Showing papers in "Plant and Cell Physiology in 1975"

Characterization of plant growth substances in Citrus unshiu and their change in fruit development

Abstract: Citrus unshiu is a popular Citrus species cultivated in Japan. It blooms in the middle of May and ten days after full bloom, the fruit abscission starts; the pattern (7) varies every year, two peaks in average daily drop (about thirty and fifty days after full bloom) being observed in 1966 and .one peak (about thirty days after full bloom) in 1968. These physiological abscissions are considered to be controlled by the endogenous hormonal balance. We have studied the hormonal changes in the development of the young fruits and the role of endogenous plant hormones in the physiological abscission of Citrus unshiu. A group at the Citrus Research Center in Riverside, California claimed (10) the occurrence of a new type of non-indolic auxin, \"citrus auxin\", and non-occurrence of indolic auxin in Citrus plants . On the other hand, physiological and chemical evidence to warrant a reappraisal of the above claim has accumulated. A group at the Hebrew University, Israel, detected auxin-like activity (2, 3, 6) in various Citrus tissues and further identified ( 4) IAA in elongating shootlets of Citrus limon by paper chromatography using labelled IAA. In 1971, we preliminarily reported ( 8) the isolation and identification of IAA and lAM in very young fruits of Citrus unshiu. Thu5 the proposal (5) to avoid the term \"citrus auxin\" has been made. Herein we wish to report not only the hormonal changes in young fruits of Citrus unshiu during development but also details of the isolation and identification of plant growth regulators such as IAA, lAM and IAA-Me.

Panicum milioides, a Gramineae plant having Kranz leaf anatomy without C4-photosynthesis

Abstract: Light and electron microscopic observations of the leaf tissue of Panicum milioides showed that the bundle sheath cells contained a substantial number of chloroplasts and other organelles. The radial arrangement of chlorenchymatous bundle sheath cells, designated as Kranz leaf anatomy, has been considered to be specific to C4 plants. However, photosynthetic 14CO2 fixation and 14CO2 pulse-and-chase experiments revealed that the reductive pentosephosphate pathway was the main route operating in leaves of P. milioides. The interveinal distance of the leaves was intermediate between C3and C4Gramineae species. These results indicate that P. milioides is a natural plant species having chracteristics intermediate between C3 and C4 types.

Fatty acid synthesis by spinach chloroplasts I. Property of fatty acid synthesis from acetate

Abstract: Intact chloroplasts (about 70% Class I chloroplasts) isolated from spinach leaves incorporated 150 nmoles of [1-C] acetate into fatty acids per mg chlorophyll in 1 hr at pH 8.3, 25°C and 25,000 lux. On electron and phase-contrast microscopies combined with hypotonic treatment of chloroplasts, this synthetic activity was shown to be proportional to the percentage of Class I chloroplasts in the preparation. Light was necessary for the synthesis, the activity in the complete reaction mixture in the dark being only 2% of that in the light. The synthetic activity increased with increasing intensities of light to reach saturation at 6,000 lux. CoA and ATP were most effective as cofactors, HCO3-, HPO4 -, Mg and Mn were less effective. ATP could be replaced by ADP in the presence of Pi, suggesting possible supply of ATP by photophosphorylation. Omission of the NADPH-generation system and NADH did not affect the synthesis, indicating sufficient provision of endogenous NADPH and NADH in intact chloroplasts under light. Addition of DTE did not cause recovery of the synthetic activity of intact chloroplasts in the dark.