainable agriculture, with an increasing scarcity of new arable land and of water for irrigation. For all important crops, average yields are only a fraction-somewhere between 20% and 50%-of record yields; these losses are mostly due to drought and high soil salinity, environmental conditions which will worsen in many regions because of global climate change. Therefore, the simplest way to increase agricultural productivity would be to improve the abiotic stress tolerance of crops. Considering the limitations of traditional plant breeding, the most promising strategy to achieve this goal will rely on the generation of transgenic plants expressing genes conferring tolerance. However, advances using this approach have been slow, since it requires a deep understanding of the mechanisms of plant stress tolerance, which are still largely unknown. Paradoxically, most studies on the responses of plants to abiotic stress have been performed using stress-sensitive species-such as Arabidopsis thaliana-although there are plants (halophytes, gypsophytes, xerophytes) adapted to extremely harsh environmental conditions in their natural habitats. We propose these wild stress-tolerant species as more suitable models to investigate these mechanisms, as well as a possible source of biotechnological tools ('stress tolerance' genes, stress-inducible promoters) for the genetic engineering of stress tolerance in crop plants.

Understanding the molecular events underpinning cultivar differences in the physiological performance and heat tolerance of cotton (Gossypium hirsutum)

“…2) compared with Sicot 53 may indicate differences in the reliance on alternative energy pathways such as glycolysis and lipid degradation for heatsensitive cotton cultivars under high temperature stress (Zhang et al 2005). Downregulation of genes associated with glycolysis and the oxidative pentose pathway under heat stress in this experiment (Table 1) is in contrast to increased reliance on these pathways for tobacco under heat stress (Rizhsky et al 2002), indicating alternate mechanisms of heat alleviation in various plant species and highlighting the importance of profiling various crop species for performance under heat stress (Boscaiu et al 2012).…”

An Interdisciplinary Approach to Study the Performance of Second-generation Genetically Modified Crops in Field Trials: A Case Study With Soybean and Wheat Carrying the Sunflower HaHB4 Transcription Factor

“…It is well known and documented that there are plant species exhibiting a high tolerance to certain abiotic stress factors and others more susceptible to them (Boscaiu et al, 2012). Moreover, it is possible to find different varieties of the same species with differential tolerance to a stress factor for which traits conferring tolerance have been pyramided along centuries, first by farmers and subsequently by professional crop breeders.…”

Plant Life in Extreme Environments: How Do You Improve Drought Tolerance?

“…The advantages of Arabidopsis as a model for plant molecular biology and the role it played and still plays in investigating abiotic stress response pathways is undisputed (Provart et al, 2016 ). Many of the stress signaling pathways identified are now known to be general responses that appear to be conserved in many higher plant species (Boscaiu et al, 2012 ; Provart et al, 2016 ).…”

“…However, there are counterarguments which suggest that too much emphasis is being placed on investigating unsuitable experimental models, such as Arabidopsis (Boscaiu et al, 2012 ). For example, Arabidopsis and many crop plants die at leaf water potentials of around −3 MPa (van der Weele et al, 2000 ; Fitter and Hay, 2002 ).…”

“…This has raised several questions with regard to the experimental conditions applied in gene discovery studies, the appropriateness of the stress phenotypes being assessed (Blum and Tuberosa, 2018 ), or whether common stress signaling pathways are indeed the best targets (Boscaiu et al, 2012 ). While vegetative desiccation tolerance in resurrection plants is clearly at the extreme end of the stress survival spectrum, it is argued that extremophile species may act as a source of novel genes for the genetic improvement of stress tolerance in crops (Boscaiu et al, 2012 ). Yet many of the TF families identified in Arabidopsis have also been identified in resurrection plants in response to drought stress (see above; Gechev et al, 2013 ; Farrant et al, 2015 ; Costa et al, 2017 ).…”