Novel Centromeric and Subtelomeric Repetitive DNA Sequences for Karyotyping the Bambara Groundnut (Vigna subterranea L. Verdc.)

Bambara groundnut (<i>Vigna subterranea</i> L. Verdc.) is an un­derutilized minor legume crop with climate resilience and great potential use in world agriculture. This study aimed to cytogenetically characterize the genome and chromosome properties of Bambara groundnut. We cloned, sequenced, and mapped a 50-bp centromere-specific tandem repeat on all chromosomes. In addition, a 400-bp subtelomeric repeat was discovered and mapped on a single pair of chromosomes. A Bambara groundnut karyotype was constructed using these novel repeats along with ribosomal RNA genes (45S and 5S) and telomeric DNA sequences. This study provides the first analysis of the genome and chromosome properties of Bambara groundnut. We discuss our findings in relation to genetic improvement of Bambara groundnut and centromere evolution in legume species.

Genome-Wide Association Analysis To Delineate High-Quality Snps For Seed Micronutrient Density In Chickpea (Cicer Arietinum L.)

Chickpea is the most important nutrient rich grain legume crop in the world. A diverse core set of 147 chickpea genotypes was genotyped with 50K Cicer SNP array and trait phenotyped in two different environments for four seed micro-nutrients (Cu, Fe, Mn, and Zn). The trait data and high-throughput 50K SNP genotypic data was used for genome-wide association study (GWAS) that led the discovery of gene/QTLs for seed Cu, Fe, Mn, and Zn concentrations in chickpea. The analysis of seed micronutrient data revealed significant differences for all the four micronutrient concentrations (P ≤ 0.05). The mean concentration of seed Fe, Zn, Cu, and Mn pooled over two-year data was 146.1 ppm, 45.9 ppm, 63.8 ppm and 27.0 ppm respectively. The analysis of results led to the identification of 35 SNPs significantly associated with seed Zn, Cu, Fe and Mn concentrations. Among these 35 MTAs, 5 were stable (consistently identified in different environments), 6 were major (explain more than 15% phenotypic variation for an individual trait) and 3 were both major and stable MTAs. The stable and major MTAs identified during the present study shall prove useful in molecular breeding programs aimed at enhancing seed nutrient density of chickpea.

Root system architecture and seed weight relations in forage pea (Pisum sativum ssp. arvense L. Poir.)

ABSTRACT: Forage pea (Pisum sativum ssp. arvense (L.) Poir.) is an important legume crop for fresh and dry herbage production with high input costs as irrigation and fertilization. Selection and breeding of accessions for improved drought tolerance, water, and mineral uptake efficiency become a necessity, rather than a choice. This study evaluated a set of forage pea accessions for the seedling root system architecture diversity and seed reserve utilization, under controlled conditions. Eight cultivars and an elite breeding line were evaluated for the first time in a plexiglass system. The number and lengths of the roots in each depth zone (0, 5, 10, 15+ cm) were evaluated and significant diversity was identified. The cultivar Livioletta had the highest number of roots and total root length. There was a significant correlation between seed weight, seed reserve utilization ratio, and root system vigor. Accessions with the highest seed reserve utilization had the highest total root length and numbers. Seedling root system vigor seems to be effective in predicting the fate of the accessions through maturity. The results suggested a possibility of “seedling root selection” for forage crop breeding.

The Role of Arbuscular Mycorrhiza Fungi in Drought Tolerance in Legume Crops: A Review

Legumes are low-cost but high-yielding crops, which are rich in dietary proteins, vitamins and minerals. Known as mycorrhizal plants, legumes are widely used as model organisms to explore the plant-microbe interactions, especially the symbiotic relationship between plants and rhizosphere microorganisms. Arbuscular mycorrhizal fungi (AMF), an important class of plant-associated microbes, can regulate many physiological and molecular responses of plants. To date, AMF has been commonly used as a bio-fertilizer, whose inoculation to host plants can confer tolerance to different abiotic stresses such as drought, salinity, heat and heavy metals. This review provides an overview of the responses of legumes to drought stress (DS), a summary of the mechanism of AMF-legume symbiosis and its effect on host plant drought tolerance, which taken together reveals the significance of this symbiosis in agriculture. The presented rich information will help understand how host plants benefit from AMF to increase drought tolerance while finetuning their metabolic pathways. The potential and importance of AMF as one of the most effective and environmental-friendly management approaches for enhancing legume crop productivity against DS is highlighted.

