Field Resistance to Willow Leaf Rust Melampsora epitea in Inter- and Intraspecific Hybrids of Salix viminalis and S. dasyclados

Families of interspecific hybrids between Salix dasyclados and S. viminalis, and intraspecific hybrids of the two species, were monitored for rust infection caused by Melampsora epitea during the years 1997–1999. The resistance of interspecific hybrids was compared to intraspecific pure species halfsibs. In addition, uredospores were sampled from the most infected interspecific hybrids to determine whether rust from interspecific hybrids differed from the rust spores that infected the pure species. The results from 1997 and 1999 showed that interspecific hybrids were more resistant than the intraspecific pure species, thus exhibiting a pattern of hybrid resistance. In 1998 the interspecific hybrids showed intermediate resistance compared to intraspecific pure species hybrids, i.e., an additive pattern of resistance. The rust sampled from the interspecific hybrids consisted of the same types of rust that infect the pure species. Comparisons of weather conditions prevailing during the three growing seasons indicated that these conditions might play a role in the infection pattern, in addition to the level of sensitivity to infection shown by the plants.     

Genetic Variation in Melampsora Larici-epitea on Biomass willows Assessed using AFLP

Five pathotypes belonging to formae speciales larici-epitea typica (LET), larici-retusae (LR) and larici-daphnoides (LD) of Melampsora larici-epitea were examined using amplified fragment length polymorphism (AFLP). Of 213 AFLP markers scored, several were found to be exclusive to different formae speciales. The dendrogram placed the five pathotypes into distinct groups. Within pathotypes, average Nei & Li's similarity coefficients were calculated as 0.71–0.85. The similarities were 0.66–0.72 among the three pathotypes within LET and 0.34–0.44 between pathotypes belonging to different formae speciales. When assessed using the Shannon index, the diversity within locations was estimated as 0.55–0.59, greater than that found within pathotypes (0.24–0.42). The average per-locus diversity was 0.37 among the pathotypes and 0.11 among the locations. When the data from both LET and LR isolates were examined using AMOVA, the majority of the variation (70.85%) was attributed to among pathotypes within location. When only LET types were included, approximately half of the variation was partitioned to among pathotypes within location and the other half to among the isolates within collection. It appears that the degree of differentiation of LET4 on S. × mollissima between Loughgall and Long Ashton sites has decreased markedly since 1992, when it was first detected.     

The susceptibility of herbal willow to <Emphasis Type="Italic">Melampsora</Emphasis> rust and herbivores

Eight Dark-leaved willow (Salix myrsinifolia) clones and two naturally hybridised clones (S. myrsinifolia × S. phylicifolia), that are considered to be suitable for herbal production, were cultivated for 2 years in Luikonlahti and Punkaharju. Both experimental sites are located in eastern Finland and the distance between the sites is 140 km. Different cultivation methods were used, including combinations of soil tillage, plastic mulch and fertilisation, with the aim of comparing the growth and susceptibility of plants to pathogens and willow-eating herbivores amongst the clones cultivated by different methods. In both study years 2001 and 2002, Melampsora rust-infected willows occurred in Luikonlahti and in Punkaharju. The extent of rust severity varied greatly between the years and experimental areas and amongst the clones. In 2002, fertilisation increased rust severity in Luikonlahti, but the effect was the converse in Punkaharju. Mulch effect on rust severity was clone-dependent. Vole feeding was observed in 56% of the plants in Luikonlahti during the winter 2001–2002 and the frequency of damaged plants was nearly twice as much amongst the willows grown in unmulched soil as those with plastic mulch. Cultivation method had no effect on feeding by leaf beetles or the abundance of aphids. Of the cultivation methods tested here, plastic mulch seems to have the most important influence on willow cultivation, particularly by improving willow growth and also by decreasing winter-feeding by voles.     

Additions to rust and smut fungi of Turkey

Entyloma linariae Schroet., Entyloma magocsyanum Bub., Uromyces arenariae–grandiflorae Mayor and Uromyces arenariae–leptoclados Vien.-Bourg. are reported for the first time from Anatolia. Additionally, Arenaria leptoclados (Rchb.) Guss. is recorded as a new host for Melampsorella caryophyllacearum Schroet. in the region.     

