Genetic diversity of the pine pathogen Lecanosticta acicola in Slovenia and Croatia

Brown spot needle blight (BSNB), a disease of pine trees caused by the fungus Lecanosticta acicola, has been known in Slovenia since 2008 and in Croatia since 1975. Recent outbreaks in Slovenia prompted this study to compare L. acicola populations in these two neighbouring European countries. Sixty-nine isolates collected from three pine species (Pinus mugo, P. halepensis and P. nigra) were used to determine the phylogenetic relationships, genetic structure, and reproductive strategy of the pathogen. EF1-α sequences showed that Slovenian and Croatian isolates share a common ancestry with individuals from central and northern Europe. Population structure analysis revealed four distinct population clusters of L. acicola in these two countries, generally corresponding to their respective geographic location and host. An unequal ratio of mating types and a low overall genetic diversity in the population indicated a strong influence of asexual reproduction. Although some of the oldest recorded European occurrences of BSNB are from Croatia, this study provided no evidence that the population studied in Croatia was the source of the sampled outbreaks in Slovenia. Recent outbreaks of L. acicola in Slovenia are most likely due to introductions from other, yet to be identified, sources.     

Evaluating diverse systems of tobacco genetic resistance to Phytophthora nicotianae in Yunnan,China

Black shank, caused by the soilborne pathogen Phytophthora nicotianae, is one of the most devastating diseases affecting tobacco production in China. The most effective strategy for reducing economic loss from this pathogen is development and use of resistant tobacco varieties. Multiple sources and systems of resistance have been developed in the Western Hemisphere; however, populations of P. nicotianae are variable around the world, including the predominance of different races. Different P. nicotianae isolates may react differently on tobacco plants with different systems of resistance, a possibility that could complicate the breeding of cultivars with resistance that is effective in different tobacco production regions worldwide. The objective of this research was to evaluate an array of tobacco germplasm possessing different systems of genetic resistance to black shank disease in tobacco-growing regions of Yunnan, China. Resistance types included simply inherited resistance mechanisms introgressed from wild Nicotiana relatives and polygenic partial resistance systems of N. tabacum origin. The loci of Wz exhibited high level resistance to black shank in the five diverse disease environments in Yunnan, China. K326 Php/−Wz/− genotype and Beinhart 1000 exhibited the greatest levels of resistance in both 2015 and 2016. Field observed results for 13 tobacco genotypes were highly correlated with those tested in growth chamber evaluation. These findings suggest that both Wz− and Beinhart 1000-mediated resistance have important commercial value in flue-cured tobacco breeding programmes in China. Cultivars developed for black shank resistance in China may also have utility in other tobacco-growing areas.     

甜瓜黄斑病毒在海南黄瓜上的发生分布及序列分析

 应用特异性引物MYSV-L-F和MYSV-L-R对海南5个市县采集的150份疑似感染病毒病的黄瓜样品进行RT-PCR检测,在三亚、乐东和东方等3个市县的18份样品中检测到甜瓜黄斑病毒(Melon yellow spot virus, MYSV)。选取采自三亚的分离物C29(MYSV-Hainan)进行MYSV全基因组克隆及序列分析,结果表明:该分离物的L RNA、M RNA和S RNA基因组全长分别为8 918 nt、4 815 nt和3 257 nt,与已知MYSV分离物的核苷酸相似性分别为97.4%~97.7%、96.2%~97.9%和94.8%~99.8%,系统进化关系分析与相似性分析一致,序列相似值越高,系统进化关系越近。     

