Ectopic expression of an expansin‐like B gene from wild Arachis enhances tolerance to both abiotic and biotic stresses

• Published in: The Plant journal : for cell and molecular biology Vol. 107; no. 6; pp. 1681 - 1696
• Main Authors: Brasileiro, Ana C. M., Lacorte, Cristiano, Pereira, Bruna M., Oliveira, Thais N., Ferreira, Deziany S., Mota, Ana P. Z., Saraiva, Mario A. P., Araujo, Ana C. G., Silva, Luciano P., Guimaraes, Patricia M.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.09.2021
• Subjects: Abiotic factors; Abscisic acid; Abscisic Acid - metabolism; Animals; Arachis; Arachis - genetics; Ascomycota - pathogenicity; Biomechanical Phenomena; Biomechanics; Biotic factors; Cell Wall - genetics; Cell Wall - metabolism; Cell walls; combined stresses; Cyclopentanes - metabolism; Defense mechanisms; Drought; Droughts; Ectopic expression; Functional analysis; Fusion protein; Gene Expression Regulation, Plant; Jasmonic acid; Localization; Mechanical properties; Meloidogyne incognita; Nicotiana - cytology; Nicotiana - genetics; Nicotiana - microbiology; Nicotiana - physiology; Oxylipins - metabolism; Phenotypes; Plant Cells - metabolism; Plant Leaves - physiology; Plant Proteins - genetics; Plant Proteins - metabolism; Plants, Genetically Modified; primed state; Proteins; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Sclerotinia sclerotiorum; Stress, Physiological - genetics; Stresses; Tobacco; Transgenic plants; Tylenchoidea - pathogenicity; Sclerotinia sclerotiorum; primed state; combined stresses; Meloidogyne incognita; drought
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.15409

Summary Plant expansins are structural cell wall‐loosening proteins implicated in several developmental processes and responses to environmental constraints and pathogen infection. To date, there is limited information about the biological function of expansins‐like B (EXLBs), one of the smallest and less‐studied subfamilies of plant expansins. In the present study, we conducted a functional analysis of the wild Arachis AdEXLB8 gene in transgenic tobacco (Nicotiana tabacum) plants to clarify its putative role in mediating defense responses to abiotic and biotic stresses. First, its cell wall localization was confirmed in plants expressing an AdEXLB8:eGFP fusion protein, while nanomechanical assays indicated cell wall reorganization and reassembly due to AdEXLB8 overexpression without compromising the phenotype. We further demonstrated that AdEXLB8 increased tolerance not only to isolated abiotic (drought) and biotic (Sclerotinia sclerotiorum and Meloidogyne incognita) stresses but also to their combination. The jasmonate and abscisic acid signaling pathways were clearly favored in transgenic plants, showing an activated antioxidative defense system. In addition to modifications in the biomechanical properties of the cell wall, we propose that AdEXLB8 overexpression interferes with phytohormone dynamics leading to a defense primed state, which culminates in plant defense responses against isolated and combined abiotic and biotic stresses. Significance Statement The exploitation of wild Arachis germplasm identified an EXLB gene involved in environmental adaptability. We show that its overexpression confers broad‐spectrum tolerance to isolated and combined biotic and abiotic stresses. We propose that AdEXLB8 acts as an inducer of the plant defense primed state, being a promising candidate for greater protection against the harmful effects of multiple stresses in an ever‐changing climate.