【作者】 陆巍；

【导师】 张荣铣；

【作者基本信息】 南京农业大学 ， 植物生理学， 2000， 博士

【摘要】 水稻是我国最重要的粮食作物之一。提高其光合效率对于揭示光合作用机理、在现有基础上大幅度增加单位面积产量具有极其重要的意义。 本文系统分析了两套杂交水稻（组合）剑叶光合功能衰退过程中光合参数的变化，结果表明：叶片光合功能衰退过程中，瞬时光合速率表现为高值持续期（APD）和速降期，叶绿素含量表现出相对稳定期（RSP）和速降期（SFP）。在各个光合参数下降过程中，碳同化关键酶RuBPCase活性的下降明显快于光合全电子传递活性的下降，提高RuBPCase的羧化效率成为提高光合效率的关键之一。 叶源量是叶片一生同化CO₂的总量。本文就水稻剑叶叶源量及其与产量性状关系进行了研究。结果表明，水稻剑叶叶源量与单株产量、单穗重及每穗实粒数均呈极显著正相关，证明叶源量与产量性状紧密相关。通径分析进一步说明，光合功能期对叶源量的直接效应最大，其次为瞬时光合速率，叶面积的效应最小。结果还表明，叶源量在水稻品种间存在极显著差异，因而存在遗传差异。说明通过育种手段选育叶源量大的品种是可行的。与此同时，叶源量存在一定程度的变异，品种内变异系数为6.19～17.34％，表明可以通过栽培措施调节叶源量。 本文还对原有测定超氧阴离子方法进行改进：在关键试剂配制中加入冰醋酸提高了检测灵敏度50％；在植物材料的O₂^-的提取过程中同时加入EDTA和羟胺，抑制SOD活性并及时“固定”O₂^-，这样所测得得的O₂^-含量更能反映体内的实际情况；同时发现O₂^-不由提取上清液产生，间接验证了O₂^-来源于光合膜系统。 提高Rubisco羧化效率对于提高光合效率具有重要的意义。本文研究了SDS滴定对水稻Rubisco结构与活性的影响。SDS作为一种两性分子，在低浓度时具有与光合膜类似的特性，研究其作用有助于了解光合膜同Rubisco可能的相互作用。结果表明，低浓度SDS（0.4mM）下，Rubisco的羧化酶活性完全丧失，大部分巯基暴露出来；SDS浓度继续增大时，Rubisco小亚基先从全酶上解离。SDS处理使Rubisco的三级结构也发生变化，但SDS对Rubisco的二级结构影响很小。比较酶的失活与构象变化，发现酶的活性中，M铂臼以防臼℃纠咽姑寻的构象变化。 Hh是光合作用能量耗散的次生产物，本文研究了其窿闪郧碰口师用嗣讹矢键酶历血曲oe活性的作用，发现在0一M…围侧处理时，历山b叨的三级结构和二纫绪阉囱吠助，ND一IhGEE和缸田一wK田电泳图谱也证明此时历凸b0和它的大J哑臼舵电泳位团脐d目氏咀昆图壮只有历比曲D的疏水表面明硼多，在划血M阶鹏－。当叽…20IDM时，RI．xaXi 8｛l＝seselq＊［IMM，a一qot明显下降，从天然酶的20％下蹦0（＆him4 HA时）：疏水表面不断下＄但始终多于天然酶的疏水表面含量 帆猢明R山色n大亚基之间发生二硫凶时勿陇RllmaXi分一。 采用生物波僧学和生理相结合的手段研究了一种野9勤恻团U和K佚吸淋的贝过由o在高温和氧化逆境下的结构和活性的变兀结果表明，正常的野生型水稻的RllDIaXIM同浓度闪0AjWT，其结构与WhfigwtgM硼显豹两个阶段：在HA浓度低于ZthllM时，绪闽动刮镣的服小；凤Q大于3)I’IM时，三骤软蚜汇潮路构发生明显变化，粉地朔刮羹翌俺o郝制。突变付的＆吐勿叨也表现同样的趋势，但地醚囤骏颠涵，在l（）IllMngTRM明显的结构与陇蜘。耐－的蹦与活栓由朗融蚁幻侣峭捧现出相同：先辫惦列、。再急剧下降。野生型柳k＆＃6｛lffFrASBll为 50’C和 45C。n RubiSC。H＄debe了 RUbiSC。在氧化逆境和高温下的共性，其差异可能是由于其在叶片一生中蜜u不同修饰造成的。更多还原

