scholarly journals First Report of Puccinia thaliae Causing leaf rust on Canna indica in Malaysia

Plant Disease ◽  
2021 ◽  
Author(s):  
Ying Wei Khoo ◽  
Tan Hui Teng ◽  
Yam Sim Khaw ◽  
Shifang Li ◽  
Khim Phin Chong
Keyword(s):  
Leaf Rust ◽  
Ribosomal Rna ◽  
Rust Fungus ◽  
Pcr Amplification ◽  
Post Inoculation ◽  
Potential Threat ◽  
Ribosomal Rna Gene ◽  
Canna Indica ◽  
First Report ◽  
Symptoms And Signs

Canna indica L. (family Cannaceae), locally known as Bunga Kana, is a perennial plant grown as a source of starch and for ornamental purposes in Malaysia. During June 2021, Bunga Kana with rust symptoms and signs were collected from the Universiti Malaysia Sabah in the province of Sabah. The severity was 95%, and the incidence was 90%. Yellow uredinia were observed primarily on the abaxial surface of the leaves. As the disease progressed, leaves were covered with coalescing pustules, and chlorosis and brown necrosis developed. Microscopic examination of pustules revealed the presence of urediniospores and teliospores. Urediniospores were round to ovoid in shape, yellow, and echinulate, 17.7 to 24.6 x 26.8 to 45.2 μm, with two equatorial pores. Teliospores were elongate-clavate, with rounded apex, yellow contents, 18.3 x 20.2 to 45.8 x 53.9 μm, with a short pedicel. Yellow urediniospores were collected using a fine brush, and genomic DNA was extracted using lysis buffer [Tris-HCl (0.1M, pH 9.5), NaCl (1M), EDTA (0.5M, pH 8)] prior to heating at 95°C for 10 min. KOD One PCR master mix containing hot-start modified KOD DNA polymerase was used for PCR amplification. The 28S ribosomal RNA gene was amplified using primers Rust28SF (Aime et al. 2018) and LR5 (Vilgalys and Hester 1990). BLASTn analysis of the newly generated 28S ribosomal RNA gene (OK462969) in GenBank revealed a 99% sequence identity to Puccinia thaliae Dietel (JX206994 of 28S ribosomal RNA gene). The morphological and molecular characterization of the rust fungus matched P. thaliae described by Padamsee and McKenzie (2012). Koch's postulates were performed with spray inoculations of urediniospores suspended in water (106 spores/ml) on leaves of three healthy Bunga Kana plants, while water was sprayed on three additional Bunga Kana plants which served as control. The inoculated Bunga Kana plants were covered with plastics for 48 h at 25°C in the dark, and then placed in the greenhouse. Symptoms and signs similar to those of the field collection occurred after 13 days post inoculation. No symptoms occurred on controls. Leaf rust on Bunga Kana plants caused by P. thaliae has been reported in Europe (Talhinhas et al. 2016), Hawaii (Nelson 2013), India (Gopi et al. 2014), Mexico (Cedas de Jesús et al. 2018), Nepal (Adhikari and Durrieu 2016), New Zealand (Padamsee and McKenzie 2012), Singapore (Neo and Tham 2010) and South Africa (van Jaarsveld et al. 2006) over the past fifteen years. To our knowledge, this is the first report of P. thaliae causing leaf rust on C. indica in Malaysia. Our findings expand the geographic range of P. thaliae and indicate it could be a potential threat limiting the starch production of C. indica in Malaysia.

scholarly journals Evaluation of 16S, map1 and pCS20 probes for detection of Cowdria and Ehrlichia species

1999 ◽  
Vol 122 (2) ◽  
pp. 323-328 ◽  
Author(s):  
M. T. E. P. ALLSOPP ◽  
C. M. HATTINGH ◽  
S. W. VOGEL ◽  
B. A. ALLSOPP
Keyword(s):  
16S Rrna ◽  
Ribosomal Rna ◽  
Pcr Amplification ◽  
16S Ribosomal Rna ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Amblyomma Hebraeum ◽  
Ribosomal Rna Gene ◽  
Group Iii ◽  
16S Ribosomal Rna Gene

A panel of 16S ribosomal RNA gene probes has been developed for the study of the epidemiology of heartwater; five of these detect different cowdria genotypes, one detects five distinct genotypes; one detects any Group III Ehrlichia species other than Cowdria and one detects any Group II Ehrlichia species. These probes have been used on PCR-amplified rickettsial 16S rRNA genes from over 200 Amblyomma hebraeum ticks. Control ticks were laboratory-reared and either uninfected or fed on sheep experimentally infected with different cowdria isolates, field ticks were collected from animals in heartwater-endemic areas. All tick-derived DNA samples were also examined by PCR amplification and probing for two other cowdria genes (map1 and pCS20) which have previously been used for heartwater epidemiology. This paper describes the first direct comparison of all currently available DNA probes for heartwater-associated organisms.

