外源海藻糖对高温胁迫下穗分化期水稻叶片生理特性及产量的影响

该研究以耐热型水稻品种Nagina22和热敏型水稻品种YR343为供试材料,采用盆栽试验,设置喷施清水+常温处理(NT0)、喷施清水+穗分化期高温胁迫(HT0),以及分别喷施5、10、15、20 mmol·L^-1外源海藻糖+高温胁迫(分别记为HT1、HT2、HT3、HT4)共6个处理,分析外源海藻糖对高温胁迫下穗分化期水稻叶片叶绿素含量、光合气体交换参数、抗氧化酶活性、渗透调节物质含量、活性氧含量等生理特性,以及籽粒产量及其构成因素的影响,为水稻抗热栽培和耐热品种的选育提供理论依据。结果表明:(1)在高温胁迫下水稻穗分化期,2个水稻品种叶片的叶绿素含量、光合气体交换参数及渗透调节物质含量均降低,叶片MDA和H₂O₂含量以及■的产生速率均上升,叶片抗氧化酶活性呈先增后降的趋势,最终显示水稻籽粒产量及其构成因素显著下降。(2)喷施外源海藻糖能显著增加高温胁迫下穗分化期水稻的每穗粒数、千粒重和结实率,从而提高籽粒产量,其中弱势粒千粒重和结实率的增幅高于强势粒,外源海藻糖最适喷施浓度为15 mmol·L^-1...     

CLUSTERED PRIMARY BRANCH 1, a new allele of DWARF11, controls panicle architecture and seed size in rice

Panicle architecture and seed size are important agronomic traits that directly determine grain yield in rice (Oryza sativa L.). Although a number of key genes controlling panicle architecture and seed size have been cloned and characterized in recent years, their genetic and molecular mechanisms remain unclear. In this study, we identified a mutant that produced panicles with fascicled primary branching and reduced seeds in size. We isolated the underlying CLUSTERED PRIMARY BRANCH 1 (CPB1) gene, a new allele of DWARF11 (D11) encoding a cytochrome P450 protein involved in brassinosteroid (BR) biosynthesis pathway. Genetic transformation experiments confirmed that a His360Leu amino acid substitution residing in the highly conserved region of CPB1/D11 was responsible for the panicle architecture and seed size changes in the cpb1 mutants. Overexpression of CPB1/D11 under the background of cpb1 mutant not only rescued normal panicle architecture and plant height, but also had a larger leaf angle and seed size than the controls. Furthermore, the CPB1/D11 transgenic plants driven by panicle‐specific promoters can enlarge seed size and enhance grain yield without affecting other favourable agronomic traits. These results demonstrated that the specific mutation in CPB1/D11 influenced development of panicle architecture and seed size, and manipulation of CPB1/D11 expression using the panicle‐specific promoter could be used to increase seed size, leading to grain yield improvement in rice.     

水稻细菌性穗枯病的病原特性和抗性研究进展

水稻(Oryza sativa)细菌性穗枯病是世界性的重要病害之一, 严重威胁全球范围水稻的高产稳产。虽然该病目前仍被列为我国的检疫性病害, 但近几年的研究表明, 穗枯病随时有在内地蔓延的潜在危险, 因此除了加强检疫工作, 开展针对性的防控技术研发也十分必要。水稻细菌性穗枯病菌在侵染过程中涉及多种毒力因子, 同时, 水稻在与病原菌的长期互作过程中演化出了多种防卫机制, 抗性基因是主要的防卫机制之一。挖掘水稻基因组中抗细菌性穗枯病遗传位点并培育抗病品种是最安全且经济有效的防治途径。该文综述了水稻细菌性穗枯病的病原菌特性、发病特征、发病机制、病害循环和对水稻细菌性穗枯病的抗性研究现状, 以期为挖掘和分离水稻穗枯病抗性位点提供参考。     

Panicle Water Potential, a Physiological Trait to Identify Drought Tolerance in Rice

Two upland rice varieties （IRAT109, IAPAR9） and one lowland rice variety （Zhenshan 97B） were planted in summer and treated with both normal （full water） and drought stress in the reproductive stage. Panicle water potential （PWP） and leaf water potential （LWP） were measured every 1.0-1.5 h over 24 h on sunny days. Both PWP and LWP of upland varieties started to decrease later, maintained a higher level and recovered more quickly than that of the lowland variety. The results show that PWP can be used as an indicator of plant water status based on the parallel daily changes, and the high correlation between PWP and LWP. Similar correlations were also observed between PWP, LWP and eight traits related to plant growth and grain yield formation. PWP seemed to be more effective for distinguishing the upland rice varieties with different drought-tolerant ability. Differences in PWP and LWP between upland and lowland rice varieties were also observed at noon even under normal water conditions, implying the incorporation of the drought-tolerant mechanism to improve the photosynthesis and yield of traditional paddy rice.     

