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Plants are exposed to a wide range of temperatures during their life cycle and need to continuously adapt. These adaptations need to deal with temperature changes on a daily and seasonal level and with temperatures affected by climate change. Increasing global temperatures negatively impact crop performance, and several physiological, biochemical, morphological, and developmental responses to increased temperature have been described that allow plants to mitigate this. In this review, we assess various growth-, development-, and yield-related responses of crops to extreme and moderately high temperature, focusing on knowledge gained from both monocot (e.g. wheat, barley, maize, and rice) and dicot crops (e.g. soybean and tomato) and incorporating information from model plants (e.g. Arabidopsis and Brachypodium). This revealed common and different responses between dicot and monocot crops, and defined different temperature thresholds depending on the species, growth stage, and organ.

ACCERBATIN is an ethylene-mimicking small molecule that affects auxin homeostasis and ROS accumulation in etiolated seedlings. In light-grown plants, it exhibits auxin-like herbicidal properties., The volatile two-carbon hormone ethylene acts in concert with an array of signals to affect etiolated seedling development. From a chemical screen, we isolated a quinoline carboxamide designated ACCERBATIN (AEX) that exacerbates the 1-aminocyclopropane-1-carboxylic acid-induced triple response, typical for ethylene-treated seedlings in darkness. Phenotypic analyses revealed distinct AEX effects including inhibition of root hair development and shortening of the root meristem. Mutant analysis and reporter studies further suggested that AEX most probably acts in parallel to ethylene signaling. We demonstrated that AEX functions at the intersection of auxin metabolism and reactive oxygen species (ROS) homeostasis. AEX inhibited auxin efflux in BY-2 cells and promoted indole-3-acetic acid (IAA) oxidation in the shoot apical meristem and cotyledons of etiolated seedlings. Gene expression studies and superoxide/hydrogen peroxide staining further revealed that the disrupted auxin homeostasis was accompanied by oxidative stress. Interestingly, in light conditions, AEX exhibited properties reminiscent of the quinoline carboxylate-type auxin-like herbicides. We propose that AEX interferes with auxin transport from its major biosynthesis sites, either as a direct consequence of poor basipetal transport from the shoot meristematic region, or indirectly, through excessive IAA oxidation and ROS accumulation. Further investigation of AEX can provide new insights into the mechanisms connecting auxin and ROS homeostasis in plant development and provide useful tools to study auxin-type herbicides.

Characterization of Rht-B1c suppressor alleles in different cultivars and environments highlights a unique role of the N-terminal domain of DELLA in grain dormancy, and reveals opportunities for improving pre-harvest sprouting resistance., During the Green Revolution, substantial increases in wheat (Triticum aestivum) yields were realized, at least in part, through the introduction of the Reduced height (Rht)-B1b and Rht-D1b semi-dwarfing alleles. In contrast to Rht-B1b and Rht-D1b, the Rht-B1c allele is characterized by extreme dwarfism and exceptionally strong dormancy. Recently, 35 intragenic Rht-B1c suppressor alleles were created in the spring wheat cultivar Maringá, and termed overgrowth (ovg) alleles. Here, 14 ovg alleles with agronomically relevant plant heights were reproducibly classified into nine tall and five semi-dwarf alleles. These alleles differentially affected grain dormancy, internode elongation rate, and coleoptile and leaf lengths. The stability of these ovg effects was demonstrated for three ovg alleles in different genetic backgrounds and environments. Importantly, two semi-dwarf ovg alleles increased dormancy, which correlated with improved pre-harvest sprouting (PHS) resistance. Since no negative effects on grain yield or quality were observed, these semi-dwarf ovg alleles are valuable for breeding to achieve adequate height reduction and protection of grain quality in regions prone to PHS. Furthermore, this research highlights a unique role for the first 70 amino acids of the DELLA protein, encoded by the Rht-1 genes, in grain dormancy.

In plants, numerous developmental processes are controlled by cytokinin (CK) levels and their ratios to levels of other hormones. While molecular mechanisms underlying the regulatory roles of CKs have been intensely researched, proteomic and metabolomic responses to CK deficiency are unknown. Transgenic Arabidopsis seedlings carrying inducible barley cytokinin oxidase/dehydrogenase (CaMV35S>GR>HvCKX2) and agrobacterial isopentenyl transferase (CaMV35S>GR>ipt) constructs were profiled to elucidate proteome- and metabolome-wide responses to down- and up-regulation of CK levels, respectively. Proteome profiling identified >1100 proteins, 155 of which responded to HvCKX2 and/or ipt activation, mostly involved in growth, development, and/or hormone and light signalling. The metabolome profiling covered 79 metabolites, 33 of which responded to HvCKX2 and/or ipt activation, mostly amino acids, carbohydrates, and organic acids. Comparison of the data sets obtained from activated CaMV35S>GR>HvCKX2 and CaMV35S>GR>ipt plants revealed unexpectedly extensive overlaps. Integration of the proteomic and metabolomic data sets revealed: (i) novel components of molecular circuits involved in CK action (e.g. ribosomal proteins); (ii) previously unrecognized links to redox regulation and stress hormone signalling networks; and (iii) CK content markers. The striking overlaps in profiles observed in CK-deficient and CK-overproducing seedlings might explain surprising previously reported similarities between plants with down- and up-regulated CK levels.