Rabi Groundnut Area Estimation using Synthetic Aperture Radar (SAR) in Thiruvannamalai District of Tamil Nadu

Background: Groundnut, commonly known as peanut, is a significant oil, food and feed legume crop grown in all seasons in Tamil Nadu, including kharif, rabi and summer and it is cultivated both under irrigated and rainfed conditions in all the seasons at Thiruvannamlai district. One of the most important applications of remote sensing in agriculture is a Crop Acreage and Production Estimation (CAPE). The CAPE’s main goal is to estimate crop acreage and production of important crops, so that advanced food production, distribution and supply data were achieved. Methods: Multi-temporal Sentinel 1A SAR IW- GRD data with 20 m spatial resolution and 12 days temporal resolution of Vertical - Horizontal (V-H) polarization were downloaded for the period of 4th October 2020 to 8th January 2021 to have the full coverage during the crop growth period in the study area used for this work. Crop backscattering and multi-temporal features were extracted from MAPscape 5.2 automated pre-processing tool and its classified using supervised maximum likelihood classification for groundnut acreage extraction for Thiruvannamalai district. Result: The rabi groundnut area of Thiruvannamalai district of Tamil Nadu was estimated using SAR Sentinel-1A data as 32298 ha with a higher accuracy percentage of 87.4 and kappa coefficient of 0.75.

Laser Microdissection of Pisum sativum L. Nodules Followed by RNA-Seq Analysis Revealed Crucial Transcriptomic Changes During Infected Cell Differentiation

Garden pea (Pisum sativum L.) is a globally important legume crop. Like other legumes, it forms beneficial symbiotic interactions with the soil bacteria rhizobia, gaining the ability to fix atmospheric nitrogen. In pea nodules, the meristem is long-lasting and results in the formation of several histological zones that implicate a notable differentiation of infected host cells. However, the fine transcriptional changes that accompany differentiation are still unknown. In this study, using laser microdissection followed by RNA-seq analysis, we performed transcriptomic profiling in the early infection zone, late infection zone, and nitrogen fixation zone of 11-day-old nodules of pea wild-type line SGE. As a result, a list of functional groups of differentially expressed genes (DEGs) in different nodule histological zones and a list of genes with the most prominent expression changes during nodule development were obtained. Their analyses demonstrated that the highest amount of DEGs was associated with the nitrogen fixation zone. Among well-known genes controlling nodule development, we revealed genes that can be novel players throughout nodule formation. The characterized genes in pea were compared with those previously described in other legumes and their possible functions in nodule development are discussed.

Genome wide identification of mungbean (Vigna radiata [L.] R. Wilczek) Late Embryogenesis Abundant (LEA) protein gene family

Mungbean (Vigna radiata L. Wilczek) an important legume crop with valuable nutritional and health benefits is severely affected by drought conditions. Desiccation tolerance is a capacity of seeds to survive and maintain physiological activities during storage and stress conditions. LEA proteins are group of stress associated proteins that help the plants survive water deficit stress. Here we have performed genome-wide analysis of mungbean LEA (VrLEA) genes, and also insilico physical/functional characterization. Gene-positioning showed that 307 VrLEAs are present in all the eleven chromosomes, but are unevenly distributed.Upstream promoter sequence analysis of LEA genes revealed the occurrence of MYB transcription factor (TF)in higher number compared to other TFs i.e., bZIP, AP2, WRKY, NAC and bHLH.Further, we downstreamed our analysis to fewer VrLEAs, based on drought responsive data. The VrLEAs obtained from the earlier experimental data were examined for its organelle localization and found that they are intracellular functional proteins.

iTRAQ based protein profile analysis revealed key proteins involved in regulation of drought-tolerance during seed germination in Adzuki bean

