scholarly journals First report of Fusarium oxysporum f. sp. cubense Tropical Race 4, causing Fusarium wilt in Cavendish bananas in Peru

Plant Disease ◽  
2021 ◽  
Author(s):  
Rosalyn Acuña ◽  
Mathieu Rouard ◽  
Ana Maria Leiva ◽  
Claudio Marques ◽  
Arturo Olortegui ◽  
...  

Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc TR4), the causal agent of Fusarium wilt of banana (FWB), is currently the major threat to the banana industry worldwide (Dita et al. 2018). Restricted to South Asia for more than 20 years, Foc TR4 has spread in the last years to the Middle East, Mozambique, and Colombia (García-Bastidas et al. 2019; https://pestdisplace.org/embed/news/map/disease/11). The incursion of Foc TR4 in Colombia increased awareness and prevention efforts across Latin American and the Caribbean (LAC). However, new Foc TR4 outbreaks in LAC countries were considered a matter of time. In April 2021, banana (Musa spp., Cavendish, AAA) plants (30% of incidence) showing typical symptoms of FWB, such as leave yellowing, wilting and vascular discoloration were observed in one farm (about 1 ha) located in Querecotillo, Peru (4°43’54.84”S 80°33’45.00”W). Mycological analyses of samples (pseudostem strands) collected from 10 symptomatic plants were performed as described by Dita et al. (2010). These analyses revealed a continuous presence of fungal colonies identified as Fusarium oxysporum species complex. Molecular diagnostics targeting two different genome regions (Dita et al 2010; Li et al. 2013) identified nine of these isolates as Foc TR4. These results were further confirmed by qPCR analyses using the commercial Clear Detections TR4 kit. The genome of four single-spore isolates (PerS1, PerS2, PerS3 and PerS4) was sequenced using the Illumina platform (MiSeq Kit, 2x151 bp Paired-End). The strain PerS4 was also sequenced using Oxford Nanopore (FLOW-MIN111; R10.3 chemistry) as described by Lopez-Alvarez et al., (2020). The generated draft assembly yielded 533 contigs for a size of 47 Mbp (BioProject: PRJNA755905), which is comparable with sizes of previously reported Foc TR4 strains (Asai et al. 2019; García-Bastidas et al. 2019; Maymon et al. 2020; Warmington et al. 2019; Zheng et al. 2018). The sequence assembly showed high contiguity (94.9%) and high similarity (95.48%) with the high-quality genome sequence of the Foc TR4 isolate ‘UK0001’ (Warmington et al. 2019). Further analyses to identify the presence/absence of full sequences for the putative effector genes (Secreted In Xylem - SIX) and their allelic copies, also revealed that the SIX genes profile of the strains isolated from Querecotillo matched with previously reported Foc TR4 isolates (Czislowski et al. 2017). Pathogenicity tests with three isolates and water controls were performed as described by Dita et al. (2010), using five Cavendish plantlets per treatment. Four weeks after the inoculation typical external and internal symptoms of FWB were observed only in the inoculated plants. Fungal isolates recovered from inoculated plants tested positive for Foc TR4 when analyzed with PCR diagnostics as mentioned above. No fungal isolates were recovered from water-control plants which did not show any symptoms. Altogether, our results confirm the first incursion of Foc TR4 in Peru. Currently, Foc TR4 has the phytosanitary status of a present pest with restricted distribution in Peru and it is under official control of the National Plant Protection Organization – SENASA. Reinforced prevention and quarantine measures, disease monitoring and capacity building to detect, contain and manage eventual new outbreaks of Foc TR4 are strongly encouraged across LAC banana producing countries, especially for those bordering Peru with larger banana plantations, such as Ecuador and Brazil.

