scholarly journals First Report of ‘Candidatus phytoplasma ziziphi’ in Sweet Potato in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Qicheng Li ◽  
Peng Chen ◽  
Qiqi Yang ◽  
Lichuan Chen ◽  
Yu Zhang ◽  
...  
Keyword(s):  
16S Rrna ◽  
Sweet Potato ◽  
Accession Number ◽  
Sweet Potatoes ◽  
Disease Symptoms ◽  
First Report ◽  
Potato Plants ◽  
Leaf Disease ◽  
Dna Fragment

Sweet potato (Ipomoea batatas; family Convolvulaceae) is an important food crop and serves as a ground cover in orchards of jujube trees. In August 2020, sweet potatoes growing under jujube trees showed obvious jujube witches’ broom phytoplasma disease symptoms in an abandoned jujube orchards in Xinzheng county, Henan province, China (GPS：113°49′56″N， 34°35′54″E). The sweet potato plants were showing symptoms such as small, yellowing leaves and witches’ broom. (Figure 1). The incidence of symptomatic sweet potato plants in the orchard (60× 100 m2 ) was about 60%. Leaf samples of sweet potatoes and jujube trees exhibiting disease symptoms were collected to confirm the presence of JWB phytoplasma by PCR. The phytoplasma primers R16mF2/R16mR1 (Gundersen and Lee, 1996) and secAfor1/secArev3 (Hodgetts et al., 2008) were used. Leaf samples of three sweet potato plants and three jujube trees exhibiting disease symptoms were collected to confirm the presence of JWB phytoplasma by PCR. Two healthy sweet potatoes collected from the experimental station at Henan Agricultural University and two healthy, in vitro-grown jujube plantlets were used as negative controls. A JWB-diseased in vitro-grown jujube plantlets was set as the positive control. The total DNA of 3 leaves from each sample was extracted using the Hi-DNA secure Plant Kit (DP350, TianGen, Beijing, China). The phytoplasma amplicon was detected in all leaf samples (Figure 2). The expected 16S rDNA (GenBank accession number MW990090) amplicon is 1,348 bp, and the expected secA (GenBank accession number MZ292648) amplicon is 842 bp. These two fragments were detected in the sweet potato samples (Figure 2a, 2b). The DNA fragment amplified from the diseased sweet potato and the diseased jujube leave samples exhibiting disease symptoms using the 16S rRNA primers was then sequenced (Sangon Biotech, Shanghai, China) and was 100% identical to that of 23 JWB phytoplasma strains through BLAST analysis. The DNA fragment amplified using the secA primers was sequenced and was 100% identical to that of JWB phytoplasma strain ZQ secA gene (GU471770.1). RFLP analysis of the 16S rRNA sequence fragment by the online tool iPhyClassifier (Wei et al., 2007) indicated that the pathogen strain was a member of subgroup 16SrV-B and a ‘Candidatus Phytoplasma ziziphi’-related strain. Sweet potato witches’ broom disease was reported by Gundersen (1994) and Lee, I. M. (2004). Sweet potato little leaf disease was reported and classified as a phytoplasma in the 16 SrII group (Tairo et al., 2006). According to the evolutionary analysis, the 16S rRNA nucleotide sequences found in sweet potato in this study were quite different from that detected in sweet potato little leaf disease (Figure 2c). Taken together, the results indicated that the phytoplasma associated with sweet potato in the present study is a ‘Ca. Phytoplasma ziziphi’ strain. To our knowledge, this is the first report of its presence in sweet potato in China.

scholarly journals First report of Berkeleyomyces basicola (synonymous: Thielaviopsis basicola) on roots of sweet potato (Ipomoea batatas (L.) Lam) in Argentina

2021 ◽  
Vol 53 (1) ◽  
pp. 283-287
Author(s):  
Julia A. Martino ◽  
Liliana del Valle Di Feo ◽  
Mauro Paccioretti ◽  
Clara Adriana Contardi ◽  
Miguel A. Sanchez ◽  
...  
Keyword(s):  
Sweet Potato ◽  
Root Rot ◽  
Ipomoea Batatas ◽  
Optical Microscope ◽  
Thielaviopsis Basicola ◽  
Accession Number ◽  
Sweet Potatoes ◽  
Potential Threat ◽  
Black Root Rot ◽  
First Report

