Plant Breeding Research Articles

Transgressive Variability of Quantitative Characters in Second Generation (Wheat Hybrids)

The article presents the results of a study of the degree and frequency of transgression in reciprocal hybrids of soft wheat of the second generation (F2). The studies were conducted in the 2020-2021 vegetation year on an experimental plot of the experimental base of the Research Institute of Crop Husbandry of Azerbaijan under irrigated conditions. During the research year, some yield indicators (length of the ear, number of spikelets, number of grains and weight of grains in the ear) of 9 local varieties (Mirbashir-128, Azeri, Gobustan, Fatima, Gyrmyzy gul-1, Murov-2, Askeran, Matin and Onur) of soft wheat and 32 combinations of second-generation hybrids were studied. The degree and frequency of transgression were determined. During the growing season, phenological observations were carried out in accordance with the methodology of scientific research in the field of breeding of grain-crop plants. In the second-generation hybrids (F2), transgressive variability in quantitative traits was calculated using the method of G. S. Voskresensky and V. I. Shpot. The results of the study showed that positive transgression was observed in the second-generation hybrid combinations (F2), which were characterized by high dominance and heterosis in the first generation (F1). In the combinations obtained with the participation of the Gobustan variety, high transgression and frequency were mainly noted in quantitative traits, regardless of whether it was taken as the maternal or paternal form, and negative transgression was mainly recorded when using the Fatima variety as the maternal one. In the reciprocal hybrids Onur × Azeri and Onur × Gyrmyzy gul-1, when the Onur variety was taken as the maternal form, and in the reciprocal hybrids Mirbashir-128 × Gyrmyzy gul-1, when the Mirbashir-128 variety was taken as the maternal form, a positive level of transgression was recorded for all studied traits.

Epigenetic Regulation for Heat Stress Adaptation in Plants: New Horizons for Crop Improvement under Climate Change

Global warming poses a significant threat to plant ecosystems and agricultural productivity, primarily through heat stress (HS), which disrupts photosynthesis, respiration, and overall plant metabolism. Epigenetic modifications, including DNA methylation, histone modifications, and RNA modifications, enable plants to dynamically and heritably adjust gene expression in response to environmental stressors. These mechanisms not only help plants survive immediate stress but also confer stress memory, enhancing their resilience to future HS events. This review explores the mechanisms underlying plant thermotolerance, emphasizing the critical role of epigenetic regulation in adapting to HS. It also highlights how DNA methylation modulates stress-responsive genes, histone modifications facilitate transcriptional memory, and RNA modifications influence mRNA stability and translation. Recent advancements in genome editing technologies, such as CRISPR-Cas9, have enabled precise modifications of epigenetic traits, offering new avenues for breeding climate-resilient crops. The integration of these modern tools with traditional breeding methods holds significant promise for developing crops with enhanced thermotolerance. Despite the potential, challenges such as the stability and heritability of epigenetic marks and the complex interplay between different epigenetic modifications need to be addressed. Future research should focus on elucidating these interactions and identifying reliable epigenetic markers for selection. By leveraging the insights gained from epigenetic studies, we can develop innovative breeding strategies to improve crop resilience and ensure sustainable agricultural productivity in the face of global warming. This review underscores the importance of epigenetic regulation in plant adaptation to heat stress and its potential to revolutionize crop breeding, offering a pathway to secure food production and sustainability under changing climatic conditions.

Unravelling Morpho‐Physiological Mechanism and Candidate Genes Associated With Salinity Tolerance in Superior Haplotypes of Barley (Hordeum vulgare L.)

