Genome-wide identification, characterization, and expression analysis of MIPS family genes in legume species.

BACKGROUND: Evolutionarily conserved in plants, the enzyme D-myo-inositol-3-phosphate synthase (MIPS; EC 5.5.1.4) regulates the initial, rate-limiting reaction in the phytic acid biosynthetic pathway. They are reported to be transcriptional regulators involved in various physiological functions in the plants, growth, and biotic/abiotic stress responses. Even though the genomes of most legumes are fully sequenced and available, an all-inclusive study of the MIPS family members in legumes is still ongoing. RESULTS: We found 24 MIPS genes in ten legumes: Arachis hypogea, Cicer arietinum, Cajanus cajan, Glycine max, Lablab purpureus, Medicago truncatula, Pisum sativum, Phaseolus vulgaris, Trifolium pratense and Vigna unguiculata. The total number of MIPS genes found in each species ranged from two to three. The MIPS genes were classified into five clades based on their evolutionary relationships with Arabidopsis genes. The structural patterns of intron/exon and the protein motifs that were conserved in each gene were highly group-specific. In legumes, MIPS genes were inconsistently distributed across their genomes. A comparison of genomes and gene sequences showed that this family was subjected to purifying selection and the gene expansion in MIPS family in legumes was mainly caused by segmental duplication. Through quantitative PCR, expression patterns of MIPS in response to various abiotic stresses, in the vegetative tissues of various legumes were studied. Expression pattern shows that MIPS genes control the development and differentiation of various organs, and have significant responses to salinity and drought stress. CONCLUSION: The MIPS genes in the genomes of legumes have been identified, characterized and their expression was analysed. The findings pave way for understanding their molecular functions and evolution, and lead to identify the putative MIPS genes associated with different cell and tissue development.

Understanding the role of P-type ATPases in regulating pollen fertility and development in pigeonpea.

The P-type ATPase superfamily genes are the cation and phospholipid pumps that transport ions across the membranes by hydrolyzing ATP. They are involved in a diverse range of functions, including fundamental cellular events that occur during the growth of plants, especially in the reproductive organs. The present work has been undertaken to understand and characterize the P-type ATPases in the pigeonpea genome and their potential role in anther development and pollen fertility. A total of 59 P-type ATPases were predicted in the pigeonpea genome. The phylogenetic analysis classified the ATPases into five subfamilies: eleven P1B, eighteen P2A/B, fourteen P3A, fifteen P4, and one P5. Twenty-three pairs of P-type ATPases were tandemly duplicated, resulting in their expansion in the pigeonpea genome during evolution. The orthologs of the reported anther development-related genes were searched in the pigeonpea genome, and the expression profiling studies of specific genes via qRT-PCR in the pre- and post-meiotic anther stages of AKCMS11A (male sterile), AKCMS11B (maintainer) and AKPR303 (fertility restorer) lines of pigeonpea was done. Compared to the restorer and maintainer lines, the down-regulation of CcP-typeATPase22 in the post-meiotic anthers of the male sterile line might have played a role in pollen sterility. Furthermore, the strong expression of CcP-typeATPase2 in the post-meiotic anthers of restorer line and CcP-typeATPase46, CcP-typeATPase51, and CcP-typeATPase52 in the maintainer lines, respectively, compared to the male sterile line, clearly indicates their potential role in developing male reproductive organs in pigeonpea.

CcNFYB3-CcMATE35 and LncRNA CcLTCS-CcCS modules jointly regulate the efflux and synthesis of citrate to enhance aluminium tolerance in pigeon pea.

