用甘蓝夜蛾核型多角体病毒感染豚鼠

用纯化的甘蓝夜蛾核型多角体病毒悬液,按4×10~6PIB/克体重剂量,经腹腔接种豚鼠,在第6天和第16天解剖取胰脏,超薄切片电镜观察,可在胰脏细胞内发现多角体病毒;用豚鼠肝、脾和胰等脏器匀浆液饲养棉铃虫幼虫,被感染虫患典型病毒病,死虫率6天解剖的豚鼠为70.83%,16天解剖者为91.3%; 病死虫脓计在扫描电镜下发现典型多角体.据此可确定甘蓝夜蛾核型多角体病毒在豚鼠脏器内滞留16天.至于豚鼠脏器细胞是否复制该病毒问题,尚需进一步研究.     

First steps towards a rational use of African rice, Oryza glaberrima, in rice breeding through a ‘contig line’ concept

The inheritance of resistance to clubroot, caused by Plasmodiophora brassicae, in Brassica oleracea was studied in the F₁, F₂and backcross progenies of four crosses between resistant and susceptible doubled haploid lines. The disease severity was scored visually on a 0–3 scale of symptom grades. These were analyzed qualitatively and quantitatively. The qualitative analysis involved the conversion of symptom grades to a classification as resistant or susceptible, and segregation ratios were used to test several simple genetic models. The quantitative analysis was based on a threshold model, in which symptom grades are considered to arise from splitting a continuous response range into disjoint intervals. This analysis was based on the maximum likelihood method, and several genetic models were evaluated.Of the four resistances studied, one was shown to be largely determined by two complementary genes. Two other resistances were also shown to be probably controlled by two genes, but the mode of inheritance was not determined unambiguously. The fourth resistance appeared to be determined by more than two genes.     

Evaluation of F2 and F3 plants introgressed with QTLs for clubroot resistance in cabbage developed by using SCAR markers

Clubroot disease caused by Plasmodiophora brassicae is one of the major diseases of Brassica crops, often devastating to the cultivation of cruciferous crops in temperate regions. In a previous study (Moriguchi et al. 1999) identified three major quantitative trait loci (QTLs) for clubroot resistance, each in a separate linkage group, in a population derived from a cross between a clubroot‐susceptible inbred cabbage line, Y2A and a resistant inbred kale line, K269. In this study, the original random amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP) markers were converted into sequence‐characterized amplified region (SCAR) markers to facilitate large‐scale marker‐assisted screening of clubroot resistance in cabbage breeding. Of 15 RAPD markers closely linked to the three QTLs, nine SCARs were developed as dominant markers after cloning and sequencing. In addition, two RAPD markers were converted into co‐dominant cleaved amplified polymorphic sequence (CAPS) markers, and one RFLP marker out of three tested was converted to a dominant SCAR marker. The effect of selection for resistance by the improved markers was evaluated in progeny plants in the F2 and F3. A total of 138 F2 plants were genotyped with nine SCARs and 121 well‐distributed makers consisting of 98 RAPD, 19 RFLP, two isozymes, and two morphological markers in order to estimate the level of resistance and the proportion of undesirable alleles from the kale in non‐target areas in each of the F2 populations. An F2 plant, YK118, had kale alleles at QTL1, QTL3 and QTL9. Three F2 plants, namely, YK107, YK25 and YK51 had kale alleles at only QTL1, QTL3 and QTL9, respectively. These F2 plants were selected for their low proportion of alleles derived from kale in non‐target regions. YK118, like the resistant kale parent, expressed very high resistance to three field isolates of Plasmodiophora brassicae, whereas the mean disease index in the F2 and F3 plants carrying only single QTLs was intermediate. The QTLs showed no differential response to the isolates. These plants with improved resistance will be useful as parental inbred lines for F1 hybrids.     

