Differences between wheat and rice in the enzymic properties of ribulose-1,5-bisphosphate carboxylase/oxygenase and the relationship to photosynthetic gas exchange

Amane Makino, Tadahiko Mae, Koji Ohira

Research output: Contribution to journalArticle

177 Citations (Scopus)

Abstract

The kinetic parameters of ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (EC 4.1.1.39) in wheat (Triticum aestivum L.) and rice (Oryza sativa L.) were determined by rapidly assaying the leaf extracts. The respective Km and Vmax values for carboxylase and oxygenase activities were significantly higher for wheat than for rice. In particular, the differences in the Vmax values between the two species were greater. When the net activity of CO2 exchange was calculated at the physiological CO2-O2 concentration from these kinetic parameters, it was 22% greater in wheat than in rice. This difference in the in-vitro RuBP-carboxylase/oxygenase activity between the two species reflected a difference in the CO2-assimilation rate per unit of RuBP-carboxylase protein. However, there was no apparent difference in the CO2-assimilation rate for a given leaf-nitrogen content between the two species. When the RuBP-carboxylase/oxygenase activity was estimated at the intercellular CO2 pressure from the enzyme content and kinetic parameters, these estimated enzyme activities in wheat and rice were similar to each other for the same rate of CO2 assimilation. These results indicate that the difference in the kinetic parameters of RuBP carboxylase between the two species was offset by the differences in RuBP-carboxylase content and conductance for a given leaf-nitrogen content.

Original languageEnglish
Pages (from-to)30-38
Number of pages9
JournalPlanta
Volume174
Issue number1
DOIs
Publication statusPublished - 1988 Apr 1

Keywords

  • Gas exchange (photosynthesis)
  • Nitrogen (leaf)
  • Oryza (photosynthesis)
  • Photosynthesis (gas exchange)
  • Ribulose-1,5-bisphosphate carboxylase/oxygenase
  • Triticum (photosynthesis)

ASJC Scopus subject areas

  • Genetics
  • Plant Science

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