Selecting soybean leaves which yield mesophyll cell isolates displaying maximal rates of CO sub 2 and NO sub 2 -photoassimilations

Conference · Tue May 01 04:00:00 EDT 1990 · Plant Physiology, Supplement; (USA)

OSTI ID:5851191

Robinson, J M; de Veau, E J ^[1]

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1. USDA, Beltsville, MD (USA)

A problem, often encountered when assaying mesophyll cell isolates prepared from mature soybean leaves, was that of poor reproducibility in rates of {sup 14}CO{sub 2} photofixation (CPA) and NO{sub 2}{sup {minus}} photoreduction (NiPR). It was hypothesized that this problem was the result of pooling newly matured leaves with older matured leaves prior to cell isolation. This issue was examined further. Soybean cv. Williams plants were propagated in the growth chamber (12h Light-Dark cycle, 25{degree}C, 65% RH, and 700 {mu}E/s.m{sup 2}). At 33 d post-emergence, the 5th leaf (numbered acropetally from the unifoliates) of each plant had just attained maximum leaflet areas (120-130 cm{sup 2}) and lengths (14-15 cm). For this study, mesophyll cells were enzymatically (mascerase) isolated from leaflet sets of trifoliolates selected from each of the 4th, 5th, 6th leaf nodes. Maximal rates of CPA (5mM HCO{sub 3}{sup {minus}}) in the 4th, 5th and 6th nodal isolates were, respectively (resp), 26.5, 65.0, 9.5 {mu}mol {sup 14}CO{sub 2} fixed/h{center dot}mg Chl; simultaneously maximal rates of NiPR (1 mM NO{sub 2}{sup {minus}}) were, resp, 9.2, 11.0, 6.3 {mu}mol NO{sub 2}{sup {minus}} reduced/h{center dot}mg Chl. These studies made it clear that in order to repeatedly attain reproducible maximal rates of leaf cell isolate CPA and NiPR, it always was necessary to select the newest, fully expanded leaves (e.g. 5) for cell isolation. Mixing newly matured, fully expanded leaves (e.g. 5) with older mature leaves (e.g. 4) prior to leaf cell isolation, ultimately yielded isolates with low CPA and NiPR rates.

• OSTI ID: 5851191
• Report Number(s): CONF-9007196--
• Conference Information: Journal Name: Plant Physiology, Supplement; (USA) Journal Volume: 93:1
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
GLYCINE HISPIDA
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LEAVES
LEGUMINOSAE
MAGNOLIOPHYTA
MAGNOLIOPSIDA
NITRATES
NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PLANTS
REACTION KINETICS
TRACER TECHNIQUES