Aluminium (Al) toxicity decreases crop production in acid soils in general, but many crops have evolved complex mechanisms to resist it. However, our current understanding of how plants cope with Al stress and perform Al resistance is still at the initial stage. In this study, the citrate transporter CcMATE35 was identified to be involved in Al stress response. The release of citrate was increased substantially in CcMATE35 over-expression (OE) lines under Al stress, indicating enhanced Al resistance. It was demonstrated that transcription factor CcNFYB3 regulated the expression of CcMATE35, promoting the release of citrate from roots to increase Al resistance in pigeon pea. We also found that a Long noncoding RNA Targeting Citrate Synthase (CcLTCS) is involved in Al resistance in pigeon pea. Compared with controls, overexpression of CcLTCS elevated the expression level of the Citrate Synthase gene (CcCS), leading to increases in root citrate level and citrate release, which forms another module to regulate Al resistance in pigeon pea. Simultaneous overexpression of CcNFYB3 and CcLTCS further increased Al resistance. Taken together, these findings suggest that the two modules, CcNFYB3-CcMATE35 and CcLTCS-CcCS, jointly regulate the efflux and synthesis of citrate and may play an important role in enhancing the resistance of pigeon pea under Al stress.

Melatonin-mediated CcARP1 alters F-actin dynamics by phosphorylation of CcADF9 to balance root growth and salt tolerance in pigeon pea.

As a multifunctional hormone-like molecule, melatonin exhibits a pleiotropic role in plant salt stress tolerance. While actin cytoskeleton is essential to plant tolerance to salt stress, it is unclear if and how actin cytoskeleton participates in the melatonin-mediated alleviation of plant salt stress. Here, we report that melatonin alleviates salt stress damage in pigeon pea by activating a kinase-like protein, which interacts with an actin-depolymerizing factor. Cajanus cajan Actin-Depolymerizing Factor 9 (CcADF9) has the function of severing actin filaments and is highly expressed under salt stress. The CcADF9 overexpression lines (CcADF9-OE) showed a reduction of transgenic root length and an increased sensitivity to salt stress. By using CcADF9 as a bait to screen an Y2H library, we identified actin depolymerizing factor-related phosphokinase 1 (ARP1), a novel protein kinase that interacts with CcADF9. CcARP1, induced by melatonin, promotes salt resistance of pigeon pea through phosphorylating CcADF9, inhibiting its severing activity. The CcARP1 overexpression lines (CcARP1-OE) displayed an increased transgenic root length and resistance to salt stress, whereas CcARP1 RNA interference lines (CcARP1-RNAi) presented the opposite phenotype. Altogether, our findings reveal that melatonin-induced CcARP1 maintains F-actin dynamics balance by phosphorylating CcADF9, thereby promoting root growth and enhancing salt tolerance.

Organic amendments modulate the crop yield and rhizospheric bacterial community diversity: a 3-year field study with Cajanus cajan.

Excessive use of chemicals to enhance soil nutrient status and crop yield has resulted in a decline in soil health. Organic farming promotes organic amendments, which help to balance the ecosystem. Understanding the dynamic patterns of belowground microbial populations is essential for developing sustainable agricultural systems. Therefore, the study was designed to evaluate the effect of different agri-practices on rhizospheric bacterial diversity and crop yield in an Indian agricultural system. A 3-year field experiment was set up in a randomized block design using Cajanus cajan as a model crop, comparing conventional farming with organic practice (with animal manure and bio-compost as amendments). Plant and rhizospheric soil samples were collected at the harvest stage for assessing various growth attributes, and for characterizing rhizospheric bacterial diversity. Enhanced crop productivity was seen in conventional farming, with a 2.2-fold increase in grain yield over control. However, over the 3 years, an overall positive impact was observed in the bio-compost-based organic amendment, in terms of bacterial abundance, over other treatments. At the harvest stage of the third cropping season, the bacterial diversity in the organic treatments showed little similarity to the initial bacterial community composition of the amendment applied, indicating stabilization along the growth cycles. The study emphasizes the significance of the choice of the amendment for ushering in agricultural sustainability.

Three stilbenes from pigeon pea with promising anti-methicillin-resistant Staphylococcus aureus biofilm formation activity.

