Regulation of Drought Tolerance by the F-Box Protein MAX2 in Arabidopsis

We show that the max2 mutant is strongly hypersensitive to drought stress compared with wild-type Arabidopsis

Q. Bu; T. Lv; H. Shen; P. Luong; J. Wang; Z. Wang; Z. Huang; L. Xiao; C. Engineer; T. H. Kim; J. I. Schroeder; E. Huq


Scholarcy highlights

  • F-box proteins, which can form SCF E3 ubiquitin ligases, have been shown to play essential roles in plant growth and development, including multiple phytohormone-signaling pathways, such as auxin, gibberellin, ethylene, jasmonic acid, and strigolactone The Arabidopsis genome encodes more than 700 putative F-box proteins
  • In an effort to understand MAX2’s role in photomorphogenesis, we have shown that multiple hormones, including abscisic acid, are defective in the max2 mutant compared with wild-type seeds and seedlings
  • Because max2 showed a dramatic drought-sensitive phenotype, we examined the expression levels of genes involved in the ABA biosynthesis, catabolism, transport, and signaling pathways, including Nine CisEpoxycarotenoid Dioxygenase3, Cytochrome P450 707A3, ABC Transporter G Family Protein22, ABI1, ABA Insensitive1, and Hypersensitive to ABA1. Quantitative real-time reverse transcription-PCR showed that the expression of all the above genes was induced significantly by drought treatment
  • These results demonstrated that max2 mutant plants are more sensitive to ABA than wild-type plants, suggesting that MAX2 acts as a negative regulator of ABA signaling during early seedling establishment
  • The data presented here show a novel function of MAX2 in ABA and drought responses, expanding its roles in the regulation of plant growth and development as well as in responding to abiotic stress conditions
  • The results showed that there was no significant difference in the average stomatal apertures and densities between the wild type and the max2 mutant
  • Max2 mutants were less sensitive to ABA-induced stomatal closure and displayed larger stomatal aperture compared with the wild type under drought conditions
  • Another F-box protein mutant, dor1, did not show an abscisic acid-related phenotype during seed germination and the early seedling development stage but displayed hypersensitivity to ABA-induced stomatal closure and drought-resistant phenotypes

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