Genetic Models of Host–pathogen Gene Interaction Based on Inoculation of Loblolly Pine Seedlings with the Fusiform Rust Fungus

Loblolly pine (Pinus taeda) seedlings from 12 full-sib families obtained from a six-parent half diallel mating design were challenged in a greenhouse using two basidiospore inocula of the fusiform rust fungus (Cronartium quercuum f.sp. fusiforme) at extremely high spore density. Each basidiospore inoculum originated from a mixed gall collection of aeciospores obtained from field-infected trees. Assessments at 4.5 months after inoculation showed that rust disease levels were high for every full-sib family and were typically above 90% for most full-sib families for both inocula. However, disease (% galled) for family E by A progeny, even at 9 months post inoculation, was lower, around 75%. A genetic model for interaction of two pairs of genes was proposed to explain the observed infection levels (% galled) in this diallel based on a gene-for-gene hypothesis. The putative genotypes of host parents and virulence compositions of mixed inocula were postulated. A bulk-segregant analysis approach based on phenotype (gall vs. no gall) was used to search for dominant molecular markers associated with the potential resistance genes in the host parents. A few candidate marker polymorphisms were observed between the gall vs. no gall bulks; however, none of the candidates appropriately co-segregated with phenotype when tested across the progeny set. An alternative model involving recessive resistance controlled by a single locus was also considered, but as with the two gene model, no markers to support the appropriateness of the recessive resistance model were observed.     

Effects of heavy metals and acid irrigation on the birch rust,Melampsoridium betulinum

Effects of simulated acid rain and heavy metals on the occurrence of Melampsoridium betulinum in naturally infected mountain-birch trees and seedlings (Betula pubescens subsp. tortuosa) were studied in a subarctic area where background polution levels are low. The short term (2 years) effects of copper, nickel and sulphuric acid, and long term (8 years) effects of nitric- and sulphuric-acid deposition on birch-rust infection were determined.     

Aster albescens Rust Caused by Aecidium asterum and Its Hyperparasitic Fungus Tuberculina persicina

Aster albescens is a medicinal plant. The rust caused by Aecidium asterum is a new record in China and an important disease of A. albescens in Feng Tong-zhai national reservation area. The percentages of diseased plant and the diseased leaf reach 100 and 28% respectively when the disease is serious. The disease results in leaf spot and leaf cast. Tuberculina persicina is a natural hyperparasite of A. asterum and is firstly reported in the world. The hyperparasite attacks aecium of A. asterum and hinderes the release of aeciospores. The symptom of the rust and the morphological characteristics of A.asterum is reported. The hyperparasitism of A. asterum and the morphological characteristics of the Tuberculina persicina are also reported.     

不同袋型果袋套袋对“翠冠”梨果实品质的影响

[目的]研究3种袋型果袋套袋对＂翠冠＂梨（Pyrus pyrifolia‘Cuiguan’）果实品质的影响。[方法]3种袋型分别为＂外黄内白＂、＂外花内黑＂和＂外黄内黑＂3种袋型。[结果]与对照（不套袋）相比,＂外黄内白＂袋处理果实基本能保持原有果面绿色和风味,而＂外花内黑＂袋和＂外黄内黑＂袋处理果实果面呈现黄白色,果实风味变淡;＂外黄内白＂、＂外花内黑＂和＂外黄内黑＂3种果袋处理都极显著减少果面锈斑的产生,其锈斑指数分别为25.5、55.5、82.8,其中＂外黄内白＂袋效果最为明显;＂外黄内白＂袋处理果实硬度极显著下降,而＂外花内黑＂和＂外黄内黑＂袋处理果实硬度则极显著升高,其中,＂外黄内白＂、＂外花内黑＂和＂外黄内黑＂3种果袋处理果实硬度分别为6.30、7.34、7.05 kg/cm2,对照为6.65 kg/cm2。＂外黄内白＂、＂外花内黑＂和＂外黄内黑＂3种果袋处理果实可溶性固形物和可溶性糖含量都极显著下降,可溶性固形物分别为10.85%、12.93%、12.43%和13.90%,可溶性糖含量分别为4.43%、4.30%、5.19%和6.33%。＂外黄内白＂、＂外花内黑＂和＂外黄内黑＂3种果袋处理和对照间可滴定酸含量无明显差异,其可滴定酸含量分别为0.57%、0.48%、0.41%和0.56%。与对照相比,＂外黄内白＂、＂外花内黑＂和＂外黄内黑＂3种果袋处理果实VC含量显著下降,分别为54.61、55.10、55.10 mg/kg。[结论]综合来看,＂外黄内白袋＂是生产绿色无锈＂翠冠＂梨的理想果袋。     

甘南玛曲高寒草地蒲公英锈病初步调查研究

[目的]探索蒲公英锈病的发生规律,寻求最佳的病害防治措施。[方法]对甘南玛曲不同季节和不同海拔的蒲公英锈病发生情况进行初步调查,对其病害症状进行描述,对病原进行鉴定,并对冬孢子的形态进行光学显微镜和扫描电镜表面超微结构拍照。[结果]蒲公英锈病的病原菌为山柳菊柄锈菌,冬孢子双胞,表面光滑。地形对蒲公英感病率有影响,随着海拔的升高,蒲公英锈病发病率和病情指数呈明显降低趋势。海拔每升高100m,其发病率和病情指数分别平均降低17．6％和16．2％。较高的温度、湿度和光照条件可以促进蒲公英锈病的发生与蔓延。[结论]该研究为蒲公英病害致病机理的研究提供了理论依据。     

甘肃省药用植物锈病调查与病原鉴定

2004年以来,对甘肃省的92种药用植物锈病进行了调查和病原鉴定,发现有13科14种药用植物感染锈菌。     

我国冷季性草坪草锈病的研究进展

锈病是冷季性草坪草上的重要病害之一,近年来在我国发生较为普遍。本文较系统的总结了我国冷季性草坪草锈病的分布与危害、症状类型与特点、病原种类以及病害发生规律,并对草坪草锈病的防治方法进行了较为详细的介绍。     

30％龙灯福连悬浮剂对冬枣主要病害的防治效果研究

[目的]研究30％龙灯福连悬浮剂对冬枣抗病性的影响。[方法]试验设30％龙灯福连悬浮剂和常规真菌药剂2个处理,以喷施清水为对照,研究啧施30％龙灯福连悬浮剂对冬枣主要真菌病害的防治效果。【结果】喷施杀菌剂30％龙灯福连悬浮剂,冬枣树褐斑病、青癍病和锈病的病叶率分别为0～0．43％、0．55％～1．12％、0,校正防效分别为95．92％～100％、98．15％～99．11％、100％,与对照差异显著。[结论]30％龙灯福连悬浮剂对褐斑病、青斑病、枣锈病的病害防治效果显著,而且省工、省时,可作为防治冬枣真菌性病害药剂。     

唐松草作为小麦叶锈菌的转主寄主问题的研究

 1984年在内蒙古卓资县白石头沟野外调查中发现4种唐松草和5种禾本科杂草都发生有叶锈病。但无迹象表明该地区自然界唐松草上发生的叶锈病与小麦叶锈病有关。在室内用小麦、华北剪股颖和无芒雀麦叶锈菌的冬孢子对亚欧和瓣蕊唐松草接种,都长出了锈孢子腔和锈孢子。用三种锈孢子分别对小麦、华北剪股颖和无芒雀麦回接,都产生了夏孢子,完成了生活循环。从此得出结论:亚欧和瓣蕊唐松草是小麦、叶锈菌的转主寄主,但在室外不起作用。而田间所见唐松草上的锈病主要与杂草上的锈病有关。