Cajaninstilbene acid (CSA), longistylin A (LLA), and longistylin C (LLC) are three characteristic stilbenes isolated from pigeon pea. The objective of this study was to evaluate the antibacterial activity of these stilbenes against Staphylococcus aureus and even methicillin-resistant Staphylococcus aureus (MRSA) and test the possibility of inhibiting biofilm formation. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of these stilbenes were evaluated. And the results showed that LLA was most effective against tested strains with MIC and MBC values of 1.56 µg/mL followed by LLC with MIC and MBC values of 3.12 µg/mL and 6.25 µg/mL as well as CSA with MIC and MBC values of 6.25 µg/mL and 6.25-12.5 µg/mL. Through growth curve and cytotoxicity analysis, the concentrations of these stilbenes were determined to be set at their respective 1/4 MIC in the follow-up research. In an anti-biofilm formation assay, these stilbenes were found to be effectively inhibited bacterial proliferation, biofilm formation, and key gene expressions related to the adhesion and virulence of MRSA. It is the first time that the anti-S. aureus and MRSA activities of the three stilbenes have been systematically reported. Conclusively, these findings provide insight into the anti-MRSA mechanism of stilbenes from pigeon pea, indicating these compounds may be used as antimicrobial agents or additives for food with health functions, and contribute to the development as well as application of pigeon pea in food science.

Bacterial exopolysaccharide amendment improves the shelf life and functional efficacy of bioinoculant under salinity stress.

AIM: Bacterial exopolysaccharides (EPS) possess numerous properties beneficial for the growth of microbes and plants under hostile conditions. The study aimed to develop a bioformulation with bacterial EPS to enhance the bioinoculant's shelf life and functional efficacy under salinity stress. METHODS AND RESULTS: High EPS-producing and salt-tolerant bacterial strain (Bacillus haynessi SD2) exhibiting auxin-production, phosphate-solubilization, and biofilm-forming ability, was selected. EPS-based bioformulation of SD2 improved the growth of three legumes under salt stress, from which pigeonpea was selected for further experiments. SD2 improved the growth and lowered the accumulation of stress markers in plants under salt stress. Bioformulations with varying EPS concentrations (1% and 2%) were stored for 6 months at 4°C, 30°C, and 37°C to assess their shelf life and functional efficacy. The shelf life and efficacy of EPS-based bioformulation were sustained even after 6 months of storage at high temperature, enhancing pigeonpea growth under stress in both control and natural conditions. However, the efficacy of non EPS-based bioformulation declined following four months of storage. The bioformulation (with 1% EPS) modulated bacterial abundance in the plant's rhizosphere under stress conditions. CONCLUSION: The study brings forth a new strategy for developing next-generation bioformulations with higher shelf life and efficacy for salinity stress management in pigeonpea.

Nano zinc oxide mediated resuscitation of aged Cajanus cajan via modulating aquaporin, cell cycle regulatory genes and hormonal responses.

KEY MESSAGE: Nanoparticle pretreatment improved the health of aged Cajanus cajan seeds viz., regulation of redox status, gene expression, and restoration of hormonal homeostasis. Ageing deteriorates the quality of seeds by lowering their vigor and viability, and terminating with loss of germination. These days, nanotechnology has been seen to revolutionize the agricultural sectors, and particularly nano zinc oxide (nZnO) has gained considerable interests due to its distinctive properties. The aim of the present work was to decipher the possibilities of using nZnO to rejuvenate accelerated aged (AA) seeds of Cajanus cajan. Both chemically (CnZnO) and green (GnZnO; synthesized using Moringa oleifera) fabricated nZnOs were characterized via standard techniques to interpret their purity, size, and shape. Experimental results revealed erratic germination with a decline in viability and membrane stability as outcomes of reactive oxygen intermediate (ROI) buildup in AA seeds. Application of nZnO substantially rebated the accrual of ROI, along with enhanced production of antioxidants, α-amylase activity, total sugar, protein and DNA content. Higher level of zinc was assessed qualitatively/ histologically and quantitatively in nZnO pulsed AA seeds, supporting germination without inducing toxicity. Meantime, augmentation in the gibberellic acid with a simultaneous reduction in the abscisic acid level were noted in nZnO invigorated seeds than that determined in the AA seeds, suggesting possible involvement of ROI in hormonal signalling. Furthermore, nZnO-subjected AA seeds unveiled differential expression of aquaporins and cell cycle regulatory genes. Summarizing, among CnZnO and GnZnO, later one holds better potential for a revival of AA seeds of Cajanus cajan by providing considerable tolerance against ageing-associated deterioration via recouping the cellular redox homeostasis, hormonal signaling, and alteration in expression patterns of aquaporin and cell cycle regulatory genes.