ABSTRACTThe lack of suitable genetic resources for saline regions and the complexity of the traits involved impede the progress in crop breeding for salt tolerance. The present investigation was carried out using 27 diverse barley genotypes chosen based on the assessment of salt tolerance potential within the barley mini‐core collection at the National Genebank of India. The genotypes were exposed to salinity stress (200 mM NaCl) and were examined for morpho‐agronomic, physiological traits and salt uptake parameters. Exposure to salt stress resulted in a significant decline in all parameters ranging from 5.94% in relative water content to 80.04% in shoot K+/Na+ ratio compared to the control in the evaluated accessions. Moreover, the grain yield and its key attribute hundred‐grain weight decreased substantially by 65.35% and 48.62%, respectively, under saline treatment. The majority of the resilient accessions managed to uphold a higher K+/Na+ ratio ranging from 0.51 in EC0578359 to 1.19 EC0578251 in contrast to vulnerable germplasm (<0.56) under saline circumstances. The analysis of haplotype variants disclosed allelic diversity linked with two promising candidate genes, HVA1 and HvHKT2, recognised for conferring salt tolerance. Examination of nucleotide sequences revealed that the HVA1 remained considerably conserved among the evaluated genotypes as the majority of the SNPs (single‐nucleotide polymorphisms) were synonymous. Conversely, for HvHKT2, a significant level of genetic variation led to the identification of two primary haplotypic clusters—Hap1 associated with sensitivity to salinity and Hap2 linked with tolerant traits. Hap2 predominantly consisted of In/Dels which caused a modification in the overall protein length alongside the phospho‐variant allelic form of the HKT2 gene, further enhancing the biological specificity and functional stress response in a spatiotemporal fashion. These haplotype clusters correlated with favourable traits could be utilised for trait integration into breeding populations, thereby expediting the enhancement of superior salt‐tolerant barley cultivars.

Genome editing in angiosperm chloroplasts: targeted DNA double-strand break and base editing.

Chloroplasts are organelles that are derived from a photosynthetic bacterium and have their own genome. Genome editing is a recently developing technology that allows for specific modifications of target sequences. The first successful application of genome editing in chloroplasts was reported in 2021, and since then, this research field has been expanding. Although the chloroplast genome of several dicot species can be stably modified by a conventional method, which involves inserting foreign DNAs into the chloroplast genome via homologous recombination, genome editing offers several advantages over this method. In this review, we introduce genome editing methods targeting the chloroplast genome and describe their advantages and limitations. So far, CRISPR/Cas systems are inapplicable for editing the chloroplast genome because guide RNAs, unlike proteins, cannot be efficiently delivered into chloroplasts. Therefore, protein-based enzymes are used to edit the chloroplast genome. These enzymes contain a chloroplast-transit peptide, the DNA-binding domain of transcription activator-like effector nuclease (TALEN), or a catalytic domain that induces DNA modifications. To date, genome editing methods can cause DNA double-strand break or introduce C:G-to-T:A and A:T-to-G:C base edits at or near the target sequence. These methods are expected to contribute to basic research on the chloroplast genome in many species and to be fundamental methods of plant breeding utilizing the chloroplast genome.

OsWRKY70 Plays Opposite Roles in Blast Resistance and Cold Stress Tolerance in Rice

The transcription factor WRKYs play pivotal roles in the adapting to adverse environments in plants. Prior research has demonstrated the involvement of OsWRKY70 in resistance against herbivores and its response to abiotic stress. Here, we reported the functional analysis of OsWRKY70 in immunity against fungal diseases and cold tolerance. The results revealed that OsWRKY70 was induced by various Magnaporthe oryzae strains. Knock out mutants of OsWRKY70, which were generated by the CRISPR/Cas9 system, exhibited enhanced resistance to M. oryzae. This was consistent with fortifying the reactive oxygen species (ROS) burst after inoculation in the mutants, elevated transcript levels of defense-responsive genes (OsPR1b, OsPBZ1, OsPOX8.1 and OsPOX22.3) and the observation of the sluggish growth of invasive hyphae under fluorescence microscope. RNA sequencing (RNA-seq) and quantitative real-time PCR (qRT-PCR) validations demonstrated that differentially expressed genes were related to plant-pathogen interactions, hormone transduction and MAPK cascades. Notably, OsbHLH6, a key component of the JA signaling pathway, was down-regulated in the mutants compared to wild type plants. Further investigation confirmed that OsWRKY70 bound to the promoter of OsbHLH6 by semi-in vivo chromatin immunoprecipitation (ChIP). Additionally, the loss-function of OsWRKY70 impaired cold tolerance in rice. The enhanced susceptibility in the mutants characterized by excessive ROS production, elevated ion leakage rate and increased malondialdehyde content, as well as decreased activity of catalase (CAT) and peroxidase (POD) under low temperature stress was, which might be attributed to down-regulation of cold-responsive genes (OsLti6b and OsICE1). In conclusion, our findings indicate that OsWRKY70 negatively contributes to blast resistance but positively regulates cold tolerance in rice, providing a strategy for crop breeding with tolerance to stress.

