草莓白化相关病毒中国分离物全基因组分析

草莓白化相关病毒(strawberrypallidosis-associatedvirus,SPa V)属于长线形病毒科(Closteroviridae)毛形病毒属(Crinivirus),可引起草莓病害,2017年在中国首次报道。采用高通量测序、RACE和RT-PCR技术获得了SPa V中国分离物(FJ)的基因组全长。该病毒含有两条正单链基因组RNA1和RNA2。RNA1全长8 048 nt,5′和3′非编码区序列分别为264和197 nt,含有3个开放阅读框(ORF),分别编码ORF 1a/1b融合蛋白和p9蛋白。RNA2全长7 977 nt,5′和3′非编码区序列分别为248和186 nt,含有8个开放阅读框(ORF),分别编码HSP70h、CPh、CP、CPm、p7、p6、p9和p28等8个蛋白。RNA1和RNA2与美国M1分离物分别具有98.5%和99.0%的核苷酸一致性;系统发育分析结果表明,SPa V中国分离物(FJ)单独处在一个分支。对SPa V来源的小RNA的分析表明,来源于SPa V的小RAN长度以21和22 nt为主。     

早熟豇豆新品种贺研2号的选育

贺研2号是全能豆角与丰产2号的杂交后代经系统选育而成的早熟豇豆新品种。春季栽培全生育期90～100 d（天）,播种至始花45～50 d（天）,播种至始收55～60 d（天）;夏季栽培全生育期70～80 d（天）,播种至始花40～45 d（天）,播种至始收45～50 d（天）。豆荚淡绿色,荚长54～59 cm,横径0.84～0.86 cm,单荚质量24.5 g左右,荚条粗细匀称,无鼠尾,不易老化,鲜食口感佳。春季栽培每667 m²产量2 300～2 600 kg,适宜春季及越夏延秋栽培。     

压砂西瓜间套马铃薯油葵栽培试验

针对宁夏压砂西瓜产业发展的需要,探索压砂西瓜高效栽培模式技术(间套)。结果表明:压砂西瓜套种油葵共生期长,前期油葵与西瓜争光和肥水,西瓜坐瓜和大小受限制,影响西瓜产量;压砂西瓜套种马铃薯共生期长,马铃薯与西瓜争光、争肥水不明显,西瓜坐瓜和大小不受限制,西瓜产量不受影响,每667 m2套种马铃薯生产比对照多收入231.2元。     

A yellows disease system with differing principal host plants for the obligatory pathogen and its vector

A stolbur‐type phytoplasma is the putative pathogen of grapevine yellows disease that causes economic damage to vineyards in most growing areas around the world. The pathogen is known to be transmitted to vines by two planthoppers, Hyalesthes obsoletus and Reptalus panzer; the latter is found in Europe but has not yet been observed in Israel. The establishment of a vector–pathogen–plant relationship requires that the pathogen and the vector meet on a shared host plant. This does not happen in the ecosystem examined here, where two different principal host plants for the obligate pathogen and its vector exist: the pathogen is established on vines, while its vector, H. obsoletus, develops on Vitex agnus‐castus. The present study verified that: (i) the vector cannot complete its life cycle on vines; (ii) V. agnus‐castus does not grow in the immediate vicinity of vines, and does not harbour the pathogen; and (iii) the pathogen is not vertically transmitted from mother to offspring. Moreover, in a thorough search of plants in vine growing areas, no other plants were found that host both the vector and the pathogen. However, it was found that the planthopper can acquire the phytoplasma from infected vines. Nonetheless, this does not prove the ability of the planthopper to further transmit the pathogen to vines and does not explain the presence of the vector on the non‐preferred vines. Thus, the enigma of the pathogen–vector–host triangle in this system remains unresolved.     