Insights into the role of SUMO in regulating drought stress responses in pigeonpea (Cajanus cajan).

KEY MESSAGE: We have identified and analyzed 28 SUMO-pathway proteins from pigeonpea. Enhanced transcripts of pathway genes and increased SUMO conjugation under drought signifies the role of SUMO in regulating stress. Being a protein-rich and nutrient-dense legume crop, pigeonpea (Cajanus cajan) holds a vital position in a vegetarian meal. It is a resilient crop capable of striving in harsh climates and provides a means of subsistence to small-holding farmers. Nevertheless, extremes of water scarcity and drought conditions, especially during seedling and reproductive stages, remains a major issue severely impacting the growth and overall productivity of pigeonpea. Small ubiquitin-like modifier (SUMO), a post-translational modification system, plays a pivotal role in fortifying plants against stressful conditions by rapid reprogramming of molecular events. In this study, we have scanned the entire pigeonpea genome and identified 28 candidates corresponding to SUMO machinery components of pigeonpea. qRT-PCR analysis of different SUMO machinery genes validated their presence under natural conditions. The analysis of the promoters of identified SUMO machinery genes revealed the presence of abiotic stress-related cis-regulatory elements highlighting the potential involvement of the genes in abiotic stress responses. The transcript level analysis of selected SUMO machinery genes and global SUMO status of pigeonpea proteins in response to drought stress suggests an integral role of SUMO in regulating drought stress conditions in pigeonpea. Collectively, the work puts forward a detailed in silico analysis of pigeonpea SUMO machinery candidates and highlights the essential role of SUMOylation in drought stress responses. Being the first report on a pulse crop, the study will serve as a resource for devising strategies for counteracting drought stress in pigeonpea that can be further extended to other pulse crops.

Identification of superior haplotypes for flowering time in pigeonpea through candidate gene-based association study of a diverse minicore collection.

KEY MESSAGE: In current study candidate gene (261 genes) based association mapping on 144 pigeonpea accessions for flowering time and related traits and 29 MTAs producing eight superior haplotypes were identified. In the current study, we have conducted an association analysis for flowering-associated traits in a diverse pigeonpea mini-core collection comprising 144 accessions using the SNP data of 261 flowering-related genes. In total, 13,449 SNPs were detected in the current study, which ranged from 743 (ICP10228) to 1469 (ICP6668) among the individuals. The nucleotide diversity (0.28) and Watterson estimates (0.34) reflected substantial diversity, while Tajima's D (-0.70) indicated the abundance of rare alleles in the collection. A total of 29 marker trait associations (MTAs) were identified, among which 19 were unique to days to first flowering (DOF) and/or days to fifty percent flowering (DFF), 9 to plant height (PH), and 1 to determinate (Det) growth habit using 3 years of phenotypic data. Among these MTAs, six were common to DOF and/or DFF, and four were common to DOF/DFF along with the PH, reflecting their pleiotropic action. These 29 MTAs spanned 25 genes, among which 10 genes clustered in the protein-protein network analysis, indicating their concerted involvement in floral induction. Furthermore, we identified eight haplotypes, four of which regulate late flowering, while the remaining four regulate early flowering using the MTAs. Interestingly, haplotypes conferring late flowering (H001, H002, and H008) were found to be taller, while those involved in early flowering (H003) were shorter in height. The expression pattern of these genes, as inferred from the transcriptome data, also underpinned their involvement in floral induction. The haplotypes identified will be highly useful to the pigeonpea breeding community for haplotype-based breeding.

Genetic diversity and population structure of Fusarium udum in India and its correlation with pigeonpea wilt incidence.