48 Dietary functional fiber properties for improved health and disease outcomes in pigs

Abstract In swine production, using feed antibiotics as antimicrobial growth promotants has been reduced; thus, feed alternatives to manage gut health are required. Dietary fiber and similar carbohydrate structures such as resistant starch, oligosaccharides, and exopolysaccharides are nutritional tools that may enhance gut health in pigs. Dietary fiber may have a role to alleviate diarrheal diseases including in pigs post-weaning but can also reduce constipation in sows, but specific functionality depends on fiber properties. Antibiotics are hypothesized to influence gut health via modulation of intestinal microbial profiles; fermentation and intestinal inflammation are considered important mechanisms. Dietary fiber sources differ in a key functional property: fermentability. Rapid fermentation of fiber and oligosaccharides is associated with changes in microbial profiles and increased metabolite production. Recently, microbial composition was hypothesized to be less important and combined output of metabolites should be the focus. Fiber properties may also manipulate retention time and physico-chemical properties of the undigested residue; hence, non-fermentable fiber may prevent constipation in sows. The fiber-like structure resistant starch is not digested and acts as fermentable fiber but has unique properties, because it specifically increases intestinal abundance of bifidobacteria, which are associated with improved gut health. Using crop breeding, feed processing, and feed additives, the structure of fiber and starch can be altered thereby changing its degradation kinetics and affecting its prebiotic activity. Finally, fiber-like structures such as exopolysaccharides from Limosilactobacillus reuteri and unique oligosaccharides may serve as receptor analogues for pathogenic bacteria, e.g., enterotoxigenic Escherichia coli (ETEC). These receptor analogues block lectin domains of bacterial adhesins and thus prevent adherence of pathogens to the gut wall, thereby avoiding initiation of post-weaning diarrhea. In conclusion, dietary fiber and similar structures possess important functional properties that may also provide important solutions to maintain gut health in pigs.

Research Progress on miRNAs and Artificial miRNAs in Insect and Disease Resistance and Breeding in Plants.

MicroRNAs (miRNAs) are small, non-coding RNAs that are expressed in a tissue- and temporal-specific manner during development. They have been found to be highly conserved during the evolution of different species. miRNAs regulate the expression of several genes in various organisms, with some regulating the expression of multiple genes with similar or completely unrelated functions. Frequent disease and insect pest infestations severely limit agricultural development. Thus, cultivating resistant crops via miRNA-directed gene regulation in plants, insects, and pathogens is an important aspect of modern breeding practices. To strengthen the application of miRNAs in sustainable agriculture, plant endogenous or exogenous miRNAs have been used for plant breeding. Consequently, the development of biological pesticides based on miRNAs has become an important avenue for future pest control methods. However, selecting the appropriate miRNA according to the desired target traits in the target organism is key to successfully using this technology for pest control. This review summarizes the progress in research on miRNAs in plants and other species involved in regulating plant disease and pest resistance pathways. We also discuss the molecular mechanisms of relevant target genes to provide new ideas for future research on pest and disease resistance and breeding in plants.

