Promotion of Photosynthesis of Transgenic Rice Plant with Overexpressing C4 pepc from Maize under Low Concentration NO
CHEN Ping-Bo;LI Xia*
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In order to reveal the relationship between physiological difference and high photosynthetic efficiency in C3 plant with high expression C4 pepc, the transgenic rice with high expression of maize C4 pepc(PC) and the untransformed rice plant Kitaake (WT) were used as the material plants. The upsecond leaves of the rice plants were used to treat by root system during the booting stage. After the treatments of the different concentrations of NO donor, NO synthesis inhibitors and related signal related reagents as well as in the dark for 12 h, the effects of NO on the net photosynthetic rate (Pn), stomatal conductance (Gs) and intercellular CO2 concentration (Ci) of the test material leaves were measured. The results showed that: Pn of WT and PC increased by 20.8% and 10.7%, respectively under the treatments of 200 μmol·L-1 SNP(Sodium nitroprusside) and 1 mmol·L-1 L-Arg (L-Arginine), which was significantly different(p<0.05); However, with increasing the concentrations of SNP and L-Arg, the Pn, Gs and Ci of two rice plants were gradually suppressed. Compared with PC, the Pn of WT was significantly inhibited (p<0.05), but the changes of Gs and Ci were opposite; When treated by 200 μmol·L-1 SNP and 1 mmol·L-1 L-Arg as well as SA (salicylic acid) for the test materials, the changes of Pn, Gs and Ci were similar with those under high concentrations of NO donors treatment; Under united 6 mmol·L-1 EGTA of Ca2+ chelator treatment, compared with the PC, the Pn of WT was significantly inhibited at the level (p<0.01), that Ci was opposite (p<0.05). Correlation analysis showed that: The correlationship between the Pn and the Gs in PC was less than that of WT, the determination coefficients were 0.654 9 and 0.773 5; However, The correlationship between the Pn and the Ci in PC was larger than that of WT, the determination coefficients were 0.466 5 and 0.419 6, which implied that there might be different way of the regulation of photosynthesis between PC and WT, especially at lower concentrations of NO in PC, NO might participate in the process of the stomatal movement with high concentration of free Ca2+. It can still maintain the stability of Pn in PC under the conditions in stomatal closure.