Effects of UV-B radiation intensity and timing on epidemiological components of wheat stripe rust

Stripe rust caused by Puccinia striiformis f. sp. tritici is an important wheat disease worldwide that is greatly influenced by environmental conditions. Ultraviolet B (UV-B) radiation is one important environmental factor affecting the occurrence and epidemiology of wheat stripe rust. Investigating UV-B radiation effects on the epidemiology of stripe rust may be conducive to monitoring and predicting this disease. In this study, wheat seedlings were exposed to UV-B radiation during different periods under laboratory conditions and radiation effects on epidemiological components of wheat stripe rust were investigated. Results showed that incubation period was shortened, and the infection efficiency, sporulation quantity and disease index increased when UV-B radiation was performed only pre-inoculation. When the UV-B radiation was performed only post-inoculation or both pre- and post-inoculation, the incubation period was prolonged, and the infection efficiency, sporulation quantity and disease index were reduced. When healthy wheat seedlings were inoculated using urediospores collected from wheat leaves irradiated by UV-B only post-inoculation or both pre- and post-inoculation, infection efficiency, sporulation quantity and disease index were also reduced. However, in the latter, the disease incubation period did not differ under varying UV-B radiation intensities compared to that when wheat leaves were not treated with UV-B radiation. Overall, the effects of direct exposure of wheat plants to UV-B radiation with different intensities in different periods on epidemiological components of wheat stripe rust were systematically explored, and the results suggest that the effects of UV-B radiation increased gradually with the increase of UV-B radiation intensity. This information provides a basis for monitoring and predicting this disease as well as for conducting further studies on pathogen virulence variation.     

331份四川小麦品种(系)在甘肃陇南抗条锈性表现及利用价值

2014年-2017年度先后对331份四川省小麦生产品种(系)在温室进行苗期人工接种条锈菌混合菌鉴定和甘谷试验站大田成株期分别接种CYR32、CYR33、CYR34、G22-14、中4-1和混合菌鉴定,同时在甘谷试验站和汪川良种场两地进行自然诱发鉴定。结果发现:在人工接种条件下,苗期、成株期表现抗病的分别有‘XK201465’等36份和‘XK20132’等72份材料,分别占10.88%和21.75%;有‘XK62483’等11份材料全生育期表现抗病,占3.32%;两地三年自然诱发鉴定发现,仅有‘XK20132’等5份材料在两地均表现抗病,有‘川农17’等30份材料具有慢条锈性。对供鉴材料在甘肃陇南的利用前景进行了分析。     

复合高效配方药剂对甘蔗褐条病防控效果评价

为了筛选防控甘蔗褐条病的复合高效配方药剂及精准施药技术,选用多菌灵、苯菌灵、百菌清、嘧菌脂、吡唑醚菌脂、苯甲嘧菌酯进行田间药效试验。结果表明,（50%多菌灵可湿性粉剂1500 g+75%百菌清可湿性粉剂1500 g+磷酸二氢钾2400 g+农用增效助剂300 mL）/hm²、（50%苯菌灵可湿性粉剂1500 g+75%百菌清可湿性粉剂1500 g+磷酸二氢钾2400 g+农用增效助剂300 mL）/hm²和（25%吡唑醚菌脂悬浮剂600 mL+磷酸二氢钾2400 g+农用增效助剂300 mL）/hm²等3个配方药剂对甘蔗褐条病均具有良好的防治效果,其病指均在14.02以下,防效均达84.41%以上。本研究显示3个配方药剂是防控甘蔗褐条病理想的复合高效配方药剂,可在7—8月人工和无人机飞防叶面喷施,7~10天喷1次,连喷2次。     

Banishing barberry: The history of Berberis vulgaris prevalence and wheat stem rust incidence across Britain

Wheat stem rust, caused by the fungus Puccinia graminis f. sp. tritici (Pgt), is a notoriously damaging disease of wheat and barley. Pgt requires two hosts to complete its lifecycle; undergoing asexual reproduction on cereal crops and completing sexual reproduction on Berberis spp. The latter stage of its lifecycle is of particular importance in temperate regions such as western Europe, where asexual urediniospores are unable to survive cold winter weather. In the past, the crucial role of Berberis in the lifecycle of stem rust led to intensive eradication campaigns, initially carried out by farmers in the face of hostile scientific opinion. In the United Kingdom, common barberry (Berberis vulgaris) is today a relatively rare plant. Stem rust is, however, currently experiencing a resurgence; at the same time, there has been a general increase in the prevalence of barberry and an upsurge in its planting which, in the United Kingdom, is associated with attempts to encourage the endangered barberry carpet moth (Pareulype berberata). This article situates current developments within a broader chronological framework, examining changing attitudes towards barberry and rust in England in the past and the history of the plant's use and cultivation. It assesses how widespread B. vulgaris really was in the environment historically, and thus the scale of its eradication. We suggest that Berberis was never widely established as an archaeophyte in the United Kingdom. Current attempts to re-establish it are based on a misunderstanding of the plant's historical status and could potentially pose a serious threat to food security.     

