生防菌株1404的鉴定及其对采后柑橘炭疽病的防治效果

【目的】柑橘是世界上重要的果树。由胶孢炭疽菌[Colletotrichum gloeosporioides(Penz.)Sacc.]引起的柑橘炭疽病是柑橘生产的主要病害。为开发对采后柑橘炭疽病有效的生防措施,对从辣椒根际土壤中分离的一株生防细菌1404进行了鉴定,并对其特性及生防效果进行了研究。【方法】根据菌株1404的形态特征、生理生化特性以及16SrDNA序列对其进行鉴定;通过连续在人工培养基上转代培养,测定该菌株拮抗活性的稳定性;用果实刺伤接种法对采后柑橘炭疽病的防效进行测定。【结果】菌株1404与来自GenBank的短短芽孢杆菌[Brevibacillus brevis(Migula)Shidaetal.]以100%bootstrap水平类聚一群。该菌株的形态特征及生理生化特性与Brevibacillus brevis相符。连续4次在人工培养基上转代培养,菌株1404对柑橘炭疽病菌生长的抑制力没有发生明显改变。该生防菌对柑橘炭疽病的防治效果明显,处理后第20天防效达到64.9%。【结论】根据16SrDNA序列、形态特征、生理生化特性,将菌株1404鉴定为短短芽孢杆菌。本文首次报道对柑橘采后炭疽病具有较好防效的生防菌Brevibacillus brevis。     

柑橘愈伤组织生长速度与体细胞胚胎发生的关系

为了探讨柑橘愈伤组织不能再生的原因,试图寻找柑橘愈伤组织生长速度与其体细胞胚胎发生之间的关系,对7种柑橘类型的29种基因型的愈伤组织的生长速度进行了测定,并对愈伤组织生长速度与体细胞胚胎发生之间的相关性进行了统计分析。结果表明,柑橘愈伤组织生长速度与体细胞胚胎发生之间的相关系数为r=-0.3683。由此推断在这两者之间还存在其它影响因素。     

Galectin-3 in apoptosis,a novel therapeutic target

During the past decade, extensive progress has been made toward understanding the molecular basis for the regulation of apoptosis. In mammalian cells undergoing apoptosis, two distinct mechanisms or pathways are operated and are triggered by cell death stimuli from intra- or extra-cellular environments, namely the intrinsic or extrinsic pathways, resulting in mitochondrial membrane depolarization. Several lines of evidence from our laboratories and others have indicated that galectin-3 plays an important role in these pathways by binding to various ligands. Here the authors provide a brief discussion on the role of endogenous or extra-cellular galectin-3 in the regulation of apoptosis and how it could be used as a therapeutic target using natural plant products as its functional inhibitors.     

桔核中柠檬苦素类物质消炎镇痛作用的研究

为探讨柑桔果实中柠檬苦素类物质对实验动物模型的抗炎镇痛作用,本文通过小鼠耳廓肿胀模型和角叉菜胶致大鼠足肿胀模型观察柠檬苦素的抗炎作用;采用小鼠福尔马林实验及扭体实验观察柠檬苦素的镇痛作用。结果表明：柑桔果实中柠檬苦素类物质能显著抑制二甲苯致小鼠耳廓肿胀和角叉菜胶致大鼠足肿胀程度;减少扭体次数;显著提高小鼠福尔马林实验中的痛域。因此,柑桔果实中柠檬苦素类物质对本实验中的动物模型具有显著的抗炎及镇痛作用。     

RAPD-based genetic analysis of offsprings from the sexual cross using allotetraploid citrus somatic hybrid as pollen parent

Thirty-one polymorphic decamer primers were selected to genotype 92 progenies from the cross between Yiben No.4, a monoembryonic diploid F₁ hybrid of Citrus reticulata Blanco cv Huanongbendizao tangerine and C. ichangensis Swingle, and [Hamlin sweet orange + Rough lemon], an allotetraploid somatic hybrid of Citrus sinensis Osbeck cv. Hamlin and C. jambhiri Lush cv. Rough Lemon. χ² (Chi-square) analysis of RAPD markers in the progenies indicated they were randomly transmitted from the four donor parents, without significant difference between the diploids and triploids. However, these progenies were clustered into three major groups using dendrogram constructed by UPGMA, skewed to three parents in certain degrees, 15 (13 triploids and 2 diploids) to Hamlin, 16 (9 and 7) to Yiben No. 4, and 61 (57 and 4) to [Hamlin sweet orange + Rough Lemon] from which genomic contribution was predominant in progenies, respectively.     

