Relationship between leaf photosynthetic function at grain filling stage and yield in super high-yielding hybrid rice (Oryza sativa. L)

The characteristics of dry matter production before and after heading and the relationships between photosynthesis of flag leaves and dry matter accumulation in panicles were investigated on super high-yielding rice cv. Xieyou 9308 (the yield of up to 12 t/ha) with rice cv. Xieyou 63 as a control. The results showed that (i) the capacity of dry matter production before and after heading in Xieyou 9308, i.e. biomass and daily dry matter production, was remarkably higher than that in Xieyou 63, especially after heading; (ii) CO2 assimilation capacity in flag leaves in Xieyou 9308, namely Leaf Source Capacity (LSC), was also significantly higher than that in Xieyou 63, and the supply of photosynthate in leaves and the demand of grain filling were completely synchronous in Xieyou 9308, but photosynthetic function in flag leaves in Xieyou 63 declined sharply 20 days after heading and it was not enough to meet the demand of grain filling. These results confirmed that high efficient photosynthetic function in     

Relationship between leaf photosynthetic function at grain filling stage and yield in super high-yielding hybrid rice (<Emphasis Type="Italic">Oryza sativa</Emphasis>. L)

The characteristics of dry matter production before and after heading and the relationships between photosynthesis of flag leaves and dry matter accumulation in panicles were investigated on super high-yielding rice cv. Xieyou 9308 (the yield of up to 12 t/ha) with rice cv. Xieyou 63 as a control. The results showed that (i) the capacity of dry matter production before and after heading in Xieyou 9308, i.e. biomass and daily dry matter production, was remarkably higher than that in Xieyou 63, especially after heading; (ii) CO₂ assimilation capacity in flag leaves in Xieyou 9308, namely Leaf Source Capacity (LSC), was also significantly higher than that in Xieyou 63, and the supply of photosynthate in leaves and the demand of grain filling were completely synchronous in Xieyou 9308, but photosynthetic function in flag leaves in Xieyou 63 declined sharply 20 days after heading and it was not enough to meet the demand of grain filling. These results confirmed that high efficient photosynthetic function in leaves after heading and its complete synchronization with grain filling are the key approaches to super high yield of rice.     

Limiting factors for panicle photosynthesis at the anthesis and grain filling stages in rice (Oryza sativa L.)

Panicle photosynthesis is crucial for grain yield in cereal crops; however, the limiting factors for panicle photosynthesis are poorly understood, greatly impeding improvement in this trait. In the present study, pot experiments were conducted to investigate the limiting factors for panicle photosynthesis at the anthesis stage in seven rice genotypes and to examine the temporal variations in photosynthesis during the grain filling stage in the Liangyou 287 genotype. At the anthesis stage, leaf and panicle photosynthesis was positively correlated with stomatal conductance and maximum carboxylation rate, which were in turn associated with hydraulic conductance and nitrogen content, respectively. Panicle hydraulic conductance was positively correlated with the area of bundle sheaths in the panicle neck. During grain filling, leaf and panicle photosynthesis remained constant at the early stage but dramatically decreased from 8 to 9 days after anthesis. The trends of variations in panicle photosynthesis were consistent with those in stomatal conductance but not with those in maximum carboxylation rate. At first, the maximum carboxylation rate and respiration rate in the panicle increased, through elevated panicle nitrogen content, but then drastically decreased, as a result of dehydration. The present study systematically investigated the limiting factors for panicle photosynthesis, which are vital for improving photosynthesis and crop yield.     