Leveraging soil mapping and machine learning to improve spatial adjustments in plant breeding trials

Leveraging soil mapping and machine learning to improve spatial adjustments in plant breeding trials

Why Contexts Matter for Gender Equal Outcomes in Research-Based Plant Breeding: The Case of Maize in Nigeria

Why Contexts Matter for Gender Equal Outcomes in Research-Based Plant Breeding: The Case of Maize in Nigeria

Comparative physiological and transcriptomic analyses reveal genotype specific response to drought stress in Siberian wildrye (Elymus sibiricus)

Siberian wildrye (Elymus sibiricus) is a xero-mesophytic forage grass with high nutritional quality and stress tolerance. Among its numerous germplasm resources, some possess superior drought resistance. In this study, we firstly investigated the physiological differences between the leaves of drought-tolerant (DT) and drought-sensitive (DS) genotypes under different field water contents (FWC) in soil culture. The results showed that, under drought stress, DT maintained a lower leaf water potential for water absorption, sustained higher photosynthetic efficiency, and reduced oxidative damage in leaves by efficiently maintaining the ascorbic acid-glutathione (ASA-GSH) cycle to scavenge reactive oxygen species (ROS) compared to DS. Secondly, using RNA sequencing (RNA-seq), we analyzed the gene expression profiles of DT and DS leaves under osmotic stress of hydroponics induced by PEG-6000. Through differential analysis, we identified 1226 candidate unigenes, from which we subsequently screened out 115/212 differentially expressed genes (DEGs) that were more quickly induced/reduced in DT than in DS under osmotic stress. Among them, Unigene0005863 (EsSnRK2), Unigene0053902 (EsLRK10) and Unigene0031985 (EsCIPK5) may be involved in stomatal closure induced by abscisic acid (ABA) signaling pathway. Unigene0047636 (EsCER1) may positively regulates the synthesis of very-long-chain (VLC) alkanes in cuticular wax biosynthesis, influencing plant responses to abiotic stresses. Finally, the contents of wax and cutin were measured by GC–MS under osmotic stress of hydroponics induced by PEG-6000. Corresponding to RNA-seq, contents of wax monomers, especially alkanes and alcohols, showed significant induction by osmotic stress in DT but not in DS. It is suggested that limiting stomatal and cuticle transpiration under drought stress to maintain higher photosynthetic efficiency and water use efficiency (WUE) is one of the critical mechanisms that confer stronger drought resistance to DT. This study provides some insights into the molecular mechanisms underlying drought tolerance in E. sibiricus. The identified genes may provide a foundation for the selection and breeding of drought-tolerant crops.

Training set optimization is a feasible alternative for perennial orphan crop domestication and germplasm management: an Acrocomia aculeata example.

Orphan perennial native species are gaining importance as sustainability in agriculture becomes crucial to mitigate climate change. Nevertheless, issues related to the undomesticated status and lack of improved germplasm impede the evolution of formal agricultural initiatives. Acrocomia aculeata - a neotropical palm with potential for oil production - is an example. Breeding efforts can aid the species to reach its full potential and increase market competitiveness. Here, we present genomic information and training set optimization as alternatives to boost orphan perennial native species breeding using Acrocomia aculeata as an example. Furthermore, we compared three SNP calling methods and, for the first time, presented the prediction accuracies of three yield-related traits. We collected data for two years from 201 wild individuals. These trees were genotyped, and three references were used for SNP calling: the oil palm genome, de novo sequencing, and the A. aculeata transcriptome. The traits analyzed were fruit dry mass (FDM), pulp dry mass (PDM), and pulp oil content (OC). We compared the predictive ability of GBLUP and BayesB models in cross- and real validation procedures. Afterwards, we tested several optimization criteria regarding consistency and the ability to provide the optimized training set that yielded less risk in both targeted and untargeted scenarios. Using the oil palm genome as a reference and GBLUP models had better results for the genomic prediction of FDM, OC, and PDM (prediction accuracies of 0.46, 0.45, and 0.39, respectively). Using the criteria PEV, r-score and core collection methodology provides risk-averse decisions. Training set optimization is an alternative to improve decision-making while leveraging genomic information as a cost-saving tool to accelerate plant domestication and breeding. The optimized training set can be used as a reference for the characterization of native species populations, aiding in decisions involving germplasm collection and construction of breeding populations.

