Heat tolerance in plants: An overview

As the result of intensive research and breeding efforts over the last 20 years, the yield potential and yield quality of cereals have been greatly improved. Nowadays, yield safety has gained more importance because of the forecasted climatic changes. Drought and high temperature are especially considered as key stress factors with high potential impact on crop yield. Yield safety can only be improved if future breeding attempts will be based on the valuable new knowledge acquired on the processes determining plant development and its responses to stress. Plant stress responses are very complex. Interactions between plant structure, function and the environment need to be investigated at various phases of plant development at the organismal, cellular as well as molecular levels in order to obtain a full picture. The results achieved so far in this field indicate that various plant organs, in a definite hierarchy and in interaction with each other, are involved in determining crop yield under stress. Here we attempt to summarize the currently available information on cereal reproduction under drought and heat stress and to give an outlook towards potential strategies to improve yield safety in cereals.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-3040.2007.01727.x

The effect of drought and heat stress on reproductive processes in cereals.

High temperature (HT) stress is a major environmental stress that limits plant growth, metabolism, and productivity worldwide Plant growth and development involve numerous biochemical reactions that are sensitive to temperature Plant responses to HT vary with the degree and duration of HT and the plant type HT is now a major concern for crop production and approaches for sustaining high yields of crop plants under HT stress are important agricultural goals Plants possess a number of adaptive, avoidance, or acclimation mechanisms to cope with HT situations In addition, major tolerance mechanisms that employ ion transporters, proteins, osmoprotectants, antioxidants, and other factors involved in signaling cascades and transcriptional control are activated to offset stress-induced biochemical and physiological alterations Plant survival under HT stress depends on the ability to perceive the HT stimulus, generate and transmit the signal, and initiate appropriate physiological and biochemical changes HT-induced gene expression and metabolite synthesis also substantially improve tolerance The physiological and biochemical responses to heat stress are active research areas, and the molecular approaches are being adopted for developing HT tolerance in plants This article reviews the recent findings on responses, adaptation, and tolerance to HT at the cellular, organellar, and whole plant levels and describes various approaches being taken to enhance thermotolerance in plants

Physiological, biochemical, and molecular mechanisms of heat stress tolerance in plants

Abiotic stresses are one of the major constraints to crop production and food security worldwide. The situation has aggravated due to the drastic and rapid changes in global climate. Heat and drought stress are undoubtedly the two most important stresses having huge impact on growth and productivity of the crops. It is very important to understand the physiological, biochemical and ecological interventions related to these stresses for better management. A wide range of plant responses to these stresses could be generalized into morphological, physiological and biochemical responses. Interestingly, this review provides a detailed account of plant responses to heat and drought stresses with special focus on highlighting the commonalities and differences. Crop growth and yields are negatively affected by sub-optimal water supply and abnormal temperatures due to physical damages, physiological disruptions and biochemical changes. Both these stresses have multi-lateral impacts and therefore, complex in mechanistic action. A better understanding of plant responses to these stresses has pragmatic implication for remedies and management. A comprehensive account of conventional as well as modern approaches to deal with heat and drought stresses have also been presented here. A side-by-side critical discussion on salient responses and management strategies for these two important abiotic stresses provides a unique insight into the phenomena. A holistic approach taking into account the different management options to deal with heat and drought stress simultaneously could be a win-win approach in future.

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Crop Production under Drought and Heat Stress: Plant Responses and Management Options

Global warming is predicted to have a general negative effect on plant growth due to the damaging effect of high temperatures on plant development. The increasing threat of climatological extremes including very high temperatures might lead to catastrophic loss of crop productivity and result in wide spread famine. In this review, we assess the impact of global climate change on the agricultural crop production. There is a differential effect of climate change both in terms of geographic location and the crops that will likely show the most extreme reductions in yield as a result of expected extreme fluctuations in temperature and global warming in general. High temperature stress has a wide range of effects on plants in terms of physiology, biochemistry and gene regulation pathways. However, strategies exist to crop improvement for heat stress tolerance. In this review, we present recent advances of research on all these levels of investigation and focus on potential leads that may help to understand more fully the mechanisms that make plants tolerant or susceptible to heat stress. Finally, we review possible procedures and methods which could lead to the generation of new varieties with sustainable yield production, in a world likely to be challenged both by increasing population, higher average temperatures and larger temperature fluctuations.

Plant tolerance to high temperature in a changing environment: scientific fundamentals and production of heat stress-tolerant crops

Heat stress is common in most cereal-growing areas of the world In this paper, we summarize the current knowledge on the molecular and genetic basis of thermotolerance in vegetative and reproductive tissues of cereals Significance of heat stress response and expression of heat shock proteins (HSPs) in thermotolerance of cereal yield and quality is discussed Major avenues for increasing thermotolerance in cereals via conventional breeding or genetic modification are outlined

Molecular genetics of heat tolerance and heat shock proteins in cereals.

Bioactive peptides in plant-derived foodstuffs.

Phytoremediation is a green, sustainable and promising solution to problems of environmental contamination. It entails the use of plants for uptake, sequestration, detoxification or volatilization of inorganic and organic pollutants from soils, water, sediments and possibly air. Phytoremediation was born from the observation that plants possessed physiological properties useful for environmental remediation. This was shortly followed by the application of breeding techniques and artificial selection to genetically improve some of the more promising and interesting species. Now, after nearly 20 years of research, transgenic plants for phytoremediation have been produced, but none have reached commercial existence. Three main approaches have been developed: (1) transformation with genes from other organisms (mammals, bacteria, etc.); (2) transformation with genes from other plant species; and (3) overexpression of genes from the same plant species. Many encouraging results have been reported, even though in some instances results have been contrary to expectations. This review will illustrate the main examples with a critical discussion of what we have learnt from them.

Transgenic plants for phytoremediation.

The proteomics of heavy metal hyperaccumulation by plants.

Functional toxicology has enabled the identification of genes involved in conferring tolerance and sensitivity to engineered nanomaterial (ENM) exposure in the model plant Arabidopsis thaliana (L.) Heynh. Several genes were found to be involved in metabolic functions, stress response, transport, protein synthesis, and DNA repair. Consequently, analysis of physiological parameters, metal content (through ICP-MS quantification), and gene expression (by RT-qPCR) of A. thaliana orthologue genes were performed across different plant species of agronomic interest to highlight putative biomarkers of exposure and effect related to ENMs. This approach led to the identification of molecular markers in Solanum lycopersicum L. and Cucurbita pepo L. (tomato and zucchini) that might not only indicate exposure to ENMs (CuO, CeO2, and La2O3) but also provide mechanistic insight into response to these materials. Through Gene Ontology (GO) analysis, the target genes were mapped in complex interatomic networks representing ...

Nelson Marmiroli

Papers

Molecular genetics of heat tolerance and heat shock proteins in cereals.

Bioactive peptides in plant-derived foodstuffs.

Transgenic plants for phytoremediation.

The proteomics of heavy metal hyperaccumulation by plants.

Molecular Response of Crop Plants to Engineered Nanomaterials