Evidence of durable resistance in nine Chinese land races and one Italian cultivar ofTriticum aestivum toPuccinia striiformis

In this study carried out from 1987 to 1994, in a very conducive environment to stripe rust, nine Chinese land races and one Italian cultivar of wheat showed fair levels of quantitative resistance to rust disease. The nine old Chinese cultivars had a commercial planting history in this conducive environment ranging from 20 to 100 years, in a cultivation area of 20 to 467 thousand hectares p.a. with no apparent erosion of resistance. The Italian cultivar has been used commercially for 15 years in China without showing a decrease in the level of quantitative resistance. All these data warrant the conclusion that the ten cultivars have a form of durable resistance to stripe rust.     

土壤表土中植物根系影响其抗蚀性的模拟降雨试验研究——以张家口试验区为例

土壤中植物根系的存在可以增强土壤的抗蚀性,溅蚀量、贯入深度和被崩解的情况等都是土壤抗蚀性的反映。通过对人工添加根系、固有根系和缺少根系三种不同土壤类型,进行的溅蚀、贯入和崩解试验,发现具有植物根系的土壤,其崩解速率远比少根系或缺少根系的土壤为慢,而根系的多少则似乎与溅蚀、贯入不存在明显的关系,后者更多地取决于土壤的颗粒组成特性。     

Morphological, cytological and disease resistance studies of the intersectional hybrid between Arachis hypogaea L. and A. glabrata Benth.

Arachis glabrata Benth, variety glabrata collector GK 10596 (PI276233; ICG 8176) belonging to section Rhizomatosae has resistance to rust, late leaf spot and viral diseases. A. hypogaea L. cv MK 374 (section Arachis) is susceptible to rust, late leaf spot and to the viral diseases peanut stripe, peanut mottle and peanut bud necrosis. Hybrids between A. hypogaea cv MK 374 and A. glabrata were produced after inter specific pollinations and embryo culture. The hybrids produced had morphological characters of both parents plus floral abnormalities not seen in either parent. It was possible to identify the hybrids by esterase isozyme analysis when still in culture. Cytological research showed variable chromosome association and also homeology between the genomes of A. hypogaea and A. glabrata. The hybrids inherited resistance to rust, late leaf spot, peanut bud necrosis and peanut stripe diseases from the pollen parent A. glabrata. This revised version was published online in August 2006 with corrections to the Cover Date.     

霜霉病菌侵染的黄瓜叶片cDNA文库的构建及抗病相关基因筛选

以接种黄瓜霜霉病菌的抗病黄瓜品种‘649’的叶片为材料,使用改良SDS法提取总RNA,构建黄瓜叶片全长cDNA文库,得到的原始文库滴度为5.5 × 106 pfu • mL-1,扩增后的文库滴度达6.5 × 109 pfu • mL-1,重组率约为99%,插入片段在0.5 ~ 2.0 kb之间,大多在1.0 kb左右。随机选取3 360个克隆进行测序,共拼接出2 507个unigenes,其中包括211个重叠群（Contigs）和2 296个单拷贝EST（Singlets）。生物信息学分析显示：这些unigenes中存在427条与植物防御/抗病相关的基因,其中包括两类抗病基因和细胞程序性死亡相关基因,这些基因的发现为下一步研究黄瓜抗病机理,克隆抗霜霉病相关基因提供了重要的参考。     

Secretion of Natural and Synthetic Toxic Compounds from Filamentous Fungi by Membrane Transporters of the ATP-binding Cassette and Major Facilitator Superfamily

This review provides an overview of members of the ATP-binding cassette (ABC) and major facilitator superfamily (MFS) of transporters identified in filamentous fungi. The most common function of these membrane proteins is to provide protection against natural toxic compounds present in the environment of fungi, such as antibiotics produced by other microorganisms. In plant pathogenic fungi, these transporters can also be an important determinant of virulence on host plants by providing protection against plant defence compounds or mediating the secretion of host-specific toxins. Furthermore, they play a critical role in determining base-line sensitivity to fungicides and other antimycotic agents. Overexpression of some of these transporters can lead to the development of resistance to chemically-unrelated compounds, a phenomenon described as multidrug resistance (MDR). This has been observed in a variety of organisms and can impose a serious threat to the effective control of pathogenic fungi.     

