Differential expression of Arabidopsis sulfurtransferases under various growth conditions.

Sulfurtransferases (Str) comprise a group of enzymes widely distributed in archaea, eubacteria, and eukaryota which catalyse the transfer of a sulfur atom from suitable sulfur donors to nucleophilic sulfur acceptors. Neither the in vivo sulfur donors nor the acceptors of Str could be clearly identified in any of the organisms investigated so far. In Arabidopsis thaliana 20 Str proteins have been identified and grouped according to sequence homology. To investigate their respective in vivo function, Arabidopsis plants were grown in sterile hydroponic cultures at different sulfate (50, 500, and 1500 microM) and phosphate (0.1 and 1mM) concentrations, and in medium supplemented with 1mM thiosulfate. Northern blot analysis revealed the differential expression of the Str investigated. Thiosulfate Str activity was significantly increased at low sulfate concentrations in the medium. The Str mRNA levels were highly dependent on the developmental stage of the Arabidopsis plants. The expression of most Str analysed increased with progressing plant age in parallel with increasing 3-mercaptopyruvate and thiosulfate Str activities. The Str investigated were differentially expressed in a light/dark cycle whereas Str enzyme activities were not affected by the light conditions. The results indicate that each Str is regulated in a different way and plays an individual specific role in the plant metabolism.     

Permeability of receptive fig fruits and its effects on the re‐emergence behaviour of pollinators

1. Figs and pollinating fig wasps provide a model system for studying mutualism. The permeability of the syconium changes during receptivity or between seasons, which may affect the behaviour of pollinators. Fig fruits are permeable during receptivity, and in some species, pollinators can enter and re‐emerge after oviposition/pollination. We studied the relationship between fig permeability and pollinator re‐emergence behaviour with a functional dioecious fig, Ficus hispida and the obligate pollinator Ceratosolen solmsi marchali. 2. The relationship reflects the interaction of figs and pollinators in the mutualism and also the conflicts of interests between the two partners: figs benefit from the enclosed fig fruits which have low permeability, but pollinators benefit from their re‐emergence behaviour, which requires high fig permeability. 3. The results showed that at the end of receptivity, the permeability of fig fruits lowered rapidly with changes to the ostiole structures, and re‐emergence rate was low, with more re‐emerging pollinators trapped in the ostiolar bracts. Our results also showed that in the rainy season, the length of receptivity was shorter and fig permeability was lower. The re‐emergence rates were also lower than those in the dry season. The results elucidated that figs' interests dominated in the conflicts between fig and pollinating wasp. 4. Based on a new criteria which employed the classification of pollinators found dead in the ostiolar bracts and which involved a survey of 6 monoecious and 12 dioecious fig species, we found that re‐emergence behaviour was prevalent among fig species, and was more prevalent in functional dioecious figs than monoecious ones.     

Evaluation of genetic diversity within asparagus germplasm based on morphological traits and ISSR markers

Asparagus officinalis L. is a dioecious perennial plant globally known for its fine flavor and high nutritional value. An evaluation of genetic diversity in 46 asparagus accessions was carried out based on morphological and inter-simple sequence repeat (ISSR) markers. The result show that the coefficient of variation for 20 morphological characteristics is between 12.45 and 62.22%. Factor analysis revealed that nine factors explained 83.37% of the total variance. At Euclidean distance of 135.7, 46 accessions were divided into two clusters. Genetic similarity coefficient (GSC) based on ISSR data ranged from 0.60 to 0.97, suggesting a relatively abundant genetic base. Furthermore, the 46 asparagus accessions could also be grouped into three major clusters at a GSC of 0.74. And there is no significant relation between the two marker systems using the Mantel test. Clustering based on morphological traits compared with that based on ISSR data was not consistent, however, some common groupings were observed between two dendrograms. Therefore the results elucidated asparagus germplasm genetic background and determined hybrid parents, which will facilitate optimal application of asparagus germplasm resources and provide additional data for genetic improvement.

     

First Report of Dieback of Mango Caused by Fusarium decemcellulare in China

During 2009–2011, a dieback disease of mango (Mangifera indica) has recently emerged on mango trees in Panzhihua City, Sichuan province of China. The disease is characterized by large irregular brown‐coloured speckles on the petioles and twigs, vascular necrosis and dry leaves and complete twig mortality. Fusarium species were isolated repeatedly from the infected petioles and twigs. The species was identified as Fusarium decemcellulare Brick based on morphology and sequence analysis of Translation Elongation Factor‐1alpha (TEF‐1α) gene. Koch's postulates were fulfilled by pathogenicity tests on potted mango seedlings. To our knowledge, this is the first record of dieback on mango caused by F. decemcellulare in China.     