Symptomatic sweet potato cv Arapey INIA samples were collected from a commercial production field in Colonia Molina, Guaymallén department, Mendoza province, Argentina. They showed dark rounded lesions, sometimes coalescing with white granular mycelium. Fungus was obtained from symptomatic sweet potatoes, which represented the generalized infection that affected the crop. They were seeded in PDA with streptomycin sulfate and incubated for seven days at 21°C, alternating white/black (UV400nm) light. Observations with an optical microscope revealed the presence of hyaline, not septated, cylindrical endoconidia with rounded ends. They were 8-16 μm length and 4–6 μm width. Phialides were 43-46 μm length, rounded bases (7-9 μm width) and tapering to the neck´s tip (4-6 μm width). Brown chlamydospores (aleuriospores), 9-13 μm length and 8-12 μm width, in chains of 2-8 spores were observed. For molecular identification, total genomic DNA was extracted. ITS fragment of 565 pb was amplified using ITS5/ITS4 primers and sequenced. The sequence indicated 99% identity with Berkeleyomyces basicola (synonymous: Thielaviopsis basicola). This was deposited in GenBank as (KX580957) (CBS: C430.74, Gen Bank accession number AF275482.1). This is the first report of B. basicola in sweet potato in Argentina, a potential threat to storage root yields. Highlights: Sweet potato black root rot, new disease in Argentina. First report of Berkeleyomyces basicola  causing black root rot on sweet potato in Mendoza, Argentina.

scholarly journals Herbicide Evaluation for Sweet Potatoes

1969 ◽  
Vol 66 (4) ◽  
pp. 254-260 ◽  
Author(s):  
Lii-Chyuan Liu ◽  
Edwin Acevedo-Borrero ◽  
F. H. Ortiz
Keyword(s):  
Weed Control ◽  
Sweet Potato ◽  
Tuber Yield ◽  
Potato Cultivar ◽  
Weed Competition ◽  
Sweet Potatoes ◽  
Minimum Rate ◽  
Potato Plants ◽  
Herbicide Treatments ◽  
Rate Controlled

Two herbicide experiments were carried out in 1980 to evaluate Alachor and Metribuzin alone or combined for weed control in sweet potato cultivar Miguela at the Isabela and Fortuna Substations, Metribuzin at 1.12 kg ai/ha rate controlled effectively both broadleaf weeds and grasses. A minimum rate of 6.73 kg ai/ha of Alachor was needed for acceptable weed control. Metribuzin at the 1.12 kg al/ha rate in combination with Alachor at the 3.36 kg ai/ha rate provided the best weed control. There was no visible herbicide injury to sweet potato plants at the Isabela Substation. Moderate crop injury as a consequence of Metribuzin application at 2.24 kg ai/ha was apparent at the Fortuna Substation. The highest tuber yield was obtained with Metribuzin at 1.12 kg ai/ha in combination with Alachor at 3.36 kg ai/ha at both Substations. Metribuzin at 1.12 kg ai/ha rate alone or in combination with any other herbicide also produced good tuber yield. Sweet potatoes with standard herbicide treatments, Diphenamid and Chloramben, yielded poorly because of weed competition.

scholarly journals HAMA PENTING TANAMAN UBI JALAR (Ipomea batatas L.(Lamb)) DI KABUPATEN MINAHASA, MINAHASA UTARA, DAN KOTA TOMOHON

EUGENIA ◽  
2011 ◽  
Vol 17 (2) ◽  
Author(s):  
Odi R. Pinontoan ◽  
Maxi Lengkong ◽  
Henny V.G. Makal
Keyword(s):  
Sweet Potato ◽  
Field Research ◽  
Laboratory Research ◽  
Survey Method ◽  
Pest Species ◽  
Sweet Potatoes ◽  
Potato Plants ◽  
Cylas Formicarius ◽  
Ipomea Batatas ◽  
Important Pest

