Identification of Pathogens of a New Cotton Boll Disease in Xinjiang Cotton Field

[Objective] Since 2015, there has been a new cotton boll disease in Xinjiang cotton fields which was obviously different from the common boll rot, leading to stiffness and cracking boll. Olive-black mildew layer was observed on the surface of diseased bolls under wet conditions. It is of great significance to clarify the types of pathogens for the prevention of the disease. [Method] From 20 cotton planting locations of Xinjiang, 38 samples of stiffness and cracking boll disease were collected, and the pathogens were isolated and purified by conventional dilution separation and single-spore separation. And 20 representative strains were selected according to sampling location, cotton varieties and colony characteristics. The selected strains were identified by morphological observation and sequence analysis of rDNA internal transcribed spacer (rDNA-ITS), actin (ACT) and translation elongation factor 1-α (TEF1-α) gene. According to Koch’s law, the spore suspensions of three representative strains C2, C13 and C7 were inoculated to observe and record the incidence of the disease, and the diseased bolls were used for re-separation to observe the similarities and differences between the re-isolated strains and the inoculated strains. [Result] The result shows that these isolates belong to the Cladosporium, and according to its morphological characteristics and molecular biology analysis, 13 of the 20 strains belong to C. cladosporioides, 4 strains belong to C. velox, 3 strains belong to C. limoniforme. The symptoms of three representative strains C2, C13 and C7 were similar to those in the field when inoculated with injuries, and the disease spread was slower when inoculated without injuries. The inoculated strains can be separated from the lesions. [Conclusion] The new cotton boll disease causing stiffness and cracking in Xinjiang cotton fields is caused by three species of Cladosporium, C. cladosporioides, C. velox and C. limoniforme, with C. cladosporioides as the dominant species.     

瓜枝孢弱毒菌株诱导黄瓜抗病相关基因表达的cDNA-AFLP 分析

 利用cDNA-AFLP 技术,分析瓜枝孢弱毒菌株诱导黄瓜苗后72 h 内抗病相关基因的差异表达。结果显示,诱导的基因表达差异始于接种后3 h,接种后6 h 差异表达片段总数达到高峰。8 个取样时间点的诱导性差异表达片段数大于抑制性表达片段数。仅在接种后第12 h 呈现相反趋势。通过回收、克隆、测序和同源性比对,获得的5 个片段分别与拟南芥中病原菌诱导的水杨酸糖基转移酶、梨磷脂酶C编码的基因等具有较高的同源性,初步推断瓜枝孢弱毒菌株诱导黄瓜抗病可能是通过依赖于水杨酸介导的信号传导途径诱导黄瓜的系统抗病性（system acquired resistance, SAR）,作为胁迫抗性信号传递中的关键酶——磷脂酶C 可能参与了上述过程。经Northern 杂交结果证实,克隆分离的DNA 差异片段是瓜枝孢弱毒菌株诱导表达的特异片段。     

Assessment of the pathogenicity of marine Cladosporium spp. towards mangroves

Mangroves play an important role in coastal ecosystems. In this work, Cladosporium spp were isolated from a natural mangrove environment in Zhanjiang Bay, Guangdong Province, China. Ninety‐one isolates were obtained and identified as Cladosporium cladosporioides, C. colocasiae, C. oxysporum, C. perangustum, C. sphaerospermum, C. tenuissimum and C. uredinicola. Forty‐two isolates were selected and tested for pathogenicity towards mangroves. The results showed that pathogenic isolates were found on Avicennia marina, Kandelia candel and Rhizophora stylosa with prevalence of 93.40%, 83.52% and 7.41%, respectively. This indicated that A. marina and K. candel were more vulnerable to Cladosporium ssp. than R. stylosa. Among the seven species, C. colocasiae had the strongest pathogenic effect towards A. marina and K. candel with a prevalence of 100.00%. The rest of the seven species also showed pathogenic effects on the same plants. These results provided valuable insights into the effect of various pathogens on mangroves.     

斑替枝孢生物学特性及致病性初步研究

从患病加州鲈鱼(Micropterus salmonides)体表分离到的斑替枝孢(Cladosporium bantianum)菌株,通过不同温度和不同p H对斑替枝孢菌株生长速率的影响来研究其生物学特性,再以草鱼(Ctenopharyngodon idellus)和鲤鱼(Cyprinus carpio)为感染对象,用该菌进行回复感染,对其致病性作初步研究。结果表明,斑替枝孢在p H 5~11均能生长,p H为9.0时生长最快;在温度为5~35℃时均能生长,以20℃时生长最快,菌落最为致密。在实验室条件下,单一菌株对草鱼和鲤鱼不具有致病性。     