Adzuki bean is an important legume crop due to its high-quality protein, fiber, vitamins, minerals as well as rich bioactive substances. However, it is vulnerable to drought at the germination stage. However, little information is available about the genetic control of drought tolerance during seed germination in adzuki bean. In this study, some differential expression proteins (DEPs) were identified during seed germination between the drought-tolerant variety 17235 and drought-sensitive variety 17033 in adzuki bean using iTRAQ method. A total of 2834 proteins were identified in the germinating seeds of these two adzuki beans. Compared with the variety 17033, 87 and 80 DEPs were increased and decreased accumulation in variety 17235 under drought, respectively. Meanwhile, in the control group, a few DEPs, including 9 up-regulated and 21 down-regulated proteins, were detected in variety 17235, respectively. GO, KEGG, and PPI analysis revealed that the DEPs related to carbohydrate metabolism and energy production were significantly increased in response to drought stresses. To validate the proteomic function, the ectopic overexpression of V-ATPase in tobacco was performed and the result showed that V-ATPase upregulation could enhance the drought tolerance of tobacco. The results provide valuable insights into genetic response to drought stress in adzuki bean, and the DEPs could be applied to develop biomarkers related to drought tolerant in adzuki bean breeding projects.

Comparative Efficiency of Mineral, Chelated and Nano Forms of Zinc and Iron for Improvement of Zinc and Iron in Chickpea (Cicer arietinum L.) through Biofortification

Nanoparticles (NPs), due to their tailored properties, serve as potential sources of nutrients for the biofortification of edible grains. Chickpeas are a valued legume crop, widely consumed in developing countries. Thus, to improve the Zn and Fe content in chickpeas, a two-year study was conducted to examine the potential of the foliar application of mineral (0.5% Zn and Fe), chelated (0.3% Zn and Fe) and nanoforms (0.5% ZFN) of fertilizers to enhance Zn and Fe content in chickpea. The foliar application of 0.5% ZnO NPs + 0.5% Fe2O3 NPs (ZFN) at the pre-flowering stage showed the highest potential to increase grain yield, Zn and Fe content and their uptake as a single foliar application of nano-fertilizers showed comparable results to two foliar applications of mineral and chelated forms. The grain and straw yield (14.07 and 33.04 q ha−1, respectively) under ZFN treatment was significantly higher over the control (9.20 and 27.49 q ha−1, respectively). A similar trend was observed for Zn and Fe content in grain (42.29 and 86.51 mg kg−1, respectively). For nutrient uptake, ZFN treatment showed the highest uptake of Zn and Fe in grain (604.49 and 1226.22 g ha−1, respectively) and straw (729.55 and 9184.67 g ha−1, respectively). Thus, nano-fertilizers, due to their altered structural properties, demonstrated higher translocation over the mineral and chelated forms of nutrient fertilizers and thus improved yield and nutrient content to a greater extent. Thus, the foliar application of 0.5% ZnO NPs + 0.5% Fe2O3 NPs may prove to be a feasible option for the enrichment of chickpeas with Zn and Fe to ameliorate malnutrition in burgeoning human populations.

Legume Breeding for the Agroecological Transition of Global Agri-Food Systems: A European Perspective

Wider and more profitable legume crop cultivation is an indispensable step for the agroecological transition of global agri-food systems but represents a challenge especially in Europe. Plant breeding is pivotal in this context. Research areas of key interest are represented by innovative phenotypic and genome-based selection procedures for crop yield, tolerance to abiotic and biotic stresses enhanced by the changing climate, intercropping, and emerging crop quality traits. We see outmost priority in the exploration of genomic selection (GS) opportunities and limitations, to ease genetic gains and to limit the costs of multi-trait selection. Reducing the profitability gap of legumes relative to major cereals will not be possible in Europe without public funding devoted to crop improvement research, pre-breeding, and, in various circumstances, public breeding. While most of these activities may profit of significant public-private partnerships, all of them can provide substantial benefits to seed companies. A favorable institutional context may comprise some changes to variety registration tests and procedures.