Auxin and brassinosteroid differentially regulate the expression of three members of the 1-aminocyclopropane-1-carboxylate synthase gene family in mung bean (Vigna radiata L.)

摘要: Indole-3-acetic acid (IAA) markedly increased ethylene production by inducing the expression of three 1-aminocyclopropane-1-carboxylate (ACC) synthase cDNAs (pVR-ACS1, pVR-ACS6 and pVR-ACS7) in mung bean hypocotyls. Results from nuclear run-on transcription assay RNA gel blot studies revealed that all genes were transcriptionally active displaying unique patterns induction IAA various hormones etiolated Particularly, 24-epibrassinolide (BR), an brassinosteroid, specifically enhanced VR-ACS7 a distinct temporal mechanism compared to IAA. In addition, BR synergistically IAA-induced VR-ACS6 transcript levels, while it effectively abolished both IAA- kinetin-induced accumulation VR-ACS1 mRNA. light-grown plants, was induced roots, epicotyls. BR-treatments not able increase tissues. These results indicate ACC multigene family is regulated complex hormonal developmental networks gene- tissue-specific manner plants. The gene isolated, chimeric fusion between 2.4 kb 5′-upstream region β-glucuronidase (GUS) reporter constructed introduced into Nicotiana tabacum. Analysis transgenic tobacco plants promoter-driven GUS activity at highly localized hypocotyl-root junction control seedlings, marked detected only hypocotyl IAA-treated seedlings where rapid cell elongation occurs. Although there modest synergistic effect on activity, alone failed suggesting occurs via separate signaling pathways response BR. A scheme multiple regulatory for auxin presented.