Differential accumulation of osmolytes in 4 cultivars of peanut (Arachis hypogaea L.) under drought stress

Understanding the impacts of drought on peanuts (Arachis hypogaea L.): exploring physio-genetic mechanisms to develop drought-resilient peanut cultivars

Peanut is a vital source of protein, particularly in the tropical regions of Asian and African countries. About three-quarters of peanut production occurs worldwide in arid and semi-arid regions, making drought an important concern in peanut production. In the US about two-thirds of peanuts are grown in non-irrigated lands, where drought accounts for 50 million USD loss each year. The looming threat of climate change exacerbates this situation by increasing erratic rainfall. Drought not only reduces yield but also degrades product quality. Peanuts under drought stress exhibit higher levels of pre-harvest aflatoxin contamination, a toxic fungal metabolite detrimental to both humans and animals. One way to sustain peanut production in drought-prone regions and address pre-harvest aflatoxin contamination is by developing drought-tolerant peanut cultivars, a process that can be accelerated by understanding the underlying physiological and genetic mechanisms for tolerance to drought stress. Different physiological attributes and genetic regions have been identified in drought-tolerant cultivars that help them cope with drought stress. The advent of precise genetic studies, artificial intelligence, high-throughput phenotyping, bioinformatics, and data science have significantly improved drought studies in peanuts. Yet, breeding peanuts for drought tolerance is often a challenge as it is a complex trait significantly affected by environmental conditions. Besides technological advancements, the success of drought-tolerant cultivar development also relies on the identification of suitable germplasm and the conservation of peanut genetic variation.

Differential expression of leaf proteins in four cultivars of peanut (Arachis hypogaea L.) under water stress

Drought is a major constraint to the productivity of many crops affecting various physiological and biochemical processes. Seventy percent of the peanuts are grown in semiarid tropics that are frequently prone to drought stress. So, we analyzed its effect in 4 cultivars of peanut, with different degrees of drought tolerance, under 10 and 20 days of water stress using two-dimensional gel electrophoresis and mass spectrometry. A total of 189 differentially expressed protein spots were identified in the leaf proteome of all the 4 cultivars using PD Quest Basic software; 74 in ICGV 91114, 41 in ICGS 76, 44 in J 11 and 30 in JL 24. Of these, 30 protein spots were subjected to in-gel trypsin digestion followed by MALDI-TOF that are functionally categorized into 5 groups: molecular chaperones, signal transducers, photosynthetic proteins, defense proteins and detoxification proteins. Of these, 12 proteins were sequenced. Late embryogenesis abundant protein, calcium ion binding protein, sucrose synthase isoform-1, 17.3 kDa heat shock protein and structural maintenance of chromosome proteins were overexpressed only in the 15 and 20 days stressed plants of ICGV 91114 cultivar while cytosolic ascorbate peroxidase was expressed with varying levels in the 10 and 20 days stressed plants of all the 4 cultivars. Signaling protein like 14-3-3 and defense proteins like alpha-methyl-mannoside-specific lectin and mannose/glucose-binding lectins were differentially expressed in the 4 cultivars. Photosynthetic protein like Rubisco was down-regulated in the stressed plants of all 4 cultivars while Photosystem-I reaction center subunit-II of chloroplast precursor protein was overexpressed in only 20 days stressed plants of ICGV 91114, ICGS 76 and J11 cultivars. These differentially expressed proteins could potentially be used as protein markers for screening the peanut germplasm and further crop improvement.

Exogenous application of urea and a urease inhibitor improves drought stress tolerance in maize (Zea mays L.)

Drought is believed to cause many metabolic changes which affect plant growth and development. However, it might be mitigated by various inorganic substances, such as nitrogen. Thus, the study was carried out to investigate the effect of foliar-applied urea with or without urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) on a maize cultivar under drought stress simulated by 15% (w/v) polyethylene glycol 6000. Foliar-applied urea resulted in a significant increase in plant dry weight, relative water content, and photosynthetic pigments under water stress condition. Furthermore, the activities of superoxide dismutase (SOD), peroxidase (POD), and hydrogen peroxidase (CAT), were enhanced with all spraying treatments under drought stress, which led to decreases in accumulation of hydrogen peroxide (H₂O₂), superoxide anion ([Formula: see text]) and malondialdehyde (MDA). The contents of soluble protein and soluble sugar accumulated remarkably with urea-applied under drought stress condition. Moreover, a further enhancement in above metabolites was observed by spraying a mixture of urea and urease inhibitor as compared to urea sprayed only. Taken together, our findings show that foliar application of urea and a urease inhibitor could significantly enhance drought tolerance of maize through protecting photosynthetic apparatus, activating antioxidant defense system and improving osmoregulation.