籼粳杂交稻籽粒库活性与其充实关系的研究

以两个籽粒充实程度不同的籼粳亚种间杂交稻ＰＣ３１１＊早献党１８（充实差）和测０３＊扬稻４号（充实好）材料,研究两组合的强、弱势粒发育过程中籽粒库活性与其充实之间的关系。结果表明：（１）充实好的亚杂组合强,、弱势粒干重、淀粉积累速率都盯应高于充实差的亚杂组合,两组合的强、弱势粒灌浆特性均表现异步型特征;（２）在灌浆早期,两亚杂组合强、弱热粒胚乳中蔗糖含量都比较高,且测扬要明显高于Ｐ早;在籽粒发育后期     

水稻品种灌浆期耐热性的综合评判

建立了一种对水稻品种的灌浆期耐热性进行综合评判的方法.选取籽粒充实度、秕粒率、饱粒密度、垩白米率、垩白度等5个与水稻灌浆期耐热性强弱密切相关的性状,以参评品种这5个性状的耐热系数为指标,应用主成分分析法将5个彼此相关的单项指标转化为2个累计贡献率达到85%以上的相互独立的综合指标,根据每一品种的5个单项性状的耐热系数和综合指标的标准化特征向量求出每一品种2个综合指标的得分.计算每一品种2个综合指标得分的隶属函数值,并以综合指标的贡献率来确定2个综合指标的权重,在此基础上进行加权求和,从而得到每一品种灌浆期耐热性的综合评判值（D值）.采用系统聚类分析方法对各品种的综合评判值（D值）进行数量分类,同时结合生产实际的要求,可把每一品种划归为不同的耐性等级.外部独立样本组的统计检验以及实践验证的结果表明,所建立的综合评判方法具有理想的效果,可以对不同品种灌浆期综合耐热性能的强弱作出客观、准确的评判.     

干旱胁迫对大豆鼓粒期叶片光合能力和根系生长的影响

以晋大70(抗旱型)和晋豆26(敏感型)2个大豆品种为材料,采用盆栽方法,在鼓粒期设置充分供水、轻度干旱和重度干旱3种水分处理,研究了干旱胁迫对大豆鼓粒期叶片光合能力和根系生长的影响.结果表明： 随着干旱程度加剧,2个品种的叶面积、叶绿素含量、净光合速率、叶片气孔导度、蒸腾速率、胞间CO₂浓度、株质量、株高、籽粒产量和收获指数均降低;根长和根质量在轻度干旱胁迫下增加,在重度干旱胁迫下减少;根冠比随干旱程度加剧而升高.重度干旱胁迫下,抗旱型品种晋大70根冠比的增幅达到135.7%,大于敏感型品种晋豆26根冠比的增幅(116.7%),晋大70的叶面积和叶绿素含量分别为对照的69.3%和85.5%,均优于晋豆26,晋大70的气孔导度和净光合速率分别下降了67.9%和77.9%,降幅均小于晋豆26,晋大70的收获指数的降幅为43.8%,小于晋豆26 (78.8%).不同干旱处理下,2个品种的叶面积、叶绿素含量、净光合速率、气孔导度、蒸腾速率、胞间CO₂浓度两两之间均呈显著正相关;株质量、株高、根长、根质量、籽粒产量、收获指数两两之间均呈显著正相关;根冠比与根质量呈显著正相关,而与其他5个指标呈显著负相关.     

水稻黄绿叶突变体ygl-63的特征和基因定位

叶绿体的正常发育对于植物至关重要,突变体研究是探明叶绿体发育过程中基因功能的有效途径。叶色突变体已引起人们广泛的关注,通过对各种植物材料的研究,叶色突变的分子机制已取得一定进展,但远未被阐明,尤其在水稻当中。目前,已报道的水稻叶色突变体,主要表现为黄化、白化、亮绿、条斑条纹、温敏变色、转绿和转紫等。该研究使用甲基磺酸乙酯( EMS)处理粳稻日本晴,获得一份遗传稳定的突变体ygl-63,其整个生育期叶片均表现为黄绿色。通过测定ygl-63和野生型苗期叶片的叶绿素含量发现,ygl-63中叶绿素a、叶绿素b和总叶绿素含量与野生型相比分别下降了31.9％、42.2％和34.1％,同时叶绿素a/b值较野生型增加。这表明叶绿素含量的降低是导致ygl-63黄绿叶突变性状的主要原因,并且叶绿素b的降幅大于叶绿素a。在成熟后调查主要农艺性状发现ygl-63单株有效穗数和结实率分别减少8.9％和8.5％;千粒重增加10.4％;而株高,穗长和每穗着粒数和野生型相比差异并不显著。通过测量微量元素发现,ygl-63种子中的铁和锌含量较野生型显著降低,分别减少85.7％和64.8％。将ygl-63与正常绿色品种明恢63杂交获得F1和F2群体,进行遗传分析发现,ygl-63突变性状受1对隐性基因控制,通过基因定位,将该基因定位到水稻第11染色体长臂的分子标记InDel-3和InDel-5之间约2.4 cM范围内。该基因被认为是一个新的水稻叶色突变基因,暂命名为ygl-63( g)。所得结果为今后对ygl-63( g)基因的进一步研究奠定了基础。     