ABSTRACT The research aimed to identify important pests which attack sweet potato in the field. Field and laboratory research were conducted. The field research was carried out in sweet potato cropping areas in Minahasa Regency, North Minahasa regency and  Tomohon. The laboratory research was conducted in plant pests and disease laboratory, Faculty of Agriculture Sam Ratulangi University Manado to idedntify the important pest species which were found on sweet potato plants. The duration of the study was four months starting from December 2010 until March 2011. Survey method was applied with purposive random sampling.  The research was used 4 period of plant growth namely 1 month, 2 months,3 months, and 4-5 months after planting. The result showed that there were five orders identified, attacking sweet potato since the age of 1-4 months in Minahasa regency, Tomohon and North Minahasa regency. The five orders were Orthoptera, Hemiptera, Homoptera, Lepidoptera, and Coleoptera. The damage on the leaves were caused by pests coreidae, Cicadelidae, Spodoptera sp (Noctuidae), Valanga sp (Acrididae), and Oxya sp. (Acrididae), whereas on the stem was Omphisa sp (Pyralidae). Damage on the tuber was caused by Gryllotalpa sp (Gryllotalpidae), Cylas formicarius (Curculionidae) and Oryctes sp (Dynastidae). Key words : Important Pest Plant Sweet Potatoes, Ipomea batatas L.

scholarly journals USING NATURAL LIGHT ON MICROPROPAGATION OF SWEET POTATO ( Ipomoea batatas L. ) IN AREA OF HO CHI MINH CITY

2012 ◽  
Vol 15 (3) ◽  
pp. 36-46
Author(s):  
Giap Dang Do ◽  
Hien Thi Dieu Huynh ◽  
The Danh Tran ◽  
Tuan Trong Tran
Keyword(s):  
Sweet Potato ◽  
Ipomoea Batatas ◽  
Natural Light ◽  
Ex Vitro ◽  
Ambient Conditions ◽  
Potato Plants ◽  
Standard Culture ◽  
Survival And Growth ◽  
Better Than

Plantlets of sweet potato ( Ipomoea batatas L. ) were cultured in vitro under three different ambient conditions including a standard culture room - PS, a culture room inside a glasshouse with natural light but controlled temperature - TH, and a standard glasshouse with natural light (natural fluctuations of temperature) - NP. Plantlets from three treatments were compared in terms of pathogen rate, growth, survival plant at the end of the in vitro stage and at the ex vitro acclimatization. This result showed that, after 28 days of culture, sweet potato plants were cultured in vitro TH conditions have reduced entirely due to susceptibility to fungal disease causing outside air. After 14 days of ex vitro acclimatization, plants originally grow in vitro under the TH condition had ability to adapt about field survival and growth rates better than the other two treatments.

scholarly journals INVENTARISASI DAN KARAKTERISASI PLASMA NUTFAH PERTANAMAN UBI JALAR (Ipomoea batatas L.) DI PULAU LOMBOK

2020 ◽  
Vol 8 (1) ◽  
pp. 136
Author(s):  
Sumarjan Sumarjan ◽  
Lestari Ujianto ◽  
Agung Bagus Darma
Keyword(s):  
Sweet Potato ◽  
Ipomoea Batatas ◽  
Food Sources ◽  
Sweet Potatoes ◽  
Local Varieties ◽  
Potato Plants ◽  
Potato Germplasm ◽  
High Level ◽  
Descriptive Method ◽  
Lombok Island

