Phospholipases C and D and Their Role in Biotic and Abiotic Stresses

In silico profiling, docking analysis, and protein interactions of secondary metabolites in Musa spp. Against the SGE1 protein of Fusarium oxysporum f. sp. cubense

Banana Fusarium Wilt (BFW), caused by Fusarium oxysporum f. sp. cubense (Foc), threatens banana crops globally, with the pathogen's virulence partially regulated by the Sge1 transcription factor, which enhances disease severity. Certain Musa species display resistance to Foc, suggesting inherent genetic traits that confer immunity against Sge1Foc. This study utilized bioinformatics tools to investigate the mechanisms underlying this resistance in Musa accuminata subsp. aalaccensis. Through in silico analyses, we explored interactions between Musa spp. and Foc, focusing on the Sge1 protein. Tools such as Anti-SMASH, AutoDockVina 4.0, STRING, and Phoenix facilitated the profiling of secondary metabolites in Musa spp. and the identification of biosynthetic gene clusters involved in defense. Our results indicate that secondary metabolites, including saccharides, terpenes, and polyketides, are crucial to the plant's immune response. Molecular docking studies of selected Musa metabolites, such as 3-Phenylphenol, Catechin, and Epicatechin, revealed 3-Phenylphenol as having the highest binding affinity to the Sge1Foc protein (-6.7 kcal/mol).Further analysis of gene clusters associated with secondary metabolite biosynthesis in Musa spp. identified key domains like Chalcone synthase, Phenylalanine ammonia-lyase, Aminotran 1-2, and CoA-ligase, which are integral to phenylpropanoid production-a critical pathway for secondary metabolites. The study highlights that the phenylpropanoid pathway and secondary metabolite biosynthesis are vital for Musa spp. resistance to Foc. Flavonoids and lignin may inhibit Sge1 protein formation, potentially disrupting Foc's cellular processes. These findings emphasize the role of phenylpropanoid pathways and secondary metabolites in combating BFW and suggest that targeting these pathways could offer innovative strategies for enhancing resistance and controlling BFW in banana crops. This research lays the groundwork for developing sustainable methods to protect banana cultivation and ensure food security.

Genome-Wide Identification and Analysis of Phospholipase C Gene Family Reveals Orthologs, Co-Expression Networks, and Expression Profiling Under Abiotic Stress in Sorghum bicolor

Phospholipase C (PLC) is an essential enzyme involved in lipid signaling pathways crucial for regulating plant growth and responding to environmental stress. In sorghum, 11 PLC genes have been identified, comprising 6 PI-PLCs and 5 NPCs. Through phylogenetic and interspecies collinearity analyses, structural similarities between SbPLCs and ZmPLCs proteins have been observed, with a particularly strong collinearity between SbPLCs and OsPLCs. Promoter function analysis has shown that SbPLCs are significantly enriched under abiotic stress and hormonal stimuli, like ABA, jasmonic acid, drought, high temperature, and salt. Gene co-expression networks, constructed using a weighted gene co-expression network analysis (WGCNA), highlight distinct expression patterns of SbPLC1, SbPLC3a, and SbPLC4 in response to abiotic stress, providing further insights into the expression patterns and interactions of SbPLCs under various environmental stimuli. qRT-PCR results reveal variations in expression levels among most SbPLCs members under different stress conditions (drought, NaCl, NaHCO3), hormone treatments (ABA), and developmental stages, indicating both specific and overlapping expression patterns. This comprehensive analysis offers valuable insights into the roles of SbPLCs in sorghum, shedding light on their specific expression patterns, regulatory elements, and protein interactions across different environmental stimuli and developmental stages.

