Evaluating stress responses in cowpea under drought stress

Abstract

A B S T R A C TDrought impact on plants is an increasing concern under the climate change scenario. Cowpea (Vigna unguiculata L. Walp.) is considered as one of the most tolerant legume crops to drought, being the search for the best welladapted genotypes crucial to face the future challenges. Different approaches have been used for differentiating plant responses to drought stress. Plants of four cowpea genotypes were submitted to three watering regimens (a severe and moderate drought stress, and well-watered control) during 15 days, and several physiological, biochemical and molecular parameters were evaluated. Stressed plants revealed commonly-described drought stress characteristics, but not all assayed parameters were useful for discriminating plants with different drought severities or genotypes. The analyses which have contributed most to genotype discrimination were those related with stomatal function, and biochemical markers such as proline and anthocyanin contents. Antioxidant enzymes activities and related genes expression did not differed among genotypes or upon drought stress treatments, suggesting that scavenging enzymes are not involved in the differential ability of cowpea plants to survive under drought stress. This information will be useful to evaluate and use genetic resources, as well as design strategies for breeding cowpea resistance to drought stress.

Seasonal variation in soil CO2 emission and leaf gas exchange of well-managed commercial Citrus sinensis (L.) orchards

“…Several studies have shown that soil moisture controls CO2 assimilation through its impact on stomatal conductance (Carvalho et al 2019;Munjonji et al 2017;Rivas et al 2016;Tankari et al 2019;Zhang et al 2013). Under unlimited soil moisture, leaf CO2 assimilation is high due to a higher stomatal conductance with the reverse being true for limited water supply.…”

Overexpression of the Panax ginseng MYB4 gene enhances stress tolerance in transgenic Arabidopsis thaliana

“…A severe lack of water damages the structure of chloroplast lamellae and lowers the chlorophyll content of plant leaves. Accordingly, the chlorophyll content may be a useful indicator of plant sensitivity to drought stress (Dong et al 2019, Carvalho et al 2019. In this study, we observed that drought stress decreased the chlorophyll content considerably more in the wild type than in the PgMYB4-overexpressing Arabidopsis, which indicates a more substantial drought tolerance of the transgenic plants.…”

Water restriction in different phenological stages and increased temperature affect cowpea production

“…Changes in enzymatic activities under multiple stress conditions, such as water deficit and high temperature, as observed in the present study, may be associated with the activation of oxidative defense mechanisms of plants (Mansoor;Naqvi, 2013). The higher activity of antioxidant enzymes can contribute to a better tolerance to water deficit, thus justifying greater enzymatic activities in plants subjected to water stress, such as the activity of enzymes responsible for maintaining oxidative homeostasis in cowpea (Carvalho et al, 2019). For plants that were subjected to reduction in water availability in the vegetative and flowering stages, it can be noted that, in general, the lower the water availability, the greater the specific activity of SOD (first line of defense), as well as the enzymes that act in the second line of defense against oxidative stress (CAT, APX and GPX).…”

“…Some authors consider this legume as a species with greater tolerance to water stress compared to other crops (Ndiso et al, 2016;Merwad;Desoky;Rady, 2018). These characteristics make cowpea cultivation relevant for food security, especially in the face of global climate change (Carvalho et al, 2019). Although this crop is adapted to semiarid conditions, water deficit and high temperatures during its development cycle can have a negative impact on production (Ndiso et al, 2016).…”