Lombok Island as an area that still has a high level of food insecurity is deemed necessary to develop tuber crops such as sweet potatoes, this is to support the diversity of existing food sources. This study aims to determine: 1) sweet potato germplasm cultivated on Lombok Island; and 2) the characteristics of sweet potato germplasm on Lombok Island. This research uses a descriptive method. Inventarization is carried out by the exploration method, and using cluster analysis which is then displayed in the form of a phenogram. The results showed: 1) obtained 17 accessions of sweet potato plants spread in 4 districts of Lombok Island; 2) the accessions found consisted of accessions of Sweet Potato KLU, Honey KLU, Purple 04 KLU, Orange Lobar, White Lobar, Purple 01 Lobar, Purple 02 Lobar, Purple 03 Lobar, Ornamental Attic, Attic Yellow, Attic White, Purple 01 Attic, Purple 02 Attic, Honey Lotim, Sokan Lotim, Purple 05 Lotim, and Purple 06 Lotim; 3) the cause of the differences in the characteristics of all observed accessions is genetic factors that are supported by different growing environmental conditions. In the accession of Sweet Potato Beduk KLU and Sokan Lotim are local varieties of sweet potato from Lombok Island, so it needs to be developed to maintain local superior sweet potato varieties from Lombok Island.

scholarly journals Binding and processing of small dsRNA molecules by the class 1 RNase III protein encoded by sweet potato chlorotic stunt virus

2014 ◽  
Vol 95 (2) ◽  
pp. 486-495 ◽  
Author(s):  
Isabel Weinheimer ◽  
Kajohn Boonrod ◽  
Mirko Moser ◽  
Michael Wassenegger ◽  
Gabi Krczal ◽  
...  
Keyword(s):  
Sweet Potato ◽  
Transcriptional Gene Silencing ◽  
Specific Class ◽  
Dependent Manner ◽  
Small Interfering Rnas ◽  
Rnase Iii ◽  
Potato Plants ◽  
Post Transcriptional Gene Silencing ◽  
Class 1

Sweet potato chlorotic stunt virus (SPCSV; genus Crinivirus, family Closteroviridae) causes heavy yield losses in sweet potato plants co-infected with other viruses. The dsRNA-specific class 1 RNase III–like endoribonuclease (RNase3) encoded by SPCSV suppresses post-transcriptional gene silencing and eliminates antiviral defence in sweet potato plants in an endoribonuclease activity-dependent manner. RNase3 can cleave long dsRNA molecules, synthetic small interfering RNAs (siRNAs), and plant- and virus-derived siRNAs extracted from sweet potato plants. In this study, conditions for efficient expression and purification of enzymically active recombinant RNase3 were established. Similar to bacterial class 1 RNase III enzymes, RNase3-Ala (a dsRNA cleavage-deficient mutant) bound to and processed double-stranded siRNA (ds-siRNA) as a dimer. The results support the classification of SPCSV RNase3 as a class 1 RNase III enzyme. There is little information about the specificity of RNase III enzymes on small dsRNAs. In vitro assays indicated that ds-siRNAs and microRNAs (miRNAs) with a regular A-form conformation were cleaved by RNase3, but asymmetrical bulges, extensive mismatches and 2′-O-methylation of ds-siRNA and miRNA interfered with processing. Whereas Mg2+ was the cation that best supported the catalytic activity of RNase3, binding of 21 nt small dsRNA molecules was most efficient in the presence of Mn2+. Processing of long dsRNA by RNase3 was efficient at pH 7.5 and 8.5, whereas ds-siRNA was processed more efficiently at pH 8.5. The results revealed factors that influence binding and processing of small dsRNA substrates by class 1 RNase III in vitro or make them unsuitable for processing by the enzyme.

scholarly journals Supply fertilization systems (ipomoea batatas) in the conditions of the left bank Forest Steppe of Ukraine

2021 ◽  
Author(s):  
O. Kuts ◽  
◽  
S. Shevchenko ◽  
V. Mikhailin ◽  
I. Semenenko ◽  
...  
Keyword(s):  
Sweet Potato ◽  
Total Yield ◽  
Nitrate Content ◽  
Mineral Fertilizers ◽  
Potato Tubers ◽  
Sweet Potatoes ◽  
Foliar Fertilization ◽  
Potato Plants ◽  
Mobile Forms ◽  
Fertilizer System

