A model defining carbon isotope discrimination (delta13C) for crassulacean acid metabolism (CAM) plants was experimentally validated using Kalanchoe daigremontiana. Simultaneous measurements of gas exchange and instantaneous CO2 discrimination (for 13C and 18O) were made from late photoperiod (phase IV of CAM), throughout the dark period (phase I), and into the light (phase II). Measurements of...

C4 photosynthesis involves a close collaboration of the C3 and C4 metabolic cycles across the mesophyll and bundle-sheath cells. This study investigated the coordination of C4 photosynthesis in maize plants subjected to two salinity (50 and 100mM NaCl) treatments and one shade (20% of full sunlight) treatment. Photosynthetic efficiency was probed by combining leaf gas-exchange measurements with...

A mutant of the NAD-malic enzyme-type C(4) plant, Amaranthus edulis, which lacks phosphoenolpyruvate carboxylase (PEPC) in the mesophyll cells was studied. Analysis of CO(2) response curves of photosynthesis of the mutant, which has normal Kranz anatomy but lacks a functional C(4) cycle, provided a direct means of determining the liquid phase-diffusive resistance of atmospheric CO(2) to sites o...

Our previous research characterized two phosphoenolpyruvate (PEP) carboxylase (PEPC) isoforms (PEPC1 and PEPC2) from developing castor oil seeds (COS). The association of a shared 107-kD subunit (p107) with an immunologically unrelated bacterial PEPC-type 64-kD polypeptide (p64) leads to marked physical and kinetic differences between the PEPC1 p107 homotetramer and PEPC2 p107/p64 heterooctamer...

So far, it has been suggested that phosphoenolpyruvate carboxylases (PEPCs) and PEPC kinases (PPCKs) fulfill several important non-photosynthetic functions. However, the biological functions of soybean PPCKs, especially in alkali stress response, are not yet well known. In previous studies, we constructed a Glycine soja transcriptional profile, and identified three PPCK genes (GsPPCK1, GsPPCK2 ...

Phosphoenolpyruvate carboxylase (PEPC) is a tightly controlled cytosolic enzyme situated at a crucial branch point of central plant metabolism. In developing castor oil seeds (Ricinus communis) a novel, allosterically desensitized 910-kD Class-2 PEPC hetero-octameric complex, arises from a tight interaction between 107-kD plant-type PEPC and 118-kD bacterial-type (BTPC) subunits. The native Ca2...

The transcription of 16 genes encoding 12 peptidases (pepC, pepN, pepX, pepP, pepA, pepF2, pepDA1, pepDA2, pepQ, pepT, pepM, and pepO1), P(I) and P(III) proteinases (prtP1 and prtP3), and three transport systems (dtpT, dtpP, and opp-pepO1) of Lactococcus lactis MG1363 was analyzed in response to different environmental factors. Promoter fusions with luciferase reporter genes and/or mRNA analysi...

Rising atmospheric carbon dioxide (CO2) concentration and temperaturewill influence photosynthesis, growth andyield of agronomic crops.To investigate effects of elevatedCO2andhigh temperature on leaf gas exchanges, activities of Rubisco and phosphoenolpyruvate carboxylase (PEPC) and growth of grain sorghum (Sorghum bicolorL.Moench), plants were grown in controlled environments at day-time maxim...

PREMISE OF THE STUDY Morphologically diverse clades are useful for detecting adaptive morphological evolution. Each of their variants may have evolved once or several times, suggesting that their repeated appearance may be due to environmental pressures. The North American Manihot species are an excellent system to detect possible adaptations and to assess the effect of mono- or polyphyly on cl...