Rubisco and nitrogen relationships in rice: Leaf photosynthesis and plant growth

Abstract

This review describes how ribulose-l,5-bisphosphate carboxylase (Rubisco) is related to photosynthesis, N economy, and whole plant growth in rice (Oryza sativa L.). Rubisco is a rate-limiting factor for potential photosynthesis under the present atmospheric air conditions. Although there is no variation in the enzymic properties of Rubisco among rice varieties including old and modern cultivars, the specific activity is 30 to 40% lower than that in other higher plants such as wheat, spinach, and tobacco. In the future, the use of recombinant DNA technology in the chloroplast may enable to improve the kinetic efficiency of rice leaf Rubisco. Rubisco content is correlated with leaf-N content, but its amount in senescent leaves is often much lower than predicted from leaf-N content. Degradation of Rubisco is the major determinant of Rubisco content in senescent leaves. In sub-optimal environments characterized by a moderately low temperature, low irradiance, and CO 2 enrichment, Rubisco content does not limit photosynthesis and remains excessive. Even when rice is adapted to such environments, rice does not optimize Rubiscu content. 1i"ansgenic rice with theoretically optimal Rubisco content at elevated [C0 2 ] by antisense rbcS shows higher rates of photosynthesis only under elevated [C0 2 ] conditions. However, such an improvement at the level of a single leaf does not necessarily lead to a higher production of plant biomass. Decrease in Rubisco content induces the operation of the cyclic electron flow around PS I, which enables to prevent photoinhibition as well as to downregulate the quantum yield of PS II. Thus, the photosynthetic processes are highly integrated and strictly regulated. It is considered that there is a limit to improvement which can be achieved only by alteration of Rubisco.Key Words: Nitrogen, Oryza sativa L., photosynthesis, ribulose-l,5-bisphosphate carboxylase I oxygenase (Rubisco). 319The highly positive correlation between light-saturated photosynthesis in air and the N content in leaves of higher plants is widely observed, because N invested in chloroplasts accounts for the majority of leaf-N content (Evans 1989;Evans and Seemann 1989;Makino and Osmond 1991a). This relationship indicates that the increase in leaf-N content leads to an increase in the photosynthetic capacity. In fact, crop breeding up to the present had selected plants with a higher leaf-N content depending on large inputs of N fertilizer. This is also because N is often extremely deficient for plants in both natural and agricultural environments. oxygenase (Rubisco) activity in C 3 higher plants have revealed that Rubisco is a rate-limiting factor for potential photosynthesis under the present atmospheric air conditions (Makino et al. 1985b(Makino et al. , 1988Evans 1986). In addition, it has been found that large amounts of N are invested in Rubisco protein, accounting for 15 to 30% of total leaf-N content (Evans 1989;Makino et al. 1992). The amount of Rubisco protein is considered to be the most abundant protein in th...

Carbon Assimilation, Biomass Partitioning and Productivity in Grasses

“…Grasses undergo progressive senescence where the older leaves senesce and are replaced by younger leaves on a continual basis. Photosynthetic rates at ambient CO2 levels scale with leaf Rubisco content [42], which increases rapidly during leaf emergence, reaches a peak around full expansion, and declines through until senescence [43,44]. However, even under high exogenous supply, approximately half of the nitrogen for new leaf growth comes from the remobilization of leaf proteins including Rubisco from older leaves [45].…”

Mapping of QTLs Controlling Carbon Isotope Discrimination in the Photosynthetic System using Recombinant Inbred Lines Derived from a Cross between Two Different Rice(Oryza sativaL.) Cultivars

“…Numerous studies revealed a high positive correlation between light-saturated photosynthesis and nitrogen content in leaves of rice plants, since nitrogen invested in photosynthetically associated enzymes in chloroplasts accounts for a substantial part of leaf nitrogen content (Sinclair and Horie, 1989;Peng et al, 1995;Makino, 2003). Also, a higher stomatal conductance has been associated with a higher leaf photosynthetic rate (Wong et al, 1979;Kuroda and Kumura, 1990).…”

Water regime affects soil N2O emission and tomato yield grown under different types of fertilisers

“…The higher carbon gain in OM plants under well-watered conditions is likely due to the higher (P<0.01) total leaf area, which increased light interception ( Figure 2D) as previously reported by Vitale et al (2017) on tomato gown upon same conditions, rather than to an enhanced unit photosynthesis rate or to higher photosynthetic pigments and/or proteins content. In fact, the leaf-nitrogen content (Table 2), also related to Rubisco content (Makino, 2003) and Fv/Fm values (Table 3), related to functionality of photosystem 2 (Maxwell and Johnson, 2000), were comparable among treatments, thus suggesting that the unit photosynthetic rate was the same for all treatments.…”