【Abstract】 Rice is cue of tie most impoitant anps in China It is of great significance to hierease largely erop yield per acie on the present basis aix] discover photosynilic nedianism by ovmg photosyndic efficiency Photosynthetic perarnetas of flag leaves of two s of tice hybrids were systanlilLcally analyzed during leaf photosynthetic fixetion decline. lAPS (Instantaneous aamit photosynthesis rate) displayed APD (Active photosynthetic during) aix] SF1?(Sharp Fall phase) while tie chlorophyll content displayed RSP (Relative Steady Phase) and SF1?during leaf pkK)tosyntletc function decline. The decline of RuBPCase activity was obviously aster than that offrtosyntietic electttm transfer activity. Thfore hiaeasing RuBPCase carboxylase efficiency has become one of keys to imriove photosynthetic efficiency. lie relationship of leaf scxmx capacity (which is tie total amoinit of assimilated CO2 of leaf cluing whole life) in flag leaf to yield traits was studied. lie results showed that tie relationships betwcai leaf source capacity hi flag leaf and yield per plant city weight per panicle, full spikekts per panide were all positive significant at 1% level, confirming its tight conelaficm with yield fruits. Path analysis further showed that APD had the largest direct eflcts on leaf souree capacity, while leaf area tie smallest. Tie results also showed that lie differuice of leaf soiree capacity in flag leaves among rice varieties was significant at 1% level aid accordingly among gax)types ii rice, indicating it is viable for rice varieties with high leaf source capacity to be selected Also, tl was variation of leaf source capacity hi rice, aid its variation coefficient within a rice variety was 6.l9l7.34%, suggesting that leaf source capacity maybe regulated by some planting measures. The nediod of assaying supaxide anion content in plant was improved by adding ice acetic acid hi key regents, which increased sensitivity by 50 % superoxjde anion fivm plant leaves, adding EDTA aid hydmxylarnine could inhii,it SOD activity aid fixing supezo,dde anion in situ. By this wy tie st.oxide anion amitait could reflect the truth M situ. We also found supaoxide anicm was not generated frm stwnatant, which indirectly confirmed that peroxide anion is flomphotosyndiic maub,ure. lie effects of SDS titmdon on the atmcture and inactivation of rice Rubison v.e studied. As a detergent, S1)S, when in low has the similar character wietasyntietic membrane. The study on the effect of SDS on tie stnctize and inactivation of rice Rubisco 1psto tnxieratumi tie hitaaction of Rnbisco with p tosynthetic nnlnie. lie results showecL Rnbisco lost all carboxylase activity in lowof SDS (0.4mM)aid most sulfiiydiyl groq exposed; when SDSined, SSU fii dociHnd from Rubisoo holocnzyme. The tertiary structure of Rubisco was hanged by SDS tzUnmit bit seccmdary structurc little aflbeted. We can find that tie conhruatianakhange of active site of Rubiaco is ster tan that ofholoa]zyme of 11202 on the atnicture aid inactivation of rice Rnbisco vu inve4gated. The tertiary aix] secondary sxs were little inThiezeed by 0-20mM H2 taeat that as thought to be in physiological concu1ia.L While tie hydrophobic sure of Ruihisco increased to lie maximum by 2(knM H202 treaflyrmt lie tertiary aid seccrdary stwcUzrc changed greatly when H202 concermm was ne than 20mM. Tie content of ez4zlix dedlied obviously flom 20% in native form to zero by 60mM 11202 kattnert lie hychuphobic surface content also declined but a更多还原