Regional and temporal differentiation of virulence phenotypes of Puccinia triticina from common wheat in Russia during the period 2001–2018

Leaf rust, caused by the fungus Puccinia triticina, is one of the most damaging rust diseases of wheat in Russia. Populations of P. triticina were monitored in seven regions of Russia from 2001 to 2018, with a total of 5,191 single urediniospore isolates from bread wheat (Triticum aestivum) being analysed. Populations have changed significantly in all regions since 2012, after 2 years of drought (2010–2011). Regional collections of P. triticina were also significantly different between the two periods 2001–2009 and 2012–2018, with changes along two geographic gradients from West Siberia to the north-west and south-west (North Caucasia) of the European part of Russia. All tested isolates were avirulent to resistance gene Lr9 in 2001–2009 but, since 2010, virulence to Lr9 has occurred and annually increased in the Asian part of Russia (Ural and West Siberia) due to deployment of cultivars with the Lr9 gene. Virulence to Lr2a and Lr15 was considerably lower in Dagestan (6%–33%) and all European regions (35%–67%) than in Asian regions (84%–96%). During 2001–2009, virulence on Lr1 was also lower in Dagestan (33%) and the European regions (50%–77%) than in Asia (91%–96%); however, by 2012–2018, nearly all isolates were virulent on Lr1. Remarkable changes were observed in frequencies of P. triticina races defined by their virulence/avirulence to Lr1 and Lr2a genes. We postulate the P. triticina population in Dagestan is specific to that area and pathogen populations in European and Asian parts of Russia are distinct.     

褪黑素诱导小豆抗锈病机理的初步研究

为明确外源褪黑素诱导小豆抗锈性的作用及机理,以感病小豆品种‘宝清红’为材料,采用叶面喷施不同浓度褪黑素激发处理小豆真叶,而后对真叶挑战接种锈菌夏孢子,结果表明,低浓度(11.61 mg/L)褪黑素可显著提升小豆对锈病的抗性。夏孢子萌发试验表明,褪黑素对夏孢子萌发及芽管生长无显著抑制作用,表明褪黑素无抑菌活性。进一步的基因表达分析发现,与对照相比,褪黑素激发诱导了水杨酸(SA)通路关键基因NPR1于接种后24 h显著上调表达,且病程相关蛋白PR1、几丁质酶(CHI)、β-1,3-葡聚糖酶(GLU)及PR5均于接种后24～120 h被显著诱导表达,说明褪黑素可能通过诱导NPR1表达,进而激活下游PR蛋白的高水平应答,使感锈病小豆品种获得对锈病的抗性。     

Impact of Austropuccinia psidii in New Caledonia,a biodiversity hotspot

Myrtle rust, caused by the fungus Austropuccinia psidii, infects a wide range of host species within the Myrtaceae family worldwide. Since its first report in 2013 from New Caledonia, the extent of the host range, geographical distribution and genetic diversity of A. psidii in this territory have been unknown. This study reports 67 new host species distributed in 13 different Myrtaceae genera, including five new genera. The pathogen was found in various types of plant communities, where Myrtaceae species are the dominant or codominant species, as well as in several nurseries. It is now considered a significant threat to the biodiversity of ecosystems and the Myrtaceae‐related economy. A 3‐year disease monitoring trial with 35 cultivated Myrtaceae species showed variations in disease severity at the species and individual scales. This suggests that some level of genetic resistance to myrtle rust may possibly exist among the endemic Myrtaceae of New Caledonia. A population genetic investigation revealed that only one single genotype of A. psidii occurs across its entire host range in New Caledonia. Therefore, it is essential to carry out population genetic surveillance to identify the appearance of mutations or the introduction of potentially more virulent genotypes of A. psidii. The outcomes from this study will assist with the ongoing management of the disease in New Caledonia.     

寄生橡胶树叶上的头孢藻

由头孢藻引起的藻斑病在世界各国热带和亚热带地区的很多植物物种上均有报道。弄清寄生橡胶树叶上寄生藻的种类、为害症状以及不同橡胶树品系和环境对寄生藻发生为害的影响，为橡胶树藻斑病防治提供参考依据。通过田间调查、观察其为害特性症状；采集藻斑病标本，切片显微观察寄生藻在宿主组织内和表面的寄生习性；提取寄生藻的DNA，分析比对其核糖体小亚基基因序列。结合寄生藻的形态和核糖体小亚基(18S rRNA)基因序列分析结果，将本研究发现的橡胶树藻类叶斑病原物鉴定为茂盛头孢藻，这是首次在我国大陆橡胶树上发现由该寄生藻引起的橡胶树叶斑病。结果表明，种植于不同坡向、相同品系的橡胶树受害程度不一样，种植在阴坡的病害级别要高于阳坡的；同一株橡胶树上层树冠叶受害最轻，下层树冠叶受害最重；相比较而言橡胶树品系云研272较为抗病。