In a study conducted in India, 50 Fusarium isolates were collected from pigeonpea growing regions and extensively examined for their cultural and morphological characteristics. These isolates exhibited significant variations in traits including growth rate, mycelial growth patterns, color, zonation, pigmentation, spore size, and septation. Subsequently, 30 isolates were chosen for pathogenicity testing on eight pigeonpea genotypes. Results showed distinct reactions, with four genotypes displaying differential responses (ICP8858, ICP8859, ICP8862, and BDN-2), while ICP9174 and ICP8863 consistently exhibited resistance and ICP2376 and BAHAR remained susceptible to wilt disease. To study the interaction between Fusarium isolates and pigeonpea host differentials (HDs), an additive main effects and multiplicative interaction analysis was conducted. The majority of disease incidence variation (75.54%) was attributed to HD effects, while Fusarium isolate effects accounted for only 1.99%. The interaction between Isolates and HDs (I × HD) contributed 21.95% to the total variation, being smaller than HD but larger than I. Based on HD reactions, isolates were classified into nine variants, showing varying distributions across pigeonpea growing states, with variants 2 and 3 being prevalent in several regions. This diversity underscores the need for location-specific wilt-resistant pigeonpea cultivars. Furthermore, genetic analysis of 23 representative isolates, through internal transcribed spacer region of ribosomal DNA and translation elongation factor 1-α gene sequencing, revealed three major clusters: Fusarium udum, Fusarium solani, and Fusarium equiseti. These findings hold potential for developing location-specific wilt-resistant pigeonpea cultivars and enhancing disease management strategies.

Identification, characterization, and comprehensive expression profiling of floral master regulators in pigeon pea (Cajanus cajan [L.] Millspaugh).

Pigeon pea is an important protein-rich pulse crop. Identification of flowering master regulators in pigeon pea is highly imperative as indeterminacy and late flowering are impediments towards yield improvement. A genome-wide analysis was performed to explore flowering orthologous groups in pigeon pea. Among the 412 floral orthologs identified in pigeon pea, 148 genes belong to the meristem identity, photoperiod-responsive, and circadian clock-associated ortholog groups. Our comparative genomics study revealed purifying selection pressures (ka/ks) on floral orthologs, and duplication patterns and evolution through synteny with other model species. Phylogenetic analysis of floral genes substantiated a connection between pigeon pea plant architecture and flowering time as all the PEBP domain-containing genes belong to meristem identity floral networks of pigeon pea. Expression profiling of eleven major orthologs in contrasting determinate and indeterminate genotypes indicated that these orthologs might be involved in flowering regulation. Expression of floral inducer, FT, and floral repressor, TFL1, was non-comparable in indeterminate genotypes across all the developmental stages of pigeon pea. However, dynamic FT/TFL1 expression ratio detected in all tissues of both the genotypes suggested their role in floral transition. One TFL1 ortholog having high sequence conserveness across pigeon pea genotypes showed differential expression indicating genotype-dependent regulation of this ortholog. Presence of conserved 6mA-methylation patterns in light-responsive elements and in other cis-regulatory elements of FT and TFL1 across different plant genotypes indicated possible involvement of epigenetic regulation in flowering.

The characterization and quantification of structures of Cajanus scarabaeoides phytochemicals and their seasonal variation analysis using ultra-performance liquid chromatography-tandem mass spectrometry.

RATIONALE: Cajanus scarabaeoides, belonging to the Fabaceae family, is an underutilized herb and traditionally used to treat several ailments. However, it is not well explored phytochemically. Therefore, mass spectrometry (MS)-based phytochemical analysis was carried out to investigate the bioactive ingredients of the herb. METHODS: A ultra-performance liquid chromatography (UPLC) coupled to photodiode array detection (PDA) and electrospray ionization (ESI) tandem mass spectrometry (UPLC-PDA-ESI-MS/MS) system was used for the qualitative and quantitative analysis of phytochemicals. The chromatographic separation was achieved on the Acquity BEH C18 column (150 × 2.1 mm, 1.7 µm) using a gradient system consisting of three solvents, acetonitrile, methanol, and 0.1% formic acid, used at a flow rate of 0.300 ml/min. RESULTS: Sixteen bioactive ingredients (gallic acid, gallocatechin, epigallocatechin, catechin, procyanidin dimer, epicatechin, procyanidin trimer, isoorientin, orientin, vitexin, isovitexin, quercetin-mono-O-glycoside, isoquercitrin, luteolin-7-O-glucoside, quercetin, and luteolin) were identified and structurally characterized. Consequently, 12 compounds were reported for the first time from C. scarabaeoides, and 13 were quantitatively determined in different seasons. Isoorientin (10.2-7.1% w/w) and orientin (5.78-5.17% w/w) were the most abundant constituents in the dry weight of plant material, followed by vitexin and isovitexin in the rainy season. CONCLUSIONS: The phytochemical investigation has revealed that C. scarabaeoides could be a potential alternate source of bioactive ingredients, namely, isoorientin, orientin, vitexin, and isovitexin, contributing to further exploration of its biological activity. In addition, analytical methods can be used for the rapid identification and quantification of bioactive ingredients in C. scarabaeoides.

