Elevated CO2 alters the feeding behaviour of the pea aphid by modifying the physical and chemical resistance of Medicago truncatula.

Elevated CO(2) compromises the resistance of leguminous plants against chewing insects, but little is known about whether elevated CO(2) modifies the resistance against phloem-sucking insects or whether it has contrasting effects on the resistance of legumes that differ in biological nitrogen fixation. We tested the hypothesis that the physical and chemical resistance against aphids would be increased in Jemalong (a wild type of Medicago truncatula) but would be decreased in dnf1 (a mutant without biological nitrogen fixation) by elevated CO(2). The non-glandular and glandular trichome density of Jemalong plants increased under elevated CO(2), resulting in prolonged aphid probing. In contrast, dnf1 plants tended to decrease foliar trichome density under elevated CO(2), resulting in less surface and epidermal resistance to aphids. Elevated CO(2) enhanced the ineffective salicylic acid-dependent defence pathway but decreased the effective jasmonic acid/ethylene-dependent defence pathway in aphid-infested Jemalong plants. Therefore, aphid probing time decreased and the duration of phloem sap ingestion increased on Jemalong under elevated CO(2), which, in turn, increased aphid growth rate. Overall, our results suggest that elevated CO(2) decreases the chemical resistance of wild-type M. truncatula against aphids, and that the host's biological nitrogen fixation ability is central to this effect.

In vitro protein bioaccessibility and human serum amino acid responses to white bread enriched with intact plant cells.

The cell structure and low glycaemic benefits of pulses are compromised by conventional flour-milling. Cellular chickpea powders ('CCPs') are a new alternative to pulse flours. Here we investigated the in vitro bioaccessibility of essential amino acids ('EAAs') from CCP-enriched bread products and determined the effect of their consumption on serum amino acid responses in healthy humans (n = 20, randomised cross-over design). Breads were prepared with 0, 30 and 60 % of the wheat flour replaced by CCP (intact cells containing encapsulated protein). We found that significant proportion of EAAs from encapsulated protein became bioaccessible during in vitro duodenal digestion, and that in vivo serum EAA responses from healthy human participants were significantly higher following consumption of CCP-enriched breads. Furthermore, the EAA profile of in vitro digestion products were well-correlated with in vivo peak serum EAAs responses. We conclude that CCP-enrichment of wheat bread improved the amount and diversity of bioavailable EAAs.

Residues of Legume AG41 Peptide Crucial to Its Bio-Insecticidal Activity.

Currently, crop protection relies heavily on chemical treatments, which ultimately leads to environmental contamination and pest resistance. Societal and public policy considerations urge the need for new eco-friendly solutions. In this perspective, biopesticides are effective alternatives to chemical insecticides for the control of various insect pests. Legumes contain numerous insecticidal proteins aimed at protecting their high nitrogen content from animal/insect predation. Investigating one such protein family at genome scale, we discovered a unique diversity of the albumin 1 family in the (model) barrel medic genome. Only some members retained very high insecticidal activity. We uncovered that AG41 peptide from the alfalfa roots displays an outstanding insecticidal activity against several pests such as aphids and weevils. Here we report the 3D structure and activity of AG41 peptide. Significant insights into the structural/functional relationships explained AG41 high insecticidal activity. Such observations pave the way for the development of bio-insecticides, with AG41 peptide as the lead compound.

Genome-wide investigation of AP2/ERF gene family in the desert legume Eremosparton songoricum: Identification, classification, evolution, and expression profiling under drought stress.

Eremosparton songoricum (Litv.) Vass. is a rare leafless legume shrub endemic to central Asia which grows on bare sand. It shows extreme drought tolerance and is being developed as a model organism for investigating morphological, physiological, and molecular adaptations to harsh desert environments. APETALA2/Ethylene Responsive Factor (AP2/ERF) is a large plant transcription factor family that plays important roles in plant responses to various biotic and abiotic stresses and has been extensively studied in several plants. However, our knowledge on the AP2/ERF family in legume species is limited, and no respective study was conducted so far on the desert shrubby legume E. songoricum. Here, 153 AP2/ERF genes were identified based on the E. songoricum genome data. EsAP2/ERFs covered AP2 (24 genes), DREB (59 genes), ERF (68 genes), and Soloist (2 genes) subfamilies, and lacked canonical RAV subfamily genes based on the widely used classification method. The DREB and ERF subfamilies were further divided into A1-A6 and B1-B6 groups, respectively. Protein motifs and exon-intron structures of EsAP2/ERFs were also examined, which matched the subfamily/group classification. Cis-acting element analysis suggested that EsAP2/ERF genes shared many stress- and hormone-related cis-regulatory elements. Moreover, the gene numbers and the ratio of each subfamily and the intron-exon structures were systematically compared with other model plants ranging from algae to angiosperms, including ten legumes. Our results supported the view that AP2 and ERF evolved early and already existed in algae, whereas RAV and DREB began to appear in moss species. Almost all plant AP2 and Soloist genes contained introns, whereas most DREB and ERF genes did not. The majority of EsAP2/ERFs were induced by drought stress based on RNA-seq data, EsDREBs were highly induced and had the largest number of differentially expressed genes in response to drought. Eight out of twelve representative EsAP2/ERFs were significantly up-regulated as assessed by RT-qPCR. This study provides detailed insights into the classification, gene structure, motifs, chromosome distribution, and gene expression of AP2/ERF genes in E. songoricum and lays a foundation for better understanding of drought stress tolerance mechanisms in legume plants. Moreover, candidate genes for drought-resistant plant breeding are proposed.