Characterization ofRhizoctonia solani isolates from potatoes in turkey and screening potato cultivars for resistance to AG-3 isolates

A total of 304Rhizoctonia solani isolates and 60 binucleateRhizoctonia-like fungi were recovered from stems and tubers of infected potato plants over a 2-yr period in northeast Turkey.R. solani isolates were identified to 11 anastomosis groups (AGs): AG-1 (0.66%), AG-2-1 (5.6%), AG-2-2 (0.99%), AG-3 (83.9%), AG-5 (4.6%), AG-6 (0.66%), AG-8 (1.32%), AG-9 (0.33%), AG-10 (1.32%), AG-12 (0.33%), and AG-13 (0.33%). In the greenhouse tests, most of the AG-3 isolates were significantly more virulent than isolates belonging to other AGs on potato cv. Batum. Isolates of other anastomosis groups differed in their virulence. Results indicated that AG-3 is an important pathogen on potatoes grown in the study area. Five of 22 commercial and local potato cultivars evaluated for their reaction toR. solani AG-3 isolates (TP-2) under greenhouse conditions were highly resistant; the remaining cultivars exhibited different levels of susceptibility to the pathogen isolate. http://www.phytoparasitica.org posting July 14, 2005.     

云南小麦条锈菌群体对18个抗条锈近等基因系的毒性分析

为监测云南省小麦条锈菌群体毒性及小麦抗条锈基因的有效性动态,2016年采用18个抗条锈近等基因系鉴别寄主对云南省9个州市的136个小麦条锈菌株进行毒性分析,并按八进制法对小种进行命名。结果表明,云南省小麦条锈菌群体毒性丰富,共鉴定出64个小种类型,其中居于前2位的小种是550273和550073,出现频率分别为28.68%和11.76%,是本年度优势小种;其它小种出现频率均在4.41%以下,为次要小种。条锈菌群体对Yr5、Yr10、Yr15、Yr32四个抗条锈基因的毒力频率均为0,对Yr24、Yr Tr1、Yr8、Yr17四个抗条锈基因的毒力频率在0.74%~11.76%之间,表明这8个基因是云南省当前有效的抗条锈基因;对Yr27的毒力频率为52.94%,对Yr1、Yr6、Yr7、Yr9、Yr43、Yr44、Yr SP、Yr Exp2、Yr Tye九个抗条锈基因的毒力频率为77.94%~91.91%,表明这10个抗条锈基因的抗性已减缓或丧失,说明这些基因在云南省已失效。     

Adult-plant resistance to yellow rust in wild emmer wheat

Seventy-six entries of wild emmer, susceptible to a culture of yellow rust, race 39E134, in the seedling stage at a low temperature-profile, were tested with the same culture for field resistance at two locations in the Netherlands. While most entries were susceptible also in the adult-plant stage, 15 showed an intermediate or resistant infection-type in Flevoland and 18 at Wageningen. In subsequent seedling tests at low and high temperature-profiles, including 20 entries which at either of the two locations had displayed field resistance, 16 entries were shown to possess temperature-sensitive genes, whereas four appeared to have true host stage-bound adult-plant resistance.Samenvatting Voor dit onderzoek werden 76 herkomsten van wilde emmer tarwe (Triticum dicoccoides Körn.) geselecteerd op basis van vatbaarheid voor gele roest (Puccinia striiformis Westend f. sp.tritici) in het kiemplantstadium. In een veldtoets met hetzelfde gele roest isolaat (fysio 39E134) werd de reaktie in het volwassenplantstadium bepaald. Deze toets werd in Wageningen in een plastic kas uitgevoerd en in Flevoland in een geïsoleerd veld.In Flevoland vertoonden 15 herkomsten een intermediaire of resistente reaktie, in Wageningen werd dit bij 18 herkomsten waargenomen. Om na te gaan of de waargenomen veldresistentie mogelijk berust op temperatuurgevoelige genen, werd de resistentie vergeleken bij hoge en lage temperatuur. Van de 20 herkomsten, die resistentie vertoonden in de veldtoets in Wageningen of in Flevoland, bleken er 16 temperatuurgevoelige resistentiegenen te hebben. Vier herkomsten lijken echte, stadium afhankelijke, volwassenplantresistentie te vertonen.     

