Distinguishing characteristics and vegetative compatibility of Colletotrichum kahawe in comparison with other related species from coffee

On the basis of pathogenicity tests on green berries or hypocotyls of coffee and by morphological and biochemical characteristics in culture, 31 isolates of Colletotrichum were classified into C. kahawe (24 isolates), C. gloeosporioides (six isolates) or C. acutatum (one isolate). Within these groups of isolates, vegetative compatibility groups (VCGs) were determined by complementation tests with mutants in the nitrate assimilation pathway. There were distinct incompatibility barriers between the three species. Among the C. gloeosporioides group, the three isolates tested were self-compatible but incompatible with each other. Within C. kahawe , 18 isolates were self-compatible and only one main VCG was detected. However, partial compatibility in C. kahawe was also indicated by variation in the intensity of heterokaryon formation between different pairs of isolates and between different types of mutant. The existence of only one VCG in C. kahawe is consistent with the low level of variation found in previous work on DNA polymorphism.     

Sonneradon A Extends Lifespan of Caenorhabditis elegans by Modulating Mitochondrial and IIS Signaling Pathways

Aging is related to the lowered overall functioning and increased risk for various age-related diseases in humans. Sonneradon A (SDA), a new compound first extracted from the edible fruits of mangrove Sonneratia apetala, showed remarkable antiaging activity. However, the role of SDA in antiaging remains unclear. In this article, we studied the function of SDA in antiaging by using the animal model Caenorhabditis elegans. Results showed that SDA inhibited production of reactive oxygen species (ROS) by 53%, and reduced the accumulation of aging markers such as lipids and lipofuscins. Moreover, SDA also enhanced the innate immune response to Pseudomonas aeruginosa infection. Genetic analysis of a series of mutants showed that SDA extended the lifespan of the mutants of eat-2 and glp-1. Together, this effect may be related to the enhanced resistance to oxidative stress via mitochondrial and insulin/insulin-like growth factor-1 signaling (IIS) pathways. The results of this study provided new evidence for an antiaging effect of SDA in C. elegans, as well as insights into the implication of antiaging activity of SDA in higher organisms.     

Phototropism and Phytochrome

向光性是植物为捕捉更多光能而建立起来的对不良光照条件的适应机制之一．蓝光被证明是引起植物向光性最有效的光源．最近的研究进一步揭示植物体内一定存在一种对蓝光具特殊敏感性从而引起向光性反应的光受体．光生物学家已克隆得到数种ｃＤＮＡ并证明它们当中至少有一种对向光性受体负责,遗憾的是至今并没有弄清楚到底是哪一种ｃＤＮＡ表达向光性受体．就诱导向光性反应而言,红光是无效的,但早在本世纪５０年代就已有人证明红光对植物向光性行为产生深刻影响．最新的研究（Ｌｉｕ＆Ｉｉｎｏ１９９６）已证明红光对蓝光所诱导向光性的影响是由光敏色素这一红光／远红光受体参与调节的．研究发现对蓝光和远红光敏感的向光性受由对红光敏感的光敏色素的严格控制．绝对黑暗条件下生长的植物向光性蓝光刺激无反应,不表现向光性．这样的植物只有接受了红光或远红光前处理后才对向光性蓝光刺激有反应．这一重大发现揭示了向光性反应中光敏色素与向光性受体的相互作用,并为光生物学家彻底搞清楚植物向光性受体提供了一条全新的研究思路．本文就是在这一背景基础上总结了近几年来有关光敏色素和向光性方面研究的新进展．我们希望通过这样的工作能使有关植物向光性受体和植物体内吸收不同波长光的光受体     

灰葡萄孢BcKMO在病菌生长、发育和致病过程中的功能

【目的】明确灰葡萄孢BcKMO在病菌生长、发育和致病过程中的功能,为阐明该基因调控灰葡萄孢生长、发育和致病的分子机理奠定基础,并为灰霉病的防治提供理论依据。【方法】利用生物信息学方法,对BcKMO及其编码产物进行分析。扩增BcKMO的编码区,与pBARKS1-eGFP载体连接,构建基因的表达载体pBARKS1-BcKMO-eGFP;利用PEG介导的原生质体转化方法,转化BcKMO的T-DNA插入突变体BCG183的原生质体;利用PCR、Southern blotting和real-time PCR技术,对所获得转化子进行鉴定;对野生型菌株BC22、突变体BCG183和回复突变体BCG183/BcKMO的表型（菌落形态、菌丝形态、生长速度、产孢量等）和致病力进行分析。【结果】BcKMO编码犬尿氨酸单氧酶（kynurenine 3-monooxygenase,KMO）,含有单氧酶FAD的保守结构域和4个类似芳香环羟化酶（Aromatic-ring hydroxylase-like）的基序,与核盘菌（Sclerotinia sclerotiorum）的Rossmann卷曲NAD(P)(+)-结合蛋白（Rossmann-fold NAD(P)(+)-binding proteins,gi156049701）和从线嘴壳（Ophiostoma piceae）的FAD依赖性氧化还原酶（FAD-dependent oxidoreductase,gi512192943）同源性较高。成功构建了BcKMO的表达载体pBARKS1-BcKMO-eGFP,利用PEG介导的转化方法,转化突变体BCG183的原生质体,获得了草胺膦抗性的转化子;利用PCR、Southern blotting和real-time PCR技术鉴定转化子,获得了BcKMO的回复突变体BCG183/BcKMO。对突变体BCG183和回复突变体BCG183/BcKMO的表型进行了分析,发现BCG183突变体的生长速率减慢,不产生分生孢子和菌核,菌丝纤细;回复突变体和野生型菌株的生长速率、菌丝形态基本一致,均产生分生孢子和菌核。致病力分析发现,BCG183突变体在芸豆叶片和黄瓜叶片上的致病力均较野生型和回复突变体明显增强。【结论】灰葡萄孢BcKMO正调控病菌的生长、发育,负调控病菌的致病力。     

