PubMed · 5810060
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B V Milborrow. 1969. Current research on abscisic acid.. https://doi.org/10.1042/bj1140001pb
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Phytotoxic effects from allelopathy occur due to signaling pathways that induce alterations in hormonal balance within the plants, thereby hindering weed growth. Signaling crosstalk between various hormones and signaling pathways (Ca2⁺, MAPK, ROS) is involved in the molecular response mechanisms found through omics. Utilizing such mechanisms would help develop new environmentally friendly methods for sustainable weed management. Allelopathy serves as an essential component of plant-plant interaction via controlling the secretion of secondary metabolites (allelochemicals), which affect the growth, development, and physiological activity of nearby plants. The latest findings indicate that allelochemicals disturb phytohormone balance and signaling pathways resulting in oxidative stress, metabolism dysfunctions, cellular processes disturbances, and eventually inhibiting the growth of target weed species. Molecular biology progress and omics techniques brought information about the sophisticated regulation processes involved in allelopathic interactions. This review summarizes the information about the molecular mechanism of weed suppression mediated by allelopathy with the emphasis on allelochemical perception, phytohormone signaling, ROS responses, and evidence obtained by the application of transcriptomics, proteomics, metabolomics, and other omics-based studies. In addition, it introduces novel approaches, such as rhizosphere engineering, nanotechnologies, and genome editing, which may improve the effectiveness and reliability of allelopathic weed suppression. Overall, these achievements provide prospects for creating a new generation of weed control technologies that are sustainable, environmentally friendly, and climate-adaptive.
Thirty-six BraABCB genes were identified in Brassica rapa var. parachinensis; expression and interaction analyses suggest BraABCB27 and BraABCB28 as hormone-responsive candidates associated with BRI1-related proteins. ABCB transporters are ATP-dependent membrane proteins that mediate the transport of diverse substrates, including phytohormones, and play important roles in plant development and environmental adaptation. Previous studies in Arabidopsis have shown that several ABCB proteins participate in phytohormone transport, including auxin and brassinosteroid transport, whereas the functions of their homologs in Brassica rapa var. parachinensis remain poorly understood. In this study, 36 BraABCB genes were identified and classified into four phylogenetic groups. Conserved domain analysis showed that BraABCB proteins contain typical nucleotide-binding domains and transmembrane domains. Chromosomal distribution, collinearity, and Ka/Ks analyses suggested that the BraABCB family is evolutionarily conserved and mainly subject to purifying constraints. Promoter analysis and RT-qPCR assays of selected Group IV BraABCB genes revealed diverse expression patterns and responses to drought, high temperature, brassinolide, and indole-3-acetic acid treatments. Subcellular localization assays showed that selected Group IV BraABCB proteins exhibited predominant plasma membrane localization. Notably, BraABCB27 and BraABCB28, two close AtABCB1/AtABCB19-related homologs, showed detectable physical associations with BRI1-related proteins in BiFC and split-ubiquitin yeast two-hybrid assays. Together, these results provide a genome-wide characterization of the BraABCB gene family and identify BraABCB27 and BraABCB28 as candidate genes for future studies of their possible associations with BR-related membrane processes and hormone-regulated growth responses in B. rapa var. parachinensis.
BACKGROUND: The covalent attachment of ubiquitin to a substrate protein changes its fate. Notably, proteins typically tagged with a lysine48-linked polyubiquitin chain become substrates for degradation by the 26S proteasome. In recent years many experiments have been performed to characterize the proteins involved in the ubiquitylation process and to identify their substrates, in order to understand better the mechanisms that link specific protein degradation events to regulation of plant growth and development. SCOPE: This review focuses on the role that ubiquitin plays in hormone synthesis, hormonal signalling cascades and plant defence mechanisms. Several examples are given of how targeted degradation of proteins affects downstream transcriptional regulation of hormone-responsive genes in the auxin, gibberellin, abscisic acid, ethylene and jasmonate signalling pathways. Additional experiments suggest that ubiquitin-mediated proteolysis may also act upstream of the hormonal signalling cascades by regulating hormone biosynthesis, transport and perception. Moreover, several experiments demonstrate that hormonal cross-talk can occur at the level of proteolysis. The more recently established role of the ubiquitin/proteasome system (UPS) in defence against biotic threats is also reviewed. CONCLUSIONS: The UPS has been implicated in the regulation of almost every developmental process in plants, from embryogenesis to floral organ production probably through its central role in many hormone pathways. More recent evidence provides molecular mechanisms for hormonal cross-talk and links the UPS system to biotic defence responses.