34份甘蔗栽培原种抗褐锈病性鉴定及Bru1基因的分子检测

明确甘蔗栽培原种对黑顶柄锈菌的抗性水平,了解Bru1基因在甘蔗栽培原种资源中的分布状况,可以帮助筛选甘蔗原种抗源种质,提高抗褐锈病育种效率。本研究于2013年对中国国家甘蔗种质资源圃保存的34份甘蔗栽培原种进行苗期抗褐锈病鉴定和抗褐锈病基因Bru1的分子检测。苗期抗性鉴定结果表明,34份供试材料中,1级高抗至3级中抗的有26份,占76.5%。其中13份材料表现1级高抗,占38.2%,6份材料表现2级抗病,占17.6%,7份材料表现3级中抗,占20.6%。分子检测结果显示:34份供试材料中25份抗病材料含有抗褐锈病基因Bru1,出现频率为73.5%;其余1份抗病材料和8份感病材料不含抗褐锈病基因Bru1。本研究结果显示了中国国家甘蔗种质资源圃保存的甘蔗栽培原种资源中褐锈病抗性主要由Bru1控制,这一发现为利用Bru1防治由黑顶柄锈菌引起的甘蔗褐锈病提供了重要信息和参考依据。     

甘蔗野生种质资源抗褐锈病基因Bru1的分子检测

在甘蔗栽培品种‘R570’上发现和定位的甘蔗抗褐锈病主效基因Bru1对世界上不同国家和不同地区的黑顶柄锈菌具有广谱抗性。针对该基因开发的两个分子标记能有效、稳定地检测和筛选含有该基因的种质资源。为筛选甘蔗野生种抗源种质,利用R12H16和9O20-F4两个标记对云南农业大学甘蔗种质资源圃保存的部分野生种质资源进行抗褐锈病基因Bru1的分子检测,包括割手密96份、蔗茅15份、滇蔗茅1份、斑茅11份、河八王4份、金茅2份、五节芒9份,共计138份。结果表明,有7份割手密含抗褐锈病基因Bru1,占参试材料的5.1%。本研究为甘蔗的转基因育种和抗褐锈病杂交育种提供优良抗源材料,为进一步开展甘蔗育种研究提供了科学依据。     

31份甘蔗野生核心种质资源褐锈病抗性鉴定及Bru1基因的分子检测

为明确甘蔗野生资源对黑顶柄锈菌的抗性水平,了解Bru1基因在甘蔗野生资源中的分布状况,于2013年对中国国家甘蔗种质资源圃保存的31份野生核心种质资源进行苗期抗褐锈病鉴定和抗褐锈病基因Bru1的分子检测。结果表明,31份供试材料中,高抗(1级)至中抗(3级)的有28份,占90.3%。其中19份材料表现高抗(1级),占61.3%,3份材料表现抗病(2级),占9.7%,6份材料表现中抗(3级),占19.4%。31份供试材料中只有贵州78-2-12、云南97-4、E.rockii95-19、E.rockii 95-20、云南83-224、广西79-8、云南95-35和广西89-13含抗褐锈病基因Bru1,占参试材料的25.8%;其余20份抗病材料和3份感病材料均不含抗褐锈病基因Bru1,表明除Bru1外,可能还有其他抗褐锈病基因存在。结果暗示中国国家甘蔗种质资源圃保存的野生核心种质资源中蕴藏着优良的抗褐锈病基因,是选育抗褐锈病甘蔗品种很有利用前景的抗源种质。     

甘蔗抗褐锈病新基因抗感病池构建及SSR多态性引物筛选

由黑顶柄锈菌(Puccinia melanocephala H. Sydow ＆ P. Sydow)引起的甘蔗褐锈病是危害中国甘蔗生产的主要病害之一。为了鉴定和发掘抗褐锈病新基因,防止褐锈病爆发流行和保证甘蔗安全生产,本研究以杂交组合‘粤糖03-393’× ‘ROC 24’抗感分离真实性F₁代群体为材料,构建抗感基因池,合成449对引物对抗感亲本及抗感基因池进行抗、感连锁SSR分子标记筛选。结果表明,25对引物在抗感亲本间有多态性,其中4对引物(SMC236CG、SCESSR0928、SCESSR0636、SCESSR2551)在抗感亲本及抗感池间有多态性,初步判定这4个SSR标记在染色体上的位点可能与抗褐锈病新基因存在连锁关系。研究结果为后续开展抗褐锈病新基因定位、为中国甘蔗褐锈病防控及抗病育种奠定了良好的基础。     