Plants ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1133
Author(s):  
Freddy Magdama ◽  
Lorena Monserrate-Maggi ◽  
Lizette Serrano ◽  
José García Onofre ◽  
María del Mar Jiménez-Gasco

The continued dispersal of Fusarium oxysporum f. sp. cubense Tropical race 4 (FocTR4), a quarantine soil-borne pathogen that kills banana, has placed this worldwide industry on alert and triggered enormous pressure on National Plant Protection (NPOs) agencies to limit new incursions. Accordingly, biosecurity plays an important role while long-term control strategies are developed. Aiming to strengthen the contingency response plan of Ecuador against FocTR4, a population biology study—including phylogenetics, mating type, vegetative compatibility group (VCG), and pathogenicity testing—was performed on isolates affecting local bananas, presumably associated with race 1 of F. oxysporum f. sp. cubense (Foc). Our results revealed that Foc populations in Ecuador comprise a single clonal lineage, associated with VCG0120. The lack of diversity observed in Foc populations is consistent with a single introduction event from which secondary outbreaks originated. The predominance of VCG0120, together with previous reports of its presence in Latin America countries, suggests this group as the main cause of the devastating Fusarium wilt epidemics that occurred in the 1950s associated to the demise of ‘Gros Michel’ bananas in the region. The isolates sampled from Ecuador caused disease in cultivars that are susceptible to races 1 and 2 under greenhouse experiments, although Fusarium wilt symptoms in the field were only found in ‘Gros Michel’. Isolates belonging to the same VCG0120 have historically caused disease on Cavendish cultivars in the subtropics. Overall, this study shows how Foc can be easily dispersed to other areas if restriction of contaminated materials is not well enforced. We highlight the need of major efforts on awareness and monitoring campaigns to analyze suspected cases and to contain potential first introduction events of FocTR4 in Ecuador.


Plant Disease ◽  
2020 ◽  
Author(s):  
Raman Thangavelu ◽  
Gopi Muthukathan ◽  
Periaswamy Pushpakanth ◽  
Loganathan Murugan ◽  
Esack Edwin Raj ◽  
...  

Fusarium wilt caused by Fusarium oxysporum f.sp. cubense (Foc) is the most devastating disease affecting commercial and subsistence cultivation of banana (Musa spp.) worldwide. Generally, the Cavendish bananas are resistant to Foc race 1 that destroyed cv. ‘Gros Michel’ (AAA) and susceptible to tropical race 4 (TR4), which is causing severe epidemics in different banana-growing countries including India (Thangavelu et al. 2019). In 2019, a roving survey was conducted in major banana growing states of India such as Bihar, Uttar Pradesh, Gujarat and Tamil Nadu to assess the incidence of Fusarium wilt disease in Cavendish bananas and also to characterize the pathogens by different methods including Vegetative Compatibility Grouping (VCG) and molecular methods. The Fusarium wilt incidence in cv. Grand Naine (Cavendish group-AAA) was 6-65% in Bihar, 30-45% in Uttar Pradesh, 5-15% in Gujarat and 15- 21% in Tamil Nadu. For characterization, a total of 61 samples from the Fusarium wilt infected Cavendish bananas were collected and single spore culture of Foc was obtained. The morphological characterization revealed the presence of one to two oval- to kidney-shaped cells in false heads and sickle-shaped macroconidia and a foot-shaped basal cell. The pathogenicity was demonstrated by adopting randomized block design with five replications on cv. Grand Naine. The Koch’s postulate was successfully completed by re-isolation of the inoculated Foc pathogen and characterization by PCR method. The VCG analysis carried out using nit–M testers of all known VCGs indicated the presence of VCG 0125 from the Foc samples collected from cv. Grand Naine grown in Uttar Pradesh (Siswabazar of Maharakanj district) and Tamil Nadu (Cumbum of Theni district), VCG 01220 from the Foc samples collected from cv. Grand Naine grown in Uttar Pradesh (Siswabazar of Maharakanj district) and Gujarat (Kamrej of Surat district,) and VCG 01213/16 from Foc samples collected from Uttar Pradesh (Siswabazar of Maharakanj district) and Bihar (Falka village of Katihar district) . The molecular confirmation of these VCGs 0125, and 01220 (Foc R1) isolates was carried out by PCR method using the primer set SIX6b_210_F and SIX6b_210_R (Carvalhais et al. 2019) for Foc R1, primer sets Foc TR4-F & Foc TR4 –R (Dita et al. 2010) for Foc TR4 and primer set Foc-1/Foc -2 (Lin et al. 2009) for Race 4. The results showed that only the primer set for Foc R1 has generated the expected amplicon size of 210 bp in the Foc isolates of VCG 0125 and 01220. Besides, the sequencing of Translation Elongation Factor (TEF) 1-α gene and BLAST searches in Genbank for the representative Foc isolates of VCG 0125 (Genbank no. MW 286800) showed 99.84% similarity to Foc R1 (KX365393.1) and Foc isolates of VCG 01220 (Genbank no. MW 286803) showed 99.69% similarity to Foc R1 (KX365413.1). Further, a phylogenetic analysis performed using the TEF1-α gene sequences showed that the Foc race 1 isolates (VCGs 0125 and 01220) from India were grouped with known Foc race 1 isolates from Tanzania and Australia. Based on the experimental results the study has confirmed the presence of VCGs 0125 and 01220 of Foc Race 1 in cv. Grand Naine in India. As these VCGs are most widely distributed and do not found to infect Cavendish bananas so far (Mostert et al. 2017), this report is very important from the quarantine and management perspectives. To the best of our knowledge, this is the first report of the occurrence of VCGs 0125 and 01220 of Foc Race 1 in cv. Grand Naine in India.


