Karl Y. Biel

Structural features of the salt glands of the leaf of Distichlis spicata 'Yensen 4a' (Poaceae)

The epidermal salt glands of the leaf of Distichlis spicata ‘Yensen 4a’ (Poaceae) have a direct contact with one or two water-storing parenchyma cells, which act as collecting cells. A vacuole occupying almost the whole volume of the collecting cell has a direct exit into the extracellular space (apoplast) through the invaginations of the parietal layer of the cytoplasm, which is interrupted in some areas so that the vacuolar-apoplastic continuum is separated only by a single thin membrane, which looks as a valve. On the basis of ultrastructural morphological data (two shapes of the extracellular channels, narrow and extended, are found in basal cells), the hypothesis on the mechanical nature of the salt pump in the basal cell of Distichlis leaf salt gland is proposed. According to the hypothesis, a driving force giving ordered motion to salt solution from the vacuole of the collecting cell through the basal cell of the salt gland to cap cell arises from the impulses of a mechanical compression–expansion of plasma membrane, which penetrates the basal cell in the form of extracellular channels. The acts of compression–expansion of these extracellular channels can be realized by numerous microtubules present in the basal cell cytoplasm.

THE PATH OF CARBON IN PHOTOSYNTHESIS. XXVI. UPTAKE AND TRANSPORT OF METHYLGLUCOPYRANOSIDE THROUGHOUT PLANTS

14Carbon methyl-β-D-glucopyranoside (14C-MeG) was applied to roots and shoots of Beta vulgaris L. and the label was tracked as it was transported and assimilated, primarily as a plant nutrient. Foliar application resulted in 6.7% of the 14C-MeG absorbed within 15 min of the solution drying into leaves. Roots in liquid medium with dissolved 14C-MeG absorbed approximately 97% of the 14C-label in 22 h. Whether fed in the light or dark, 40% of the 14C-MeG that was applied appeared in the cellulose fraction, incorporated completely intact. Rapid incorporation of 14C-MeG into the insoluble fraction with few 14C-labeled metabolites found in the soluble fraction were observed. In contrast to roots, a higher percentage of 14C-MeG was incorporated into starch and lipids of shoots.

THE PATH OF CARBON IN PHOTOSYNTHESIS. XXVII. SUGAR-CONJUGATED PLANT GROWTH REGULATORS ENHANCE GENERAL PRODUCTIVITY

We have found that applications of sugar-conjugated plant growth regulators (SPGRs) by exposures of roots or shoots to millimolar (mM) SPGRs are key to their uptake and transport for enhancement of vegetative productivity of the entire plant as compared to control populations. Initial surveys utilizing foliar applications of identically nutrient-supplemented 0.3 mM cytokinin glycosides, N6-benzyladenine glycosides, kinetin glycosides; and a 0.3 mM auxin glycoside, indoxyl-β-D-glucopyranoside (IG) resulted in significant shoot enhancements over controls. Foliar application of 0.3 mM kinetin glucoside resulted in significant root increase above the control. Foliar application of 3 mM to 6 mM IG resulted in enhanced root and shoot growths over controls. Similarly, increases of root and shoot yields over controls were observed as a result of foliar application of 3 mM indoxyl-β-D-glucuronide. Foliar application of 1 mM trans-zeatin-β-D-glucoside was particularly effective, resulting in significant enhancement of root and shoot growth with no phytotoxicity.

Untangling metabolic and spatial interactions of stress tolerance in plants. 1. Patterns of carbon metabolism within leaves

The localization of the key photoreductive and oxidative processes and some stress-protective reactions within leaves of mesophytic C3 plants were investigated. The role of light in determining the profile of Rubisco, glutamate oxaloacetate transaminase, catalase, fumarase, and cytochrome-c-oxidase across spinach leaves was examined by exposing leaves to illumination on either the adaxial or abaxial leaf surfaces. Oxygen evolution in fresh paradermal leaf sections and CO2 gas exchange in whole leaves under adaxial or abaxial illumination was also examined. The results showed that the palisade mesophyll is responsible for the midday depression of photosynthesis in spinach leaves. The photosynthetic apparatus was more sensitive to the light environment than the respiratory apparatus. Additionally, examination of the paradermal leaf sections by optical microscopy allowed us to describe two new types of parenchyma in spinach—pirum mesophyll and pillow spongy mesophyll. A hypothesis that oxaloacetate may protect the upper leaf tissue from the destructive influence of active oxygen is presented. The application of mathematical modeling shows that the pattern of enzymatic distribution across leaves abides by the principle of maximal ecological utility. Light regulation of carbon metabolism across leaves is discussed.

Andrew A. Benson: personal recollections

Abstract Andrew A. Benson, one of the greatest and much loved scientists of our century, passed away on January 16, 2015; he was born on September 24, 1917. A grand celebration of his life was held on February 6, 2015, in California. Here, we present one of his photographs and key excerpts from what was said then, and soon thereafter.

Metabolic Strategy of Annual Desert Plants: Adaptive Phenomenon of CAM and C4 Photosynthesis Functioning in a Leaf

Three types of autotrophic tissues are shown to be present in the leaves of four species from Chenopodiaceae and their anatomo-morphological and physiological characteristics are described. It has been concluded that C4 photosynthesis can function in two chlorenchyma layers. The potential ability of water storage parenchyma to carry out photosynthesis has been estimated; the dynamics of cell sap pH, the degree of the stomata opening, and starch content in the chloroplasts of a certain tissue during a day have been studied. Rates of CO2 assimilation over the period of 24 h, the kinetics of radiocarbon incorporation into photosynthates, and the carbon distribution in assimilating tissues as well as the activities of ribulose bisphosphate carboxylase, phosphoenolpyruvate carboxylase, and aspartate and alanine aminotransferases were measured in the leaves of some Chenopodiaceae species grown on salt marsh of the Kara-Kum Desert. It was demonstrated that in the leaves of Suaeda arcuata, Suaeda crassifolia, and Climacoptera crassa the C4 pathway of photosynthesis was operated between the two layers of chlorenchyma cells while in the water storage chlorenchyma, a heterotrophic CO2 fixation took place with high rates in the night. In ontogenesis of the investigated plants, CO2 assimilation function of water storage tissue (WST) is found only in the leaves of summer generation during the period of the most severe xerothermic conditions. Anatomy structure and photosynthetic carbon metabolism in plants grown on soils with varying salinity in the Central Kara-Kum Desert were investigated. Annual plants grown on slightly saline soils were mainly presented by C3 and C4 xerophytes, but those on heavily saline soils and on salt marsh—by C4 and C4-CAM succulents with WSTs assimilating CO2 by the CAM pathway.

Untangling metabolic and spatial interactions of stress tolerance in plants. 2. Accelerated method for measuring and predicting stress tolerance. Can we unravel the mysteries of the interactions between photosynthesis and respiration

A simple method using the O2 electrode that allows examination of the response of respiration and photosynthesis in leaf slices or algae to anoxia and high light under different temperatures useful for the examination of the interactions among photosynthesis, photorespiration, and respiration is described. The method provides a quantifiable assessment of stress tolerance that also permits us to examine fundamental biochemically and genetically related responses involved in stress tolerance and the cooperation among organelles. Additionally, we demonstrated a role for compounds, such as

The paths of Andrew A. Benson: a radio-autobiography

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