Evaluation of morphology of infection structures in distinguishing between different Allium rust fungi

Three cultivars of white cabbage with different levels of resistance toMycosphaerella brassicicola were tested for seedbed infection. Seedlings grown in seedbeds, to which infected plant debris was added as an inoculum, showed typical ring spot lesions on the cotyledons and first two leaves before seedlings reached the transplanting stage, whereas non-inoculated controls had few lesions only. Differences in levels of resistance between cultivars were present in seedlings grown under field conditions. Disease severity of transplants at the end of the season reflected disease severity of seedlings before transplanting in each cultivar.To lower the risk of a severe epidemic of ringspot at the end of the growing season, the seedbed should be protected from infection byM. brassicicola.     

Susceptibility of Broccoli Cultivars to Bacterial Head Rot: In Vitro Screening and the Role of Head Morphology in Resistance

Head rot is a major disease of broccoli caused by the soft rot pathogens Pseudomonas fluorescens and Erwinia carotovora. Two in vitro pathogenicity tests were evaluated as a methods to identify broccoli cultivars susceptible or resistant to bacterial head rot. One test used mature heads excised from the plant and inoculated with squares of cotton lint which had been soaked in a bacterial suspension. The other test involved stab-inoculating axenically grown seedlings. With the excised head test, susceptible cultivars showed a black soft rot, whilst less susceptible or moderately resistant cultivars showed only watersoaking, or browning and slight softening of the tissue. No cultivar was completely resistant. Ten cultivars were tested, and their susceptibility ratings corresponded with previously recorded field data, with one exception. This laboratory test could be used to screen for susceptibility to head rot in broccoli breeding programmes. The seedling test distinguished differences in aggressiveness among bacterial isolates but not cultivar susceptibility. Increasing head size correlated negatively with disease resistance. Head shape, i.e. cultivars which showed a domed shape rather than a flat shape, was positively correlated with disease resistance. Thus small domed heads are more resistant to head rot than large flat heads. Other morphological characteristics, viz. floret prominence and number, and sepal stomatal number were not correlated with host resistance.     

Germination and appressorium formation of wheat leaf rust on susceptible,partially resistant and resistant wheat seedlings and on seedlings of other Gramineae

Germination and appressorium formation of wheat leaf rust urediospores were studied in two experiments. No consistent differences could be detected between 11 genotypes of wheat (Triticum aestivum), two of barley, one ofTriticum dicoccum, one ofT. dicoccoides, one ofT. boeoticum and one ofAegilops squarrosa. Host genotypes and non-hosts gave similar results, suggesting that the phases before penetration of the host leaf are not affected by the resistance mechanisms operating in hosts and non-host genotypes.Samenvatting Kieming en de vorming van appressoria is bestudeerd in twee experimenten. Er zijn geen systematische verschillen waargenomen tussen 11 genotypen van tarwe, twee van gerst, een vanTriticum dicoccum, een vanT. dicoccoides, een vanT. boeoticum en een vanAegilops squarrosa. Waard en niet-waard genotypen gaven overeenkomstige resultaten, dit suggereert dat de fasen voor penetratie van het gastheerblad niet beïnvloed worden door de resistentiemechanismen werkzaam in waard en niet-waard.     

不同小豆抗性品种对锈菌侵染的生化响应和防卫反应基因的表达特征

为探究小豆应答锈菌侵染的生理机制,以不同小豆抗性品种与豇豆单胞锈菌Uromyces vignae互作为研究对象,采用紫外分光光度法和实时荧光定量PCR技术分析锈菌侵染后不同抗性品种中防御酶活性及防卫反应基因表达的变化特征。结果表明,接种豇豆单胞锈菌后小豆抗病品种叶片内过氧化氢酶(catalase,CAT)、超氧化物歧化酶(superoxide dismutase,SOD)、过氧化物酶(peroxidase,POD)和多酚氧化酶(polyphenol oxidase,PPO)活性均比感病品种显著提高;接种192 h后,小豆抗病品种中CAT和SOD活性最高,分别为16.93 nmol·g^-1·s^-1和950.89 U/g,较对照提高了496.13%和89.61%,小豆感病品种中CAT和SOD活性分别在接种192 h和120 h后达到峰值,分别为10.54 nmol·g^-1·s^-1和884.51 U/g,较对照增加了256.08%和55.50%,增加幅度小于抗病品种;接种12 h后,小豆抗病品种和感病品种...     