甘蔗(Saccharum species hybrid)种质资源褐锈病和黄锈病抗性位点分子检测

开展种质资源抗锈病分子检测,对甘蔗筛选抗性资源和抗锈病育种具有重要意义。本研究利用已报道的褐锈病抗性位点Bru1和黄锈病抗性位点G1对中国甘蔗育种中的亲本资源和创新材料进行分析。在164份材料中共检测到‘粤糖07-913’、‘桂糖02-281’、‘赣南05-352’等23份带有Bru1抗性标记的材料,占参试材料的14%。在180份材料中共检测到‘粤糖96-86’、‘桂糖03-8’、‘赣南81-1035’等10份带有黄锈病抗性位点G1的材料,占参试材料的5.56%。‘粤糖96-86’、‘ROC16’、‘ROC22’等6份材料同时带有Bru1和G1位点,可能兼具褐锈病和黄锈病两种抗性。本研究结果可为选择优异抗锈病基因资源,开展杂交育种提供科学依据。     

基于田间表型和Bru1基因检测分析甘蔗褐锈病抗性遗传

由黑顶柄锈菌(Puccinia melanocephala)引起的甘蔗褐锈病具有产孢量大、流行性强的特点, 可导致甘蔗产量和蔗糖分的严重损失, 了解抗病性遗传有助于抗锈病育种中的亲本选择和组合配制, 而有效的抗性鉴定技术则是分离个体选择所必需的。本研究以甘蔗分离群体为材料, 利用表型与抗褐锈病主效基因Bru1检测相结合, 研究甘蔗褐锈病抗性遗传倾向并评价Bru1基因检测与表型抗性的关联性。结果显示, 发病盛期, 感病个体中, Bru1基因未检出率为96.7%, 但未感病个体中, Bru1基因的检出率仅为66.0%, 且高抗组合CP84-1198×云蔗89-7群体中的未感病个体, 该基因检出率为0, 尽管也发现有2个组合的未感病个体中, 该基因的检出率为100%。说明由Bru1基因控制的抗性可根据该基因的检测结果判断其抗/感病性, 同时, 甘蔗基因池中还存在其他未知的控制抗病性状的主效基因。值得强调的是, 父母本的抗病性均影响杂交后代的抗病性, 但以抗病亲本为父本的组合, 其分离群体的感病个体明显减少, 说明父本对杂交后代的褐锈病抗性影响可能更大。     

甘蔗抗褐锈病新基因定位遗传群体的构建

为发掘甘蔗抗褐锈病新基因,本研究以4个高抗褐锈病不含Bru1基因的甘蔗品种为父本,4个高感褐锈病的甘蔗品种为母本配置杂交组合,对获得的5个杂交组合F1代群体进行SSR真实性鉴定、人工接种褐锈病抗性表型鉴定和Bru1基因分子检测。结果显示:‘粤糖03-393’בROC24’和‘柳城03-1137’ב德蔗93-88’的F1代群体分别符合3R:1S和1R:3S的遗传分离比例,且都未检测出Bru1基因;表明‘粤糖03-393’בROC24’群体的褐锈病抗性由一对显性未知新抗病基因控制,而‘柳城03-1137’ב德蔗93-88’群体的褐锈病抗性由一对隐形未知新抗病基因控制。本研究成功构建了2个能用于甘蔗抗褐锈病新基因定位的遗传分离群体,为今后的褐锈病抗性遗传分析,遗传图谱构建和抗褐锈病新基因定位和开发与其紧密连锁的分子标记提供了科学的参考数据。     

云南蔗区首次发现由屈恩柄锈菌引起的甘蔗黄锈病

为明确在国家甘蔗体系云南示范点甘蔗新品种上发生的锈病病原菌种类。采用田间症状观察,结合病原菌形态特征观察及分子生物学方法对20份锈病样品进行病原菌鉴定。鉴定结果表明：来源于云南勐海‘‘海引1号’’的4份甘蔗锈病样品属甘蔗黄锈病,病原菌为屈恩柄锈菌,其核苷酸序列与GenBank中登录的屈恩柄锈菌相应核苷酸序列（GenBank登录号：GU058021和GQ283004—GQ283009）同源性在99.9%以上,并在系统发育树中聚为一簇;来源于云南保山、临沧、勐海其他甘蔗新品种（系）的16份甘蔗锈病样品属甘蔗褐锈病,病原菌为黑顶柄锈菌,它们的核苷酸序列与GenBank中登录的黑顶柄锈菌相应核苷酸序列（GenBank登录号：EU164548,GU058001和JX036025）同源性在99.8%以上,在系统发育树中处于同一分枝。本研究首次在云南蔗区发现由屈恩柄锈菌引起的甘蔗黄锈病。     