Coupling Root Diameter With Rooting Depth to Reveal the Heterogeneous Assembly of Root-Associated Bacterial Communities in Soybean.

Root diameter and rooting depth lead to morphological and architectural heterogeneity of plant roots; however, little is known about their effects on root-associated microbial communities. Bacterial community assembly was explored across 156 samples from three rhizocompartments (the rhizosphere, rhizoplane, and endosphere) for different diameters (0.0-0.5 mm, 0.5-1.0 mm, 1.0-2.0 mm, and>2.0 mm) and depths (0-5 cm, 5-10 cm, 10-15 cm, and 15-20 cm) of soybean [Glycine max (L.) Merrill] root systems. The microbial communities of all samples were analyzed using amplicon sequencing of bacterial 16S rRNA genes. The results showed that root diameter significantly affected the rhizosphere and endosphere bacterial communities, while rooting depth significantly influenced the rhizosphere and rhizoplane bacterial communities. The bacterial alpha diversity decreased with increasing root diameter in all three rhizocompartments, and the diversity increased with increasing rooting depth only in the rhizoplane. Clearly, the hierarchical enrichment process of the bacterial community showed a change from the rhizosphere to the rhizoplane to the endosphere, and the bacterial enrichment was higher in thinner or deeper roots (except for the roots at a depth of 15-20 cm). Network analysis indicated that thinner or deeper roots led to higher bacterial network complexity. The core and keystone taxa associated with the specific root diameter class and rooting depth class harbored specific adaptation or selection strategies. Root diameter and rooting depth together affected the root-associated bacterial assembly and network complexity in the root system. Linking root traits to microbiota may enhance our understanding of plant root-microbe interactions and their role in developing environmentally resilient root ecosystems.

Involvement of Glutaredoxin and Thioredoxin Systems in the Nitrogen-Fixing Symbiosis between Legumes and Rhizobia.

Leguminous plants can form a symbiotic relationship with Rhizobium bacteria, during which plants provide bacteria with carbohydrates and an environment appropriate to their metabolism, in return for fixed atmospheric nitrogen. The symbiotic interaction leads to the formation of a new organ, the root nodule, where a coordinated differentiation of plant cells and bacteria occurs. The establishment and functioning of nitrogen-fixing symbiosis involves a redox control important for both the plant-bacteria crosstalk and the regulation of nodule metabolism. In this review, we discuss the involvement of thioredoxin and glutaredoxin systems in the two symbiotic partners during symbiosis. The crucial role of glutathione in redox balance and S-metabolism is presented. We also highlight the specific role of some thioredoxin and glutaredoxin systems in bacterial differentiation. Transcriptomics data concerning genes encoding components and targets of thioredoxin and glutaredoxin systems in connection with the developmental step of the nodule are also considered in the model system Medicago truncatula⁻Sinorhizobium meliloti.

The response of rat submandibular salivary gland to plant protein diet; Biological and histochemical study.

OBJECTIVE: This investigation aimed at studying the effect of plant protein diets on the salivary glands. It compares 3 protein's types on the submandibular gland structure and function. The submandibular gland was chosen because it contains all the elements of the salivary glands. The different protein types were chosen to answer if the plant protein or legume plant protein can be replaced for the animal proteins. METHODS: Thirty young albino rats were divided into 3 dietary groups: group I was fed 10% skim milk and acts as a control, group II was fed corn that is a cereal plant protein, while group III was fed 10% soybean, which is a legume plant protein. The animals were sacrificed after 2 months from the beginning of the experiment and the submandibular salivary glands were prepared for the biochemical analysis and histological, as well as, histochemical studies. RESULTS: The biochemical analysis revealed that total protein in soybean fed group was nearly the same as that of the control, while being significantly decreased in the corn fed group. The histological appearance of the submandibular salivary gland of both study groups showed shrinkage in the acini and ducts. The histochemical results showed an intense precipitation for total protein in the soybean group, while the corn fed group showed a mild precipitation. The reaction for DNA and RNA was intense in the control group as compared with both study groups. CONCLUSION: From this study, it was apparent that the plant protein had adverse effects on the submandibular salivary gland and impairs its function. Thus, plant protein including the soybean cannot replace animal protein which is ideal for the normal growth and function of the gland.