Calcium-dependent protein kinases (CDPKs/CPKs) are plant-specific Ser/Thr kinases whose catalytic activity is directly controlled by intracellular Ca2+ binding. As core Ca2+ signal sensors and transducers, CDPKs decode stimulus-specific spatiotemporal Ca2+ oscillations triggered by diverse biotic and abiotic stresses, translating transient calcium signatures into downstream phosphorylation cascades to coordinate plant physiological adaptation. Unlike other plant Ca2+ decoder families (CaM/CMLs, CBL-CIPKs), CDPKs integrate Ca2+-sensing EF-hand motifs and kinase catalytic domains within a single polypeptide, enabling rapid, autonomous signal transduction without auxiliary protein partners. Upon stress activation, CDPKs phosphorylate a broad spectrum of downstream substrates, including NADPH oxidase RBOHs, ion channels, 14-3-3 scaffolding proteins, and transcription factors (WRKYs, ABFs, ABI5), forming multi-layered signaling networks that integrate stress responses with plant growth and developmental programs. Autophosphorylation acts as a core post-translational regulatory switch to tune CDPK Ca2+ sensitivity, subcellular localization, and substrate selectivity, generating isoform-specific signaling specificity. CDPKs participate comprehensively in stomatal movement control, pollen polar growth, nutrient homeostasis, and morphogenesis, while functioning as central regulatory hubs mediating salt, drought, extreme temperature, oxidative stress, and pathogen defense responses. Notably, CDPK signaling forms synergistic crosstalk with abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) hormone pathways, as well as MAPK kinase cascades to amplify stress resistance outputs. This review systematically summarizes the evolutionary expansion, structural characteristics, classification, and activation mechanisms of plant CDPK families. Different from previous reviews mainly focused on model and temperate plants, this work compiles scattered functional evidence from tropical crops (banana, cassava, seashore paspalum, patchouli, mango, licorice, yam, pepper, pineapple and others) which are rarely synthesized in existing literature. We categorize all published functional evidence into four standardized levels to distinguish correlative transcriptomic induction from causal genetic and biochemical validation, clarify mechanistic contradictions between CDPK isoforms with opposing stress regulatory roles, and systematically compare CDPK functional uniqueness relative to parallel Ca2+ sensor and kinase cascades. Finally, we highlight unresolved critical knowledge gaps and propose multi-omics, structural biology, and gene-editing translational research strategies to guide targeted molecular breeding of climate-resilient tropical crops.
Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao is a widely used medicinal herb whose yield and quality are often affected by environmental factors such as drought stress. WRKY transcription factors play key regulatory roles in plant stress responses. In this study, we performed a genome-wide identification of the WRKY gene family in A. mongholicus (designated as AmWRKY) and functionally characterized the core candidate gene through heterologous overexpression in Arabidopsis thaliana (L.) Heynh. A total of 86 AmWRKY members were identified and phylogenetically classified into three major groups (groups I, II, and III), with group II being the most abundant and further subdivided into five subgroups. Evolutionary analysis revealed that segmental duplication events served as the primary driving force for family expansion, and purifying selection dominated the evolutionary process. Expression profiling demonstrated that AmWRKY75, AmWRKY29, and AmWRKY30 were consistently upregulated in roots under drought conditions, and their promoter regions were enriched with abscisic acid (ABA)- and drought-responsive cis-elements. Functional validation confirmed that overexpression of AmWRKY75 significantly enhanced drought tolerance in transgenic Arabidopsis thaliana by augmenting antioxidant capacity and osmotic adjustment. Collectively, this study systematically elucidates the molecular evolutionary features and drought-responsive expression patterns of the AmWRKY gene family, and identifies AmWRKY75 as a positive regulator of drought tolerance, thereby providing valuable genetic resources and a theoretical foundation for drought-resistant breeding in A. mongholicus.
