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Polar transport of the plant hormone auxin controls many aspects of plant growth and development. A number of synthetic compounds have been shown to block the process of auxin transport by inhibition of the auxin efflux carrier complex. These synthetic auxin transport inhibitors may act by mimicking endogenous molecules. Flavonoids, a class of secondary(More)
Active transport across the vacuolar components of the eukaryotic endomembrane system is energized by a specific vacuolar H+-ATPase. The amino acid sequences of the 70- and 60-kDa subunits of the vacuolar H+-ATPase are approximately equal to 25% identical to the beta and alpha subunits, respectively, of the eubacterial-type F0F1-ATPases. We now report that(More)
Flavonoids have been implicated in the regulation of auxin movements in Arabidopsis. To understand when and where flavonoids may be acting to control auxin movement, the flavonoid accumulation pattern was examined in young seedlings and mature tissues of wild-type Arabidopsis. Using a variety of biochemical and visualization techniques, flavonoid(More)
 The 1-N-naphthylphthalamic acid (NPA)-binding protein is a putative negative regulator of polar auxin transport that has been shown to block auxin efflux from both whole plant tissues and microsomal membrane vesicles. We previously showed that NPA is hydrolyzed by plasma-membrane amidohydrolases that co-localize with tyrosine, proline, and(More)
A new vertical mesh transfer (VMT) technique has been developed to facilitate the rapid isolation of plant metal-tolerance mutants. The technique is quantitative, allowing comparisons of the growth responses of different strains or ecotypes. Using the VMT technique, we have characterized the dose responses of 10 ecotypes of Arabidopsis thaliana to Cu2+,(More)
Polar transport of the plant hormone auxin is regulated at the cellular level by inhibition of efflux from a plasma membrane (PM) carrier. Binding of the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA) to a regulatory site associated with the carrier has been characterized, but the NPA-binding protein(s) have not been identified. Experimental(More)
Gene families encoding two types of metallothioneins (MTs) MT1 and MT2, have been identified in Arabidopsis thaliana, and their respective mRNAs have been shown to be regulated by copper in a tissue-specific manner (J. Zhou and P.B. Goldsbrough [1994] Plant Cell 6: 875-884; J. Zhou and P.B. Goldsbrough [1995] Mol Gen Genet 248: 318-328; A.S. Murphy and L.(More)
The vacuolar-type H(+)-ATPase acidifies intracellular compartments and is essential for many processes, including cotransport, guard cell movement, development, and tolerance to environmental stress. We have identified at least 26 genes encoding subunits of the vacuolar-type H(+)-ATPase in the Arabidopsis thaliana genome, although inconsistent nomenclature(More)
Seedlings of 10 Arabidopsis ecotypes were compared with respect to copper tolerance, expression of two metallothionein genes (MT1 and MT2), and nonprotein thiol levels. MT1 was uniformly expressed in all treatments, and MT2 was copper inducible in all 10 ecotypes. MT1 and MT2 mRNA levels were compared with various growth parameters for the 10 ecotypes in(More)
Proton pumping ATPases are found in all groups of present day organisms. The F-ATPases of eubacteria, mitochondria and chloroplasts also function as ATP synthases, i.e., they catalyze the final step that transforms the energy available from reduction/oxidation reactions (e.g., in photosynthesis) into ATP, the usual energy currency of modern cells. The(More)