Environmental conditions predetermine quality, germination, and innate antioxidants pool in sea oat (Uniola paniculata L.) seeds

Secondary metabolites such as antioxidants are critical components that protect seeds from stress damage during seed development, desiccation, and ex-situ storage. Antioxidants are essential determinants of seed quality, longevity, and persistence. Understanding the environmental factors that regulate the accumulation, content, and function of antioxidant pools in sea oat seeds is critical for gene banking and understanding the environmental impacts on seed quality. Germination, viability, and Trolox Equivalent Antioxidant Capacity (TEAC) were analyzed on seeds from 18 sea oat populations from the US Atlantic and Gulf of Mexico coasts. We first assessed baseline TEAC, followed by TEAC performed on imbibed seeds for 36 h at 35/25°C during the day and night, respectively. Then, we analyzed the relationship of the antioxidant pools from these 18 sea oat populations to sampling site environmental classifications. Higher baseline antioxidants were common in regions with extreme environmental conditions corresponding to sea oat populations growing at latitudinal extremes characterized by warmer and colder temperatures. Baseline antioxidants did not correlate with prevailing seed germination. However, higher concentrations of antioxidants following imbibition were associated with poor seed germination in warmer conditions. Our results indicate that climatic conditions and environmental components associated with temperatures and precipitation may largely influence the innate pool of antioxidants in sea oat seeds. Also, a high amount of antioxidants following sea oat seed imbibition suggest seed damage or poor viability influenced by environmental stress conditions during seed development

Compared to Australian Cultivars, European Summer Wheat (Triticum aestivum) Overreacts When Moderate Heat Stress Is Applied at the Pollen Development Stage

Heat stress frequently imposes a strong negative impact on vegetative and reproductive development of plants leading to severe yield losses. Wheat, a major temperate crop, is more prone to suffer from increased temperatures than most other major crops. With heat waves becoming more intense and frequent, as a consequence of global warming, a decrease in wheat yield is highly expected. Here, we examined the impact of a short-term (48 h) heat stress on wheat imposed during reproduction at the pollen mitosis stage both, at the physiological and molecular level. We analyzed two sets of summer wheat germplasms from Australia (Kukri, Drysdale, Gladius, and RAC875) and Europe (Epos, Cornetto, Granny, and Chamsin). Heat stress strongly affected gas exchange parameters leading to reduced photosynthetic and transpiration rates in the European cultivars. These effects were less pronounced in Australian cultivars. Pollen viability was also reduced in all European cultivars. At the transcriptional level, the largest group of heat shock factor genes (type A HSFs), which trigger molecular responses as a result of environmental stimuli, showed small variations in gene expression levels in Australian wheat cultivars. In contrast, HSFs in European cultivars, including Epos and Granny, were strongly downregulated and partly even silenced, while the high-yielding variety Chamsin displayed a strong upregulation of type A HSFs. In conclusion, Australian cultivars are well adapted to moderate heat stress compared to European summer wheat. The latter strongly react after heat stress application by downregulating photosynthesis and transpiration rates as well as differentially regulating HSFs gene expression pattern

Heat stress during seed development leads to impaired physiological function and plasticity in seed oil accumulation in Camelina sativa

Camelina sativa, a member of the Brassicaceae, is a low-cost, renewable oilseed crop that produces seeds up to 40% oil by weight with high potential for use in food, feed, and biofuel applications. Camelina seeds contain high levels of the fatty acids α-linolenic acid (C18:3), linoleic acid (C18:2), oleic acid (C18:1), and gondoic acid (C20:1), which have high nutritional and industrial value. The impact of climate change, especially increased frequency and amplitude of heat waves, poses a serious threat to crop productivity. In this study, we evaluated the effect of elevated temperatures post-anthesis on the developing seeds of C. sativa and performed physiological, morphological, and chemical characterizations at 7, 14, 21, and 28 days post-anthesis (DPA), as well as at maturity. While the seed oil accumulation peaked at 21 DPA under control conditions, reaching 406mg/g dry weight, under heat stress it was only 186mg/g. Physiologically, transpiration rate (E) and internal CO2 concentration (Ci) increased between 2 to 9 days post-stress imposition and overall net photosynthesis was impaired. Seed yield, seed weight, and oil content reduced by 84.5%, 38.5% and 54.1% respectively. We demonstrate that post-anthesis heat stress causes severe yield losses and developmental plasticity in fatty acid accumulation in oilseeds

Land Access in the Development of Horticultural Crops in East Africa. A Case Study of Passion Fruit in Burundi, Kenya, and Rwanda

Rapid population growth in fertile agricultural lands of East Africa creates land scarcity, which has become a major hindrance to land access for the introduction of new horticultural crops. But their introduction in these areas is increasing, because of their high market price, which improves farmers’ income. As such, this research evaluated land access dynamics (availability, acquisition, and use changes) on the introduction of passion fruits in East Africa. The study used purposeful sampling to collect information from 171 passion fruit farmers from Burundi (60), Kenya (51), and Rwanda (60) through interviews during field surveys. Among the respondents from all three countries, inheritance and land purchase were the predominant modes of land access (>50% and >21%, respectively). Furthermore, the substitution of other crops by passion fruits was high (>60%) among Kenyan and Rwandan farmers, but low (18%) among Burundian farmers. Our findings indicate that land access influences the patterns of adoption of new crops, since, when limited in supply, it may require the acquisition of new land space, abandonment of other crops, or opting for mixed farming. As such, land access should be a consideration in the promotion of new crops for sustainable agricultural ventures

Table_1_Heat stress during seed development leads to impaired physiological function and plasticity in seed oil accumulation in Camelina sativa.xlsx

Camelina sativa, a member of the Brassicaceae, is a low-cost, renewable oilseed crop that produces seeds up to 40% oil by weight with high potential for use in food, feed, and biofuel applications. Camelina seeds contain high levels of the fatty acids α-linolenic acid (C18:3), linoleic acid (C18:2), oleic acid (C18:1), and gondoic acid (C20:1), which have high nutritional and industrial value. The impact of climate change, especially increased frequency and amplitude of heat waves, poses a serious threat to crop productivity. In this study, we evaluated the effect of elevated temperatures post-anthesis on the developing seeds of C. sativa and performed physiological, morphological, and chemical characterizations at 7, 14, 21, and 28 days post-anthesis (DPA), as well as at maturity. While the seed oil accumulation peaked at 21 DPA under control conditions, reaching 406mg/g dry weight, under heat stress it was only 186mg/g. Physiologically, transpiration rate (E) and internal CO2 concentration (Ci) increased between 2 to 9 days post-stress imposition and overall net photosynthesis was impaired. Seed yield, seed weight, and oil content reduced by 84.5%, 38.5% and 54.1% respectively. We demonstrate that post-anthesis heat stress causes severe yield losses and developmental plasticity in fatty acid accumulation in oilseeds.</p