Production,characterization and interaction of single-spore isolates ofPlasmodiophora brassicae

Out of 164 plants of clubroot-susceptible Chinese cabbage inoculated with single resting spores ofPlasmodiophora brassicae, two plants developed clubroot symptoms. The two single-spore isolates (SSIs) extracted from these plants gave an identical reaction pattern on the European Clubroot Differential set (ECD) and seven doubled-haploid lines (DH-lines). Their reaction pattern differed from that of the original field isolate on four hosts: ECD hosts 06 and 07 were susceptible to the field isolate but resistant to both SSIs, while for DH-lines Bi and Pt the reverse was true. DH-line Pt was significantly less diseased by mixed inocula consisting of the field isolate and SSI-1 than by SSI-1 alone. It was concluded that the SSI-1 pathotype was a minor component of the field isolate, although it was isolated twice. The results also suggest that the alleviating effect of the field isolate in mixed inoculations with SSI-1 on DH-line Pt was due to induced resistance, rather than to competitive interactions.Abbreviations cv cultivar - DH-line doubled haploid line - ECD European Clubroot Differential set - SSI single-spore isolate     

The use of host resistance in disease management of rust in common bean

Bean rust, caused by Uramyces appendiculatus, is one of the major diseases in dry and snap bean production world-wide. Numerous advancements in disease management have been made to reduce rust losses. Host resistance is an important component of rust management. However, durability of disease resistance has often been short due to the use of single genes for resistance interacting with extremely high virulence diversity of the bean rust fungus. The challenge to increase durability of resistance has led to strategies such as gene pyramiding of race-specific resistance, selection and use of partial resistance, and investigation and discovery of leaf morphological features that may slow the rust epidemic. Germplasm with multiple sources of rust resistance has been developed in specific bean seed classes and released for public and commercial use in intensive production systems such as those in the United States. However, progress to develop rust resistant germplasm for the subsistence agriculture of Latin America and Africa where intercropping and mixed cultivars dominate the production system has been slow. Incorporation of high yielding, disease-resistant components as partial replacement in farmer's mixtures has the potential to reduce severity in the crop and increase yield in the presence of rust. This strategy would not erode the genetic diversity that is historically known to enhance resistance durability and for many years has given stability in production in the subsistent agriculture systems.     

蚕豆和豌豆锈病病原菌的分子鉴定

为明确我国热带和亚热带地区蚕豆Vicia faba和豌豆Pisum sativum锈病的病原菌种类,通过致病性测定和ITS序列系统发育分析对来自我国云南省玉溪市的4份豌豆锈菌分离物及云南、广西、重庆和四川省(区、市)的5份蚕豆锈菌分离物进行系统鉴定。结果显示,分离自豌豆的锈菌WX1分离物对蚕豆和豌豆均具有高致病性,在侵染叶片上产生大量锈子器;分离自蚕豆的锈菌CX3分离物仅对蚕豆具有高致病性,能在叶片上产生大量夏孢子,而对豌豆的致病性相对较低,仅产生少量的夏孢子堆;分离物WX1和CX3对小扁豆和鹰嘴豆不具有致病性。基于ITS序列系统发育分析表明,所有不同寄主来源的蚕豆单胞锈菌分离物均聚类于一个系统发育组,但分离自蚕豆和豌豆的分离物分别聚类在不同的亚组。表明分离自云南省玉溪市豌豆上的蚕豆单胞锈菌Uromyces viciae-fabae应为豌豆专化型,定名为U. viciae-fabae ex P. sativaum,而来源于云南、广西、重庆和四川省(区、市)的蚕豆锈病病原菌为蚕豆专化型U. viciae-fabae ex V. faba。     