Genome-wide identification and expression analysis of MYB gene family in Cajanus cajan and CcMYB107 improves plant drought tolerance.

MYB transcription factor (TF) is one of the largest superfamilies that play a vital role in multiple plant biological processes. However, the MYB family has not been comprehensively identified and functionally verified in Cajanus cajan, which is the sixth most important legume crop. Here, 170 CcR2R3-MYBs were identified and divided into 43 functional subgroups. Segmental and tandem duplications and alternative splicing events were found and promoted the expansion of the CcR2R3-MYB gene family. Functional prediction results showed that CcR2R3-MYBs were mainly involved in secondary metabolism, cell fate and identity, developmental processes, and responses to abiotic stress. Cis-acting element analysis of promoters revealed that stress response elements were widespread in the above four functional branches, further suggesting CcR2R3-MYBs were extensively involved in abiotic stress response. The transcriptome data and qRT-PCR results indicated that most of the CcR2R3-MYB genes responded to various stresses, of which the expression of CcMYB107 was significantly induced by drought stress. Overexpression of CcMYB107 enhanced antioxidant enzyme activity and increased proline and lignin accumulation, thus improving the drought resistance of C. cajan. Furthermore, Overexpression of CcMYB107 up-regulated the expression of stress-related genes and lignin biosynthesis genes after drought stress. Our findings established a strong foundation for the investigation of biological function of CcR2R3-MYB TFs in C. cajan.

Cocultivation of pigeon pea hairy root cultures and Aspergillus for the enhanced production of cajaninstilbene acid.

Pigeon pea hairy root cultures (PPHRCs) have been proven to be a promising alternative for the production of health-beneficial phenolic compounds, such as the most important health-promoting compound, i.e., cajaninstilbene acid (CSA). In this study, PPHRCs were cocultured with live Aspergillus fungi for further improving phenolic productivity via biological elicitation. Aspergillus oryzae CGMCC 3.951 (AO 3.951) was found to be the optimal fungus that could achieve the maximum increment of CSA (10.73-fold increase) in 42-day-old PPHRCs under the inoculum size of mycelia 0.50% and cocultivation time 36 h. More precisely, the contents of CSA in hairy roots and culture media after fungal elicitation increased by 9.87- and 62.18-fold over control, respectively. Meanwhile, the contents of flavonoid glycosides decreased, while aglycone yields increased upon AO 3.951 elicitation. Moreover, AO 3.951 could trigger the oxidative stress and pathogen defense response thus activating the expression of biosynthesis- and ABC transporter-related genes, which contributed to the intracellular accumulation and extracellular secretion of phenolic compounds (especially CSA) in PPHRCs. And PAL2, 4CL2, STS1, and I3'H were likely to be the potential key enzyme genes regulating the biosynthesis of CSA, and ABCB11X1-1, ABCB11, and ABCG24X2 were closely related to the transmembrane transport of CSA. Overall, the cocultivation approach could make PPHRCs more commercially attractive for the production of high-value phenolic compounds such as CSA and flavonoid aglycones in nutraceutical/medicinal fields. And the elucidation of crucial biosynthesis and transport genes was important for systematic metabolic engineering aimed at increasing CSA productivity. KEY POINTS: • Cocultivation of PPHRCs and live fungi was to enhance CSA production and secretion. • PPHRCs augmented CSA productivity 10.73-fold when cocultured with AO 3.951 mycelia. • Several biosynthesis and transport genes related to CSA production were clarified.