甘蔗转基因育种研究进展

由于复杂的遗传背景、较低的可育性和缺乏优异种质资源等因素给甘蔗品种改良带来了很大的困难,而通过转基因技术为甘蔗品种改良提供了有效的途径。甘蔗通过转基因,不仅在其抗虫性(螟虫和蚜虫)、抗病性(白条病、花叶病和黑穗病)、蔗糖改良(蔗糖产量、蔗糖纯度和色泽)、抗除草剂、抗旱性等方面已经取得了很大的进展,而且转基因甘蔗作为生物反应器生产重组蛋白(GM-CSF等)和生物塑料聚羟基丁酸酯(PHB)也取得了很好的成果。综述甘蔗主要性状遗传改良研究进展、转基因存在的问题以及转基因安全性研究状况,并对今后的甘蔗转基因育种前景和研究方向进行分析。     

5种杀虫剂对入侵害虫椰子织蛾的室内毒力测定

椰子织蛾是一种外来新入侵害虫,对棕榈科植物造成了严重危害。采用叶片浸渍法测定了甲维盐等5种杀虫剂对入侵害虫椰子织蛾5～6龄幼虫的室内毒力。5种药剂处理72 h后的室内毒力大小顺序为甲维盐＞氯虫苯甲酰胺＞毒死蜱＞高效氯氟氰菊酯水乳剂＞烟碱;72 h 致死中浓度（ LC50）为5．2604、9．7126、24．8202、104．0584、643．1496 mg· L-1。选取同样毒力效果所需成本依次为毒死蜱＜甲维盐＜高效氯氟氰菊酯＜氯虫苯甲酰胺＜烟碱。本研究可用于指导椰子织蛾的应急化学防控。综合毒力和成本,建议在生产上采用毒死蜱和甲维盐等相关药剂防治椰子织蛾。     

四种食料植物对斜纹夜蛾生长发育及营养指标的影响

在室内平均温度28.1℃,平均相对湿度84.0%的条件下研究了蓖麻、豇豆、番木瓜和香蕉等4种食料植物对斜纹夜蛾Prodenia litura(Fabricius)生长发育及营养效应的影响。结果表明:不同食料植物对斜纹夜蛾的幼虫发育历期、蛹重及营养效应等均有显著差异。幼虫发育历期以蓖麻组最短(9.93 d),香蕉组的最长(15.84 d);蛹重以蓖麻组最重(377.8 mg),香蕉组最轻(245.6 mg);幼虫存活率蓖麻组最高(98%),香蕉组最低(66.0%);斜纹夜蛾幼虫的相对取食量、近似消化率和相对生长率等以蓖麻组最高(分别为5.46,68.49,0.53),而以香蕉组最低(分别为0.86,16.30,0.26)。斜纹夜蛾嗜食蓖麻等,而不喜食香蕉。     

草地贪夜蛾幼虫自残捕食量分析

为了明确草地贪夜蛾Spodoptera frugiperda幼虫对同类低龄幼虫的捕食作用,在实验室条件下研究了草地贪夜蛾3~6龄幼虫对不同密度2龄幼虫和4~6龄幼虫对不同密度3龄幼虫的日捕食量,同时从捕食功能的角度解析了草地贪夜蛾高龄幼虫对低龄幼虫的捕食行为;并对不同龄期幼虫进行称重比较,用不同龄期幼虫间的重量关系来替换不同龄期幼虫间的捕食量,得到不同龄期幼虫间的捕食量方程。结果表明,草地贪夜蛾3~6龄幼虫对2龄幼虫和4~6龄幼虫对3龄幼虫的捕食功能反应均符合Holling Ⅱ型功能反应类型。草地贪夜蛾3~6龄幼虫对2龄幼虫的最大捕食量分别为76.47头、85.70头、117.92头、96.05头;4~6龄幼虫对3龄幼虫的最大捕食量分别为38.83头、59.49头、58.87头。高龄幼虫对低龄幼虫的捕食量随猎物密度的增加而增加。最大理论捕食质量方程y=47.231x^0.4591,捕食者的捕食量随着猎物虫态的增大而逐渐减小。研究结果为理解草地贪夜蛾幼虫的种间自残行为规律奠定了一定的理论基础。     

Differential Colonization Patterns of Bananas (Musa spp.) by Physiological Race 1 and Race 4 Isolates of Fusarium oxysporum f.sp. cubense

Fusarium oxysporum f.sp. cubense (Foc) is the causative agent of Fusarium wilt of bananas (Musa spp.). To clarify the colonization patterns of Foc in bananas, two green fluorescent protein‐tagged isolates, NT320 (race 1) and B2‐gfp (race 4), were used to follow infection of the banana varieties Pisang Awak and Brazil. Penetration and colonization of both isolates in roots of these two banana varieties were observed within 6 days, but sporulation in xylem vessels was not observed until day 30 postinoculation. Interestingly, B2‐gfp penetrated into xylem vessels of Pisang Awak banana roots more quickly than NT320, implying that the race 4 isolate is more virulent than the race 1 isolate. This result was further confirmed by comparing the disease severity of plants inoculated with NT320 with that of plants inoculated with B2‐gfp. Quantitative real‐time PCR revealed that some pathogenicity‐associated genes, including Fga1, Fhk1, Fow2 and Ste12, were upregulated by B2‐gfp during exposure to Brazil bananas, while they were either downregulated by NT320 or not significantly changed. These data might partly explain why the race 4 isolate was more virulent than the race 1 isolate.