The research was conducted during 2019–2020 in the laboratory of agrochemical research and product quality of the Institute of Vegetable and Melon NAAS. The soil of the experimental site - typical low-humus loamy chernozem on loess loam (in the plow layer (0-25 cm) of humus contained 4.3%N hydrolyzed - 139,0 mg/kg, mobile P - 106-119 mg/kg and exchangeable K - 93 mg/kg of soil, hydrolytic acidity - 2.8 mg-Eq per 100 g of soil, pH of salt extract - 5.7, the sum of absorbed bases - 26.0 mg-Eq per 100 g of soil). The research studied the effectiveness of different fertilizing systems: 1) without fertilizer (control); 2) N185P185K225; 3) N370P370K450; 4) N370P370K450 + foliar fertilization with complex fertilizer "Nutrivant plus universal" 2 kg / ha in 3 terms; 5) mold 20 t/ha + ash 1 t/ha 6) mold 20 t/ha + ash 1 t/ha + tillage planting soil fertilizer "Hraundfiks" (3 l/ha) + the first fertigation microbial drug " Azotophyte ”(1 l/ha) + for the second fertigation microbial preparation“ Organic Balance ”(1 l/ha) + foliar fertilization“ Help-rost for vegetable plants ”2 l/ha in 3 terms. Foliar fertilization was carried out in three terms: 30 days after planting (III decade of June), with active growth of vegetative mass (III decade of July), with active growth of tubers (III decade of August). The research was conducted in accordance with generally accepted methods. The total area of the plot was 33.6 m2, accounting - 21 m2, repetition - three times. In the study, sweet potatoes of the Slobozhansky Ruby variety were grown under drip irrigation, planting schemes (100 + 40) x 25 cm and mulching the soil with straw. According to the results of the study, it was found that the use of mineral and organic fertilizers by improving the nutritional conditions of plants provided an increase in the yield of sweet potato tubers and had a positive effect on their biochemical properties. On average, over the years of research, the use of different fertilizer systems causes an increase in the total yield of tubers by 5.3–8.7 t / ha or 34–56%, the yield of standard tubers - by 2.9–4.6 t / ha or 27–42 %. The highest level of sweet potato yield was provided by the use of N370P370K450 in combination with Nutrivant plus universal foliar fertilizers. The total yield of such a fertilizer system is 24.3 t / ha, of which 15.5 t / ha of standard tubers. According to our data, the effectiveness of increasing the dose of mineral fertilizers from N185P185K225 to N370P370K450 has not been proven, as there is no significant difference between the options. Additional fertilization with complex fertilizers provides a positive trend to increase the yield of sweet potatoes by 3.3 t/ha. The use of an organic fertilizer system (20 t / ha of humus and 1 t / ha of ash) provides an increase in the total yield of tubers by 6.7 t / ha or 43%, while the additional use of a set of microbial drugs is not justified by a significant increase in yield (22.8 t / ha). It was found that the use of organic fertilizers in combination with microbial preparations had the most positive effect on the biochemical composition of sweet potato tubers. Under this system of nutrition optimization, the dry matter content in tubers (18.6%), starch (9.06%) increased, and the low nitrate content (28.1 mg / kg) was noted. Under the mineral fertilizer system N370P370K450 with the use of complex fertilizers significantly increased the dry matter content (17.7%), however, the nitrate content was the highest in the experiment (78.5 mg / kg). There is a tendency to reduce the total sugar in sweet potato tubers with the use of all fertilizer systems, especially with the use of mineral fertilizer system N370P370K450 in combination with foliar fertilization "Nutrivant plus universal" (3.4% with the value of this indicator in control - 4.74%). To adjust the doses of mineral fertilizers under sweet potatoes, we calculated the absorption coefficients of nutrients from fertilizers and soil. It was found that on chernozem, a typical low-humus light loam plant, sweet potatoes absorb up to 57% of mobile forms of N, 11.6% of mobile forms of P and up to 61.2% of mobile forms of K. Nutrient utilization factors from mineral fertilizers are 40.7% for N; P - 26.1%, K - 73.5%. It should be noted that the utilization rates of soil nutrients vary not only depending on the biological characteristics of plants, but also due to changes in soil fertility, weather conditions, level of technological support, etc., which to some extent complicates their use in determining estimated doses of fertilizers. The rate of absorption of nutrients by sweet potato plants under different fertilizer systems was established. Without fertilizers, sweet potato plants absorb 88.2% N, 60.6% P and 80.5% K from the total consumption of plant nutrients in the first two months of growth. With mineral and organic fertilizer systems, the peak of nutrient consumption occurs at 2-3 months of plant growth, ie with the active formation and growth of tuber mass. Without the use of fertilizers by the end of the growing season significantly reduced uptake by plants P (104.4 kg/ha) and K (252.4 kg/ha), which, in our opinion, affect the reduction in yield yam. It should be noted that the uptake of K by sweet potato plants in the Forest-Steppe of Ukraine is higher than in the soils of the southern regions (according to Degras [34], the removal of K with sweet potato plants is 110–135 kg/ha). It is noted that depending on the fertilizer system 56.9–76.9% of N accumulates in the leaves, 10.2–13.6% in the stems, 12.9–29.5% in the roots and tubers. P 31.2–49.9% accumulates in leaves, 13.4–20% in stems, 30.1–55.4% in roots and tubers; for K 41.6–51.9% in leaves, 13.2–21.2% in stems, 26.9–45.2% in tubers and roots.