Plant Disease ◽  
2018 ◽  
Vol 102 (2) ◽  
pp. 448-448 ◽  
Author(s):  
T. N. Hung ◽  
N. Q. Hung ◽  
D. Mostert ◽  
A. Viljoen ◽  
C. P Chao ◽  
...  

Plant Disease ◽  
1999 ◽  
Vol 83 (7) ◽  
pp. 694-694 ◽  
Author(s):  
S. N. Smith ◽  
D. M. Helms ◽  
S. R. Temple ◽  
C. Frate

Fusarium wilt of blackeyed cowpeas has been known in California since the 1930s, and breeding for resistance to this disease pathogen has been a continuous effort. During the 1960s and 1970s, California Blackeye 5 (CB 5) cowpea (Vigna unguiculata L. Walp.), a widely grown cultivar of the time, became increasingly diseased by Fusarium oxysporum f. sp. tracheiphilum (Fot) Race 3 (2) throughout the growing regions of California. University of California cultivars CB 46 and CB 88 (1) were developed for resistance to Fot Races 1, 2, and 3. CB 46 is currently the principal blackeye cultivar grown on the majority of the acreage in the San Joaquin Valley. In 1989, a new race we designate “Fot Race 4” was isolated from wilted plants at a single field site in Stanislaus County. In years prior to identification, Fot Race 4 had caused severe wilt of CB 46 and CB 88 in this field. Even though the new Fot Race 4 remained confined to a small area for a number of years, sources of host plant resistance to Fot Race 4 were identified, hybridized, and screened, resulting in new progeny with desirable commercial agronomic characteristics. As observed in Stanislaus County, F. oxysporum f. sp. tracheiphilum Race 4 has the potential to cause serious crop damage, depending on virulence and soil inoculum levels, which may vary from year to year. In 1997 and 1998, an entirely different area in the southern San Joaquin Valley, about 140 miles from the original site in Stanislaus County, was found to have plants infected with Fot Race 4. Diseased plants were collected from patches in three separate CB 46 or CB 88 field sites in Tulare County. About 30 cultures were isolated from the diseased plants, which showed stunting, yellowing, and vascular discoloration. In greenhouse fusarium dip tests CB 46, CB 88, CB 5, and several Fot Race 4 resistant breeding lines were inoculated with all the collected isolates and evaluated. CB 46, CB 88, and CB 5 proved to be susceptible to these isolates, showing typical Fot Race 4 symptoms. The Fot Race 4 pathogen was then reisolated from greenhouse-grown, diseased stem tissue of CB 46, CB 88, and CB 5. These findings emphasize the importance of vigilance and necessity of continual disease surveys. They serve as an early alert for the University of California breeding program, and validate local cooperation with University of California Extension Farm Advisors. As a result of this effort new cultivar candidates with resistance to Fot Race 4 are in the final phases of multi-year commercial testing. References: (1) D. M. Helms et al. Crop Sci. 31:1703, 1991. (2) K. S. Rigert and K. W. Foster. Crop Sci. 27:220, 1987.