三种杀菌剂对牡丹红斑病病菌分生孢子形成和萌发的影响

为筛选防治牡丹红斑病的杀菌剂,采用涂布平板法测定了多菌灵、戊唑醇、嘧菌酯对病菌分生孢子形成和萌发的影响。结果表明:3种杀菌剂对病菌孢子萌发均有很强的抑制作用,浓度越高,抑制作用越强,以嘧菌酯最强,1μg/mL浓度处理其孢子萌发率低于10%,5μg/mL处理孢子完全不能萌发;3种杀菌剂均可显著抑制病菌芽管的伸长生长,1μg/mL处理下孢子萌发24 h后芽管长度均不足10μm,5μg/mL处理对芽管伸长的抑制率达到90%;3种杀菌剂可使分生孢子及芽管发生畸形,多菌灵的致畸作用最强,0.1μg/mL处理即表现出明显的致畸作用,而戊唑醇致畸作用较弱;嘧菌酯和戊唑醇对病菌产孢结构形成和分生孢子产生数量有强烈的抑制作用,0.05μg/mL浓度下即完全不产孢,但多菌灵在0.05μg/mL浓度下则促进病菌产孢结构形成及产孢量增加。表明3种杀菌剂均可作为保护剂在病害发生前期喷施,但在流行期应尽量使用嘧菌酯和戊唑醇,以减少病菌再侵染数量。     

黄瓜黑星病菌致病机理的研究Ⅱ细胞壁降解酶及其在致病中的作用

 本文通过活体内外黄瓜黑星病菌(Cladosporium cucumerinum)产生的细胞壁降解酶活性分析,初步明确了Cx-酶(羧甲基纤维素酶)、β-葡萄糖苷酶和PMG(聚甲基半乳糖醛酸酶)、PMTE(果胶甲基反式消除酶)在该菌侵染黄瓜中的作用。瓜条感病的各部位,以病健交界处细胞壁降解酶活性最高;在检测的各类酶中,活性最高的为PMG、PMTE,Cx-酶、β-葡萄糖苷酶和FPA(滤纸酶)活性较低。抗感病黄瓜品种染病后,细胞壁降解酶活性均迅速增强。感病品种染病后,果胶酶(PMG、PMTE)活性远远高于抗病品种,其高峰值是抗病品种的2.72~7.52倍。感病品种接种后纤维素酶(Cx-酶、β-葡萄糖苷酶)活性一直增强;抗病品种接种后β-葡萄糖苷酶随着接种天数的增加酶活性一直增强,Cx-酶在染病后初期活性迅速增强,增至高峰后逐渐降低。     

番茄叶霉菌CfHNNI1基因5'端序列的功能分析

番茄叶霉菌(Cladosporium fulvum)CfHNNI1是一种寄主和非寄主抗病性的广谱激发子.但CfHNNI1cDNA序列是否为全长序列尚不明确.本研究构建了两个缺失不同长度5端序列的CfHNNI1序列结构,并研究了这些缺失型序列与坏死诱导功能之间的关系.研究结果表明,缺失包括ATG3在内的5端100bp序列,使缺失型CfHNNI1的翻译起始于ATG101,形成一个新的开读框,导致对番茄、烟草(Nicotiana tabacum)和N.clevelandii植株坏死诱导能力的完全丧失.而缺失所有在ATG273以前的4个ATG、长度为272bp的序列,但与ATG3处于同一密码框架中的缺失型CfHNNI1,丧失了诱发番茄、N.clevelandii以及N.paniculata产生坏死反应的能力,却仍能诱发N.tabacum,N.benthamiana,N.langsdorfii,N.glutinosa及N.solanifolia等5个Nicotiana种的植株产生明显坏死反应.这些结果说明,以ATG3为起始密码子的开读框是CfHNNI1真正开读框;5端272bp序列在诱导产生坏死反应中的作用因植物对象而异.     

双抗番茄新品种‘粉多纳’的选育

‘粉多纳’是以‘RT1402’为母本、‘YT1102’为父本选育而成的无限生长型中熟番茄新品种。该品种生长势强,叶色深绿,7~8叶着生第1花序,坐果能力强。郑州地区秋延后栽培全生育期157 d;幼果无青肩,成熟果粉红色,高圆形,硬度高,平均单果质量215 g;含有Ty-1和Ty-3a基因,田间表现抗番茄黄化曲叶病毒病、高抗叶霉病;维生素C质量分数18.07 mg?100 g^-1,可溶性固形物质量分数4.60%,番茄红素质量分数66.70 mg?kg^-1,品质优良;丰产稳产性较好,适宜河南、河北、山西、陕西等地区日光温室越冬茬及秋延后塑料大棚栽培。2018年获得农业农村部植物新品种权,2019年通过农业农村部非主要农作物品种登记。     

枝孢属的一个国内新记录

报道枝孢属一新记录种:马缨丹枝孢C lad osporium lantanae。其形态特点是:分生孢子梗直立,稍弯曲,淡褐色;枝孢顶具2~3个孢痕,淡褐色,无隔膜。分生孢子顶生或侧生,形成短孢子链,椭圆形,0~1个隔膜,大多数无隔膜,基部有孢痕,淡褐色,平滑。另报道6种枝孢的8种国内新寄主植物、2个已知种的地理新分布和4个已知种。研究标本存云南农业大学真菌标本室(MHYAU)。     

中国枝孢属研究(Ⅺ)

 报道枝孢属Cladosporium 4个国内新记录种:褐色枝孢C.brunneum Corda,多主枝孢柳生变种C.herbarum(Pers.) Linkvar.saxicolum Saccardo,细枝孢C.subtileRabenhorst和豇豆枝孢C.VignaeM.W.Gardner,附有形态特征及显微结构图,研究标本收藏于云南农业大学植物病理真菌标本室(MHYAU)。