C4-Pathway photosynthesis inPortulaca oleraceaand the significance of alanine labelling

✍ Scribed by M. D. Hatch

• Publisher: Springer-Verlag
• Year: 1975
• Tongue: English
• Weight: 452 KB
• Volume: 125
• Category: Article
• ISSN: 0032-0935
• DOI: 10.1007/bf00385603

✦ Synopsis

Portulaca oleracea L. has some features common to C a species but it has been suggested from other studies that a substantial proportion of assimilated carbon dioxide is incorporated into pyruvate and alanine by routes not involving C a acids or 3-phosphoglycerate. The present paper reports that enzyme activities in P. oleracea leaves, and the labelling patterns observed during assimilation of ~4CO~, are entirely consistent with the operation of the C~ pathway, with most of the label appearing initially in the C-4 of Ca acids, followed by the prominent labelling of 3-phosphoglycerate, hexose phosphates and then sucrose and starch after longer periods. In contrast to other recent observations, neither alanine nor pyruvate was a prominent early-labelled product, and the observed labelling of alanine was consistent with it being derived from radioactive carbon initially incorporated into C4 acids.