Development and drought escape response in Arabidopsis thaliana are regulated by AtPLC1 in response to abscisic acid

MAIN CONCLUSION

AtPLC1 plays a critical role in plant growth, development, and response to drought stress. Phosphoinositide-specific phospholipase C (PI-PLC) hydrolyzes substrates to generate secondary messengers crucial for plant growth, development, and stress responses. Drought escape (DE) response is an adaptive strategy that plants employ under drought conditions. The expression levels of the flower meristem-specific gene APETALA 1 and flowering regulatory genes FLOWERING LOCUS T and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 were downregulated in plc1, and FLOWERING LOCUS C was upregulated. The flowering time of the plc1flc double mutant was earlier than that of the wild type. Transcriptome analysis revealed that the Gene Ontology of differentially expressed genes (DEGs) was enriched in abscisic acid (ABA) response signaling, and Kyoto Encyclopedia of Genes and Genomes analysis revealed differential gene expression annotated to plant hormone signaling pathways. Our experiments show that AtPLC1 is upregulated by ABA in Arabidopsis. Under ABA induction and water stress, wild-type plants exhibit a DE response, and the DE response in plc1 disappears. Expression levels of ABA signaling pathway transcription factors ABA-responsive element-binding factors 3 (ABF3) and ABF4 were downregulated in plc1. In conclusion, our study suggests that AtPLC1 participates in regulating plant growth and development and participates in the DE response through the regulation of ABA signaling pathway transcription factors ABF3/ABF4. The study enhances our comprehension of the role of AtPLC1 in plant development and drought stress, providing a theoretical foundation for further investigation into DE responses.

Uptake, translocation, and metabolism of organophosphate esters (OPEs) in plants and health perspective for human: A review

Plant uptake, accumulation, and transformation of organophosphate esters (OPEs) play vital roles in their geochemical cycles and exposure risks. Here we reviewed the recent research advances in OPEs in plants. The mean OPE concentrations based on dry/wet/lipid weight varied in 4.80-3,620/0.287-26.8/12,000-315,000 ng g-1 in field plants, and generally showed positive correlations with those in plant habitats. OPEs with short-chain substituents and high hydrophilicity, particularly the commonly used chlorinated OPEs, showed dominance in most plant samples, whereas some tree barks, fruits, seeds, and roots demonstrated dominance of hydrophobic OPEs. Both hydrophilic and hydrophobic OPEs can enter plants via root and foliar uptake, and the former pathway is mainly passively mediated by various membrane proteins. After entry, different OPEs undergo diverse subcellular distributions and acropetal/basipetal/intergenerational translocations, depending on their physicochemical properties. Hydrophilic OPEs mainly exist in cell sap and show strong transferability, hydrophobic OPEs demonstrate dominant distributions in cell wall and limited migrations owing to the interception of Casparian strips and cell wall. Additionally, plant species, transpiration capacity, growth stages, commensal microorganisms, and habitats also affect OPE uptake and transfer in plants. OPE metabolites derived from various Phase I transformations and Phase II conjugations are increasingly identified in plants, and hydrolysis and hydroxylation are the most common metabolic processes. The metabolisms and products of OPEs are closely associated with their structures and degradation resistance and plant species. In contrast, plant-derived food consumption contributes considerably to the total dietary intakes of OPEs by human, particularly the cereals, and merits specifical attention. Based on the current research limitations, we proposed the research perspectives regarding OPEs in plants, with the emphases on their behavior and fate in field plants, interactions with plant-related microorganisms, multiple uptake pathways and mechanisms, and comprehensive screening analysis and risk evaluation.

The intricate role of lipids in orchestrating plant defense responses

Plants are exposed to a variety of pests and pathogens that reduce crop productivity. Plants respond to such attacks by activating a sophisticated signaling cascade that initiates with the recognition of pests/pathogens and may culminate into a resistance response. Lipids, being the structural components of cellular membranes, function as mediators of these signaling cascades and thus are instrumental in the regulation of plant defense responses. Accumulating evidence indicates that various lipids such as oxylipins, phospholipids, glycolipids, glycerolipids, sterols, and sphingolipids, among others, are involved in mediating cell signaling during plant-pathogen interaction with each lipid exhibiting a specific biological relevance, follows a distinct biosynthetic mechanism, and contributes to specific signaling cascade(s). Omics studies have further confirmed the involvement of lipid biosynthetic enzymes including the family of phospholipases in the production of defense signaling molecules subsequent to pathogen attack. Lipids participate in stress signaling by (1) mediating the signal transduction, (2) acting as precursors for bioactive molecules, (3) regulating ROS formation, and (4) interacting with various phytohormones to orchestrate the defense response in plants. In this review, we present the biosynthetic pathways of different lipids, their specific functions, and their intricate roles upstream and downstream of phytohormones under pathogen attack to get a deeper insight into the molecular mechanism of lipids-mediated regulation of defense responses in plants.

