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To ensure the food security of future generations and to address the challenge of the ‘no hunger zone’ proposed by the FAO (Food and Agriculture Organization), crop production must be doubled by 2050, but environmental stresses are counteracting this goal. Heat stress in particular is affecting agricultural crops more frequently and more severely. Since the discovery of the physiological, molecular, and genetic bases of heat stress responses, cultivated plants have become the subject of intense research on how they may avoid or tolerate heat stress by either using natural genetic variation or creating new variation with DNA technologies, mutational breeding, or genome editing. This review reports current understanding of the genetic and molecular bases of heat stress in crops together with recent approaches to creating heat-tolerant varieties. Research is close to a breakthrough of global relevance, breeding plants fitter to face the biggest challenge of our time.

The increasing use of engineered nanomaterials (ENMs) raises questions regarding their environmental impact. Improving the level of understanding of the genetic and molecular basis of the response to ENM exposure in biota is necessary to accurately assess the true risk to sensitive receptors. The aim of this Review is to compare the plant response to several metal-based ENMs widely used, such as quantum dots, metal oxides, and silver nanoparticles (NPs), integrating available "omics" data (transcriptomics, miRNAs, and proteomics). Although there is evidence that ENMs can release their metal components into the environment, the mechanistic basis of both ENM toxicity and tolerance is often distinct from that of metal ions and bulk materials. We show that the mechanisms of plant defense against ENM stress include the modification of root architecture, involvement of specific phytohormone signaling pathways, and activation of antioxidant mechanisms. A critical meta-analysis allowed us to identify relevant genes, miRNAs, and proteins involved in the response to ENMs and will further allow a mechanistic understanding of plant-ENM interactions.

Cadmium sulfide quantum dots (CdS QDs) are used in the manufacture of a number of electronics products. Their small size allows their ready entry into living cells, but as yet no attempt has been made to assess their toxicity. Our aim was to exploit two Ds transposition-induced mutant lines of Arabidopsis thaliana which tolerated exposure to CdS QDs to identify the genetic basis of their tolerance. Both a genome-wide top-down (from mutant to genes) and a bottom-up (from gene expression to phenotype) approach were applied. The differential responses of the mutants compared to the wild type showed that sensitivity to CdS QDs was unrelated to sensitivity to Cd(2+) ions. A transcriptomic analysis identified a number of genes whose transcript abundance was correlated with the tolerance. The phenotype of one of the mutants was correlated with the overexpression of ELM2, an MYB containing gene visited by a Ds transposon. Segregation analysis showed that the genetic basis of CdS QDs tolerance in both mutants was monogenic. The phenotype of the other mutant could be explained by the mutation of HCF101, a gene involved in photosynthesis.

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