甘蔗新品种及主栽品种对褐锈病抗性与Bru1基因分子检测

为明确近年我国各甘蔗育种单位育成的新品种及各蔗区主栽品种对甘蔗褐锈病的抗性,筛选抗褐锈病优良新品种供生产上推广应用,本研究结合全国甘蔗新品种联合区域试验,选择甘蔗褐锈病高发的云南临沧、云南普洱、云南玉溪和广西宜州蔗区,在田间自然发病下,对我国近年来选育的60个新品种和34个主栽品种进行抗性评价,并对抗褐锈病基因Bru1进行分子检测。结果表明,94个新品种及主栽品种中,66个表现高抗到中抗,占70.21%;28个表现为感病到高感,占29.79%。分子检测结果显示,共54个抗病新品种及主栽品种含有抗褐锈病基因Bru1,频率为57.45%。目前大面积种植的桂糖29号、桂糖44号、德蔗03-83、柳城03-1137、粤糖60号、桂糖46号等主栽品种高度感病,而粤甘48号、福农09-2201、桂糖08-120、柳城09-15、中蔗1号、云蔗08-1609、云瑞10-187、中糖1201等31个新品种抗病性强。建议多雨湿润褐锈病高发蔗区,应加大淘汰感病主栽品种和推广应用抗病新品种力度,以期达到品种合理布局,从根本上控制褐锈病暴发流行,为甘蔗产业高质量发展提供安全保障。     

籼型杂交稻亲本稻瘟病抗性基因Pi-ta的分析

检测籼稻骨干亲本的稻瘟病抗性基因Pi-ta,可为抗病育种提供优良的亲本资源。本研究以92份骨干亲本为材料,采用功能基因分子标记检测了92份骨干亲本的Pi-ta基因。结果表明供试的92份材料中,21份携带Pi-ta基因,在供试材料中占22.83%。Pi-ta基因在恢复系和不育系中的分布存在差异,携带Pi-ta基因的21份材料均为恢复系,11份不育系中没有检测到Pi-ta,恢复系携带Pi-ta基因比例远高于不育系。通过本研究可以明确中国部分杂交稻亲本材料的稻瘟病抗性基因Pi-ta的分布状况,为进一步的杂交稻抗病育种提供重要依据。     

Survey of the Bru1 gene for brown rust resistance in Brazilian local and basic sugarcane germplasm

Bru1 is currently the major gene conferring brown rust resistance in sugarcane, and diagnostic markers are available. A survey for the presence of this gene was conducted on 391 genotypes including Brazilian cultivars, clones and basic germplasm. The efficiency of these markers for identifying resistant cultivars and artificially inoculated basic germplasm was also evaluated. The Bru1 frequency among cultivars (73.5%) suggests this gene is the prevalent source of brown rust resistance in Brazilian sugarcane breeding programmes. Most of the cultivars known to be resistant were positive for Bru1, although other genes for resistance could be present in lines not having Bru1. Only 17.8% of the basic germplasm accessions were positive for the Bru1 gene, and a low correlation between Bru1 diagnostic markers and brown rust severity was observed for basic germplasm accessions. Overall, Bru1 diagnostic markers proved to be efficient identifying resistant cultivars and clones and have potential to be in screening brown rust resistance in Brazilian breeding programmes.     

甘蔗新品种及主栽品种对褐锈病抗性与Bru1基因分子检测

The aim of this study was to assess brown rust resistance of new sugarcane varieties bred in China and main cultivated varieties in sugarcane planting area, and screen the elite new brown rust resistant varieties for popularization and application in production. In total, 60 new varieties in the national regional test of new sugarcane varieties were tested in Kaiyuan and Lincang, and 34 main cultivated varieties were studied in Lincang, Puer, and Yuxi, Yunnan province, and Yizhou, Guangxi province, China, where the incidence of brown rust was particularly high. The resistance of these sugarcane varieties to brown rust was investigated under natural inoculation and molecular marker-assisted identification was used to detect the brown rust resistance gene Bru1. The results of field survey showed that 66 (70.21%) of the 94 new and main cultivated varieties were highly resistant to moderately resistant, and 28 (29.79%) were susceptible to highly susceptible. Molecular detection indicated that Bru1 gene was found among 54 (57.45%) of the 94 new and main cultivated varieties. Some main cultivated varieties that were currently planted across large areas such as Guitang 29, Guitang 44, Dezhe 03-83, Liucheng 03-1137, Yuetang 60, and Guitang 46 were highly susceptible to brown rust, and 31 new varieties such as Yuegan 48, Funong 09-2201, Guitang 08-120, Liucheng 09-15, Zhongzhe 1, Yunzhe 08-1609, Yunrui 10-187, and Zhongtang 1201 were resistant. Therefore, in the sugarcane planting areas with high incidence of brown rust and wet and rainy climates, more effort should be eliminated the main susceptible varieties and promoted the application of new resistant varieties. This will help to achieve a reasonable distribution of varieties, fundamentally control the outbreak of disease in sugarcane planting areas, and provide security for the high-quality development of sugarcane industry in China in the future.     