Antagonistic Activity of Pseudomonas fluorescens Strain X1 Against Different Fusaria and it's In Vivo Analysis Against Fusarium udum Infected Pigeon Pea.

A plant growth-promoting rhizobacterial strain, Pseudomonas fluorescens X1 isolated from the garden soil was employed for antagonistic activity against different species of fusaria. Strain X1 inhibited four different fusaria (Fusarium moniliforme, Fusarium oxysporum, Fusarium semitectum and Fusarium udum) in dual culture plate assay, and in broth culture using cell-free culture filtrate. Scanning electron microscopic (SEM) analysis revealed deformation and shrinkage in mycelia of fusaria after treatment with strain X1. Confocal micrographs showed degeneration of nuclei inside the cells of fusaria for the same effect. Strain X1 exhibited maximum antifungal activity, when it was grown in nutrient broth yeast (NBY) medium amended with 1 mM NH4MoO4 and 1% glucose. The antifungal extracts eluted from thin-layer chromatography (TLC) followed by high performance liquid chromatography (HPLC) showed two fractions active against different fusaria. Liquid chromatography-mass spectrometry (LCMS) analysis of the two fractions 1 and 2 corresponded to molecular ions at m/z 177.16 and m/z 177.09, respectively. Infra-red (IR) analysis showed five similar absorption bands in both the fractions analysed. In vivo analysis of strain X1 alone and along with fungicide inhibited the growth of F. udum and improved the biomass and growth of pigeon pea. These results indicated that strain X1 could be possibly used as a biocontrol agent to inhibit the growth of soil-borne diseases of different fusaria including F. udum that causes wilting in pigeon pea.

Evaluation of machine learning approaches for prediction of pigeon pea yield based on weather parameters in India.

Pigeon pea is the second most important grain legume in India, primarily grown under rainfed conditions. Any changes in agro-climatic conditions will have a profound influence on the productivity of pigeon pea (Cajanus cajan) yield and, as a result, the total pulse production of the country. In this context, weather-based crop yield prediction will enable farmers, decision-makers, and administrators in dealing with hardships. The current study examines the application of the stepwise linear regression method, supervised machine learning algorithms (support vector machines (SVM) and random forest (RF)), shrinkage regression approaches (least absolute shrinkage and selection operator (LASSO) or elastic net (ENET)), and artificial neural network (ANN) model for pigeon pea yield prediction using long-term weather data. Among the approaches, ANN resulted in a higher coefficient of determination (R2 = 0.88-0.99), model efficiency (0.88-1.00) with subsequent lower normalised root mean square error (nRMSE) during calibration (1.13-12.55%), and validation (0.33-21.20%) over others. The temperature alone or its interaction with other weather parameters was identified as the most influencing variables in the study area. The Pearson correlation coefficients were also determined for the observed and predicted yield. Those values also showed ANN as the best model with correlation values ranging from 0.939 to 0.999 followed by RF (0.955-0.982) and LASSO (0.880-0.982). However, all the approaches adopted in the study were outperformed the statistical method, i.e. stepwise linear regression with lower error values and higher model efficiency. Thus, these approaches can be effectively used for precise yield prediction of pigeon pea over different districts of Karnataka in India.

Cajanus Scarabaeoides Yellow Mosaic Virus, a New Bipartite Begomovirus Causing Yellow Mosaic Disease in Cajanus scarabaeoides in India.

