基于单片段代换系的水稻穗长QTL加性及其上位性效应

穗长是影响水稻（Oryza sativa）产量的重要因子之一,研究水稻穗长QTL间的上位性效应对于发掘水稻产量潜力具有重要意义。该研究以16个单片段代换系（single segment substitution lines,SSSLs）和15个双片段聚合系（double segment pyramiding lines,DSPLs）为材料研究了水稻穗长QTL的加性及上位性效应。以P〈0.01为阈值,共检测到6个穗长QTL和9对基因互作座位。其中2个（Pl-2和Pl-10）是尚未报道的穗长QTL。穗长QTL互作后,一些互作对的上位性效应与单个QTL的作用方式及效应大小各不相同,预示着基因聚合后会产生不同的互作效应。该研究结果对于通过分子聚合育种手段改良穗长具有重要意义。     

水稻穗型的遗传调控研究进展

穗型作为水稻(Oryza sativa)重要的农艺性状,近年来一直是研究热点。该文简要介绍了水稻穗部发育的一般过程,总结了近年来发现的调控水稻穗型相关基因,并根据水稻幼穗发育过程将其分为4类:分别调控枝梗分生组织的形成、枝梗分生组织的大小、小穗分生组织的转变时间以及枝梗的伸长;并概括分析了上述基因在调控水稻幼穗发育过程中所呈现出的路径关系。最后对水稻穗型遗传调控研究的未来发展方向进行了展望。     

Sodium and potassium uptake of rice panicles as affected by salinity and season in relation to yield and yield components

Salinity is a major yield-reducing stress in many arid and/or coastal irrigation systems for rice. Past studies on salt stress have mainly addressed the vegetative growth stage of rice, and little is known on salt effects on the reproductive organs. Sodium and potassium uptake of panicles was studied for eight rice cultivars in field trials under irrigation with saline and fresh water in the hot dry season and the wet season 1994 at WARDA in Ndiaye, Senegal. Sodium and potassium content was determined at four different stages of panicle development and related to salt treatment effects on yield, yield components and panicle transpiration. Yield and yield components were strongly affected by salinity, the effects being stronger in the HDS than in the WS. The cultivars differed in the amount of salt taken up by the panicle. Tolerant cultivars had lower panicle sodium content at all panicle development stages than susceptible ones. Panicle potassium concentration decreased with panicle development under both treatments in all cultivars, but to a lesser extent in salt treated susceptible cultivars. Grain weight reduction in the early panicle development stages and spikelet sterility increase in the later PDS were highly correlated (p < 0.01) with an increase in panicle sodium concentration in both seasons, whereas reduction in spikelet number was not. The magnitude of salt-induced yield loss could not be explained with increases in sodium uptake to the panicle alone. It is argued that the amount of sodium taken up by the panicle may be determined by two different factors. One factor (before flowering) being the overall control mechanism of sodium uptake through root properties and the subsequent distribution of sodium in the vegetative plant, whereas the other (from flowering onwards) is probably linked to panicle transpiration. This revised version was published online in August 2006 with corrections to the Cover Date.     

基于单片段代换系的水稻穗长QTL加性及其上位性效应

穗长是影响水稻(Oryza sativa)产量的重要因子之一, 研究水稻穗长QTL间的上位性效应对于发掘水稻产量潜力具有重要意义。该研究以16个单片段代换系(single segment substitution lines, SSSLs)和15个双片段聚合系(double segment pyramiding lines, DSPLs)为材料研究了水稻穗长QTL的加性及上位性效应。以P<0.01为阈值, 共检测到6个穗长QTL和9对基因互作座位。其中2个(Pl-2和Pl-10)是尚未报道的穗长QTL。穗长QTL互作后, 一些互作对的上位性效应与单个QTL的作用方式及效应大小各不相同, 预示着基因聚合后会产生不同的互作效应。该研究结果对于通过分子聚合育种手段改良穗长具有重要意义。     

复粒稻种质资源及其遗传育种利用

水稻(Oryza sativa)是世界上最重要的粮食作物之一, 也是单子叶植物发育分子生物学研究的理想模式植物。穗部形态是影响水稻产量的重要因素, 也是当前水稻遗传改良和发育生物学研究的热点之一。复粒稻是发生于水稻穗粒部的一种突变体材料, 在形态上可分为小穗簇生型和颖壳多雌型两种, 有自然突变、杂交变异和理化诱变等多种来源途径。作为一种特异的水稻种质资源, 复粒稻在水稻新材料创建、复粒型新品种选育、改善杂交制种结实性及探讨单子叶植物成花机理等方面具有重要的研究价值, 对创造复粒新型育种材料、提高穗着粒密度及穗粒数、有效缩短穗长度、改良水稻植株性状及提高产量等都具有重要意义。该文综述了复粒稻的资源类型、来源途径、遗传分析、基因定位及其育种利用价值等方面的研究进展, 并提出了今后的研究方向, 以期为水稻遗传育种提供参考。     

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.     