优化的VHb基因和GFMcryIA基因构建的双价基因在烟草中的表达

利用人工合成的、密码子优化后的透明颤菌血红蛋白（VHb）基因与人工合成的GFMcryIA基因构建成双价基因植物高效表达载体。通过根癌农杆菌介导转化烟草,获得了36株卡那霉素抗性植株。经转基因植株的PCR及Southern blot检测,证实了双价基因在35株烟草基因组中的整合。Western blot检测证实了VHb基因的表达,杀虫实验证实GFMcryIA基因也表达出活性毒蛋白。且转基因烟草平均每株干重比非转基因烟草植株高7％。本研究结果表明转基因育种技术在培育出既高产又具抗虫性的作物或经济作物新品种方面具有良好的应用前景。     

Study of Resistance to Orobanche ramosa in Host (Oilseed Rape and Carrot) and Non-host (Maize) Plants

Orobanche ramosa is a parasitic Angiosperm responsible for severe yield losses in several economical crops. It is a serious threat in oilseed rape in France and Morocco and is appearing in carrot crops in Morocco. In this study, several varieties of oilseed rape and carrot were screened in order to identify resistant cultivars and to characterize the resistance mechanisms involved. All the 15 oilseed rape varieties tested were susceptible. In carrot, the varieties 'Colmar à coeur rouge' and 'Nantaise demi-longue' were susceptible, whereas 'Palaiseau' and 'Buror' were resistant. In the susceptible 'Colmar à coeur rouge' carrot no defence reactions were found and the development of the parasite inhibited carrot tap root formation. In the resistant carrot varieties, the parasite germinated, became attached to the host root but became necrotic before emergence. In 'Buror' carrot, formation of a mechanical barrier was associated with the restriction to the cortex of the parasite. In maize cv. 'Vigni', a non-host of O. ramosa, thickening of xylem vessels, cell divisions in the central cylinder and formation of an encapsulation layer were observed in association with restricted development of Orobanche haustoria.     

Identification and mapping of a novel Turnip mosaic virus resistance gene TuRBCS01 in Chinese cabbage (Brassica rapa L.)

We aimed to identify Turnip mosaic virus (TuMV) resistance genes in Chinese cabbage by analysing the TuMV resistance of 43 P₁ (resistant), 88 P₂ (susceptible), 26 F₁, 104 B₁ (F₁ × P₁), 108 B₂ (F₁ × P₂) and 509 F₂ individuals. All parents and progeny populations were mechanically inoculated with TuMV‐C4. Both F₁ and B₁ populations showed TuMV resistance. Resistant: susceptible ratios in the B₂ and F₂ populations were 1 : 1 and 3 : 1, respectively. TuMV resistance in P₁ was controlled by a dominant gene, TuRBCS01. Bulked segregation analysis was performed to identify simple sequence repeat or insertion or deletion markers linked to TuRBCS01. Data from 108 B₂ individuals with resistant or susceptible phenotypes were analysed using mapmake r/exp 3.0. Polymorphic marker sequences were blast searched on http://brassicadb.org/brad/ . TuRBCS01 was found to be linked to eight markers: SAAS_mDN192117a_159 (3.3 cM), SAAS_mDN192117b_196 (4.0 cM), SAAS_mDN192403_148 (13.0 cM), SAAS_mGT084561_233 (6.8 cM), BrID10723 (3.3 cM), mBr4041 (3.3 cM), SAAS_mBr4055_194 (2.6 cM) and mBr4068 (4.0 cM). Further, TuRBCS01 was mapped to a 1.98‐Mb region on chromosome A04 between markers BrID10723 and SAAS_mBr4055_194.     

Delayed cuticular penetration and enhanced metabolism of deltamethrin in pyrethroid-resistant strains of Helicoverpa armigera from China and Pakistan

The penetration and metabolism of [14C]deltamethrin was studied in susceptible and resistant Chinese and Pakistani strains of Helicoverpa armigera (Hübner), which were resistant to deltamethrin by 330- and 670-fold, respectively. The penetration of deltamethrin into resistant individuals was significantly slower than into susceptible individuals over a 24-h period. The time taken for 50% penetration of the applied deltamethrin was 1 h for the susceptible strain and 6 h for both of the resistant strains. The internal radioactivity was reduced by the larvae of resistant strains much faster than by the susceptible larvae. After 48 h, 40% of the penetrated deltamethrin was still inside the larvae of the susceptible strain, in comparison with 1.5-5% in the Pakistani strain and 8-14% in the Chinese strain. Both of the resistant strains produced methanol-soluble and water-soluble metabolites, but the susceptible strain produced methanol-soluble metabolites only. By 12, 24 and 48 h after dosing, the amount of methanol-soluble metabolites excreted by the resistant strains was almost double that of the susceptible strain. Both of the resistant strains also excreted 5-7% of the penetrated dose as a water-soluble metabolite after 48 h. In comparison with the Chinese strain, the Pakistani strain exhibited slower penetration, lower internal content and faster excretion of deltamethrin, which correlated with the higher resistance of the Pakistani strain. These findings show that the resistant Pakistani and Chinese strains of H. armigera possess mechanisms of reduced cuticular penetration and enhanced metabolism of deltamethrin and perhaps other pyrethroids.