Physiological potential and health of peanut seed treated with ozone

Peanut seed can be infected by pathogen diseases that adversely affect the oil crop’s value chain. Ozone gas (O3) can be an alternative for the control of fungal diseases due to its high oxidizing potential. In this study, we investigated the effects of O3 exposure time on physiological and health characteristics of seed from three peanut cultivars. Seed from peanut cultivars Granoleico, IAC OL3, and IAC 503 were analyzed for their health (blotter test) and physiological potential (germination, first count, and seedling length) after exposure to O3 for 0, 1, 8, and 16 h. Peanut seed physiological quality and health differed among cultivars. Exposure of seed from peanut cultivars IAC OL3, IAC 503, and Granoleico to O3 at a rate of 600 mg h-1 did not affect the development of normal seedlings as measured by the first count and germination, but seedling length increased, decreased, or was not affected in cultivars Granoleico, IAC 503, and IAC OL3, respectively. Also, O3 did not eradicate fungal infections in peanut seed treated with O3 at a rate of 600 mg h-1 for up to 16 h, but the incidence of the fungus Rhizopus sp. in seed from cultivars IAC OL3, Granoleico, and IAC 503 increased, decreased or was not affected, respectively, after 8 h.

Peanut Seed Coat Acts as a Physical and Biochemical Barrier against Aspergillus flavus Infection

Aflatoxin contamination is a global menace that adversely affects food crops and human health. Peanut seed coat is the outer layer protecting the cotyledon both at pre- and post-harvest stages from biotic and abiotic stresses. The aim of the present study is to investigate the role of seed coat against A. flavus infection. In-vitro seed colonization (IVSC) with and without seed coat showed that the seed coat acts as a physical barrier, and the developmental series of peanut seed coat showed the formation of a robust multilayered protective seed coat. Radial growth bioassay revealed that both insoluble and soluble seed coat extracts from 55-437 line (resistant) showed higher A. flavus inhibition compared to TMV-2 line (susceptible). Further analysis of seed coat biochemicals showed that hydroxycinnamic and hydroxybenzoic acid derivatives are the predominant phenolic compounds, and addition of these compounds to the media inhibited A. flavus growth. Gene expression analysis showed that genes involved in lignin monomer, proanthocyanidin, and flavonoid biosynthesis are highly abundant in 55-437 compared to TMV-2 seed coats. Overall, the present study showed that the seed coat acts as a physical and biochemical barrier against A. flavus infection and its potential use in mitigating the aflatoxin contamination.

Peanut Response to Flumioxazin and S-Metolachlor Under High Moisture Conditions

The United States produced $1.28 billion worth of peanuts in 2019 of which Georgia produced 51% of the total production (USDA-NASS 2021). Peanut is susceptible to weed competition due to slow canopy establishment, prostrate growth habit, and wide critical period for weed control from 3 to 8 weeks after planting (Burke et al. 2007; Everman et al. 2008). Georgia-06G is the dominant peanut cultivar planted in the southeast and in 2020, 87% of the acres grown for certified peanut seed available for sale to growers was Georgia-06G (Anonymous, 2020a). Peanut is commonly in rotation with cotton in the region and therefore, similar weed issues between these systems persist. This includes Palmer amaranth ( Amaranthus palmeri S. Watson) which has been documented to be resistant to multiple herbicide modes of action making its control difficult (Heap 2021). To minimize yield loss from weeds, preemergence (PRE) herbicides are frequently used in peanut to inhibit weed germination and provide residual weed control (Grichar et al. 2001). In response to resistance issues, producers have continued to integrate PRE herbicides into their herbicide programs to minimize weed emergence.

Key Regulators of Sucrose Metabolism Identified Through Comprehensive Comparative Transcriptome Analysis in Peanuts

Sucrose content is a crucial indicator of quality and flavor in peanut seed, and there is a lack of clarity on the molecular basis of sucrose metabolism in peanut seed. In this context, we performed a comprehensive comparative transcriptome study on the samples collected at seven seed development stages between a high-sucrose content variety (ICG 12625) and a low-sucrose content variety (Zhonghua 10). The transcriptome analysis identified a total of 8334 genes exhibiting significantly different abundances between the high- and low-sucrose varieties. We identified 28 differentially expressed genes (DEGs) involved in sucrose metabolism in peanut and 12 of these encoded sugars will eventually be exported transporters (SWEETs). The remaining 16 genes encoded enzymes, such as cell wall invertase (CWIN), vacuolar invertase (VIN), cytoplasmic invertase (CIN), cytosolic fructose-bisphosphate aldolase (FBA), cytosolic fructose-1,6-bisphosphate phosphatase (FBP), sucrose synthase (SUS), cytosolic phosphoglucose isomerase (PGI), hexokinase (HK), and sucrose-phosphate phosphatase (SPP). The weighted gene co-expression network analysis (WGCNA) identified seven genes encoding key enzymes (CIN, FBA, FBP, HK, and SPP), three SWEET genes, and 90 transcription factors (TFs) showing a high correlation with sucrose content. Furthermore, upon validation, six of these genes were successfully verified as exhibiting higher expression in high-sucrose recombinant inbred lines (RILs). Our study suggested the key roles of the high expression of SWEETs and enzymes in sucrose synthesis making the genotype ICG 12625 sucrose-rich. This study also provided insights into the molecular basis of sucrose metabolism during seed development and facilitated exploring key candidate genes and molecular breeding for sucrose content in peanuts.