Guava (Psidium guajava L.) is a commercial fruit with extensive variability for semi-arid conditions, important for climate-resilient cultivars amid rising aridity. This study examined fifteen guava genotypes for morpho-biochemical and molecular diversity to identify promising genetic resources for breeding and germplasm utilization. KG Guava had the largest fruit (10.56 cm in length and 398.4 g in weight); Hisar Safeda and KG Guava displayed the maximum TSS (13.7°Brix and 11.5°Brix, respectively) with optimal TSS-acidity ratios, and Lucknow-49 had the maximum ascorbic acid (234.3 mg/100 g). Molecular characterization using 34 SSR primers generated 76 alleles, ranging from 1 to 5 alleles per locus, with an average of 2.18 alleles per locus. The mean polymorphic information content (PIC) value was 0.417, ranging from 0.031 to 0.885, indicating moderate to high marker informativeness. Highly informative markers, including mPgCIR220 (PIC = 0.885), mPgCIR15 (PIC = 0.818), and mPgCIR05 (PIC = 0.729), exhibited strong discriminatory ability among cultivars. Marker mPgCIR236 produced a unique amplification pattern in Pant Red, suggesting its potential application for cultivar identification after validation using a broader germplasm collection. Population structure analysis based on SSR markers identified two major genetic groups (K = 2), with admixed ancestry observed in Lucknow-49, Pant Red, and Aishwarya, indicating possible shared ancestry or historical gene flow. Principal component analysis supported the genetic relationships inferred from STRUCTURE analysis, while UPGMA clustering using the Jaccard similarity coefficient grouped the germplasm into three major clusters. The integration of morphological, biochemical, and SSR-based diversity analysis revealed distinct genetic resources, including KG Guava, Hisar Safeda, Lucknow-49, Pant Red, and Aishwarya, possessing complementary traits valuable for future breeding programmes. These findings provide a foundation for guava germplasm characterization and parent selection for improvement of fruit quality and commercial traits.
The cork oak (Quercus suber L.) is a long-lived evergreen tree of major ecological and economic importance and a keystone species of Mediterranean forest ecosystems, where it supports biodiversity, ecosystem functioning, and landscape restoration. This review synthesizes current knowledge on the biology, ecology, genetic diversity, and genomics of Q. suber L., using Morocco’s Maâmora Forest as a representative case study. As the world’s largest lowland cork oak forest and a peripheral population at the southwestern limit of the species’ distribution, Maâmora provides a unique model for investigating the ecological and genetic mechanisms underlying adaptation and resilience to climate change. We summarize the species’ botanical characteristics, ecological requirements, and geographical distribution, followed by a critical assessment of phenotypic, morphological, and molecular studies that have revealed substantial genetic diversity and population structure throughout its range. We further examine recent advances in nuclear and organellar genomics, highlighting insights into reproductive biology, responses to biotic and abiotic stresses, and the molecular regulation of cork formation and quality. Finally, we discuss how integrating genomic, ecological, and physiological knowledge can improve the understanding of adaptive processes and support evidence-based conservation, provenance selection, and forest restoration. Despite considerable progress, important challenges remain in linking genomic variation to adaptive phenotypes and long-term resilience under changing environmental conditions. Future research should integrate multi-omics, ecological, and silvicultural approaches to accelerate conservation strategies, breeding programs, and the sustainable management of this emblematic Mediterranean tree species.
We conducted a comparative proteomic analysis of the wheat cultivar Xinmai 45 and its parental lines, Jimai 20 (paternal) and Xinmai 26 (maternal), to clarify the proteomic differences associated with delayed senescence in flag leaves. Data-independent acquisition (DIA) quantitative proteomics, coupled with bioinformatic analysis, was employed to identify differentially expressed proteins (DEPs) in mature leaf tissues and assess their enriched functions and pathways. A total of 599 and 670 DEPs were identified in Xinmai 45 relative to Jimai 20 (paternal) and Xinmai 26 (maternal), respectively, with most being down-regulated. Gene Ontology (GO) enrichment analysis revealed that DEPs were significantly associated with metabolic processes, responses to stimuli, and biological regulation, primarily driven by changes in catalytic activity and binding. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that the MAPK signaling and phenylpropanoid biosynthesis pathways were uniquely enriched in Xinmai 45 vs. Jimai 20 (paternal), suggesting enhanced stress signaling and defense priming; in contrast, pathways related to lipid metabolism (e.g., α-linolenic acid metabolism) were more prominent in Xinmai 45 vs. Xinmai 26 (maternal), pointing to differential membrane remodeling during senescence. Protein–protein interaction network analysis revealed that ribosomal proteins and RNA helicases occupied central positions, suggesting that protein synthesis and RNA metabolism may be important regulators of phenotypic differences. These proteomic differences may be associated with the superior stress resistance of Xinmai 45.