Modern Technologies Provide New Opportunities for Somatic Hybridization in the Breeding of Woody Plants.

Advances in cell fusion technology have propelled breeding into the realm of somatic hybridization, enabling the transfer of genetic material independent of sexual reproduction. This has facilitated genome recombination both within and between species. Despite its use in plant breeding for over fifty years, somatic hybridization has been limited by cumbersome procedures, such as protoplast isolation, hybridized-cell selection and cultivation, and regeneration, particularly in woody perennial species that are difficult to regenerate. This review summarizes the development of somatic hybridization, explores the challenges and solutions associated with cell fusion technology in woody perennials, and outlines the process of protoplast regeneration. Recent advancements in genome editing and plant cell regeneration present new opportunities for applying somatic hybridization in breeding. We offer a perspective on integrating these emerging technologies to enhance somatic hybridization in woody perennial plants.

Genome-wide analysis of flavonoid biosynthetic genes in Musaceae (Ensete, Musella, and Musa species) reveals amplification of flavonoid 3ʹ,5ʹ-hydroxylase

Abstract Flavonoids in Musaceae are involved in pigmentation and stress responses, including cold resistance, and are a component of the healthy human diet. Identification and analysis of the sequence and copy number of flavonoid biosynthetic genes are valuable for understanding the nature and diversity of flavonoid evolution in Musaceae species. In this study, we identified 71–80 flavonoid biosynthetic genes in chromosome-scale genome sequence assemblies of Musaceae, including those of Ensete glaucum, Musella lasiocarpa, Musa beccarii, M. acuminata, M. balbisiana and M. schizocarpa, checking annotations with BLAST and determining the presence of conserved domains. The number of genes increased through segmental duplication and tandem duplication. Orthologues of both structural and regulatory genes in the flavonoid biosynthetic pathway are highly conserved across Musaceae. The flavonoid 3ʹ,5ʹ-hydroxylase gene F3ʹ5ʹH was amplified in Musaceae and ginger compared with grasses (rice, Brachypodium, Avena longiglumis, and sorghum). One group of genes from this gene family amplified near the centromere of chromosome 2 in the x = 11 Musaceae species. Flavonoid biosynthetic genes displayed few consistent responses in the yellow and red bracts of Musella lasiocarpa when subjected to low temperatures. The expression levels of MlDFR2/3 (dihydroflavonol reductase) increased while MlLAR (leucoanthocyanidin reductase) was reduced by half. Overall, the results establish the range of diversity in both sequence and copy number of flavonoid biosynthetic genes during evolution of Musaceae. The combination of allelic variants of genes, changes in their copy numbers, and variation in transcription factors with the modulation of expression under cold treatments and between genotypes with contrasting bract-colours suggests the variation may be exploited in plant breeding programmes, particularly for improvement of stress-resistance in the banana crop.

Conservation status of three rare endemic Phaseolus bean (Leguminosae, Phaseoleae) species of Costa Rica

We aimed at an inventory of all populations of wild Phaseolus (bean) species in Costa Rica, in relation to future plant breeding. During the field work in 2003–2018, three new and rare bean species (i.e. P. albicarminus, P. angucianae and P. hygrophilus) were found in different montane forest habitats which originally occupy a small acreage. Field observations, together with satellite images, indicate deforestation due to coffee plantations or pastures. To date only eleven populations of these species are known, distributed along the Talamanca and Fila Cruces mountainous ranges, making them endemic. Their narrow distribution, deforestation affecting the original habitats, and occurrence outside established and enforced protected areas motivate the assessment of their conservation status as ‘Endangered' (EN).

A bioassay that yields quantifiable symptoms of cucurbit yellow vine disease caused by Serratia marcescens.

