Modified Crosstalk between Phytohormones in Arabidopsis Mutants for PEP-Associated Proteins

• Published in: International journal of molecular sciences Vol. 25; no. 3; p. 1586
• Main Authors: Bychkov, Ivan A, Andreeva, Aleksandra A, Vankova, Radomira, Lacek, Jozef, Kudryakova, Natalia V, Kusnetsov, Victor V
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01-02-2024
• Subjects: Abscisic acid; Acetic acid; Albinism; Amino acids; Arabidopsis thaliana; Biosynthesis; Chloroplasts; Enzymes; Gene expression; Genomes; Homeostasis; Hormones; Metabolism; Metabolites; mutants; PEP-associated proteins; Photosynthesis; Physiological aspects; phytohormones; Plant hormones; Plastids; Proteins; RNA; RNA polymerase; Arabidopsis thaliana; PEP-associated proteins; mutants; gene expression; phytohormones
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms25031586

Plastid-encoded RNA polymerase (PEP) forms a multisubunit complex in operating chloroplasts, where PEP subunits and a sigma factor are tightly associated with 12 additional nuclear-encoded proteins. Mutants with disrupted genes encoding PEP-associated proteins (PAPs) provide unique tools for deciphering mutual relationships among phytohormones. A block of chloroplast biogenesis in
mutants specifying highly altered metabolism in white tissues induced dramatic fluctuations in the content of major phytohormones and their metabolic genes, whereas hormone signaling circuits mostly remained functional. Reprogramming of the expression of biosynthetic and metabolic genes contributed to a greatly increased content of salicylic acid (SA) and a concomitant decrease in 1-aminocyclopropane-1-carboxylic acid (ACC) and oxophytodienoic acid (OPDA), precursors of ethylene and jasmonic acid, respectively, in parallel to reduced levels of abscisic acid (ABA). The lack of differences in the free levels of indole-3-acetic acid (IAA) between the
mutants and wild-type plants was accompanied by fluctuations in the contents of IAA precursors and conjugated forms as well as multilayered changes in the expression of IAA metabolic genes. Along with cytokinin (CK) overproduction, all of these compensatory changes aim to balance plant growth and defense systems to ensure viability under highly modulated conditions.