Exploring the Role of TaPLC1-2B in Heat Tolerance at Seedling and Adult Stages of Wheat through Transcriptome Analysis

Heat stress is a major abiotic stress that can cause serious losses of a crop. Our previous work identified a gene involved in heat stress tolerance in wheat, TaPLC1-2B. To further investigate its mechanisms, in the present study, TaPLC1-2B RNAi-silenced transgenic wheat and the wild type were comparatively analyzed at both the seedling and adult stages, with or without heat stress, using transcriptome sequencing. A total of 15,549 differentially expressed genes (DEGs) were identified at the adult stage and 20,535 DEGs were detected at the seedling stage. After heat stress, an enrichment of pathways such as phytohormones and mitogen-activated protein kinase signaling was mainly found in the seedling stage, and pathways related to metabolism, glycerophospholipid metabolism, circadian rhythms, and ABC transporter were enriched in the adult stage. Auxin and abscisic acid were downregulated in the seedling stage and vice versa in the adult stage; and the MYB, WRKY, and no apical meristem gene families were downregulated in the seedling stage in response to heat stress and upregulated in the adult stage in response to heat stress. This study deepens our understanding of the mechanisms of TaPLC1-2B in regard to heat stress in wheat at the seedling and adult stages.

Proteomic Insights of Cowpea Response to Combined Biotic and Abiotic Stresses

The co-occurrence of biotic and abiotic stresses in agricultural areas severely affects crop performance and productivity. Drought is one of the most adverse environmental stresses, and its association with root-knot nematodes further limits the development of several economically important crops, such as cowpea. Plant responses to combined stresses are complex and require novel adaptive mechanisms through the induction of specific biotic and abiotic signaling pathways. Therefore, the present work aimed to identify proteins involved in the resistance of cowpea to nematode and drought stresses individually and combined. We used the genotype CE 31, which is resistant to the root-knot nematode Meloidogyne spp. And tolerant to drought. Three biological replicates of roots and shoots were submitted to protein extraction, and the peptides were evaluated by LC-MS/MS. Shotgun proteomics revealed 2345 proteins, of which 1040 were differentially abundant. Proteins involved in essential biological processes, such as transcriptional regulation, cell signaling, oxidative processes, and photosynthesis, were identified. However, the main defense strategies in cowpea against cross-stress are focused on the regulation of hormonal signaling, the intense production of pathogenesis-related proteins, and the downregulation of photosynthetic activity. These are key processes that can culminate in the adaptation of cowpea challenged by multiple stresses. Furthermore, the candidate proteins identified in this study will strongly contribute to cowpea genetic improvement programs.

MYB transcription factors-master regulators of phenylpropanoid biosynthesis and diverse developmental and stress responses

