We have characterized the transport of [(3)H]indoleacetic acid (IAA) in intact corn (Zea mays L.) coleoptiles. We have used a wide range of concentrations of added IAA (28 femtomoles to 100 picomoles taken up over 60 minutes). The shape of the transport curve varies with the concentration of added IAA, although the rate of movement of the observed front of tracer is invariant with concentration...

Drought significantly reduces yield of many crop plants including wheat in the world. Identification of wheat genotypes that can thrive on limited water is vital to boost the wheat production of rainfed areas. Forty wheat genotypes were screened for drought tolerance using 0, 7.5, 15 and 22.5% Polyethylene Ethylene Glycol 6000 solutions at PMAS Arid Agriculture University, Rawalpindi, Pakistan ...

The far-red reversibility of the phytochrome-controlled stimulation of elongation of coleoptile sections by low fluence red light has been characterized in subapical coleoptile sections from dark-grown Avena sativa L., cv Lodi seedlings. The fluence dependence of the far-red reversal was the same whether or not the very low fluence response is also expressed. The capacity of far-red light to re...

The plasma membrane (PM) H(+)-ATPase has been proposed to play important transport and regulatory roles in plant physiology, including its participation in auxin-induced acidification in coleoptile segments. This enzyme is encoded by a family of genes differing in tissue distribution, regulation, and expression level. A major expressed isoform of the maize PM H(+)-ATPase (MHA2) has been charact...

Low temperatures at the initial stages of rice development prevent fast germination and seedling establishment and may cause significant productivity losses. In order to develop rice cultivars exhibiting cold tolerance, it is necessary to investigate genetic resources, providing basic knowledge to allow the introduction of genes involved in low temperature germination ability from accessions in...

The vertical elongation of normal roots of Lupinus seedlings proceeds at constant rate over periods of 4 to 5 hours. The decapitation of a root stops its elongation for a variable length of time, followed by a period of renewed elongation at a rate lower than that of the normal root. The tipping of the decapitated root with a tip of a coleoptile of Zea induces a decrease in the rate of elongati...

This study demonstrated that, in rice seedlings, genotypic difference in tolerance to anoxia only occurred when anoxia was imposed at imbibition, but not at 3 d after imbibition. When seeds were imbibed and grown in anoxia, IR22 (anoxia-'intolerant') grew much slower and had lower soluble sugar concentrations in coleoptiles and seeds than Amaroo (anoxia-'tolerant'), while Calrose was intermedia...

Fluorescence spectroscopy was used to characterize blue light responses from chloroplasts of adaxial guard cells from Pima cotton (Gossypium barbadense) and coleoptile tips from corn (Zea mays). The chloroplast response to blue light was quantified by measurements of the blue light-induced enhancement of a red light-stimulated quenching of chlorophyll a fluorescence. In adaxial (upper) guard ce...

12. ORDIN, L., R. CLELAND, AND J. BONNER. 1957. Methyl esterification of cell wall constituents under the influence of auxin. Plant Physiol. 32: 216-20. 13. RAY, P. M. 1962. Cell wall synthesis and cell elongation in oat coleoptile tissue. Am. J. Botany 49: 928-39. 14. RAY, P. M. 1963. Sugar composition of oat coleoptile cell walls. Biochem. J. 89: 144-50. 1 S. RAY, P. M. AND D. B. BAKER. 1962....

Suninwary. When C14 carboxyl in(loleacetic aci(d (IAA) is transporLe l through Avena coleoptile sections a fraction of the activity becomes bound. The nature of this bound IAA has been investigated. Upon extraction with solvents and chromatography a substance having the RF of IAA in 4 solvents was detected. No evidence could be found for the formation of indoleacetyl conjugates. In pea stem sec...