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Zhu C.,CAS Nanjing Institute of Soil Science | Zhu C.,Japan National Institute for Agro - Environmental Sciences | Ziska L.,U.S. Department of Agriculture | Zhu J.,CAS Nanjing Institute of Soil Science | And 5 more authors.
Physiologia Plantarum | Year: 2012

In this study, we tested for the temporal occurrence of photosynthetic acclimation to elevated [CO 2] in the flag leaf of two important cereal crops, rice and wheat. In order to characterize the temporal onset of acclimation and the basis for any observed decline in photosynthetic rate, we characterized net photosynthesis, g s, g m, C i/C a, C i/C c, V cmax, J max, cell wall thickness, content of Rubisco, cytochrome (Cyt) f, N, chlorophyll and carbohydrate, mRNA expression for rbcL and petA, activity for Rubisco, sucrose phosphate synthase (SPS) and sucrose synthase (SS) at full flag expansion, mid-anthesis and the late grain-filling stage. No acclimation was observed for either crop at full flag leaf expansion. However, at the mid-anthesis stage, photosynthetic acclimation in rice was associated with RuBP carboxylation and regeneration limitations, while wheat only had the carboxylation limitation. By grain maturation, the decline of Rubisco content and activity had contributed to RuBP carboxylation limitation of photosynthesis in both crops at elevated [CO 2]; however, the sharp decrease of Rubisco enzyme activity played a more important role in wheat. Although an increase in non-structural carbohydrates did occur during these later stages, it was not consistently associated with changes in SPS and SS or photosynthetic acclimation. Rather, over time elevated [CO 2] appeared to enhance the rate of N degradation and senescence so that by late-grain fill, photosynthetic acclimation to elevated [CO 2] in the flag leaf of either species was complete. These data suggest that the basis for photosynthetic acclimation with elevated [CO 2] may be more closely associated with enhanced rates of senescence, and, as a consequence, may be temporally dynamic, with significant species variation. © 2012 Physiologia Plantarum.

Chen Y.,China Pharmaceutical University | Chen Y.,Jiangsu Institute of Botany | Shan Y.,Jiangsu Institute of Botany | Zhao Y.Y.,Jiangsu Institute of Botany | And 4 more authors.
Chinese Chemical Letters | Year: 2012

Two new triterpenoid saponins named lonimacranthoide IV (1) and lonimacranthoide V (2) were isolated from the flower buds of Lonicera macranthoides Hand.-Mazz. (Caprifoliaceae). They have hederagenin as aglycone. Lonimacranthoide IV (1) is a rare chlorogenic acid ester acylated on the C-23 of hederagenin. Lonimacranthoide IV is a new sulfated triterpenoid saponin. The structures of the saponins were established by chemical and spectral methods. © 2011 Ming Wang.

Zhu C.,CAS Nanjing Institute of Soil Science | Zhu J.,CAS Nanjing Institute of Soil Science | Zeng Q.,CAS Nanjing Institute of Soil Science | Liu G.,CAS Nanjing Institute of Soil Science | And 4 more authors.
Functional Plant Biology | Year: 2014

It was anticipated that wheat net photosynthesis would rise under elevated CO2, and that this would alter the progress of senescence due to the unbalance of carbohydrates and nitrogen. Our study showed that ear carbon sink was limited, and sugar was accumulated, hexokinase activities and levels of phosphorylated sugar were increased within the flag leaves, grain nitrogen sink capacity was enhanced, and flag leaf senescence was accelerated under elevated CO2. However, if the ear of the main stem was covered, these responses to elevated CO2 were absent, and the senescence of flag leaf was not accelerated by elevated CO2. Thus, it appeared that elevated CO2 accelerated the rate of flag leaf senescence, depending on ear photosynthesis. The ears have far higher enhancement of net photosynthesis than flag leaves, and the role of the flag leaf relative to the ear was declined in supplying C assimilation to grain under elevated CO2. This indicates that as CO2 rises, the grain sink needs theNmore than C assimilate from flag leaf, so the declining rates ofN%and soluble proteins concentration were markedly accelerated under elevated CO2 conditions. This suggests that, the large increase in ear net photosynthesis accelerated grain filling, accelerated remobilising N within flag leaf as the result of the greater grain nitrogen sink capacity. In addition, as the result of grain carbon sink limitation, it limited the export of flag leaf sucrose and enhanced sugar cycling, which was the signal to accelerate leaf senescence. Hence, elevated CO2 subsequently accelerates senescence of flag leaf. © 2009 CSIRO.

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