Phenylpropanoids, the largest class of natural products including flavonoids, anthocyanins, monolignols and tannins perform multiple functions ranging from photosynthesis, nutrient uptake, regulating growth, cell division, maintenance of redox homeostasis and biotic and abiotic stress responses. Being sedentary life forms, plants possess several regulatory modules that increase their performance in varying environments by facilitating activation of several signaling cascades upon perception of developmental and stress signals. Of the various regulatory modules, those involving MYB transcription factors are one of the extensive groups involved in regulating the phenylpropanoid metabolic enzymes in addition to other genes. R2R3 MYB transcription factors are a class of plant-specific transcription factors that regulate the expression of structural genes involved in anthocyanin, flavonoid and monolignol biosynthesis which are indispensable to several developmental pathways and stress responses. The aim of this review is to present the regulation of the phenylpropanoid pathway by MYB transcription factors via Phospholipase D/phosphatidic acid signaling, downstream activation of the structural genes, leading to developmental and/or stress responses. Specific MYB transcription factors inducing or repressing specific structural genes of anthocyanin, flavonoid and lignin biosynthetic pathways are discussed. Further the roles of MYB in activating biotic and abiotic stress responses are delineated. While several articles have reported the role of MYB's in stress responses, they are restricted to two or three specific MYB factors. This review is a consolidation of the diverse roles of different MYB transcription factors involved both in induction and repression of anthocyanin, flavonoid, and lignin biosynthesis.

Understanding the salinity stress on plant and developing sustainable management strategies mediated salt-tolerant plant growth-promoting rhizobacteria and CRISPR/Cas9

Soil salinity is a worldwide concern that decreases plant growth performance in agricultural fields and contributes to food scarcity. Salt stressors have adverse impacts on the plant's ionic, osmotic, and oxidative balance, as well as numerous physiological functions. Plants have a variety of coping strategies to deal with salt stress, including osmosensing, osmoregulation, ion-homeostasis, increased antioxidant synthesis, and so on. Not only does salt stress cause oxidative stress but also many types of stress do as well, thus plants have an effective antioxidant system to battle the negative effects of excessive reactive oxygen species produced as a result of stress. Rising salinity in the agricultural field affects crop productivity and plant development considerably; nevertheless, plants have a well-known copying mechanism that shields them from salt stress by facilitated production of secondary metabolites, antioxidants, ionhomeostasis, ABAbiosynthesis, and so on. To address this problem, various environment-friendly solutions such as salt-tolerant plant growth-promoting rhizobacteria, eco-friendly additives, and foliar applications of osmoprotectants/antioxidants are urgently needed. CRISPR/Cas9, a new genetic scissor, has recently been discovered to be an efficient approach for reducing salt stress in plants growing in saline soil. Understanding the processes underlying these physiological and biochemical responses to salt stress might lead to more effective crop yield control measures in the future. In order to address this information, the current review discusses recent advances in plant stress mechanisms against salinity stress-mediated antioxidant systems, as well as the development of appropriate long-term strategies for plant growth mediated by CRISPR/Cas9 techniques under salinity stress.

Characterization and Expression of Phospholipase D Putatively Involved in Colletotrichummusae Disease Development of Postharvest Banana Fruit

Phospholipase D (PLD) in plants plays an important role in growth, development, and stress response. The effect of hexanal on PLD in banana fruit responding to Colletotrichum musae infection remains poorly understood. In this study, four putative PLD genes, named as MaPLD1, MaPLD2, MaPLD3, and MaPLD4 were identified from banana fruit. The four MaPLDs can be classified into three of the seven known PLD families according to sequence characterization. Their deduced amino acid sequences displayed homology of PLDs from other plant species. Furthermore, the specific expression analysis of PLD genes in banana fruit in response to infection in C. musae was studied and the response relationship between PLD family members and banana fruit under anthracnose stress was clarified. Changes in both the activity of PLD and PLC, and the connection between hexanal and phospholipases in the banana fruit C. musae infection were compared. The results showed that the incidence of disease in banana inoculated with C. musae was dramatically increased after 6 days of storage, the activation of PLD and PLC in infected anthracnose fruit before disease development, and that this activation was inhibited by hexanal treatment, which suggested that both enzymes play a protective role in banana fruit to cope with C. musae infection and the participation of hexanal in their regulation. Of the four MaPLD genes, the anthracnose had a stronger effect on MaPLD1 and MaPLD4. These data demonstrated that hexanal treatment could enhance fruit disease resistance to C. musae, and that PLD could take part in the disease defensive system of harvested banana fruit to C. musae by modulating the metabolism of cell membrane lipids, and thus suppress disease development in C. musae -inoculated banana during storage.