The role of auxin and protons in the gravitropic response of the sunflower (Helianthus annuus L. cv Sungold) hypocotyl has been investigated. No physiological asymmetry in acid-growth capacity could be detected between the upper and lower surfaces of gravistimulated hypocotyls. These data imply that neutral buffers inhibit shoot gravitropism by preventing the establishment of a lateral proton g...

Methyl jasmonate has a strong effect on secondary metabolizm in plants, by stimulating the biosynthesis a number of phenolic compounds and alkaloids. Common buckwheat (Fagopyrum esculentum Moench) is an important source of biologically active compounds. This research focuses on the detection and quantification of 2-phenylethylamine and its possible metabolites in the cotyledons, hypocotyl and r...

Experiments were conducted to study the interaction of ethylene and the cytokinin N(6)-benzyladenine (BA) in promoting hypocotyl elongation in a dwarf strain of watermelon (Citrullus lanatus [Thunb] Matsu. and Nakai). Optimum promotion of hypocotyl elongation is elicited by an apical treatment with 0.2 microgram BA. At dosages above 0.3 microgram per apex, BA-enhancement of elongation is reduce...

Components of quantitative resistance in sunflower (Helianthus annuus) to Plasmopara halstedii, the pathogen causing downy mildew, were investigated. Percentage infection, latent period, sporulation density and reduction of hypocotyl length were compared on two sunflower lines showing different levels of quantitative resistance in the field infected with different P. halstedii strains of races ...

Epidermal cells in the root of Arabidopsis seedling differentiate either as hair or non-hair cells, while in the hypocotyl they become either stomatal or elongated cells. WEREWOLF (WER) and GLABRA2 (GL2) are positive regulators of non-hair and elongated cell development. CAPRICE (CPC) is a positive regulator of hair cell development in the root. We show that WER, GL2 and CPC are expressed and a...

Critical responses to developmental or environmental stimuli are mediated by different transcription factors, including members of the ERF, bZIP, MYB, MYC, and WRKY families. Of these, MYB genes play roles in many developmental processes. The overexpression of one MYB gene, MYBH, significantly increased hypocotyl elongation in Arabidopsis thaliana plants grown in the light, and the expression o...

Cyclin D (CYCD) plays an important role in cell cycle progression and reentry in response to external signals. Here, we demonstrate that Arabidopsis thaliana CYCD4 is associated with specific cell divisions in the hypocotyl. We observed that cycd4 T-DNA insertion mutants had a reduced number of nonprotruding cells and stomata in the hypocotyl epidermis. Conversely, CYCD4 overexpression enhanced...

Gravity and light are major factors shaping plant growth. Light perceived by phytochromes leads to seedling deetiolation, which includes the deviation from vertical hypocotyl growth and promotes hypocotyl phototropism. These light responses enhance survival of young seedlings during their emergence from the soil. The PHYTOCHROME KINASE SUBSTRATE (PKS) family is composed of four members in Arabi...

GIGANTEA (GI) was originally identified by a late-flowering mutant in Arabidopsis, but subsequently has been shown to act in circadian period determination, light inhibition of hypocotyl elongation, and responses to multiple abiotic stresses, including tolerance to high salt and cold (freezing) temperature. Genetic mapping and analysis of families of heterogeneous inbred lines showed that natur...

Phototropism is an adaptive response allowing plants to optimize photosynthetic light capture. This is achieved by asymmetric growth between the shaded and lit sides of the stimulated organ. In grass seedlings, the site of phototropin-mediated light perception is distinct from the site of bending; however, in dicotyledonous plants (e.g., Arabidopsis), spatial aspects of perception remain debata...