Blueberry (Vaccinium spp.) production in southwest and northeast China has grown to over 100,000 ha in the last 20 years thanks to the fruit's high nutritional and economic value. As blueberry acreage increases, the diversity of diseases and challenges for control are gaining more attention. In August 2010, stem and branch blight occurred on Highbush Blueberries (Vaccinium corymbosum L.) at commercial farms in Lijiang and Zongdian, Yunnan Province (southwestern China), with crop damage ranging from 10 to 15%. Typical symptoms of the disease were blight and dieback on the stems with lesions extending along entire branches. Diseased samples (phloem and xylem sectors in the wood) were washed with running tap water, disinfected with 2% sodium hypochlorite, then 70% alcohol, rinsed in sterile distilled water, plated on potato dextrose agar (PDA), and incubated at 28°C. Fungal isolates developed copious, white aerial mycelium that became dark gray after 4 to 5 days and formed black pycnidia after 18 days. Conidia were hyaline, aseptate, thin walled, fusiform, and measured 21 to 27 × 4 to 6 μm. Identity was confirmed by analysis of the ribosomal DNA internal transcribed spacer region ITSI-5.8S -ITS2 with primers ITS1 and ITS4. BLAST searches showed 99% identity with Botryosphaeria dothidea isolates from GenBank (Accession Nos. AB693904 and JF800139). Representative sequences of B. dothidea from Highbush Blueberries from China were deposited into GenBank (Accession No. JX096631). On the basis of morphological and molecular results, the fungus isolated from diseased Highbush Blueberries stem was confirmed to be B. dothidea. Pathogenicity tests were conducted on 2-year-old blueberry seedlings (Highbush Blueberries). Mycelial plugs (2 to 3 mm in diameter) of B. dothidea from actively growing colonies (PDA) were applied to same-size bark wounds in the center of the stems. Inoculation wounds were wrapped with Parafilm. Control seedlings received sterile PDA plugs. Inoculated and control seedlings (five each) were kept in a greenhouse and watered as needed. After 12 days, all of the inoculated but none of the control blueberry seedlings showed dark vascular stem tissue. B. dothidea was reisolated from symptomatic tissues, thus fulfilling Koch's postulates. No symptoms were visible in the control seedlings. B. dothidea has been reported as a pathogen of sycamore (3), olives (1), and peach (2). However, no research has been conducted on stem blight of blueberry caused by B. dothidea in southwest or mainland China. To our knowledge, this is the first report of B. dothidea on blueberry in southwest China. References: (1) M. Chattaoui, et al. Plant Dis. 95:770, 2011. (2) Y. Ko et al. Plant Pathol. Bull. 1:70, 1992. (3) E. Turco, et al. Plant Dis. 90:1106, 2006.

译文

:由于该水果的高营养价值和经济价值,在过去的20年中,西南和东北地区的蓝莓(Vaccinium spp。)产量已增长到100,000多公顷。随着蓝莓种植面积的增加,疾病的多样性和控制挑战日益受到关注。 2010年8月,云南丽江和宗甸(中国西南部)的商业农场的高灌木蓝莓(越桔)发生了茎叶和枝叶枯萎病,对作物的危害范围为10%至15%。该病的典型症状是茎枯萎和枯萎,病斑沿整个分支延伸。患病样品(木材中韧皮部和木质部部分)用流动的自来水洗涤,先用2%次氯酸钠消毒,再用70%酒精消毒,再用无菌蒸馏水冲洗,然后涂在马铃薯葡萄糖琼脂(PDA)上,并在28°C下孵育C。真菌分离物形成大量的白色气生菌丝体,在4至5天后变成深灰色,在18天后形成黑色的粘虫。分生孢子是透明的,腹水的,薄壁的,梭形的,大小为21至27×4至6μm。通过用引物ITS1和ITS4分析核糖体DNA内部转录的间隔区ITSI-5.8S-ITS2,证实了同一性。 BLAST搜索显示与GenBank中的Botryosphaeria dothidea分离株具有99%的同一性(登录号AB693904和JF800139)。来自中国的Highbush蓝莓的B. dothidea的代表性序列被保藏到GenBank(登录号JX096631)。根据形态学和分子结果,从患病的Highbush蓝莓茎中分离出的真菌被确认为B. dothidea。对2岁的蓝莓幼苗(Highbush蓝莓)进行了致病性测试。将来自活跃生长菌落(PDA)的B. dothidea菌丝体塞(直径2到3 mm)应用于茎中央相同大小的树皮伤口。接种伤口用Parafilm包裹。对照幼苗接受无菌的PDA塞。接种和对照的幼苗(每棵5株)都放​​在温室中,并根据需要浇水。 12天后,所有已接种但没有对照的蓝莓幼苗均显示出深色的维管干组织。从症状组织中分离出双歧杆菌,从而满足了科赫的假设。在对照幼苗中没有可见的症状。据报道,B。dothidea是美国梧桐(3),橄榄(1)和桃子(2)的病原体。然而,在西南或中国大陆尚未对由多虫双歧杆菌引起的蓝莓枯萎病进行过研究。据我们所知,这是B. dothidea在中国西南蓝莓上的首次报道。参考文献:(1)M. Chattaoui等。植物病。 95:770,2011.(2)Y.Ko等。植物病理学。公牛。 1:70,1992.(3)E.Turco等人。植物病。 90:1106,2006。

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