The Internal Glycine-Rich Motif and Cysteine Suppress Several Effects of the HpaG(Xooc) Protein in Plants

ABSTRACT HpaG(Xooc), produced by Xanthomonas oryzae pv. oryzicola, is a member of harpin group of proteins that stimulate plant growth, hypersensitive cell death (HCD), and pathogen defense. The protein contains two copies of the glycine-rich motif (GRM), a characteristic of harpins, and a cysteine, which is absent in other harpins. Genetic modification generated the pro-tein mutants HpaG(Xooc)MG (MG) by deleting GRMs and HpaG(Xooc)C47T (C47T) by replacing cysteine with threonine. When applied to tobacco plants, C47T and MG were 1.2- and 1.7-fold stronger, respectively, than HpaG(Xooc) in inducing HCD, which occurred consistently with expression of the marker genes hin1 and hsr203. The proteins markedly alleviated infection of tobacco by Tobacco mosaic virus and Arabidopsis and tomato by Pseudomonas syringae. Treating tobacco plants with HpaG(Xooc), C47T, and MG decreased the viral infection by 58, 81, and 92%, respectively. In Arabidopsis and tomato plants treated with HpaG(Xooc), C47T, or MG, P. syringae multiplication was inhibited; bacterial population multiplied in 5 days in these plants were ca. 160-, 1,260-, or 15,860-fold smaller than that in control plants. So pathogen defense was induced in both plants. Defense-related genes Chia5, NPR1, and PR-1a were expressed consistently with resistance. In response to HpaG(Xooc), C47T, and MG, aerial parts and roots of tomato plants increased growth by 15 and 53%, 25 and 77%, and 46 and 106%, relative to controls. The expansin gene, EXP2, involved in the cell expansion and plant growth was expressed coordinately with plant growth promotion. These results suggest that the presence of GRM and cysteine in HpaG(Xooc) represses the effects of the protein in plants.     

番茄黑环病毒分子生物学检测方法及分离物序列分析

根据TBRV运动蛋白基因的保守序列设计引物，RT-PCR和IC-RT-PCR能从6个TBRV的分离物中分别扩增到与预期大小相同的DNA条带，序列测定和分析表明所测定的序列为TBRV运动蛋白基因的部分序列，在系统关系树上与TBRV的其它分离物形成一簇，表明所建立的RT-PCR和IC-RT-PCR检测方法是可靠的。     

国际食品法典农药残留标准介绍

本文简要介绍了国际食品法典农药残留委员会(CCPR)制订的食品和国际贸易中饲料上农药最大残留限量标准,以及与农药残留有关的标准,包括风险分析原则、分析和采样方法、残留评估FAO手册等技术规范、标准和准则.     

Comparative analysis of evaluation parameters in E. acervulina,E. maxima and E. tenella-infected broilers

Three parameters, body weight gain (BWG), intestinal lesion score (LS) and fecal oocyst shedding, were compared in broilers infected with major parasitic species; Eimeria acervulina, E. maxima, and E. tenella. First, two- and three-week-old chickens with Eimeria infection showed LS of approximately 3, but two-week-old chickens were more correlated with BWG. Second, significant differences in BWG were observed between male and female broilers challenged with Eimeria. Finally, E. maxima-infected broilers among three Eimeria species showed a higher relationship between BWG and LS, suggesting three considerations such as genders, age and Eimeria species for Eimeria experiments.     

Pyrethroid resistance in the cotton bollworm,Helicoverpa armigera (Hübner), in West Africa

The susceptibility of Helicoverpa armigera to pyrethroids has been investigated in West Africa by means of laboratory bioassays since 1985, the first year of widespread pyrethroid use. For some years, this survey has shown a tendency for the pest to become more tolerant to pyrethroids. During the 1996 growing season, farmers using calendar‐based spraying programmes reported control failures in various countries. The strong efficacy of cypermethrin on small larvae was confirmed in experimental plots, but the effect decreased quickly in successive instars. Bioassays performed on resistant strains revealed an increase in LD₅₀ that was related to different resistance mechanisms. Metabolic resistance (MFO) appears to be a possible primary mechanism of resistance to pyrethroids. Target modification (kdr) is involved to a small degree and esterases seem to appear only after additional selection pressure. © 2000 Society of Chemical Industry