高温下杂交稻培矮64S／E32与其亲本的光合和抗逆参数的比较

超级稻培矮64S／E32(F1)及其亲本(父本‘E32’和母本‘培矮64S’)的剑叶在不同温度(28、35、40℃ 和45℃)恒温水浴中保温1 h,随着处理温度的升高,F1除了较其亲本有更稳定的光合色素Chl外,还有明显 增加的Car／Chl,相对高的热稳蛋白含量,高而且稳定的总的抗氧化能力。F1在高温下也有较亲本高的光合 能力。高温下,线性电子传递过程比光化学过程对温度更敏感,F1有比亲本更敏感的调节机制,Pn下降比 ΦPSⅡ、Fv／Fm下降快说明光合限制步骤可能主要是位于光合碳同化而不是光化学和光合电子传递过程。     

A rapid screening technique for salt tolerance in rice (Oryza sativa L.)

An effecient, reproducible and simple mass screening technique for the selection of salt tolerant rice lines has been developed. Fourteen-day old seedlings raised in silica gravel culture were transplanted to foam-plugged holes in polystyrene (thermopal) sheets floated over 100 dm³ of nutrient solution in painted galvanised-iron growth tanks lined with plastic (120×90×30cm). Three days after transplanting, NaCl was added to salinize the medium in increments, at the rate of 25 mol m^-3 per 24 hours, up to the desired salinity levels which ranged from 50–200 mol m^-3 NaCl. Six plants of each line were transplanted and allowed to grow for 15 days after the maximum desired stress level was achieved in each case. Absolute shoot fresh and dry weights, as well as percent mortality, were used as criteria for assessing relative salt tolerance. Related studies were also conducted to standardize the technique. The validity of this technique was tested by conducting experiments in salinised soil (pot culture) and in salt-affected field where 9 rice lines were grown up to maturity and absolute paddy yield was considered as the criterion for salt tolerance. Salt tolerance behaviour of cultivars based on different selection criteria was compared. Good reproducibility of results among the three solution culture experiments and their close association with the results of pot culture and of salt-affected field study, authenticated the validity of this technique for practical purposes.     

Identification of salt-stress responsive genes in rice (Oryza sativa L.) by cDNA array

To identify salt stress-responsive genes, we constructed a cDNA library with the salttolerant rice cultivar, Lansheng. About 15000 plasmids were extracted and dotted on filters with Biomeck 2000 HDRT system or by hand. Thirty genes were identified to display altered expression levels responding to 150 mmol/L NaCl. Among them eighteen genes were up-regulated and the remainders downregulated. Twenty-seven genes have their homologous genes in GenBank Databases. The expression of twelve genes was studied by Northern analysis. Based on the functions, these genes can be classified into five categories, including photosynthesis-related gene, transportrelated gene, metabolismrelated gene, stress-or resistancerelated gene and the others with various functions. The results showed that salt stress influenced many aspects of rice growth. Some of these genes may play important roles in plant salt tolerance.     