Cucurbit yellow vine disease (CYVD), which is caused by the gram-negative bacterium Serratia marcescens and transmitted by squash bugs (Anasa tristis DeGeer), is a devastating disease of cucurbit crops that is emerging rapidly in the eastern half of the U.S. The lack of a robust pathogenicity assay for CYVD in the laboratory has hampered functional tests using genomic sequences to investigate the biology of this phytopathogen. In this study we developed and validated a bioassay that yielded consistent and quantifiable CYVD symptoms on squash in the lab. We compared inoculation by wounding with a multipronged floral pin frog to inoculation by injection in which a needle was moved in and out of the stem multiple times in each of multiple piercings to mimic the feeding behavior of squash bugs. We found that inoculation by needle injection of ≥108 CFU/ml of S. marcescens into the stem of squash (Cucurbita pepo) plants at the cotyledon growth stage reproducibly induced CYVD symptoms, whereas injecting 106 or 107 CFU/ml did not. Additionally, we found that S. marcescens induced symptoms on all of the squash cultivars tested, and induced symptoms that have not been previously reported, including stem elongation and leaf cupping. In short, through our injection approach of mimicking the natural process of S. marcescens transmission by squash bug feeding, we obtained robust and quantifiable CYVD symptoms. This laboratory bioassay provides a crucial tool for investigating the biology and pathology of this emerging pathogen and for plant breeding screens aimed at combatting CYVD.

Explainable artificial intelligence for genotype-to-phenotype prediction in plant breeding: a case study with a dataset from an almond germplasm collection.

Advances in DNA sequencing revolutionized plant genomics and significantly contributed to the study of genetic diversity. However, predicting phenotypes from genomic data remains a challenge, particularly in the context of plant breeding. Despite significant progress, accurately predicting phenotypes from high-dimensional genomic data remains a challenge, particularly in identifying the key genetic factors influencing these predictions. This study aims to bridge this gap by integrating explainable artificial intelligence (XAI) techniques with advanced machine learning models. This approach is intended to enhance both the predictive accuracy and interpretability of genotype-to-phenotype models, thereby improving their reliability and supporting more informed breeding decisions. This study compares several ML methods for genotype-to-phenotype prediction, using data available from an almond germplasm collection. After preprocessing and feature selection, regression models are employed to predict almond shelling fraction. Best predictions were obtained by the Random Forest method (correlation = 0.727 ± 0.020, an R 2 = 0.511 ± 0.025, and an RMSE = 7.746 ± 0.199). Notably, the application of the SHAP (SHapley Additive exPlanations) values algorithm to explain the results highlighted several genomic regions associated with the trait, including one, having the highest feature importance, located in a gene potentially involved in seed development. Employing explainable artificial intelligence algorithms enhances model interpretability, identifying genetic polymorphisms associated with the shelling percentage. These findings underscore XAI's efficacy in predicting phenotypic traits from genomic data, highlighting its significance in optimizing crop production for sustainable agriculture.

Genome-wide association scan reveals the reinforcing effect of nano-potassium in improving the yield and quality of salt-stressed barley via enhancing the antioxidant defense system.

Salinity is one of themajor environmental factor that can greatly impact the growth, development, and productivity of barley. Our study aims to detect the natural phenotypic variation of morphological and physiological traits under both salinity and potassium nanoparticles (n-K) treatment. In addition tounderstanding the genetic basis of salt tolerance in barley is a critical aspect of plant breeding for stress resilience.Therefore, a foliar application of n-K was applied at the vegetative stage for 138 barley accessions to enhance salt stress resilience. Interestingly, barley accessions showed high significant increment under n-K treatment compared to saline soil. Based on genome-wide association studies (GWAS) analysis, causative alleles /reliable genomic regions were discovered underlying improved salt resilience through the application of potassium nanoparticles. On chromosome 2H, a highly significant QTN marker (A:C) was located at position 36,665,559 bp which is associated with APX, AsA, GSH, GS, WGS, and TKW under n-K treatment. Inside this region, our candidate gene is HORVU.MOREX.r3.2HG0111480 that annotated as NAC domain protein. Allelic variation detected that the accessions carrying C allele showed higher antioxidants (APX, AsA, and GSH) and barley yield traits (GS, WGS, and TKW) than the accessions carrying A allele, suggesting a positive selection of the accessions carrying C allele that could be used to develop barley varieties with improved salt stress resilience.