scholarly journals First Report of Pectobacterium punjabense Causing Blackleg and Soft Rot on Potato in Hebei and Fujian Province, China

Plant Disease ◽  
2022 ◽  
Author(s):  
Utpal Handique ◽  
Yaning Cao ◽  
Dekang Wang ◽  
Ruofang Zhang ◽  
Wensi Li ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Housekeeping Genes ◽  
Soft Rot ◽  
Rrna Gene ◽  
Pectobacterium Carotovorum ◽  
Fujian Province ◽  
First Report ◽  
Potato Plants ◽  
Carotovorum Subsp

Pectobacterium spp. and Dickeya spp. cause blackleg and soft rot on potato worldwide (Charkowski, 2018). Potato plants (cv. Favorita or Jizhang 8#) with blackleg symptoms (vascular browning of crown stems, Fig. S1) were observed in the field in Zhangjiakou, Hebei province in 2018, and in Ningde, Fujian Province in 2019, in China. The disease incidence was around 50% and 10% in Zhangjiakou (5 ha) and Ningde (4 ha), respectively. Diseased plants (3 from each site) were collected to isolate the pathogen. Blackleg symptomatic stems were soaked in 75% ethanol for 2 min, rinsed and ground in sterile distilled water. Serial tenfold dilutions of the above solution were plated onto the crystal violet pectate agar (CVP) plate (Ge et al., 2018). Two to 3 days after incubation at 28°C, 4 bacterial colonies in total which digested pectin from the media and developed pit on CVP plates were purified and sequenced for identification using the universal 16S rRNA gene primer set 27F/1492R (Monciardini et al., 2002). Two colony sequences that showed more than 99% sequence identity to Pectobacterium punjabense type strain SS95 (MH249622) were submitted to the GenBank ( accession numbers: OK510280, MT242589). Additionally, six housekeeping genes proA (OK546205, OK546199), gyrA (OK546206, OK546200), icdA (OK546207, OK546201), mdh (OK546208, OK546202), gapA (OK546209, OK546203), and rpoS (OK546210, OK546204) of these two isolates were amplified and sequenced (Ma et al., 2007, Waleron et al., 2008). All strains show 99% to 100% identity with MH249622T . Phylogenetic trees based on 16S rRNA gene sequences (Fig. S2) and concatenated sequences of the housekeeping genes (Fig. S3) of the 2 isolates were constructed using MEGA 6.0 software (Tamura et al., 2013). Koch’s postulate was performed on potato seedlings and potato tubers (cv. Favorita) by injecting 100 μl bacterial suspension (105 CFU/ml) or sterile phosphate-buffered solution into the crown area of the stems or the tubers and kept at 100% humidity and 21°C for 1 day. Four days after inoculation, the infected area of the inoculated seedlings rotten and turned black, while the controls were symptomless (Fig. S4). Two days after inoculation, the infected tubers rotten and turned black, while the controls were symptomless (Fig. S4). Bacterial colonies were reisolated from these symptomatic tissues and identified using the same methods described above. Blackleg on potato plants or soft rot on potato has been reported to be caused by Pectobacterium atrosepticum, Pectobacterium carotovorum subsp. carotovorum, Pectobacterium carotovorum subsp. brasiliense, Pectobacterium parmentieri, Pectobacterium polaris in China (Zhao et al., 2018; Cao et al., 2021; Wang et al., 2021). To our knowledge, this is the first report of blackleg/soft rot of potato caused by Pectobacterium punjabense in China. We believe that this report will draw attention to the management of this pathogen in China.