生育前期遮光对水稻后期功能叶生长及稻米品质的影响

以2个不同直链淀粉含量的水稻品种为材料,研究了生育前期(插秧至幼穗分化期)遮光对水稻后期功能叶生长及稻米品质的影响。结果表明,前期遮光处理后,水稻剑叶面积明显增大,功能叶的碳、氮代谢水平提高;2个品种的籽粒直链淀粉积累过程受到的影响不同,而蛋白质积累受到的影响均一致(即百分含量下降幅度增大);糙米率有所降低,但未达到显著水平;精米率和垩白率极显著下降;整精米率和直链淀粉含量显著或极显著升高;粒长、粒宽和蛋白质含量无显著性变化,但蛋白质含量表现为下降趋势;2个品种间存在着差异。     

1,2,4-三氯苯胁迫对不同基因型水稻灌浆期生理特性及产量的影响

在盆栽土培条件下,研究了5种浓度(0、10、20、40、80 mg/kg土)的1,2,4-三氯苯(TCB)对两种基因型水稻品种宁粳1号(敏感基因型)和扬辐粳8号(耐性基因型)产量及灌浆期生理特性的影响。结果表明:TCB对两种基因型水稻产量和灌浆期生理特性的影响具有显著差异,随着TCB浓度的增加,宁粳1号的产量呈现递减趋势,而扬辐粳8号呈低浓度下产量增加高浓度下产量显著降低的趋势,在中高浓度TCB(40、80 mg/kg)处理时,宁粳1号每盆穗数,每穗粒数,结实率显著降低且降幅显著大于扬辐粳8号,两个基因型品种千粒重变化都不明显。宁粳1号株高、干物重受TCB抑制程度较明显,降幅显著大于扬辐粳8号。在低浓度TCB(20 mg/kg)处理时,宁粳1号根系活力、叶绿素含量、可溶性蛋白质含量显著降低,而扬辐粳8号有所提高。随着TCB浓度的增加,两个基因型品种叶片抗氧化酶SOD、POD、CAT活性均呈先升后降趋势,且在低浓度TCB(10 mg/kg、20mg/kg)处理时,扬辐粳8号抗氧化酶活性极显著高于宁粳1号,在高浓度TCB(80 mg/kg)TCB浓度胁迫下,宁粳1号抗氧化酶活性极显著低于对照,且降幅极显著大于扬辐粳8号,且MDA含量增幅较大,膜质过氧化程度高。总体而言,低浓度TCB对扬辐粳8号的产量和灌浆期株高、干物重、叶绿素含量、叶片蛋白质含量和抗氧化酶活性具有一定的促进作用,中高浓度TCB对宁粳1号的抑制作用显著大于扬辐粳8号,扬辐粳8号在不同浓度的TCB处理下较宁粳1号表现出较强的耐迫性和适应性。     

Molecular mapping of two semidwarf genes in an indica rice variety Aitaiyin3 (Oryza sativa L.)

Genetic analysis established that Aitaiyin3, a dwarf rice variety derived from a semidwarf cultivar Taiyin1, carries two recessive semidwarf genes. By using simple sequence repeat (SSR) markers, we mapped the two semidwarf genes, sd-1 and sd-t2 on chromosomes 1 and 4, respectively. Sd-t2 was thus named because the semidrawf gene sd-t has already been identified from Aitaiyin 2 whose origin could be traced back to Taiyin1. The result of the molecular mapping of sd-1 gene revealed it is linked to four SSR markers found on chromosome 1. These markers are: RM297, RM302, RM212, and OSR3 spaced at 4.7 cM, 0 cM, 0.8cM and 0 cM, respectively. Sd-t2 was found to be located on chromosome 4 using five SSR markers: two markers, SSR332 and RM1305 located proximal to sd-t2 are spaced 11.6 cM, 3.8 cM, respectively, while the three distally located primers, RM5633, RM307, and RM401 are separated by distances of 0.4 cM, 0.0 cM, and 0.4 cM, respectively. __________ Translated from Acta Genetica Sinica, 2005, 32 (2) [译自: 遗传学报, 2005,32(2)]     