Plant Disease ◽  
2018 ◽  
Vol 102 (12) ◽  
pp. 2655 ◽  
Author(s):  
M. Maymon ◽  
U. Shpatz ◽  
Y. M. Harel ◽  
E. Levy ◽  
G. Elkind ◽  
...  

Pathogens ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 43 ◽  
Author(s):  
Arfe Castillo ◽  
Cecirly Puig ◽  
Christian Cumagun

Philippine banana is currently threatened by Fusarium oxysporum f. sp. cubense Tropical Race 4 (FocR4). This study investigated the use of Trichoderma harzianum pre-treated with Glomus spp, as a means of managing Fusarium wilt on young ‘Lakatan’ banana seedlings. Results showed that Glomus applied basally significantly improved banana seedling growth with increased increment in plant height and pseudostem diameter and heavier root weight. The application of Glomus spp. alone offered 100% protection to the ‘Lakatan’ seedlings against FocR4 as indicated by the absence of the wilting symptom. A combination of T. harzianum and Glomus spp. also gave significant effect against Fusarium wilt through delayed disease progression in the seedlings but was not synergistic. Competitive effects were suspected when application of the two biological control agents on banana roots was done simultaneously.


Plant Disease ◽  
2020 ◽  
Author(s):  
Josue Diaz ◽  
Jorge Garcia ◽  
Celeste Lara ◽  
Robert B. Hutmacher ◽  
Mauricio Ulloa ◽  
...  

Fusarium oxysporum f. sp. vasinfectum (FOV) race 4, is a causal agent of Fusarium wilt of cotton (Gossypium spp.). This study aimed to characterize the existing distribution and frequency of current field populations of FOV race 4 genotypes in the San Joaquin Valley (SJV) of California and Lower Valley El Paso, Texas and examine representative isolates for aggressiveness during different stages of seedling development. A survey was conducted from 2017 to 2019 across 13 locations in the SJV and one location in El Paso, Texas during 2018. From the SJV, isolates identified as the FOV race 4 T genotype were dispersed across the SJV, while isolates identified as the FOV race 4 N genotype were most frequently isolated from cotton fields in the northern county of Merced. The FOV race 4 isolates from the Texas location were identified as the MT genotype. A selection of representative isolates was evaluated using three inoculation assays, a rolled towel, FOV infested-oat seed, and a root dip inoculation assay to test the isolates’ abilities to produce symptoms during seedling stages of cotton development. All isolates tested were capable of producing symptoms on cotton, however isolate aggressiveness varied within and across inoculation assays. In all assays, higher levels of disease development were observed in the moderately susceptible Pima (G. barbadense L.) cultivars (DP-340 or PYH-830) when compared to the moderately tolerant Upland (G. hirsutum L.) cultivar (FM-2334). However, no correlation was found among the different response variables for the rolled towel assay when compared with the root dip and infested-oat seed assays. These results suggest that different genes are involved in the resistance response during the early seedling development stage measured in the rolled towel assay compared to the later seedling development stages measured during the root dip inoculation and infested-oat seed assays, revealing the complexity of the Fusarium wilt disease and host-plant resistance mechanisms.


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