Effect of Oak Tree Sawdust Fermentation Period on Peanut Seed Germination, Seedling Biomass, and Morphology

Peanut (Arachis hypogaea L.) seeds were germinated to investigate the effect of the fermentation period of oak tree sawdust on germination viability and seedling characteristics. Its germination rate, seedling weight, length, and total vigor index were assessed. The seeds were sown in oak tree sawdust fermented for 0, 30, 45, and 60 days. The germination rates of the seeds in fermented sawdust were significantly different. The seeds in the 45-day fermented sawdust produced the heaviest biomass weight (4.6 g) with the longest true leaf (1.7 cm) and hypocotyl (3.4 cm) resulting in the highest total vigor index (925.8). In contrast, seeds in 0-day fermented sawdust had the lowest total vigor index (18.3). Microbiome analysis showed that the microbial community in the sawdust changed as the fermentation progressed, indicating that the microbial community seems to affect seed germination physiology. Taken together, 45-day fermented sawdust is recommended for optimal peanut seed germination and seedling growth.

Acquisition of the physiological quality of peanut (Arachis hypogaea L.) seeds during maturation under the influence of the maternal environment

The scarcity of information on the maturation physiology of the peanut seed (Arachis hypogaea L.; Virgínia group) makes harvesting high quality seeds a challenge for the seed industry. During two consecutive crop seasons, we studied the acquisition of physiological quality of peanut seeds during maturation in tropical conditions. We bring new insights about the period of late maturation of seeds and the influence of the maternal environment on physiological quality. We monitored water content, dry weight, ability of germination, desiccation tolerance, vigor and longevity. In addition, we monitored temperature and precipitation throughout plant growth. We demonstrate that the physiological quality of peanut seeds is acquired during development, with a maximum between 57 and 76 days after flowering in the late stage of maturation. This final period represents about 25% of the development, considered the best time to harvest peanut seeds with the highest quality. Our findings also support the idea that the adequate proportion of rainfall and thermal sum in the maternal environment are factors that favor the acquisition of peanut seed longevity.

Near infrared spectroscopy coupled chemometric algorithms for prediction of the antioxidant activity of peanut seed (Arachis hypogaea)

In the present research work, near infrared (NIR) spectroscopy coupled with chemometric algorithms such as partial least-squares (PLS) regression and some effective variable selection algorithms (synergy interval-PLS (Si-PLS), Backward interval-PLS (Bi-PLS), and genetic algorithm-PLS (GA-PLS)) were used for the quantification of antioxidant properties of peanut seed samples. The compositional parameters, such as DPPH, ABTS, FRAP, TPC, FCA, TFC, and TAC, were quantified using NIR spectroscopy. The developed models were assessed using correlation coefficients of the calibration (R2) and prediction (r2); root mean standard error of cross-validation, RMSECV; root mean square error of prediction, RMSEP and residual predictive deviation, RPD. The efficiency of the developed model was significantly enhanced with the use of Si-PLS, Bi-PLS, and GA-PLS as compared to the classical PLS model. The results of the R2 and r2 set varied from 0.76 to 0.95 and 0.72 to 0.94, respectively. The obtained results revealed that NIR spectroscopy, coupled with different chemometric algorithms, has the potential to be used for rapid assessment of the antioxidant properties of peanut seed.

Functional Uses of Peanut (Arachis hypogaea L.) Seed Storage Proteins

Peanut (Arachis hypogaea L.) is an important grain legume crop of tropics and subtropics. It is increasingly being accepted as a functional food and protein extender in developing countries. The seed contains 36% to 54% oil, 16% to 36% protein, and 10% to 20% carbohydrates with high amounts of P, Mg, Ca, riboflavin, niacin, folic acid, vitamin E, resveratrol and amino acids. Seed contains 32 different proteins comprised of albumins and globulins. The two-globulin fractions, arachin and non-arachin, comprise approximately 87% of the peanut seed proteins. Peanut worldwide is mainly used for oil production, consumption as raw, roasted, baked products, peanut butter, peanut flour, extender in meat product formulations, confectionary and soups. Peanut proteins have many properties such as good solubility, foaming, water/oil binding, emulsification that make them useful in various food products. Very limited studies have been carried out in peanut functional properties, which has been reviewed in the present article. Adequate modifications can be done in protein functionality that are influenced by pH, temperature, pressure etc. However, some individuals develop severe IgE-mediated allergies to peanut seed proteins. Thus, methods to improve nutrition and reduce allergenicity have also been discussed. Within the last decade, manipulations have been done to alter peanut chemistry and improve nutritional quality of peanuts and peanut products. Hence, improved comprehensive understanding of functional properties and nutritional chemistry of peanut proteins can generate better source of food grain to meet nutritional requirement of growing population. In the present review, composition of peanut seed proteins, functional properties, nutritional components and nutraceutical value have been discussed with respect to beneficial aspects to health, reducing hunger and usage in food end products.