scholarly journals First Report of Pectobacterium parmentieri Causing Blackleg on Potato in Inner Mongolia, China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yaning Cao ◽  
Qinghua Sun ◽  
Zhiwen Feng ◽  
Utpal Handique ◽  
Jian Wu ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Inner Mongolia ◽  
Rrna Gene ◽  
Pectobacterium Carotovorum ◽  
Distilled Water ◽  
First Report ◽  
Potato Plants ◽  
Sequence Identity ◽  
Carotovorum Subsp

Blackleg on potato plants (Solanum tuberosum) is caused by Pectobacterium spp. and Dickeya spp. (Charkowski, 2018) worldwide. From June to August in both 2018 and 2019, cases of blackleg were investigated in potato-producing areas in Hulunbuir, Ulanqab, and Hohhot in Inner Mongolia, China. The total surveyed field area was about 200 hectares. The plants showed typical blackleg symptoms, such as black and stunted stems or curled leaves (Fig. S1), and the number of infected plants were counted. The disease showed an incidence of around 8%. Five diseased plants were collected from a 10 ha potato field with approximately 75,000 potato plants (cv. mainly Favorita and Xisen) per hectare. Two-centimeter-long samples of symptomatic stems were removed from the selected plants using a sterile scalpel. The surfaces of the samples were disinfected with 75% ethanol for 2 min. They were then rinsed with sterile distilled water and soaked in 5 ml sterile distilled water for 30 min. Aliquots of three tenfold dilutions of this solution were plated onto the crystal violet pectate agar (CVP) plate and incubated for 3 days at 28°C (Ge et al., 2018). A single bacterial colony that showed pitting on CVP plates (Fig. S2) was picked with a toothpick, streaked onto nutritional agar (She et al., 2013) to obtain pure colonies. Amplification of a 1.4-kb segment containing 16S rRNA gene was performed on the pure colonies using the universal primer set 27F/1492R (Monciardini et al., 2002). The amplicons were sequenced and submitted to the GenBank Nucleotide Basic Local Alignment Search Tool analysis. The 16S rRNA gene sequences of four isolates (GenBank accession numbers: MN626412, MN626449, MN625916, and MT235556) showed more than 99% sequence identity to Pectobacterium parmentieri type strain RNS 08-42-1A (NR_153752.1) (Fig. S3). Six housekeeping genes proA (MT427753-MT427756), gyrA (MT427757–MT427760), icdA (MT427761-MT427764), mdh (MT427765–MT427768), gapA (MT427769-MT427772), and rpoS (MT427773–MT427776) of these four isolates were amplified and sequenced (Ma et al., 2007, Waleron et al., 2008). All sequences showed 99% to 100% sequence identity with Pectobacterium parmentieri strains. Phylogenetic trees (Fig. S4) were constructed by multi-locus sequence analysis (MLSA) using MEGA 6.0 software (Tamura et al., 2013). The samples were tested against Koch’s postulates on potato seedlings (cv. Favorita) by injecting 100 μl bacterial suspension (107 CFU/ml) or sterile phosphate buffered solution into the stems 2 cm above the base (Ge et al., 2018). The seedlings were incubated at 21°C and 80% humidity (She et al., 2013). Three to 5 days after inoculation, only infected seedlings showed similar symptoms as those observed in the field: the infected area turned black and rotten (Fig. S5). Bacterial colonies isolated from these symptomatic seedlings were identified using the same methods described above and were identified as inoculated Pectobacterium parmentieri strains. Blackleg on potato plants has been reported to be caused by Pectobacterium atrosepticum, Pectobacterium carotovorum subsp. carotovorum, and Pectobacterium carotovorum subsp. brasiliense in China (Zhao et al., 2018). To our knowledge, this is the first report of blackleg of potato caused by Pectobacterium parmentieri in Inner Mongolia, China. We believe that this report will draw attention to the identification of this pathogen, which is essential to disease management.