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.     

Land Use as a Driver of Patterns of Rodenticide Exposure in Modeled Kit Fox Populations

Although rodenticides are increasingly regulated, they nonetheless cause poisonings in many non-target wildlife species. Second-generation anticoagulant rodenticide use is common in agricultural and residential landscapes. Here, we use an individual-based population model to assess potential population-wide effects of rodenticide exposures on the endangered San Joaquin kit fox (Vulpes macrotis mutica). We estimate likelihood of rodenticide exposure across the species range for each land cover type based on a database of reported pesticide use and literature. Using a spatially-explicit population model, we find that 36% of modeled kit foxes are likely exposed, resulting in a 7-18% decline in the range-wide modeled kit fox population that can be linked to rodenticide use. Exposures of kit foxes in low-density developed areas accounted for 70% of the population-wide exposures to rodenticides. We conclude that exposures of non-target kit foxes could be greatly mitigated by reducing the use of second-generation anticoagulant rodenticides in low-density developed areas near vulnerable populations.     

Effect of thermal selection of the male gametes on the resistance to temperature and chlorophos of the body and muscles in tadpoles of the common frog

A study was made of the effect of thermal selection of parental spermatozoa on the heat resistance of the whole organism and of muscles in progeny of Rana temporaria, as well as of the organismal resistance to pesticides (0.0025 M chlorophos). The thermal selection of spermatozoa was performed by exposing their suspension to 36 degrees C for 30-40 minutes. With tadpoles, the resistance of muscles to 38 degrees C, was determined, in addition to the resistance of the organism to 34 degrees and to 0.0025 M chlorophos. The results of selection were stage--specific: at stages of growth (stages 39, 42, 50) the heat resistance of the organism was lower and that of muscles was higher than in controls. At the stage of metamorphosis proper (stage 52) the heat resistance of both the organism and muscles increased. The thermal selection of parental spermatozoa exerted no effect on the resistance of the progeny to 0.0025 M chlorophos.     

Evaluation of the palatability and toxicity of candidate baits and toxicants for mongooses (<Emphasis Type="Italic">Herpestes auropunctatus</Emphasis>)

The small Indian mongoose (Herpestes auropunctatus) is an invasive pest species responsible for damage to native avian, reptile, and amphibian species on Hawaii, Croatia, Mauritius, and several Caribbean Islands, among other regions. Mongoose control has been pursued through a variety of means, with varying success. One toxicant, diphacinone, has been shown to be effective in mongooses and is co-labeled in a rodenticide bait for mongoose control in Hawaii; however, preliminary observations indicate low performance as a mongoose toxicant due likely to poor consumption. We evaluated the efficacy and palatability of 10 commercial rodenticide baits, technical diphacinone powder, and two alternative acute toxicants against mongooses in laboratory feeding trials. We observed poor acceptance and subsequent low overall mortality, of the hard grain-based pellets or block formulations typical of most of the commercial rodenticide baits. The exception was Tomcat® bait blocks containing 0.1% bromethalin, an acute neurotoxin, which achieved up to 100% mortality. Mortality among all other commercial rodenticide formulations ranged from 10 to 50%. Three-day feedings of 0.005% technical diphacinone formulated in fresh minced chicken achieved 100% mortality. One-day feedings of para-aminopropiophenone (PAPP), a chemical that reduces the oxygen-carrying capacity of the blood, achieved 100% mortality at concentrations of 0.10 to 0.15%. Bait acceptance of two sodium nitrite formulations (similar toxic mode of action as PAPP) was relatively poor, and mortality averaged 20%. In general, commercially produced rodenticide baits were not preferred by mongooses and had lower mortality rates compared to freshly prepared meat bait formulations. More palatable baits had higher consumption and achieved higher mortality rates. The diphacinone bait registered for rat and mongoose control in Hawaii achieved 20% mortality and was less effective than some of the other commercial or candidate fresh bait products evaluated in this study.     

