The effective integration of hormone signals is essential to normal plant growth and development. Gibberellins (GA) and cytokinins act antagonistically in leaf formation and meristem maintenance and GA counteract some of the effects of cytokinins on epidermal differentiation. However, both can stimulate the initiation of defensive epidermal structures called trichomes. To understand how their r...

Cytokinins were discovered in the search for factors that promoted division of plant cells in culture. Naturally occurring cytokinins are N-substituted adenine derivatives that generally contain an isoprenoid derivative side chain. These hormones influence numerous aspects of plant development and physiology, including seed germination, de-etiolation, chloroplast differentiation, apical dominan...

When cytokinin-autonomous tobacco BY-2 cell cultures are transferred into 2,4-dichlorophenoxyacetic acid (2,4-D)-deprived medium, amyloplast development is initiated. Using this in vitro amyloplast-inducing system, the role of cytokinins in amyloplast formation was investigated. We show that addition of lovastatin, an inhibitor of mevalonate synthesis, to amyloplast-inducing medium reduced star...

Cytokinins promote cell division and chloroplast development in tissue culture. We previously isolated two mutants of Arabidopsis thaliana, ckh1 (cytokinin-hypersensitive 1) and ckh2, which produce rapidly growing green calli in response to lower levels of cytokinins than those found in the wild type. Here we report that the product of the CKH2 gene is PICKLE, a protein resembling the CHD3 clas...

Leaf senescence is the final stage of leaf development in which the nutrients invested in the leaf are remobilized to other parts of the plant. Whereas senescence is accompanied by a decline in leaf cytokinin content, exogenous application of cytokinins or an increase of the endogenous concentration delays senescence and causes nutrient mobilization. The finding that extracellular invertase and...

Ultra-performance liquid chromatography-tandem mass spectrometry was used to establish the cytokinin profile of the bryophyte Physcomitrella patens (Hedw.) B.S.G.; of 40 analyzed cytokinins, 20 were detected. cis-Zeatin-riboside-O-glucoside, N(6)-(Delta(2)-isopentenyl)adenosine-5'-monophosphate (iPRMP), and trans-zeatin-riboside-O-glucoside were the most abundant intracellular cytokinins. In ad...

Abstract STOP1 (sensitive to proton rhizotoxicity1) is a master transcription factor that governs the expression of set regulatory and structural genes involved in resistance aluminum low pH ( i.e ., proton) stresses Arabidopsis. However, mechanisms networks underlying STOP1-mediated are largely unclear. Here, we report low-pH severely inhibited root growth stop1 plants by suppressing meristem ...