Publications

Additional file 1.

Extreme climate induced heat stress during the reproductive phase significantly reduces yield and seed quality in chickpea, a vital cool-season pulse crop. While chickpea plants deploy various biochemical and molecular mechanisms, including the production of protective compounds and heat shock proteins to cope with heat stress, the metabolomic and lipidomic bases of heat tolerance remain poorly understood. This study used untargeted metabolomics and lipidomics to identify key metabolites, lipids, and potential biomarkers in seeds of a heat-tolerant (PI518255) and a heat-sensitive (PI598080) chickpea genotypes exposed to heat stress (35 °C day/20 °C night) under controlled environments. Results from volcano plot analysis revealed that 65 metabolites and 131 lipids were upregulated, while 17 metabolites and 195 lipids were downregulated under heat stress. Heatmap analysis showed that the heat-tolerant genotype had elevated metabolites (Naringenin, Astilbin,1-O-Cinnamoyl-(6-arabinosylglucose), Hesperetin 7-glucoside, luteolin, and neoandrographolide) and lipids [dimethylphosphatidylethanolamine (dMePE), phosphatidylinositol phosphates (PIP), phosphatidylethanolamine (PE), phosphatidylcholines (PC), phosphatidylglycerol (PG), phosphatidylinositol (PI), diacylglycerol monogalactoside (DGMG) (36:5), monogalactosyldiacylglycerol (MGDG), phosphatidic acid (PA), phosphatidylmonomethylethanolamine (PMe), Biotinyl Phosphatidylethanolamine (BiotinylPE), (O-acyl)-omega-hydroxy fatty acids (OAHFAs)], which may serve as diagnostic biomarkers for heat tolerance. Pathway enrichment analysis (KEGG) identified several heat stress-responsive metabolic pathways, including the pentose phosphate pathway, pyruvate metabolism, citrate (TCA) cycle, glyoxylate and dicarboxylate metabolism, starch and sucrose metabolism, glycolysis/gluconeogenesis, and cysteine and methionine metabolism. Lipid metabolic pathways involving MGDG, glycerophosphocholine, PI, PA, PC, phosphatidylcholines, lysophosphatidylcholine (LPC), lysophosphatidylglycerol (LPG), glycerophosphoinositol, and phosphoglyceric acid were also significantly affected. Future research employing targeted metabolomics and lipidomics profiling could elucidate candidate markers to enhance seed yield and quality, and support breeding programs to develop heat- and climate- resilient chickpea cultivars.

Chickpea is highly sensitive to cold stress during its reproductive stages, leading to significant reductions in potential pod formation due to decreased reproductive success. This study aimed to investigate the specific responses of anthers and ovules to cold stress, explore the role of oxidative stress and antioxidant mechanisms, and understand the relationship between oxidative stress and reproductive function to enhance our understanding of chickpea responses to cold stress. Chickpea seeds of contrasting genotypes-cold-tolerant (ICC 17258, ICC 16349) and cold-sensitive (ICC 15567, GPF 2)-were sown outdoors in early November under optimal conditions (25.5/15.4°C mean day/night temperatures). At 50 days after sowing, plants were subjected to 13/7°C cold stress (12 h light/dark in walk-in growth chambers. Cold stress significantly increased membrane damage and reduced cellular viability in anthers and ovules, particularly in cold-sensitive (CS) genotypes. Oxidative damage was more pronounced in anthers, particularly at anthesis (stage 2), as indicated by elevated malondialdehyde and hydrogen peroxide levels. Cold-tolerant (CT) genotypes exhibited increased antioxidant activity under stress, especially at pre-anthesis (stage 1), followed by declines at later stage, although responses varied by genotype. Anthers exhibited higher overall antioxidants activity than ovules, while ovules demonstrated notably high catalase activity. Among the antioxidants studied, ascorbate peroxidase and glutathione reductase were most prominent in the CT genotype, along with higher levels of ascorbate (AsA) and glutathione (GSH), highlighting the critical role of the AsA-GSH cycle in conferring cold tolerance to chickpea. Exogenous supplementation with 1 mM ascorbate (AsA) and glutathione (GSH) significantly stimulated pollen germination in cold-stressed plants under <i>in vitro</i> conditions, with a greater effect observed in CS genotypes. Furthermore, antioxidant activity strongly correlated with key reproductive traits such as pollen germination and ovule viability. This study revealed that the anthers and ovules exhibited distinct responses to cold stress, with significant genotypic differences across key reproductive stages. These insights provide a deeper understanding of cold tolerance mechanisms in chickpea and provide vital clues for breeding strategies to enhance resilience and reproductive success under cold stress.