广西水稻地方品种耐冷性鉴定及相关分析

对419份广西水稻地方品种初级核心种质进行芽期、苗期的耐冷性鉴定及相关分析,结果表明:广西水稻地方品种芽期、苗期耐冷性主要集中在7级和9级,总体耐冷性较弱。芽期、苗期极强耐冷种质(1级)分别为24份和27份,占参试总数的5.73%和6.44%,其中10份种质芽期和苗期均表现极强耐冷(1级)。芽期、苗期耐冷性呈极显著正相关(r=0.66)。粳稻芽期、苗期耐冷性均显著高于籼稻;粘糯稻之间耐冷性差异是由籼粳稻类型的耐冷差异引起的;来自高寒山区稻作区的品种芽期和苗期平均耐冷表现最强。利用34个SSR标记与芽期、苗期耐冷性进行Pearson相关分析,在第7和第9染色体上,各鉴定出1个同时与芽期和苗期耐冷性相关联的位点。本研究为水稻芽期、苗期耐冷育种提供新的抗源材料,并为水稻耐冷基因定位及机理研究奠定基础。     

植物灭鼠剂在青藏高原防治高原鼠兔应用试验

2003、2004年,分别在四川省甘孜州石渠县和阿坝州若尔盖县应用以蓖麻毒素为主体成分的植物源灭鼠剂进行了野外防治高原鼠兔的应用试验。结果表明,在海拔4200m的石渠县试验区,1％浓度下防效为77．7％,2％浓度下防效为81．6％;在海拔3500m的若尔盖县试验区,1％浓度下防效达91．1％,2％浓度下防效达93.8％;该植物源灭鼠剂具有较好的适口性;在千亩级控制试验中,防治高原鼠兔效果达84．0％～93．3％,显示该植物灭鼠剂在防治青藏高原的高原鼠兔中具有较好的应用前景,值得进一步深入研究和扩大试验。     

基于CSSL的水稻穗颈长度QTL的代换作图

水稻穗颈长度是影响杂交水稻制种产量提高的重要农艺性状之一。文章利用94个以籼稻品种9311为遗传背景、粳稻品种日本晴为染色体片段供体的覆盖全基因组的染色体片段置换系(Chromosome segment substi-tution lines, CSSL)为材料, 调查和分析CSSL群体及双亲的穗颈长度。结果表明: 在17个置换系中检测到8个控制水稻穗颈长度的数量性状位点(Quantitative trait loci, QTL), 分别位于第2、3、7、8、9和第11染色体; 利用代换作图法, 定位了其中的7个穗颈长度QTL; 其加性效应值介于0.10~3.20之间, 其中qPE-9和qPE-11的加性效应值较大, 平均效应值分别为3.15和2.95, 表现为主效基因特征; qPE-2-2、qPE-3-1、qPE-3-2、qPE-7和qPE-8等5个QTL被定位在小于10.0 cM的区段内。利用CSSL可以有效地鉴定水稻穗颈长度QTL, 这些QTL为分子标记辅助选育穗颈长度适中的水稻品系及其进一步的精细定位奠定了基础。     

Micropropagation of gerbera using chlorine dioxide (ClO2) to sterilize the culture medium

One of the alternatives to autoclaving culture media is chemical sterilization, which may cause fewer changes to the chemical composition of the media. In this study, the effect of chemical sterilization by inclusion of chlorine dioxide (ClO₂) in the culture medium on the in vitro development of gerbera (Gerbera jamesonii) cv. AL101, cultured at different stages of micropropagation, was evaluated. The following five concentrations of ClO₂ were tested: 0%, 0.0025%, 0.0050%, 0.0075%, and 0.010%. Autoclaved medium was used as the control. ClO₂ in the culture medium reduced contamination at rates comparable to autoclaving when tested at three stages of the culture process: in vitro establishment, multiplication, and rooting. Plantlets grown in culture media sterilized with ClO₂ showed similar or better development than those grown in autoclaved culture medium. Use of 0.0025% ClO₂ to sterilize the culture medium resulted in better plantlet development than autoclaved medium, regardless of the stage of micropropagation.     

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.     

