Zhang C-J, Chu H-J, Chen G-X, Shi D-W, Zuo M, Wang J, Lu C-G, Wang P, Chen L
Key Lab of Biodiversity and Biotechnology of Jiangsu Province, College of Life Sciences, Nanjing Normal University, Nanjing, PR China.
J Plant Res. 2007 Mar;120(2):209-17. doi: 10.1007/s10265-006-0038-z. Epub 2006 Nov 1.
Responses of net photosynthetic rates to intercellular CO(2) concentration (P (n)/C (i) curves) and photochemical characteristics were investigated in flag leaves of newly developed superhigh-yield hybrid rice (Oryza sativa L.) LiangYouPeiJiu (LYPJ) and its maternal PeiAi64S (PA64S) and paternal WuMang9311 (WM9311) lines grown in the field during the reproductive stage. The results showed that photosynthetic functions, such as the electron transport activities of photosystems and photophosphorylation, assessed in vivo from P (n)/C (i) curves under field conditions declined more or earlier than those obtained in vitro. The degradation of polypeptides of thylakoid membranes was slower than those for P (Ca=360) (light-saturated net photosynthetic rate measured at 360 mumol mol(-1)) and CE (carboxylation efficiency, obtained from the initial slope of the P (n)/C (i) curve). The initial inhibition of the PSII electron transport and oxygen-evolving activity induced by senescence occurred before the degradation of the oxygen-evolving complex. In comparison, LYPJ had intermediate photosynthetic functions in the early stage of leaf development, but greater photochemical activities in the mid and late stages. WM9311 showed a similar pattern of changes but lower values, and PA64S had higher values in the early stage but showed a faster rate of senescence than LYPJ. These findings implied that the hybrid LYPJ demonstrated intermediate photosynthetic activities between its parents in the early stage of leaf development, whereas it had higher photosynthetic activities than its parents in the mid and late stages, which may be responsible for its high yield.
在生殖生长阶段，对田间种植的新型超高产杂交水稻（Oryza sativa L.）两优培九（LYPJ）及其母本培矮64S（PA64S）和父本武粳9311（WM9311）剑叶的净光合速率对胞间CO₂浓度的响应（P(n)/C(i)曲线）及光化学特性进行了研究。结果表明，在田间条件下，根据P(n)/C(i)曲线在体内评估的光合功能，如光系统的电子传递活性和光合磷酸化，比在体外获得的下降得更早或更多。类囊体膜多肽的降解比P(Ca=360)（在360 μmol mol⁻¹下测得的光饱和净光合速率）和CE（羧化效率，从P(n)/C(i)曲线的初始斜率获得）的降解要慢。衰老诱导的PSII电子传递和放氧活性的初始抑制发生在放氧复合体降解之前。相比之下，LYPJ在叶片发育早期具有中等光合功能，但在中后期具有更高的光化学活性。WM9311表现出类似的变化模式但数值较低，PA64S在早期具有较高数值，但衰老速率比LYPJ快。这些发现表明，杂交种LYPJ在叶片发育早期表现出介于其亲本之间的中等光合活性，而在中后期具有比其亲本更高的光合活性，这可能是其高产的原因。