杂交籼稻新组合抗旱性鉴定评价及预测研究

为探索有效鉴定、评价及快速预测杂交籼稻新组合抗旱性的指标和方法,选择10个杂交籼稻新组合和1个对照品种为材料,采用盆栽试验进行正常水分和干旱处理。综合分析干旱胁迫条件下水稻产量及相关农艺性状的变化差异,借助产量抗旱系数、模糊数学隶属函数、抗旱性综合评价D值对杂交籼稻新组合抗旱性进行鉴定和评价,并通过主成分分析(PCAM)、相关分析(CAM)和逐步回归分析(SRM)进行抗旱指标筛选。结果表明:不同杂交籼稻新组合间抗旱能力存在显著差异,通过抗旱性综合评价D值聚类分析得出C8—沪旱7A/成旱恢30241属于强抗旱型,C_1—沪旱7A/Z4R(Si)、C_2—沪旱7A/成恢177、C_7—沪旱7A/成旱恢30248、C_9—沪旱7A/成旱恢31708和C_(10)—沪旱7A/成旱恢30218属于抗旱型,C_3—沪旱7A/成恢178、C_4—沪旱7A/成旱恢31701和C_5—沪旱7A/成旱恢31704属于中间类型,冈优725(对照品种)和C_6—沪旱7A/成旱恢31621属于不抗旱型;有效穗数、单穗实粒重和结实率的相对值可作为鉴定与评价杂交籼稻抗旱性的重要综合指标;利用逐步回归构建水稻材料抗旱性预测模型D=(245.231+1.645X_2+2.712X_4+6.494X_6+19.401X_7-2.791X_(10))×10~(-3)能准确、快速预测杂交籼稻新组合抗旱能力(其中:D为供试材料的抗旱综合评价D值,X_2、X_4、X_6、X_7和X_(10)分别为水稻干旱胁迫下有效穗数、单穗实粒数、单穗总粒重、单穗实粒重和千粒重的相对值)。     

Sensitivity to iprodione and boscalid of Sclerotinia sclerotiorum isolates collected from rapeseed in China

Baseline sensitivity of Sclerotinia sclerotiorum, causal agent of stem rot of rapeseed, to a dicarboximide fungicide iprodione was determined using 50 isolates (historic population) collected in 2001 from the rapeseed fields without a previous history of dicarboximide usage. The 50% effective concentration (EC₅₀) values to iprodione of these wild-type isolates ranged from 0.163 to 0.734 μg/ml with a mean of 0.428 μg/ml. In 2007 and 2008, 111 isolates (current population) were collected from rapeseed fields with 4–5 years of iprodione application. The EC₅₀ values of these 111 isolates ranged from 0.117 to 0.634 μg/ml. The historic and current populations were not significantly (P > 0.05) different in sensitivity to iprodione. The EC₅₀ values of these 161 isolates to a carboxamide fungicide boscalid ranged from 0.002 to 0.391 μg/ml with a mean of 0.042 μg/ml. In the laboratory, three iprodione-resistant (IR) isolates HA17-IR, SZ31-IR, and SZ45-IR were induced from wild-type isolates HA17, SZ31, and SZ45, respectively. The EC₅₀ values of the IR isolates were 200-fold higher than those of the original wild-type parents. The IR isolates showed an increase in osmotic sensitivity. The IR isolate HA17-IR lost its ability to produce sclerotia, and showed a significantly lower virulence on rapeseed leaves than its parent isolate HA17. In contrast, the IR isolate SZ31-IR had a significantly higher virulence than its wild-type parent SZ31. PCR assays showed that the partial two-component histidine kinase (os-1) gene, which is the putative target gene of iprodione, was deleted in the low virulent IR isolate HA17-IR. DNA sequence analysis showed that each of the other two IR isolates SZ31-IR and SZ45-IR had two point mutations in their partial os-1 genes. These results indicate that the mutations in os-1 gene may be associated with dicarboximide sensitivity, sclerotial development, and virulence in S. sclerotiorum.     