Yellow mosaic disease of Cajanus scarabaeoides (L.) Thouars (CsYMD) was observed in up to 46% of C. scarabaeoides plants in the mungbean, urdbean, and pigeon pea fields from 22 districts of Chhattisgarh State, India, during 2017 to 2019. The symptoms were characterized by yellow mosaic on green leaves and yellow discoloration of leaves in advanced stages of the disease. Severely infected plants showed shortened internodal length and reduced leaf size. CsYMD was transmissible to healthy C. scarabaeoides and C. cajan by whitefly (Bemisia tabaci). The infected plants developed typical yellow mosaic symptoms on their leaves within 16 and 22 days of inoculation, respectively, suggesting a begomovirus etiology. Molecular analysis revealed that this begomovirus has a bipartite genome composed of DNA-A (2,729 nucleotides) and DNA-B (2,630 nucleotides). Sequence and phylogenetic analyses revealed that the nucleotide sequence of the DNA-A component had the highest identity of 81.1% with DNA-A of Rhynchosia yellow mosaic virus (RhYMV; NC_038885), followed by mungbean yellow mosaic virus (MN602427; 75.3%). DNA-B had the highest identity of 74.0% with DNA-B of RhYMV (NC_038886). As per ICTV guidelines, this isolate had <91% nucleotide identity with DNA-A of any of the begomoviruses reported; so, it is proposed as a new begomovirus species, tentatively named C. scarabaeoides yellow mosaic virus (CsYMV). After agroinoculation with DNA-A and DNA-B clones of CsYMV, all Nicotiana benthamiana plants developed leaf curl symptoms along with light yellowing symptoms 8 to 10 days after inoculation (DAI), while ∼60% of the C. scarabaeoides plants developed yellow mosaic symptoms similar to those observed in the field 18 DAI, thus fulfilling Koch's postulates. From these agro-infected C. scarabaeoides plants, CsYMV was transmissible to healthy C. scarabaeoides plants by B. tabaci. Apart from these hosts, CsYMV also infected and caused symptoms in mungbean and pigeon pea.

Cajanus platycarpus Flavonoid 3'5' Hydroxylase_2 (CpF3'5'H_2) Confers Resistance to Helicoverpa armigera by Modulating Total Polyphenols and Flavonoids in Transgenic Tobacco.

Pod borer Helicoverpa armigera, a polyphagus herbivorous pest, tremendously incurs crop damage in economically important crops. This necessitates the identification and utility of novel genes for the control of the herbivore. The present study deals with the characterization of a flavonoid 3'5' hydroxylase_2 (F3'5'H_2) from a pigeonpea wild relative Cajanus platycarpus, possessing a robust chemical resistance response to H. armigera. Though F3'5'H_2 displayed a dynamic expression pattern in both C. platycarpus (Cp) and the cultivated pigeonpea, Cajanus cajan (Cc) during continued herbivory, CpF3'5'H_2 showed a 4.6-fold increase vis a vis 3-fold in CcF3'5'H_2. Despite similar gene copy numbers in the two Cajanus spp., interesting genic and promoter sequence changes highlighted the stress responsiveness of CpF3'5'H_2. The relevance of CpF3'5'H_2 in H. armigera resistance was further validated in CpF3'5'H_2-overexpressed transgenic tobacco based on reduced leaf damage and increased larval mortality through an in vitro bioassay. As exciting maiden clues, CpF3'5'H_2 deterred herbivory in transgenic tobacco by increasing total flavonoids, polyphenols and reactive oxygen species (ROS) scavenging capacity. To the best of our knowledge, this is a maiden attempt ascertaining the role of F3'5'H_2 gene in the management of H. armigera. These interesting leads suggest the potential of this pivotal branch-point gene in biotic stress management programs.

Stilbenoids and Flavonoids from Cajanus cajan (L.) Millsp. and Their α-Glucosidase Inhibitory Activities.

Two new stilbenoids, cajanstilbenoid C (1) and cajanstilbenoid D (2), together with eight other known stilbenoids (3-10) and seventeen known flavonoids (11-27), were isolated from the petroleum ether and ethyl acetate portions of the 95% ethanol extract of leaves of Cajanus cajan (L.) Millsp. The planar structures of the new compounds were elucidated by NMR and high-resolution mass spectrometry, and their absolute configurations were determined by comparison of their experimental and calculated electronic circular dichroism (ECD) values. All the compounds were assayed for their inhibitory activities against yeast α-glucosidase. The results demonstrated that compounds 3, 8-9, 11, 13, 19-21, and 24-26 had strong inhibitory activities against α-glucosidase, with compound 11 (IC50 = 0.87 ± 0.05 µM) exhibiting the strongest activity. The structure-activity relationships were preliminarily summarized. Moreover, enzyme kinetics showed that compound 8 was a noncompetitive inhibitor, compounds 11, 24-26 were anticompetitive, and compounds 9 and 13 were mixed-competitive.