Characterization of the Gyrodactylus salaris Malmberg, 1957 (Platyhelminthes: Monogenea) ribosomal intergenic spacer (IGS) DNA

Parasitology ◽  
2000 ◽  
Vol 121 (5) ◽  
pp. 555-563 ◽  
Author(s):  
C. M. COLLINS ◽  
C. O. CUNNINGHAM
Keyword(s):  
Ribosomal Rna ◽  
Tandem Repeats ◽  
Gene Array ◽  
Pcr Amplification ◽  
Intergenic Spacer ◽  
Sequence Motifs ◽  
Ribosomal Rna Gene ◽  
Intergenic Spacers ◽  
Transcription Start Sites ◽  
Pcr Products

The intergenic spacer of the ribosomal RNA gene array from the monogenean Gyrodactylus salaris was isolated using PCR amplification. PCR products were cloned and sequenced. Three different fragments of 0·63, 1·0 and 2·62 kb, were consistently obtained. These showed homology at the 5′ and 3′ termini but differed in their overall size and intervening sequence. The 5′ end showed homology to various 28S ribosomal RNA gene sequences, suggesting that this represented the 3′ terminus of the G. salaris 28S ribosomal RNA gene. A number of features common to other eukaryotic intergenic spacers were found in the longest sequence, including A + T rich sequences, palindromic sequences and tandemly repeated elements. Two regions of 23 bp sequences arranged in non-identical tandem repeats were identified. There were 9 repeats in both regions, separated by 81 bp of non-repetitive sequence. The repeat units from the two regions shared some similarity at their 3′ ends. The G. salaris intergenic spacer sequence was examined for sequence motifs involved in the transcription of the ribosomal RNA genes in other species. Several regions with homology to transcription start sites were identified.

scholarly journals First Report of Herbacious Hosts for Citrus yellow mosaic badna virus from India

Plant Disease ◽  
2002 ◽  
Vol 86 (8) ◽  
pp. 920-920 ◽  
Author(s):  
G. S. Aparna ◽  
K. Gopal ◽  
K. Venkata Subbaiah ◽  
M. N. Reddy ◽  
M. Sreenivasulu
Keyword(s):  
Mosaic Disease ◽  
Polyclonal Antiserum ◽  
Enzyme Linked Immunosorbent Assay ◽  
Cyamopsis Tetragonoloba ◽  
Dot Blot ◽  
Yellow Mosaic Disease ◽  
Potential Threat ◽  
Canna Indica ◽  
First Report ◽  
Young Leaves

Citrus mosaic disease, a potential threat to citrus production throughout India, is currently an important disease in the southern and northeastern states (2). The reported incidence of the disease ranges from 10 to 77% (K. Gopal, G. S. Aparna, M. Sreenivasuluk, K. V. Subbaiah, and A. R. K. Rao, unpublished data). This yellow mosaic disease of citrus is caused by Citrus yellow mosaic badna virus (CMBV), formerly citrus yellow mosaic disease, (CYMD) (1). Host range studies were done to find herbaceous noncitrus host plant species for virus maintenance. The following are the noncitrus plants tested in this study: Arachis hypogaea, Chenopodium amaranticolor, Chenopodium quinoa, Vigna mungo, Macrotyloma uniflorum, Cicer arietinum, Helianthus annuus, Cajanus cajan, V. sinensis, Cyamopsis tetragonoloba, V. radiata, Pisum sativum, Phaseolus vulgaris, Trichosanthes anguina, Nicotiana tabacum (Harrison special), Dolichos lablab, Petunia × hybrida, Gomphrena globosa, Cucumis melo, Cucumis pepo, Glycine max, Sorghum bicolor, Zea mays, and Canna indica. Young leaves with mosaic symptoms were collected from Citrus sinensis Osbeck, Citrus aurantiifolia Osbeck, and Citrus × limonia Osbeck plants, which are being maintained in an insect-proof glasshouse. The leaves were cut into small pieces, transferred to a chilled mortar, and macerated using 0.01 M phosphate buffer, pH 7.0, containing 0.2% (v/v) of 2-mercapto-ethanol at a tissue/buffer ratio of 1 g/9 ml (wt/vol). The extract was filtered and used for inoculation. The above-mentioned noncitrus plants were uniformly dusted with 600-mesh Carborundum and inoculated with sap extract from the citrus species. The plants were kept in an insect-proof glasshouse and observed for 6 weeks for symptom development. Only three hosts, Canna indica, sorghum, and maize produced visible symptoms. Symptoms were observed 14 days postinoculation on C. indica as chlorotic spots, which later developed into a mosaic pattern. Developing young leaves showed severe mosaic with vein banding symptoms. In sorghum and maize, chlorotic streaks were observed on young leaves after 10 days, which developed into dark green streaks in the leaf lamina. All the inoculated hosts were checked using virus double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and dot blot ELISA using CMBV polyclonal antiserum (Department of Virology, S.V. University, Tirupati, India). In both tests, only the C. indica, sorghum, and maize samples reacted positively. In dot blot ELISA, as little as 100 ng of virus could be detected in C. indica, sorghum, and maize. Virus from all three citrus sources produced the same symptoms on C. indica, sorghum, and maize. To our knowledge, this is the first report of herbaceous hosts of CMBV, which should prove useful as propagation and index hosts for CMBV. References: (1) Y. S. Ahlawat et al. Plant Dis. 80:590, 1996. (2) G. S. Reddy et al. Page 130 in: 3rd Int. Symp. Subtrop. Hortic. Bangalore, 1972.

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