126种中草药提取物对两种植物病原菌的抑菌活性

以黄瓜炭疽病菌(Colletotrichum lagenarium)和白菜黑斑病菌(Alternaria brassicae)为供试真菌,采用生长速率法对126种中草药的80%乙醇提取物进行了离体生物活性测定。结果表明:在提取物供试质量浓度为0.01 g/mL条件下(初筛),龙葵、猫爪草、枇杷叶等27种中草药提取物对至少一种病原真菌的菌丝生长抑制率超过50%,有6种提取物对2种病原菌抑制率均达50%以上。将初筛抑制率达50%以上的提取物浓度稀释为0.005 g/mL,进一步对相应病菌进行测试,发现有11种中草药提取物对黄瓜炭疽病菌的抑制率达60%以上,有3种提取物对白菜黑斑病菌的抑制率在40%以上。     

Factors affecting the pattern of the dose response curve of clubroot disease caused by Plasmodiophora brassicae

The severity of clubroot disease caused by Plasmodiophora brassicae Woron. depended on the density of resting spores in soil, soil type, soil pH, and host susceptibility. The dose response curve (DRC) was determined to indicate the relationship between the disease index and these parameters for predicting the disease severity for each field. DRC patterns varied with the soil types and even among soils of the same type depending on the sampling areas. Disease incidence was lower in the soils adjusted to a higher pH than in those at the initial pH. DRC patterns were also influenced by plant species or cultivars. The DRC is useful for estimating the potential disease severity in agricultural fields with different soils and different plants and essential for the development of an integrated pest management (IPM) strategy for the control of clubroot disease.     

植物提取物对甘蓝蚜影响的研究

提取蕊木、冲天子、膏桐、百日青、紫茎泽兰5种植物材料的提取物,用95%的乙醇浸渍法,将植物提取物稀释成1、5、10倍3个不同的浓度梯度,在室内对甘蓝蚜进行触杀、忌避作用的测定.结果表明:云南蕊木植物提取物触杀效果最佳,在24 h内平均校正死亡率为63.6%;5种植物提取物在3个浓度梯度上触杀效果无显著差异;百日青提取物的忌避效果最好,在24 h内平均忌避率为76.2%;冲天子的触杀和忌避效果均较差.     

甘蓝根肿病抗性遗传规律的研究

 采用4×4完全双列杂交的方法,对甘蓝苗期根肿病抗性遗传规律进行了研究。结果表明：抗病性受3对以上基因控制,为不完全隐性,回交效应极显著,正反交效应差异不显著,呈现核遗传,细胞质的作用不明显。甘蓝对根肿病抗性的狭义遗传力较高。一般配合力和特殊配合力均较重要,符合“加性一显性”模型,加性效应是主要的。这种抗性表现在亲代和F₁代间存在极显著正相关,呈现出数量性状遗传的特点。     

白菜黑斑病空间分布型研究及杀菌剂筛选

通过对白菜黑斑病的空间分布型进行研究,结果表明:在发病初期,白菜黑斑病空间分布型为随机分布;在病害发生1代以后白菜黑斑病多为聚集分布;在病害发生后期,单株病斑数大于1 000的地块,白菜黑斑病可能成为均匀分布.通过室内杀菌剂的筛选,结果表明:退菌特对白菜黑斑病菌的毒力最强,福美双、代森锰锌(新万生)对白菜黑斑病菌的毒力也很强,杀毒矾、速克灵、百菌清对白菜黑斑病菌也有较好的毒力.     

抗根肿病大白菜品种对不同地区根肿病菌的抗性鉴定

采用菌液注射法,以来源于山东青岛、云南双龙和陕西太白的大白菜根肿病菌为病原菌,对49个抗根肿病大白菜品种进行人工接种抗病性鉴定。结果表明:参试49个大白菜品种对3个地区根肿病菌存在抗性差异,其中32个品种对山东青岛根肿病菌和陕西太白根肿病菌抗性表现基本一致,推测这两地的生理小种一致;云南双龙根肿病菌与山东青岛、陕西太白根肿病菌为明显不同的生理小种,且致病力强、抗源少。     

甘蓝蚜取食对结球甘蓝生长和产量的影响

在温室条件下研究了甘蓝蚜取食对结球甘蓝生长及叶球产量的影响。当甘蓝在莲座后期至结球初期被大量吸食后,绝大部分外叶卷曲变形,到结球中期外叶加外茎的重量及叶面积显著下降,但叶球的鲜重、干重及大小均未受到影响。蚜虫大量取食使甘蓝的叶球占全株的相对比重显著增加,同时也使叶球含水量略有上升。