不同生长环境下水稻穗伸出度的QTL分析

以十和田/昆明小白谷225个F14家系为作图群体,在云南省弥勒县(正常生长环境)、嵩明县(自然低温胁迫环境)、丽江市(自然低温胁迫环境)等3个试点不同年份共5种不同生长环境下进行了水稻主穗和分蘖穗穗伸出度的异地鉴定,并利用SSR标记对水稻穗伸出度进行了QTL分析。检测结果表明,在5种不同的生长环境下共检测到12个与水稻穗伸出度相关的QTL,分别分布于第1(2个QTLs)、2、4、6(3个QTLs)、7(3个QTLs)、9(2个QTLs)号染色体,对表型的贡献率为3.72%~22.17%。其中与主穗穗伸出度相关的QTL共11个,与分蘖穗穗伸出度相关的QTL共7个,其中6个在主穗和分蘖穗上均检测到。在与主穗穗伸出度相关的11个QTL中,q PE-7-1在4种环境下均被检测到,解释的表型变异为9.49%~22.17%;q PE-1-1、q PE-1-2、q PE-6-1和q PE-9-2 4个QTL在2种环境下均被检测到。在与分蘖穗穗伸出度相关的7个QTL中,q PE-1-2、q PE-7-1和q PE-6-1 3个QTL在2种环境中均被检测到,解释的表型变异率分别为4.35%~12.64%、13.22%~20.89%和11.49%~15.73%。     

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.     

籼型常规早稻穗分化期低温对颖花形成和籽粒充实的影响

以籼型常规早稻中嘉早17为材料,于盆栽条件下采用人工气候箱控温,在水稻穗分化一次枝梗原基分化期(Ⅱ)与花粉母细胞减数分裂期(Ⅵ)进行17和20 ℃的低温胁迫处理,研究不同低温对水稻枝梗、颖花分化与退化及籽粒充实的影响.结果表明： 与对照相比,不同低温处理均显著降低每穗枝梗及颖花分化数和现存数,颖花现存数降幅为7.2%～12.4%,同时增加了枝梗和颖花的退化数,影响了花粉活性、花药开裂等花器官发育,导致籽粒充实不良,以17 ℃低温胁迫效应更明显.穗分化Ⅵ期低温处理总枝梗和颖花分化数与现存数低于穗分化Ⅱ期,但二次枝梗和颖花退化数较多,颖花退化数较穗分化Ⅱ期高11.6%;穗分化Ⅱ期低温处理穗部籽粒结实率显著低于穗分化Ⅵ期,降幅达3.7%,主要与花粉粒活性、柱头花粉散落数、花药开裂系数和籽粒充实度受低温影响较大有关.另外,穗分化Ⅱ、Ⅵ两时期受17 ℃低温胁迫效应大于20 ℃.综合穗分化两时期低温胁迫效应的差异,生产中需加强相应栽培措施的调控.     

Disentangling confusions in inflorescence morphology: Patterns and diversity of reproductive shoot ramification in angiosperms

Terminology of inflorescence diversity has often been used in a confusing way in the literature, partly because it was based on uncritical and outdated definitions. In particular, the terms cyme, thyrse, and panicle have been misused. Although a more critical classification worked out by several authors is available, it is unfortunately not in general use because most of the relevant publications are written in German. In addition, some terms have not been used in the same way by morphologists and developmental geneticists. The present review attempts to remedy the situation with a simple outline of a classification based on: (i) different branching patterns; (ii) differential elongation of axes of different orders; and (iii) repetition of basic ramification patterns in different ways. Racemose and cymose branching are two extreme patterns; the former with limitation of axial orders to two, the second with limitation of lateral axes of each order to two. In a branching system, a sequence of racemose → cymose and, within the cyme, of dichasial → monochasial is common, but the reverse sequence generally does not occur. Systematic and evolutionary aspects of inflorescences are briefly discussed. Branching patterns are often stable in larger clades.Infiorescences of mutants studied in developmental genetic studies are mainly altered in flower or branch numbers or relative branch length, but not in branching patterns. This is also a contribution towards the goal of a unified terminology for the different fields of biology dealing with inflorescences.     

辐射处理对冷季型草幼穗分化的影响

以C60Or射线对一年生黑麦草(品种:冠军)、多年生黑麦草(品种:爱神特)、早熟禾(品种:歌来德)及高羊茅(品种:知音)4个禾本科草坪草干种子进行辐照,剂量分别是15000rad(处理Ⅰ)、25000rad(处理Ⅱ)、35000rad(处理Ⅲ).播种生长后,田间取样观察;实验结果表明,所用剂量对冷季型草的幼穗分化进程影响不大,相对而言高剂量对多年生黑麦草的生殖生长有一定延长作用.     

江苏省直立穗型粳稻品种主要农艺性状和品质性状分析

通过对江苏省淮北稻区种植的主要粳稻品种品质状况和近十年来育成的直立穗型粳稻品种(系)主要品质和农艺性状的分析,发现前期育成直立穗型粳稻品种相时半直立穗型粳稻品种加工品质低,垩白率高和垩白度大,蛋白质含量高;而近期育成直立穗型粳稻品种在上述品质指标上有了较大改进,食味品质也有了显著提高.在主要农艺性状中,近期育成品种呈现每穗总粒数上升、穗长变长、着粒密度下降趋势,产量水平的提高与每穗粒数的增加有着紧密相关.