Arabidopsis URO Gene Involved In Auxin And Ethylene Pathway To Control Plant Development

The Arabidopsis semi-dominant mutant, upright rosettes (uro), was obtained from a T-DNA insertional mutant library. Compared with wide-type (WT) plant's, the uro mutant displays pleiotropic phenotypes including dwarf ism, loss of apical dominance, softening and thickening of shoot stem, altered numbers of petals and stamens and abnormally fused organs, elongated hypocotyls, developed adventitious roots on hypocotyls, an altered vascular differentiation, and interfascicular fiber formation defects in stem.The loss of apical dominance and the defects in vascular development and interfascicular fiber formation suggest that the URO function might be associated with auxin-mediated plant development. We introduced a DR5: :GUS construct into the uro background, and observed the altered GUS staining patterns. Several analyses showed that auxin was overproduced in uro mutant and uro mutant was hyposensitive to auxin.Also, we found that the uro mutant showed some ethylene related phenotypes included upright rosette leaves, persistent perianth and elongated hypocotyl. The Arabidopsis wild type plant showed up-ward rosette leaves after ethylene treatment which mimics the phenotype of uro mutant. The response to ethylene of uro mutant was different from that of wild type under light condition, while in darkness, both show similar responses to ethylene. The upright rosette leaves and elongated hypocotyl of uro mutant disappeared after ethylene inhibitor AgNO3 treatment. These results suggested that some of the phenotypes of uro mutant were caused by the abnormality of ethylene signal system and that the ethylene related phenotype of uro mutant was light depended.The URO gene encodes a transcript factor which belongs to C2H2 transcription family. The function of genes in this family is largely unknown, although this kind of genes is widely existed in plants. So the study of URO gene will give us a clue to the study of C2H2 transcription family. Also the results showed that the URO gene involved in auxin and ethylene pathway to control plant development, which is important for uncovering the cross talk between auxin and ethylene.