Correlation and path coefficient analysis in chilli (Capsicum annuum L.) based on yield and yield related traits

An experiment was carried out in the field laboratory of the Department of Genetics and Plant Breeding of Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur during the period from October 2018 to April 2019. The experiment was set up in a randomized complete block design (RCBD) and three replications were used. The aim of the study was to assess the character association and direct and indirect effect of independent characters on green yield of 28 chilli genotypes. A comparison between genotypic and phenotypic correlation coefficients revealed that the former was higher. At both the genotypic and phenotypic levels, correlation coefficients revealed that fruit yield per plant was significantly and positively linked with fruit length, fruit diameter, individual fruit weight, number of seeds per fruit, and plant height. Individual fruit weight had the most significant positive direct impact on fruit yield, followed by the number of fruits per plant, fruit diameter, and fruit length. Therefore, these characteristics could be regarded as critical selection criteria for the enhancement of chilli yield. Res. Agric. Livest. Fish. Vol. 11, No. 2, August 2024: 231-238

Bambara groundnut as a food, nutritional and income security crop in SubSaharan Africa

An over-reliance on the three major global food staples; maize, wheat, and rice, to continue feeding the world is a dangerous approach. Bambara groundnut originated in West-Africa, but was adopted in many African countries, and is produced almost exclusively by small-scale farmers. It has good levels of nutrients, particularly protein, carbohydrates and fat, as well as lysine, in such a balanced manner that it has been termed a “complete food”. The long duration of cooking (hard-to-cook) of bambara groundnut, and the low number of uses in food preparation (in contrast to groundnut) are also factors responsible for lower levels of production and utilization compared to other legumes. Bambara groundnuts have more than 20% protein and can be used as a meat supplement or replacer. It also has high levels of iron and zinc. Landraces with dark-coloured seeds such as red or black, generally contain higher levels of nutrients and minerals than the cream-white or plain-white coloured landraces. The iron content of red bambara seeds was found to be double that of cream-coloured seeds. Antinutrients such as phytic acid can reduce the bioavailability of iron and zinc, but dehulling of the seed can reduce antinutrients significantly. Bambara groundnut has significant potential as a food security crop, but concerted efforts should be made by governments to market the crop, and to develop products and new uses for the seed and the plant. Plant breeding efforts can improve yield and cooking quality. This paper presents progress on the industrial application for food and nutritional security and genetic improvement of bambara groundnut through breeding.

Chromosome doubling increases PECTIN METHYLESTERASE 2 expression, biomass, and osmotic stress tolerance in kiwifruit

Abstract Chromosome doubling-induced polyploidization is a popular tool for crop breeding. Polyploidy crops commonly have multiple advantages, including increased biomass and stress tolerance. However, little is known about the genes responsible for these advantages. We found kiwifruit (Actinidia chinensis cv. Hongyang) PECTIN METHYLESTERASE 2 (AcPME2)is substantially upregulated in artificially created tetraploid plants that show increased biomass and enhanced tolerance to osmotic stress. Overexpression (OE) of AcPME2 led to increased biomass and enhanced stress tolerance in Arabidopsis (Arabidopsis thaliana), tomato (Solanum lycopersicum), and kiwifruit. Upon short-term osmotic stress treatment, AcPME2-OE plants showed higher levels of demethylesterified pectins and more Ca2+ accumulation in the cell wall than Col-0 plants, which led to increased cell wall stiffness. The stress-induced plasmolysis assays indicated that AcPME2 dynamically mediated the cell wall stiffness in response to osmotic stress, which is dependent on Ca2+ accumulation. Transcriptomic analysis discovered that dozens of stress-responsive genes were significantly upregulated in the AcPME2-OE plants under osmotic stress. Besides, AcPME2-mediated cell wall reinforcement prevented cell wall collapse and deformation under osmotic stress. Our results revealed a single gene contributes to two advantages of polyploidization (increased biomass and osmotic stress tolerance) and that AcPME2 dynamically regulates cell wall stiffness in response to osmotic stress.