A/E大肠杆菌疫苗动物模型的建立

致病性和出血性大肠杆菌 (代表株 EPEC E2 34 8和 EHEC O15 7)是婴幼儿腹泻、出血性结肠炎和尿路感染综合征 (尿毒症 )的主要病原菌 ,它们同属于粘附脱落 (Attaching/ Effacing,A/ E)大肠杆菌群 ,具有许多共同的毒力基因 ,定位于致病岛 L EE(the locus of enterocyte effacement)上。本试验主要就 A/ E大肠杆菌致病岛 L EE的 2个主要调节基因 lux和 ler基因对细菌致病性和免疫原性的影响进行了研究。所使用的始发菌株为兔致病性大肠杆菌 RDEC- 1,根据同源重组的原理 ,利用自杀性载体 p CVD44 2技术 ,敲除了位于染色体上的 lux和 ler基因 ,构建了 lux和 ler基因缺失突变株 ,研究了这 2个基因对细菌生长、毒力因子表达的调控作用以及基因缺失突变株的致病性和免疫保护作用。家兔实验研究表明 ,lux基因缺失突变株仍然残存着部分致病作用 ,不足以成为理想的致弱疫苗 ;而 ler基因缺失突变株安全性好 ,具有良好的免疫保护作用 ,是理想的家兔致弱疫苗候选株。这些研究资料为人 A/ E大肠杆菌疫苗 ,尤其是 EHEC O15 7疫苗的研制指明了方向 ,并提供了技术路线。     

A mutant of Brassica napus with increased palmitic acid content

An induced mutant from European winter oilseed rape with increased palmitic acid content was phenotypically characterized and genetically analysed. The mutant showed a palmitic acid content of 9.2% compared with 4.5% in the parental cultivar. The oleic acid content decreased from 61.6% to 44.2%, whereas the linoleic and linolenic acid contents increased. The mutant plants grew poorly and their seed oil content was only 31.2% compared with 42.8% in the parental cultivar. The inheritance of the mutant was oligogenic and determined by at least four genes. In the F₂ generation, palmitic acid content was negatively correlated with oil content. This mutant may be useful to improve understanding of the genetic regulation of storage lipid synthesis, but has no immediate value for oilseed rape improvement.     

红麻花柱外露突变体的特征特性鉴定

以卫星搭载后代群体中发现的4个红麻花柱外露突变体（SPM）选育的自交系为材料,以未突变的材料作对照。形态观察表明,与对照相比,SPM的花朵明显变小,花柱和雄蕊管均缩短;但雄蕊管缩短幅度更大,导致花柱大幅外露。4个SPM自交系的花柱外露长度存在显著差异,H20-1最长,达11.6 mm;H212-1最短,仅6.5 mm。尽管4个SPM自交     

Analysis of Variations in White-Belly and White-Core Rice Kernels Within a Panicle and the Effect of Panicle Type

This study aims to investigate the variation in occurrence of white-belly rice kernel（WBRK） and white-core rice kernel（WCRK） among different positions within a panicle. Twenty-four M4 mutants involved in four panicle types, namely the compact, intermediate, loose, and chicken foot panicle were used. They derived from a japonica rice cultivar Wuyujing 3. Considerable differences in morphological characters existed among the four types of panicle, especially in panicle length, the secondary branch number and ratio of grain number to total branch length. Marked differences were found in WBRK and WCRK among different positions within a panicle for all types of panicle. In general, grains located on the primary rachis and top rachis branches had higher WBRK and WCRK percentage than those on the secondary rachis and bottom rachis branches. WCRK exhibited larger variation among grain positions than WBRK did. Moreover, there was a significant difference in WCRK/WBRK among grain positions within a panicle, with primary rachis and top rachis branches having higher values than the secondary and bottom rachis. In addition, panicle type showed no significant effect on the pattern of WBRK and WCRK occurrence within a panicle. The results indicated the difference in mechanism of WBRK and WCRK formation in grain position within a panicle, and are valuable for breeding and agronomic practices aimed at lowering chalky grain rate.     

大豆种子脂肪氧化酶缺失基因控制豆腥味效果的研究

 应用蒸馏提取法、气相色谱和气 -质联机的方法分析了大豆种子脂肪氧化酶缺失体近等位基因系在加工豆制品时所产生的挥发性气味物质。研究结果表明 ,从豆粉和豆浆中都只分离出 2 4种气味成分 ,主要为醛和醇类物质 ;在形成挥发性气味物质和豆腥味物质中 L ox2起主要作用 ,L ox1次之 ,L ox3作用最小 ,但具有降低己醛生成的作用 ;不论缺失 L ox1,还是缺失 L ox2 ,都可极显著地降低挥发性气味物质和豆腥味物质的生成量 ,而缺失 L ox3则会显著增加己醛的生成量 ;缺失基因间存在有显著或极显著的一级和二级负互作 ;不同加工条件对缺失基因的缺失平均效应和互作效应有明显的影响。全缺失体类型具有最低的挥发性物质和豆腥味物质的生成量 ,而缺 L ox3类型具有最高的生成量 ,其余的缺失体类型则介于两者之间 ;用己醛作为衡量脂肪氧化酶在形成豆腥味中的重要性和各种缺失体类型控制豆腥味效果的指标是可行的。因此 ,培育出大豆种子脂肪氧化酶全缺失的品种将有望成为食品加工业的优质原材料