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First report of a potato cyst nematode, Globodera rostochiensis , on potato, in Iran Article in Plant Pathology · April 2010 DOI: 10.1111/j.1365-3059.2009.02135.x
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Plant Pathology (2010) 59, 412
Doi: 10.1111/j.1365-3059.2009.02161.x
First report of Rhizoctonia oryzae isolated from bordered sheath spot of rice in Myanmar S. S. Ayea, Y. Y. Myintb, T. Lwinb and M. Matsumotoa* a
Institute of Tropical Agriculture, Kyushu University, Fukuoka, 812-8581, Japan; and bDepartment of Plant Pathology, Yezin Agricultural University, Naypyidaw, Myanmar
Rice diseases reduce yields and are a major concern in Myanmar (Naing, 2004), and a recent survey documented the occurrence of Rhizoctonia oryzae-sativae from diseased rice sheaths in Myanmar (Aye et al., 2009). In this same survey, three isolates from samples of rice plants in Daikoo Township (MWC2) and Hlegu Township (MWC3 and MCW5) were collected from plants that displayed oval shaped lesions, 1–3 cm in length with bleached straw-coloured centres surrounded by brownish borders. These symptoms were different from those caused by R. oryzae-sativae (Aye et al., 2009). Ten days after isolation, mature cultures on potato dextrose agar formed irregular masses of salmon -coloured sclerotia formed at the subsurface of the medium. This differed from the tan, irregular globose sclerotia formed by R. oryzae-sativae (Aye et al., 2009). Multinucleate cells were observed under light microscope by hyphal staining with Safranin O. According to the morphological criteria, the causal agent was initially identified as R. oryzae. Ribosomal DNA-ITS sequence data of isolate MWC2 (GenBank Accession No. FJ66520) were matched with all other available data sources in GenBank and were found to have up to 98% identity with R. oryzae (EU152861). A pathogenicity test was completed by inoculating the tillers of 10week-old rice plants with isolates MWC2, MWC3 and MWC5 (three plants for each isolate). A five-day-old mycelial plug was placed on the stem one cm below the axil of the fully mature leaf and wrapped with parafilm. Similar symptoms to those observed in the field were produced five to seven days after stem inoculation, while control plants did not pro-
duce any symptoms. Koch’s postulates was completed by re-isolating and confirming the identity as R. oryzae. In Australia, yield losses caused by R. oryzae and R. oryzae-sativae were as high as 10% and 20%, respectively (Lanoiselet et al., 2005). Occurrence of bordered sheath spot caused by R. oryzae has been reported in paddy fields of Japan (Inagaki, 1996), however, this is the first report in Myanmar. Acknowledgements The authors acknowledge the Director, Professor Kazuo Ogata, for his valuable suggestions and comments in this research. References Aye SS, Myint YY, Lwin T, Matsumoto M, 2009. Rhizoctonia oryzae-sativae, causal agent of aggregate sheath spot disease of rice in Myanmar. Plant Pathology 58, 1173. Inagaki K, 1996. Distribution of strains of rice bordered sheath spot fungus, Rhizoctonia oryzae, in paddy fields and their pathogenicity to rice plants. Annals of the Phytopathological Society of Japan 62, 386–92. Lanoiselet VM, Cother EJ, Ash GJ, Harper JDI, 2005. Yield loss in rice caused by Rhizoctonia oryzae and R. oryzae-sativae in Australia. Australasian Plant Pathology 4, 175–9. Naing TAA, 2004. Rice Production in Myanmar and Effects of Intensification on Crop Health. Kassel, Germany: University of Kassel, PhD Thesis.
*E-mail:
[email protected]. Accepted 12 June 2009 at http://www.bspp.org.uk/ndr where figures relating to this paper can be viewed.
Plant Pathology (2010) 59, 412
Doi: 10.1111/j.1365-3059.2009.02135.x
First report of a potato cyst nematode, Globodera rostochiensis, on potato, in Iran M. Gittya and Z. Tanha Maafib* a
Agricultural and Natural Resources Research Center of Hamadan; and bIranian Research Institute of Plant Protection, P.O. Box 1454, Tehran, 19395, Iran
In June 2008 a few ware potato fields in Hamadan Province in the western part of Iran showed patches of about 20–200 m2 of poor growth. Potato plants in these areas exhibited symptoms of severe stunting and nutrient deficiency along with yellow leaves and wilting. Roots of infested plants showed white, golden mature females and brown cysts on their surface. Cysts and second stage juveniles were extracted from soil and root samples. The morphological and morphometrical characters of second stages juveniles and perineal area of cysts were examined by light microscope. The cysts showed the general characteristics of Globodera genus i.e. almost spherical body without vulval cone, circumfenestrate opening of the perineal area and subterminal anus, with the distance from anus to the vulval basin (n = 25) 49Æ56 ± 9Æ68 (32–68) lm, the vulval basin diameter 15Æ24 ± 1Æ92 (10–17) lm, the Granek’s ratio 3Æ27 ± 0Æ61 (2Æ25–4Æ47), and the number of cuticular ridges between anus and vulval basin (n = 16) 19 ± 2Æ5 (15–24). Second stage juveniles (n = 16) had stylet length 21Æ12 ± 0Æ95 (20–23) lm with rounded knobs, tail length 52Æ7 ± 2Æ9 (48–57) lm, and hyaline part of tail 28Æ12 ± 3Æ53 (20–33) lm. A molecular test was done for complementary diagnosis. DNA was extracted from several single cysts as described by Tanha Maafi et al. (2003) and amplified by species specific primers (Fullaondo et al., 1999).
On the basis of the results obtained the cysts were identified as Globodera rostochiensis (Wouts & Baldwin, 1998; EPPO. 2004). The morphological diagnosis was confirmed by amplifying a single fragment of 315 bp length which corresponded with Fullaondo et al., 1999. No amplification was produced with the specific primers for G. pallida. Potato cyst nematodes (PCNs) are considered quarantine pests in Iran and this is the first report of the genus Globodera and G. rostochiensis from Iran. References EPPO, 2004. Globodera rostochiensis and Globodera pallida. PM 7 ⁄ 40(1), EPPO Bulletin 34, 309–14. Fullaondo A, Barrena E, Viribay M, Barrena I, Salazar A, Ritter E, 1999. Identification of potato cyst nematode species Globodera rostochiensis and G. pallida by PCR using specific primer combinations. Nematology 1, 157–63. Tanha Maafi Z, Subbotin SA, Moens M, 2003. Molecular identification of cystforming nematodes (Heteroderidae) from Iran and a phylogeny based on the ITS sequences of rDNA. Nematology 5, 99–111. Wouts WM, Baldwin JG, 1998. Taxonomy and identification. In: Sharma SB, ed. The Cyst Nematodes. Dordrecht, the Netherlands: Kluwer Academic Publishers, 83–122.
*E-mail:
[email protected]. Accepted 5 May 2009 at http://www.bspp.org.uk/ndr where figures relating to this paper can be viewed.
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