Antagonistic effects of the endophytic fungus Meira geulakonigii on the citrus rust mite Phyllocoptruta oleivora

AIMS: The fungus Meira geulakonigii has been shown to reduce populations of citrus rust mite (CRM; Phyllocoptruta oleivora) on citrus leaves and fruits, in both the field and laboratory. However, attempts to isolate the fungus from leaves and fruits have been unsuccessful. The aims of this study were therefore to determine whether M. geulakonigii is a citrus endophyte, and to assess possible mechanisms involved in its mite-antagonist activity. METHODS AND RESULTS: A quantitative real-time PCR and regular PCR approaches were developed to detect M. geulakonigii in both the field and laboratory. The fungus was detected throughout. Different methods revealed that M. geulakonigii is an endophyte, which colonizes both the peel of grapefruits. Applications of conidia protected the grapefruits against CRM, and fungal secretions extracted from growth media caused 100% CRM mortality. CONCLUSIONS: Meira geulakonigii is a beneficial endophyte of grapefruits that colonizes the fruit's peel, and protects it from CRM. SIGNIFICANCE AND IMPACT OF THE STUDY: Findings from this study demonstrate the endophytic nature of M. geulakonigii in its interaction with grapefruits. In addition, a molecular approach was developed to specifically detect the fungus inside the grapefruit peel. This approach can be used to assess the natural occurrence of M. geulakonigii in grapefruit.     

Early detection surveillance for an emerging plant pathogen: a rule of thumb to predict prevalence at first discovery

Emerging plant pathogens are a significant problem for conservation and food security. Surveillance is often instigated in an attempt to detect an invading epidemic before it gets out of control. Yet in practice many epidemics are not discovered until already at a high prevalence, partly due to a lack of quantitative understanding of how surveillance effort and the dynamics of an invading epidemic relate. We test a simple rule of thumb to determine, for a surveillance programme taking a fixed number of samples at regular intervals, the distribution of the prevalence an epidemic will have reached on first discovery (discovery-prevalence) and its expectation E(q*). We show that E(q*) = r/(N/Δ), i.e. simply the rate of epidemic growth divided by the rate of sampling; where r is the epidemic growth rate, N is the sample size and Δ is the time between sampling rounds. We demonstrate the robustness of this rule of thumb using spatio-temporal epidemic models as well as data from real epidemics. Our work supports the view that, for the purposes of early detection surveillance, simple models can provide useful insights in apparently complex systems. The insight can inform decisions on surveillance resource allocation in plant health and has potential applicability to invasive species generally.     

Oviposition behaviour and larval development of Anastrepha fraterculus from Argentina in citrus

Citrus peel physicochemical attributes are considered the main components conferring partial or even total resistance to fruit fly (Diptera: Tephritidae) infestation. Fruit fly females adapt their ovipositional strategies to overcome such resistance. Here, we explored the effects of citrus species (Rutaceae) on the ovipositional behaviour of the South American fruit fly, Anastrepha fraterculus (Wiedemann), and on its immature development. Particularly, we investigated the effects of (1) citrus species on oviposition behaviour and immature development, (2) citrus species on oviposition preference and on the location of the eggs at different depth in the citrus peel, and (3) harvest season and post‐harvest storage time on oviposition behaviour and immature development in lemon. Citrus species influenced ovipositional behaviour and affected survival of immature stages. Females laid eggs in lemon [Citrus limon (L.) Burm.], orange [Citrus sinensis (L.) Osbeck], and grapefruit (Citrus paradisi Macfadyen). In orange and lemon, larvae were found dead close to the oviposition areas, suggesting chemically mediated resistance mechanisms. Under choice conditions, females preferred grapefruit over lemon and bigger clutches were found in the layers where embryonic development is favoured. Unsuitability of lemon as a medium to complete development was neither affected by harvest season nor by storage time of the fruit after harvest. The physical and chemical characteristics of the peel were distinctive to each citrus species and may have affected the specific levels of resistance of these citrus species to infestation by A. fraterculus.