宁夏回族自治区和浙江省光肩星天牛对柳属植物的寄主适应性

为解析光肩星天牛Anoplophora glabripennis在宁夏回族自治区和浙江省对金丝垂柳Salixbabylonica×S.alba-vitellina和旱柳S.matsudana的为害差异,通过代谢组学分析2种柳树木质部次生代谢产物的差异,利用16S rDNA测序技术检测来自2个地区的光肩星天牛幼虫在取食原生地寄主后肠道细菌群落的组成,测定其肠道消化酶、解毒酶和保护酶的活性,并将2种柳树的次生代谢产物分别与光肩星天牛肠道细菌及肠道酶进行Spearman相关性分析。结果表明,在金丝垂柳和旱柳木质部中共筛选出26种抗虫性差异代谢产物,其中苯甲酸及其衍生物、肉桂醛、吲哚及其衍生物和有机氮化合物在旱柳样本中含量更高;而黄酮类化合物、芪类化合物、咪唑并嘧啶和二嗪则在金丝垂柳样本中含量更高。以旱柳为食的幼虫肠道优势菌属为肠球菌属Enterococcus、拉乌尔菌属Raoultella、肠杆菌科未确定属、假单胞菌属Pseudomonas、肠杆菌属Enterobacter和纤维单胞菌属Cellulomonas;以金丝垂柳为食的幼虫肠道优势菌属则为拉乌尔菌属和Gibbsiella。取食旱柳的幼虫肠道中外切β-1,4-葡聚糖酶、羧酸酯酶、谷胱甘肽S转移酶和细胞色素P450酶的活性均显著高于取食金丝垂柳幼虫。金丝垂柳中黄酮类化合物含量高且变量投影重要性分析值较大,推测能被肠道内优势菌属拉乌尔菌属和Gibbsiella有效代谢,因此解毒酶活性处于较低水平,且拉乌尔菌属和Gibbsiella大量增殖;在取食旱柳的幼虫肠道中没有能有效代谢苯甲酸及其衍生物和肉桂醛等化学物质的细菌群落存在,从而引起解毒酶活性显著提升以减少受到的毒害作用。表明在光肩星天牛适应寄主植物的过程中,其肠道细菌在对寄主次生代谢产物的代谢过程中发挥着重要作用。     

Comparison of the Susceptibility of Quercus petraea, Q. robur and Q. rubra to Collybia fusipes

Collybia fusipes is the cause of a root rot of Quercus petraea (sessile oak), Q. robur (pedunculate oak) and Q. rubra (red oak). This parasite is often reported to cause problems in stands of red oaks and field evidence suggests that this North American oak species is more susceptible than the two European oak species. Young saplings of the three oak species and of chestnut, Castanea sativa, in the glasshouse, and also mature sessile and red oaks growing in the same stand were inoculated with C. fusipes to compare their susceptibility. Red oak, both as young seedlings and mature trees, was more susceptible to C. fusipes than sessile oak. Chestnut seedlings were as susceptible as sessile oak. Susceptibility of pedunculate oak seedlings was intermediate between red oak and sessile oak. In one experiment this species was significantly less susceptible than red oak, and in the other it was as susceptible.     

Mendelian inheritance of rust resistance to Melampsora larici‐epitea in crosses between Salix sachalinensis and S. viminalis

Two F₁, two F₂ and two backcross (BC) full‐sib families of Salix sachalinensis × S. viminalis were tested for resistance to two pathotypes of Melampsora larici‐epitea in leaf‐disc inoculation experiments. Two single‐pustule isolates, VM and ST, belonging to pathotypes LET1 and LET5, respectively, were used in the tests. Disease was scored based on the number of uredinia, uredinial diameter and inoculum densities. Both F₁ families were completely resistant to both VM and ST. Resistance to VM segregated at a 9:6:1 ratio in the F₂ families and at a 1:2:1 ratio in the BC families, suggesting that two independently segregating genes controlled rust resistance, with resistance dominant over susceptibility. This also indicates incomplete dominance of the resistance alleles over the susceptibility to VM. For ST, the equivalent ratios were 3:1 and 1:1, showing that a single dominant gene was responsible for rust resistance. The broad sense heritabilities were >0·91 for uredinial diameter and 0·1–0·33 for the number of uredinia. There were significant overall correlations between data from inoculations with VM and those from inoculations with ST in the number of uredinia, uredinial diameter and disease scores (Spearman’s rank correlation coefficients = 0·31–0·75).