Despite frequent co-occurrence of drought and heat stress, the molecular mechanisms governing plant responses to these stresses in combination have not often been studied. This is particularly evident in non-model, perennial plants. We conducted large scale physiological and transcriptome analyses to identify genes and pathways associated with grapevine response to drought and/or heat stress during stress progression and recovery. We identified gene clusters with expression correlated to leaf temperature and water stress and five hub genes for the combined stress co-expression network. Several differentially expressed genes were common to the individual and combined stresses, but the majority were unique to the individual or combined stress treatments. These included heat-shock proteins, mitogen-activated kinases, sugar metabolizing enzymes, and transcription factors, while phenylpropanoid biosynthesis and histone modifying genes were unique to the combined stress treatment. Following physiological recovery, differentially expressed genes were found only in plants under heat stress, both alone and combined with drought. Taken collectively, our results suggest that the effect of the combined stress on physiology and gene expression is more severe than that of individual stresses, but not simply additive, and that epigenetic chromatin modifications may play an important role in grapevine responses to combined drought and heat stress.

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Maize is a cold sensitive crop that exhibits severe retardation of growth and development when exposed to cold spells during and right after germination, including the slowdown in development of new leaves and in formation of the photosynthetic apparatus. Improving cold tolerance in maize would allow early sowing to improve crop yield by prolonging a growing season and by decreasing the negative effects of summer drought, diseases, and pests. Two maize inbreds widely incorporated into American maize germplasm, B73 and Mo17, exhibit different levels of tolerance to low temperature exposure at seedling stage. In addition, thirty seven diverse inbred maize lines showed large variation for seedling response to low temperature exposure with lines with extremely low tolerance to seedling exposure to low temperatures falling into stiff stalk, non-stiff stalk, and tropical clades. We employed the maize intermated B73×Mo17 (IBM) recombinant inbred line population (IBM Syn4 RIL) to investigate the genetic architecture of cold stress tolerance at a young seedling stage and to identify quantitative trait loci (QTLs) controlling this variation. A panel of 97 recombinant inbred lines of IBM Syn4 were used to measure, and score based on several traits related to chlorophyll concentration, leaf color, and tissue damage. Our analysis resulted in detection of two QTLs with high additive impact, one on chromosome 1 (bin 1.02) and second on chromosome 5 (bin 5.05). Further investigation of the QTL regions using gene expression data provided a list of the candidate genes likely contributing to the variation in cold stress response. Among the genes located within QTL regions identified in this study and differentially expressed in response to low temperature exposure are the genes with putative functions related to auxin and gibberellin response, as well as general abiotic stress response, and genes coding for proteins with broad regulatory functions.

Climate change is expected to increase the occurrence of extreme environmental conditions. Viticulture, as agriculture in general, is highly dependent on climatic conditions, not only for yield but also for fruit quality, which is the most important factor affecting produce value at the farm-gate. This demands the development of novel plant breeding techniques that will lead to the accelerated production of more resilient grape varieties, as conventional breeding programs for perennials are often prolonged. Recent research has suggested that environmental conditions can activate a memory of stress that could result in a primed response to subsequent stress events. This is a process capable of increasing plant’s resilience to abiotic stimuli, allowing plants to better adapt to extreme environmental conditions. While the effect of priming has been observed in many plants, the underlying mechanisms are puzzling and seldom studied in perennial crops. A large body of research has been developed in the last decade linking response to stress, stress priming, and memory of stress with epigenetic mechanisms. This understanding of plant epigenetics has opened the door to the application of epigenetics to crop improvement, such as the use of epigenetic breeding for the generation of more resilient crops. Perennial crop agriculture in general, and viticulture in particular, would benefit from more in-depth knowledge on epigenetic memory of stress.

Heat radiation, combustion products, and flame engulfment are the main hazards from a fire event. Several reports have indicated that fire toxicity has caused greater numbers of human injuries and fatalities than those of heat radiation and flame engulfment. In a complex facility, the risk of fire toxicity increases significantly due to the difficulty of escaping in cases of emergency rescue and evacuation operations. This study proposes a methodology to model the impact of combustion products on humans. Several fire scenarios were considered to identify credible fire scenarios. In the most credible fire scenario, concentrations of combustion products over the layout of a facility were modeled. The results showed that the concentrations of CO and CO2 are below the short‐term exposure limit and lethal concentration 50 threshold limits at the considered time. The possible reasons for this are that the fire location was in a well‐ventilated area and equipment layouts were designed with proper safety gaps replicating a full‐scale dimension of an operating floating liquefied natural gas processing facility. The concentration of soot is above the threshold limit, and this has the potential to cause adverse health effects. This study can provide a tool for assessing fire toxicity in processing facilities, which will help improve safety measures.

Despite frequent co-occurrence of drought and heat stress, the molecular mechanisms governing plant responses to these stresses in combination have not often been studied. This is particularly evident in non-model, perennial plants. We conducted large scale physiological and transcriptome analyses to identify genes and pathways associated with grapevine response to drought and/or heat stress during stress progression and recovery. We identified gene clusters with expression correlated to leaf temperature and water stress and five hub genes for the combined stress co-expression network. Several differentially expressed genes were common to the individual and combined stresses, but the majority were unique to the individual or combined stress treatments. These included heat-shock proteins, mitogen-activated kinases, sugar metabolizing enzymes, and transcription factors, while phenylpropanoid biosynthesis and histone modifying genes were unique to the combined stress treatment. Following physiological recovery, differentially expressed genes were found only in plants under heat stress, both alone and combined with drought. Taken collectively, our results suggest that the effect of the combined stress on physiology and gene expression is more severe than that of individual stresses, but not simply additive, and that epigenetic chromatin modifications may play an important role in grapevine responses to combined drought and heat stress.

Industrial hemp (Cannabis sativa L.) is experiencing a resurgence in North America as an agricultural commodity. Germplasm improvement for locally adapted and stable cannabinoid production is an industry priority. This study used seed priming and pericarp removal to recover seedlings in low-germinating seed lots that could prove important for plant breeding and germplasm conservation. Both seed priming and pericarp removal improved early seed germination, but pericarp removal was more effective in improving overall final germination percentages. On average, pericarp removal improved final germination in low-germinating seed lots by approximately 38% compared to intact seed germination. In seeds with the pericarp removed, the initial germination substrate had an impact on normal seedling development following transplanting: those germinated for 2 to 3 days on rolled towels produced more normal seedlings compared to those started in Petri dishes. There was a dramatic increase in abnormal seedlings produced in the low-germinating seed lot initially germinated in a Petri dish wetted with 6 mL water where nearly 80% never transitioned to normal actively growing seedlings.

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