scholarly journals First Report of a Begomovirus Infecting Sweetpotato in Kenya

Plant Disease ◽  
2006 ◽  
Vol 90 (6) ◽  
pp. 832-832 ◽  
Author(s):  
D. W. Miano ◽  
D. R. LaBonte ◽  
C. A. Clark ◽  
R. A. Valverde ◽  
M. W. Hoy ◽  
...  
Keyword(s):  
Sweet Potato ◽  
Germplasm Collection ◽  
Degenerate Primers ◽  
Potato Leaf ◽  
First Report ◽  
Two Samples ◽  
Total Dna ◽  
Dna Fragment ◽  
Pcr Assays ◽  
Leaf Curl

Previous surveys for viruses in sweetpotatoes (Ipomoea batatas) in Africa did not assay for the presence of begomoviruses such as Sweet potato leaf curl virus (SPLCV), which have been found recently in the Americas and Asia. Symptomatic sweetpotato plants, including some with leaf curling symptoms similar to those observed in SPLCV-infected sweet-potato plants (2), were collected from a germplasm collection plot at Kakamega Research Station in Western Kenya during February 2005. Whiteflies, the vectors for begomoviruses, were observed in the same plots. Ipomoea setosa plants graft-inoculated with scions from the symptomatic sweetpotato developed leaf curl, leaf roll, interveinal chlorosis, and stunting symptoms similar to those caused by infection with SPLCV alone or in combination with Sweet potato feathery mottle virus. Total DNA was isolated from 10 I. setosa plants using the GenElute Plant Genomic DNA Kit (Sigma-Aldrich Inc., St. Louis, MO). Sweetpotato cuttings from 39 clones, selected from the Kenyan germplasm collection for their resistance or susceptibility to sweetpotato virus disease (SPVD), were sent to the Plant Germplasm Quarantine Office of USDA-ARS. The cuttings were planted in a greenhouse. Total DNA was extracted from sweetpotato leaves 1 month later using a cetyltrimethylammoniumbromide (CTAB) extraction method (1). Degenerate primers SPG1/SPG2, developed for PCR detection of begomoviruses (1), amplified a 912-bp DNA fragment from 3 of 10 DNA extracts from I. setosa and 5 of 39 sweetpotato plants held in quarantine. The primers anneal to regions of open reading frame (ORF) AC2 and ORF AC1 that are highly conserved in begomoviruses infecting sweetpotato. SPLCV-specific primers PW285-1/PW285-2 (2) amplified a 512-bp DNA fragment of ORF AC1 from seven samples (two from I. setosa and five from I. batatas). Amplicons from three independent PCR assays of two samples and single PCR assays of four additional samples were cloned into the pGEM-T Easy vector. Clone inserts were sequenced, and compared with sequences deposited in GenBank using the basic local alignment search tool (BLAST). Sequences were closely related to SPLCV (GenBank Accession No. AF104036) with nucleotide sequence identities varying from 93% (GenBank Accession No. DQ361004) to 97% (GenBank Accession No. DQ361005). The presence of the virus poses a challenge to the dissemination of planting materials in the region because begomovirus-infected plants often do not show symptoms. To our knowledge, this is the first report of a begomovirus infecting sweetpotato in Kenya or the East African Region. References: (1) R. Li et al. Plant Dis. 88:1347, 2004. (2) P. Lotrakul et al. Plant Dis. 82:1253, 1998.

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