贵州省白及叶褐斑病病原菌鉴定及其生物学特性

为明确贵州省白及叶褐斑病病原菌及其生物学特性,采用组织分离法和离体接种法分别对其病原菌进行分离和致病性测定,利用形态学及ITS、EF-1α、β-tubulin基因序列分析对病原菌的分类进行鉴定,并对病原菌的生物学特性进行研究。结果表明:分离得到的白及叶褐斑病病原菌菌株编号为HGUP_(17)355;该菌菌丝白色、羊绒状,菌落中心隆起呈淡黄色、背面枫叶红色,大型分生孢子窄镰刀形,3～8个分隔,未见厚垣孢子,小型分生孢子卵圆形,1～2个分隔;在以ITS、EF-1α、β-tubulin三个基因序列构建的系统发育树中,菌株HGUP_(17)355与燕麦镰刀菌Fusarium avenaceum聚于一支,且支持率达100%,结合形态特征与分子生物学将其鉴定为燕麦镰刀菌。该菌菌丝最适生长温度为20℃,最适生长pH为6,在燕麦片琼脂培养基上生长最快,以麦芽糖为碳源、以L-苯丙氨酸为氮源时利用率最高,致死温度为45℃,对光照不敏感。     

辣椒抗番茄斑萎病毒病研究进展及展望

番茄斑萎病毒（Tomato spotted wilt virus,TSWV）自19 世纪发现以来,在全世界各地蔓延,对多种作物造成重大经济损失。本文以辣椒为例,从TSWV 的发生与分布、病害症状检测、传播方式、防治方法、抗TSWV 育种及展望等6 个方面对国内外辣椒TSWV 的研究现状进行综述。     

洮藏黑山羊特性研究

本文以洮藏黑山羊为研究对象,通过查阅史料及现场资源调查、试验分析,系统研究了洮藏黑山羊的数量变化、原绒产量、营养成分等特性研究。为洮藏黑山羊的利用和保护,提供了理论依据及生产指导作用。     

不同灌水方式对砂姜黑土小麦中后期生长及产量的影响

在人工防雨篷下研究了前期不同灌水处理对砂姜黑土小麦中后期生长、光合生理及产量的影响,以期为该区小麦增产和水分高效利用提供科学依据和理论帮助。结果表明,灌1水条件下小麦叶片长宽和单茎干物重随灌水日期的推迟呈先增加后下降的趋势,并以生育前期水分充足处理CK最高,W5100d(出苗后100 d灌水)处理次之,且总灌水量一致下小麦生育前期灌1水和灌2水效果间的差异不显著。生育前期适当推迟灌水日期有利于增加小麦生育中后期的叶面积指数和叶绿素含量,且灌浆中期W5100d处理的叶面积指数和叶绿素含量高于CK。小麦生育前期适当推迟灌水日期亦有利于降低植株蒸腾速率改善小麦光合特性,其中W5100d处理的光合速率比对照CK增加了11.4%。W5100d与CK处理的产量差异不显著,分别为6 955.40,7 102.67 kg/hm2,但两者产量明显高于其他灌水处理。相关分析表明,小麦叶片叶绿素含量、光合速率与单茎干物重和产量间皆呈直线显著正相关关系。研究得出,小麦生育前期适当延长灌水日期有利于改善小麦中后期生长发育、光合特性及产量,且总灌水量一致下灌水次数效果间的差异不显著。     

沈山高速公路大雾天气气候特征及其对交通的影响及防御

利用沈山高速公路沿线8个气象观测站（沈阳、辽中、台安、盘锦、锦州、葫芦岛、兴城、绥中）1981—2012年的大雾实况资料,分析沈山高速公路沿线大雾时空分布特征。结果表明：在时间分布上,2003—2012年,沈山高速公路大雾日数呈上升趋势,年平均为16.4天,比20世纪80年代增加1.8天;辽中、台安、盘锦和沈阳4个站大雾天气主要出现在秋、冬季,而锦州、葫芦岛、兴城、绥中4个站大雾天气主要出现在夏、秋季。大雾日变化明显,有2个生成的高发阶段,一个在早晨3—6时,另一个在夜里21—24时,大雾消散的时间主要在15时之前,消散的峰值在上午9时左右,89%的大雾持续时间不超过10 h,2~4 h左右的雾发生频率最高。在空间分布上,沈山高速沿线西南部沿海雾日多,内陆地区雾日少,有明显的地区差异。在对沈山高速公路沿线大雾天气气候特征分析的基础上,结合2008—2012年沈山高速由于大雾的原因引发的交通事故分析,探讨了大雾对沈山高速公路交通的影响,选取大雾灾害隐患点,找出服务关键期,并有针对性地提出防御建议。