Bru1 gene and potential alternative sources of resistance to sugarcane brown rust disease

Brown rust, caused by the fungus Puccinia melanocephala, is responsible for important yield losses in sugarcane production globally and it is therefore an important objective to introduce resistance to this disease in breeding programs. A major gene, Bru1, has been shown to confer resistance to P. melanocephala strains from different parts of the world and two molecular markers, R12H16 and 9O20-F4, closely associated to this gene have been previously reported. The usefulness of these molecular diagnostic markers in order to predict a rust resistant phenotype under natural high pressure inoculums conditions was analyzed. A total of 129 sugarcane accessions were evaluated under field infection for resistance or susceptibility to brown rust and subsequently screened for presence or absence of the two Bru1 diagnostic markers. A total of 49 genotypes (38 %) were phenotyped as resistant to brown rust but only eight (16.3 %) of them were harboring the Bru1 gene. To determine overall frequency of the Bru1 in the local sugarcane germplasm collection, 190 additional genotypes were examined. Presence of Bru1, as determined by the diagnostic markers, was detected in only 7 % of the genotypes evaluated. In conclusion, Bru1 diagnostic markers enable positive selection for brown rust resistance in sugarcane and moreover allowed detecting at least one additional source(s) of resistance. Interestingly, whilst only little genetic variability of rust resistance independent of Bru1 has been reported previously, this alternative genetic resource(s) found in our local germplasm constitutes the predominant one and should be helpful in order to amplify the narrow genetic basis for brown rust resistance in sugarcane.     

Frequency and distribution of the brown rust resistance gene Bru1 and implications for the Louisiana sugarcane breeding programme

Brown rust, caused by the fungus Puccinia melanocephala, poses an increasing threat to sugarcane industries worldwide. Recently, markers R12H16 and 9020‐F4 were developed for a major resistance gene Bru1 that contributes to a significant proportion of brown rust resistance in multiple sugarcane industries. Marker‐assisted screening of Louisiana sugarcane germplasm showed a low frequency (4.3%, five out of 117 clones) of Bru1 among sugarcane cultivars and elite breeding clones. Likewise, among progeny of crosses involving wild/exotic germplasm, only 14 of 208 clones (6.7%) tested Bru1 positive. However, Bru1 frequency was higher (28.7%, 52 of 181 clones) in wild/exotic germplasm, which indicated that diverse genetic resources are available for Bru1 introgression. Commercial Bru1‐positive cultivar, ‘L 01‐299', was resistant to brown rust. However, Bru1‐positive cultivar, ‘L 10‐146’, was susceptible while Bru1‐negative cultivars, such as ‘L 99‐233’, showed resistance to brown rust. Bru1‐negative clones with brown rust resistance offer an opportunity to identify alternate sources of resistance, which can be pyramided with Bru1 for effective and durable resistance in sugarcane against the changing pathogen.     

Improving wheat stripe rust resistance in Central Asia and the Caucasus

Wheat is the most important cereal in Central Asia (Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan) and the Caucasus (Armenia, Azerbaijan and Georgia). Stripe rust, caused by Puccinia striiformis f. sp. tritici is considered the most important disease of wheat in Central Asia and the Caucasus (CAC). Although stripe rust has been present in the region for a long time, it has become a serious constraint to wheat production in the past 10 years. This is reflected by the occurrence of five epidemics of stripe rust in the CAC region since 1999, the most recent in 2010. Several wheat varieties occupying substantial areas are either susceptible to stripe rust or possess a low level of resistance. Information on the stripe rust pathogen in terms of prevalent races and epidemiology is not readily available. Furthermore, there is an insufficient understanding of effective stripe rust resistance genes in the region, and little is known about the resistance genes present in the commercial varieties and advanced breeding lines. The deployment of resistant varieties is further complicated by putative changes in virulence in the pathogen population in different parts of the CAC. Twenty four out of 49 improved wheat lines received through international nurseries or other exchange programs showed high levels of resistance to stripe rust to local pathogen populations in 2009. Fifteen of the 24 stripe rust resistant lines also possessed resistance to powdery mildew. It is anticipated that this germplasm will play an important role in developing stripe rust resistant wheat varieties either through direct adoption or using them as parents in breeding programs.