超级杂交稻两优培九高产的光合特性及其生理基础

Photosynthetic Characteristics and Its Physiological Basis of Super High-Yielding Hybrid Rice Liangyoupeijiu

超级杂交稻两优培九(培矮64S/9311)是中国超级稻计划完成第一步目标的标志性品种,与其亲本籼稻9311和之前大面积种植的当家杂交籼稻汕优63相比,具有明显的产量超亲优势和竞争优势,近15年来累计种植面积遥居杂交稻首位。两优培九稻谷产量高的生物学基础是源于优良光合特性而获得较高的生物学产量,因此,研究其光合特性及其生理基础,有助于了解高产杂交稻生长优势的光合特征和利用探索性育种技术提高水稻光合性能,为杂交稻超高产育种和栽培提供理论基础和技术途径。多年较系统的研究发现,与9311和汕优63相比,两优培九在正常生长和衰老过程中,光能吸收、传递和转化效率及碳同化等方面均具有优势,Pn较高,光合性能优异。表现在对强光和弱光、UV-B辐射增强的适应性或耐受能力及抗衰老能力更强;具有多种抵御偏低或过高温度的策略,对不良温度的适应性或耐受能力更强;水分亏缺造成的伤害较轻;光合速率随施用氮肥量的增加而提高,低氮或高氮条件下,均具有光合能力的比较优势;光合作用对大气CO_2浓度升高、土壤pH、盐胁迫等环境条件的适应能力更强。两优培九优异的光合性能与其光合机构和酶学基础有关,表现为叶绿体类囊体膜基粒数多、片层高而长、垛叠密集;叶绿素含量高,出现衰老特征晚,生育后期叶绿体衰败、叶绿素分解速度较慢;具有更高的Rubisco初始羧化活性、总羧化活性和活化率;C4光合途径酶活性较高,在低光强下仍有较高的碳同化效率,CO_2补偿点和光呼吸活性均较低;叶片的SOD、POD等抗氧化酶含量和活性均高,内源O2.-、H_2O_2含量低,抗膜脂过氧化能力较强。笔者认为,高产杂交稻育种要做到"遗传上有性状杂种优势,形态上有优良光合株型,功能上有优异光合性能"的遗传、形态和功能"三优"相结合;探究两优培九C4特性与高光合性能的联系和研究新的更高产杂交稻的光合特性,有助于加深对高产杂交稻光合生长优势的理解和探索针对性技术促进C4光合功能等,从而进一步提高光合生产以至于稻谷产量。

Two-line super hybrid rice Liangyoupeijiu（Peiai64S/9311） is a landmark of China＇s super rice project and proud of the largest planting area in the last fifteen years.Compared with its parent 9311 and the large-scale planted hybrid rice Shanyou 63,Liangyoupeijiu has obvious yield superiority and competitive advantage.The most important biological basis is its good photosynthetic characteristics which results in higher biomass.Studying its photosynthetic characteristics could help to understand the photosynthetic growth of high yield hybrid rice,and improve the light efficiency by exploratory breeding technology,and provide a theoretical basis and technical approaches for super high-yielding rice breeding.After summarization of the various relevant studies,it was found that,in comparison with 9311 and Shanyou 63,Liangyoupeijiu shows higher light absorption,transmission and transformation efficiency and carbon assimilation which result in obvious advantages in Pn and other photosynthetic characters.The characters are：showing adaptation or tolerance of higher or lower light intensity even UV-B enhance,and stronger resistance to aging;with various strategies to resist lower or higher temperature,showing stronger adaptation or tolerance of damaged temperatures;showing less damage under water stress;photosynthetic rate increased with nitrogen levels,and had advantages of photosynthetic capacity both in lower and higher nitrogen;photosynthesis increased by higher atmospheric CO_2 concentration,and tolerance stronger on soil pH,salt stress and so on.Those excellent photosynthetic properties have their physiological basis.Its chlorophyll content is higher,and declined later and slowly,which results in a higher chlorophyll content in its late growing stage.It has a higher Rubisco initial carboxylation activity,total carboxylation activity and activation rate.The expression of C_4 photosynthetic pathways is up-regulated by its higher activity of C_4 enzymes,and caused both lower photosynthetic compensation point of light intensity and CO_2 concentration,and a lower photorespiratory activity as well,which shows obvious C_4 photosynthetic characteristics.The activities of antioxidase such as SOD and POD in its leaves are higher,which eliminate the endogenous O_2.- and H_2O_2,so that it shows more stronger resistance to membrane lipid peroxidation.The authors consider that hybrid rice breeding with high-yielding should pay more attention to ＂three excellent traits＂ by combining with genetic trait of strong heterosis,morphological trait of plant ideotype,and functional trait of fine photosynthetic performance.Exploring the relationship among C_4 photosynthetic pathways,high photosynthesis and grain yield of Liangyoupeijiu,and studying photosynthetic characteristics of more other new types of hybrid with super high yield are both very meaningful to deepen the understanding of photosynthetic growth of such high-yielding hybrid rice,and explore the targeted technology to promote the C_4 photosynthesis function for further improving of the photosynthetic production and grain yield in future hybrid rice production.