水稻OsZAT12基因响应非生物胁迫和植物激素的研究

C2H2锌指蛋白是真核生物体内一类重要的转录因子,在植物生长发育和应对非生物胁迫方面具有重要作用。实验室前期克隆了水稻C2H2锌指蛋白OsZAT12,该基因在水稻根中特异表达,定位于细胞核,异源过表达OsZAT12的拟南芥植株矮小。为进一步研究OsZAT12在水稻中的功能,该文分析了OsZAT12的启动子元件和转录活性,并采用qRT-PCR技术分析OsZAT12在非生物胁迫和植物激素处理下的响应模式。结果表明:(1)OsZAT12含有2个典型的C2H2锌指结构域和1个EAR motif,具有转录抑制活性,该基因的启动子中含有与非生物胁迫和植物激素相关的元件。(2)对野生型水稻进行非生物胁迫和激素处理发现,低温胁迫(4 ℃)和激素脱落酸(ABA)处理显著下调OsZAT12的表达; 而渗透胁迫(20% PEG 6 000)、激素油菜素甾醇(BR)或吲哚-3-乙酸(IAA)处理则显著上调OsZAT12的表达,这说明OsZAT12介导了水稻应对多种非生物胁迫和激素的变化。(3)利用含35S启动子的过表达载体和CRISPR/Cas9基因编辑技术分别得到纯合的OsZAT12过表达植株和OsZAT12敲除植株。(4)对过表达OsZAT12的水稻表型观察发现,相比于野生型,OsZAT12过表达植株在分蘖期、抽穗期和成熟期这3个时期的株高均显著降低; OsZAT12敲除植株的株高与野生型虽无明显差异,但每株穗数和结实率均显著低于野生型,这说明OsZAT12影响了水稻株型、穗型及结实率等农艺性状的建成。(5)实验进一步表明,过表达OsZAT12降低了水稻对外源ABA的敏感性,而OsZAT12敲除植株则相反。因此推测,OsZAT12对植株生长发育的影响可能与该基因响应多种非生物胁迫和激素信号的调控有关,该研究结果为将来利用OsZAT12进行水稻耐逆稳产分子设计育种提供了依据。     

Nitrate reductase induction and molecular characterization in rice (Oryza sativa L.)

Summary Barley nitrate reductase cDNA clone bNRp10 was used as a hybridization probe to screen a genomic DNA library of rice (Oryza sativa L.) cultivar M201. Two different lambda clones were isolated, subcloned to plasmids, and partially characterized. The subclone pHBH1 was tentatively identified as encoding a NADH nitrate reductase. Southern and dot blot analysis suggest that, in rice, nitrate reductase is encoded by a small gene family. Regulation of NADH nitrate reductase was investigated in rice cultivars Labelle and M201 representing the subspecies indica and japonica, respectively. In the absence of nitrate, only trace levels of nitrate reductase activity and mRNA were detected in seedling leaves. Upon addition of nitrate to seedling roots, nitrate reductase activity and mRNA increased rapidly in leaves. Nitrate reductase activity continued to increase over a 24 h period, but the mRNA accumulation peaked at about 6 h and then declined. Western blot analysis with a barley NADH nitrate reductase antiserum showed the presence of two bands of approximately 115 and 105 kDa. These protein bands were not detected in extracts of tissue grown in the absence of nitrate.     