不同水稻品种库源的特征变化

为探讨不同年代水稻(Oryza sativa)品种间库、源及库/源的变化,用吉林省1958–2005年间育成的33个水稻品种为材料,对库、源及库/源的特征进行了研究。结果表明,吉林省47年来在水稻品种遗传改良过程中库和源性状均得到了改善。其中,单株穗重和单株粒数分别增长了62.93%和37.65%,平均年增长率分别为1.34%和0.80%,与育成年代均呈极显著正相关;单株叶面积、单株光合能力和剑叶净光合速率(Pn)分别增长了13.75%、24.80%和12.60%,年增长率分别为0.29%、0.53%和0.27%,与育成年代均呈显著正相关。不同年代育成水稻品种穗重/单株光合能力、粒数/单株光合能力无明显变化,但穗重/叶面积和粒数/叶面积与育成年代呈显著正相关,相关系数分别为0.441 0(P0.05)和0.401 7(P0.05);穗重/Pn和粒数/Pn与育成年代呈极显著正相关,相关系数分别为0.509 3(P0.01)和0.483 2(P0.01)。以上结果说明,吉林省水稻品种产量的增加是由于库和源共同作用的结果,但单位叶面积光合能力的改善远远落后于其它库源性状的增长。进一步提高叶片Pn并改善叶片的光合能力应作为高产水稻品种选育的新目标。     

Improving the performance of short‐duration basmati rice in water‐saving production systems by boron nutrition

Over exploitation of groundwater and decreasing canal water resources are threating the productivity of conventional rice production systems in Asia which is the main rice bowl. Therefore, strategies are needed to produce more rice with less water in the shortest possible duration without compromising the yield to feed the increasing world population. Panicle sterility is one of the major obstacles in wide‐scale adoption of water‐saving rice production systems. Boron (B) deficiency, in water‐saving rice production systems, has been identified as a possible reason for panicle sterility. This 2‐year field study was aimed to investigate the potential of pre‐optimised boron application through various methods in improving the productivity of short‐duration basmati rice (Shaheen Basmati) in water‐saving production systems, as delivered through seed priming (0.1 mM boron), foliar spray (200 mM boron) or soil application (1 kg boron ha^?1), while hydropriming and no boron application were taken as control. Boron nutrition, by either way, improved the growth, water relations, morphology, yield‐related traits, panicle fertility, grain yield, grain quality and grain boron contents of short‐duration basmati rice; nonetheless, boron application as seed priming was superior and cost effective with maximum marginal rate of return. In conclusion, boron nutrition through seed priming is cost effective and may help improving the productivity, quality, and boron grain contents in short‐duration basmati rice under water‐saving production systems.     

The action of a juvenile hormone synthetic analog--ether-farnesol on Xenopsylla cheopis fleas

The authors tested the effect of the analogue of juvenile hormone (AJH), ether-farnesol, synthesized at the Institute of Chemistry of the Academy of Sciences of ESSR (the city of Tallin), on immature stages of X. cheopis. When testing the following doses of AJH (0.0025, 0.00025, 0.000025, 0.0000025 ml per lg of substrate, consisting of sand and dry bull blood, for feeding larvae) it was established that the dose of 0.0025 ml/g causes 100% mortality of insects on the 2nd day of the experiment. 10 fold decrease in ether-farnesol dose causes the mortality of the majority of larvae. Only 13.6% of them formed cocoons, which failed to produce mature individuals. A repeated 10 and 100 fold decrease of AJH caused mortality in 50.0 and 46.7% of insects, respectively. The effect of the preparation stipulated the disturbance of the normal course of metamorphosis (changes in the data of phases replacement and the mortality of insects during their moulting).     

Effect of dietary protein on zinc phosphide toxicity in albino rats (Rattus norvegicus)

Adult male and female albino rats (R. norvegicus) were administered rodenticide, zinc phosphide ranging from 4, 2, 1, 0.5, 0.25 and 0.125% in the diet containing 10(A), 17(B) and 24%(C) protein. Zinc phosphide induced 100% mortality at 4, 2, 1, 0.5% in diet A; 4 and 2% in diet B; and 4% in diet C. The results reveal influence of dietary protein in modulating the toxicity of zinc phosphide, suggesting that greater caution should be exercised while formulating its baits for effectiveness. The results also suggest that baits having 10% protein are more suitable to carry the rodenticide from view point of acceptability and efficacy towards the target species.