Quinolizidine alkaloids (QAs) are toxic secondary metabolites that complicate the end use of narrow-leafed lupin (NLL; Lupinus angustifolius L.) grain, as levels sometimes exceed the industry limit for its use as a food and feed source. The genotypic and environmental influences on QA production in NLL are poorly understood. Here, the expression of QA biosynthetic genes was analysed in vegetative and reproductive tissues of bitter (high QA) and sweet (low QA) accessions. It was demonstrated that sweet accessions are characterized by lower QA biosynthetic gene expression exclusively in leaf and stem tissues than bitter NLL, consistent with the hypothesis that QAs are predominantly produced in aerial tissues and transported to seeds, rather than synthesized within the seed itself. This analysis informed our identification of additional candidate genes involved in QA biosynthesis. Drought and temperature stress are two major abiotic stresses that often occur during NLL pod set. Hence, we assessed the effect of drought, increased temperature, and their combination, on QA production in three sweet NLL cultivars. A cultivar-specific response to drought and temperature in grain QA levels was observed, including the identification of a cultivar where alkaloid levels did not change with these stress treatments.

Grain legumes are a rich source of dietary protein for millions of people globally and thus a key driver for securing global food security. Legume plant-based 'dietary protein' biofortification is an economic strategy for alleviating the menace of rising malnutrition-related problems and hidden hunger. Malnutrition from protein deficiency is predominant in human populations with an insufficient daily intake of animal protein/dietary protein due to economic limitations, especially in developing countries. Therefore, enhancing grain legume protein content will help eradicate protein-related malnutrition problems in low-income and underprivileged countries. Here, we review the exploitable genetic variability for grain protein content in various major grain legumes for improving the protein content of high-yielding, low-protein genotypes. We highlight classical genetics-based inheritance of protein content in various legumes and discuss advances in molecular marker technology that have enabled us to underpin various quantitative trait loci controlling seed protein content (SPC) in biparental-based mapping populations and genome-wide association studies. We also review the progress of functional genomics in deciphering the underlying candidate gene(s) controlling SPC in various grain legumes and the role of proteomics and metabolomics in shedding light on the accumulation of various novel proteins and metabolites in high-protein legume genotypes. Lastly, we detail the scope of genomic selection, high-throughput phenotyping, emerging genome editing tools, and speed breeding protocols for enhancing SPC in grain legumes to achieve legume-based dietary protein security and thus reduce the global hunger risk.

Low-light stress is increasingly recognized as a significant abiotic stress factor compromising global crop productivity and quality stability. To deeper understand the effects of short-term low-light stress on the starch accumulation and quality attributes in a tested maize ( Zea mays L.) hybrid, 10-day shading treatments (50% light reduction) were applied during six growth phases from anthesis to maturity, and starch accumulation and physical and chemical properties were analyzed. The results showed that low-light stress had a greater impact during early grain filling stages than later stages. Low-light stress significantly impeded the conversion of soluble sugars to starch, leading to a marked reduction in total starch content. Starch granule size distribution shifted towards larger granules, with the proportion of granules >20 μm increasing by up to 64%. Amylose content increased while relative crystallinity decreased. These structural alterations were accompanied by substantial functional declines, including lower gelatinization temperature and enthalpy, a 18.6% reduction in peak viscosity, and a dramatic 93.4% enhancement in retrogradation percentage. Principal component analysis confirmed that the primary variations induced by shading were decreases in viscosity and gelatinization parameters, alongside increases in retrogradation properties. Crucially, the S2 stage (11-20 days after anthesis) was identified as the most vulnerable period to low-light stress, providing a key target for future protective strategies. • 11-20 days after anthesis is the critical low-light sensitivity window for maize starch synthesis. • Low-light stress reduces the total starch content by 11.6% via impaired sugar conversion and increased sucrose. • Amylose content rises by 29.7%, relative crystallinity (RC) drops by 35.4%, large granules (>20μm) surge by 64%. • Pasting viscosity declines by 18.6%, thermal stability (ΔHgel) weakens by 28.8%, retrogradation accelerates.

With the increasing consumer awareness and knowledge about safe and healthy food, it is imperative to develop ‘green’ crops with reduced fertilizer application for quality food production, environmental protection and sustainable agricultural development. This study systematically evaluated and compared the water footprint (WF) including WFblue, WFgreen and WFgrey of eight crops including wheat, maize, rice, sweet potato, soybean, millet, mung bean and sorghum under green and traditional cultivation in the Huang-Huai-Hai farming region. The data came from 252 onsite questionnaires conducted in 2018 for land under green and traditional cultivation by 19 green planting companies and farming cooperatives with green food production certification authorized by the government of China. The results revealed that, compared to traditional cultivation, green cultivation under reduced N fertilizer application (1) decreased crop yields by 3–13%; (2) reduced the average WFtotal by 29% to 1168 m3 t−1 and average WFgrey by 57% to 419 m3 t−1 with no significant differences in WFblue and WFgreen; (3) decreased the WFtotal of maize by 55%, rice by 41%, wheat by 27%, mung bean by 31%, sorghum by 24%, sweet potato by 19%, millet by 17% and soybean by 17%. The WFgrey proportion of WFtotal under green cultivation ranged from 27–57% and contributed the most to the decline in WFtotal. This study offers insight into the impact of green cultivation on water requirements and pollution relative to traditional cultivation. Precision N fertilizer application and improved N use efficiencies on-farm are important pathways to sustainable agricultural development.