耕作方式对冬小麦灌浆期光合性能日变化和籽粒产量的影响

研究耕作方式对冬小麦灌浆期光合性能日变化的影响,对灌浆期干物质积累、转运以及产量形成具有重要的理论意义.本研究以中国农业大学吴桥实验站2008年设置的长期耕作定位试验为基础,分析了免耕秸秆不还田(NT)、免耕秸秆还田(NTS)、旋耕秸秆不还田(RT)、旋耕秸秆还田(RTS)、深松秸秆不还田(DT)、深松秸秆还田(DTS)、翻耕秸秆不还田(CT)和翻耕秸秆还田(CTS)耕作处理对冬小麦灌浆期旗叶光合特性日变化、光响应曲线和产量的影响.结果表明: 不同耕作方式对冬小麦灌浆期旗叶净光合速率日变化和气孔导度日变化的影响均呈双峰曲线变化趋势,秸秆还田下不同耕作方式的冬小麦旗叶净光合速率高于相应的秸秆不还田处理;各耕作方式对冬小麦旗叶胞间CO₂浓度日变化的影响均呈“广口V型”双峰曲线变化趋势;除DTS、RTS和RT处理冬小麦旗叶的蒸腾速率日变化规律呈单峰曲线变化外,其他各处理冬小麦旗叶的蒸腾速率日变化均呈“双峰曲线”变化趋势.模拟的最大净光合速率以DTS处理最大,分别比NT、DT、RT、CT、NTS、RTS和CTS处理增加了20.0%、21.7%、19.7%、21.5%、0.8%、12.1%和4.2%;秸秆还田条件下各处理的光响应曲线拟合程度均优于秸秆不还田处理.DTS籽粒产量最高,RTS次之,CTS再次,CT处理最小,DTS处理的籽粒产量分别比NTS、RTS、CTS、NT、DT、RT和CT处理高10.8%、1.3%、2.1%、5.4%、11.9%、12.4%和12.6%.通过光合速率和气孔导度日变化趋势可得,不同耕作方式下秸秆还田技术,特别是DTS和NTS处理可减缓光合午休现象,使冬小麦维持较高的光合速率,有利于干物质积累和产量的提高.     

Effect of physical desiccation on plant regeneration efficiency in rice (Oryza sativa L.) variety super basmati

This experiment assessed the effect of partial physical desiccation on plant regeneration efficiency in scutellum-derived embryogenic calluses of rice (Oryza sativa L.) variety Super basmati. A number of callusing cultures were developed, and efficient callus induction was observed on MS (Murashige and Skoog) basal medium supplemented with 2.0 mg/L 2,4-dichlorophenoxy acetic acid. The calluses were proliferated on the same medium for 3 weeks and then shifted to dehydration desiccation treatment for 72 h. The desiccated calluses were cultured on different media for somatic embryogenesis and plant regeneration. A medium with 2.0 mg/L α-napthaleneacetic acid, 10.0 mg/L abscisic acid , 2.0 mg/L kinetin was best for somatic embryogenesis only, but not for further plant development. After 10 d, differentiated calluses were sub-cultured on medium with various concentrations and types of carbohydrates (carbon source) in ¹MS_2j medium. A large number of plantlets (14.51±2.81 and 8.56±2.90 plants/callus) were regenerated via chemical desiccation, on MS with 3% maltose+3% sorbitol and 6% sucrose, respectively. Under dehydration on only simple MS (3% sucrose), 11.23±3.22 plants/callus were developed. Under conditions of dehydration and chemical desiccation, plant regeneration rates were higher than the calluses cultured on simple MS medium in the presence of plant growth regulator. After somatic embryogenesis, >25% plants were sterile. The protocol used here may allow maximum regeneration of normal and fertile plantlets of super basmati rice within 3 months.     

水稻超短根突变体ssr1的遗传分析和基因定位

该研究从甲基磺酸乙酯(EMS)诱变的籼稻‘Kasalath’突变体库中筛选到1个根系超短的突变体,命名为ssr1(super short root 1),8d苗龄突变体的主根和不定根长度分别只有野生型的8.89%和2.29%,其不定根发生正常,但侧根的发生和伸长都受到严重抑制,且根毛也非常短。此外,ssr1植株整体矮小,株高不到野生型的一半。遗传分析结果表明,该突变性状由1对隐性核基因控制。利用图位克隆技术将SSR1基因定位在第9染色体的STS(sequence tagged site)分子标记9g7047K和9g7290K之间,物理距离约为243kb,在定位区间共发现39个预测基因,经分析其中没有已克隆的根系发育基因。对SSR1的定位为进一步克隆该基因和阐明水稻根构型的分子机理奠定了基础。