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Banana cultivars with the AAB genome group comprise diverse subgroups, such as Plantain, Silk, Iholena, and Pisang Raja, among others, which play an important role in food security in many developing countries. Some of these cultivars are susceptible to Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), the most destructive pathogen threatening banana production worldwide, and some of them are still largely unknown. We evaluated the resistance of 37 banana genotypes, including Plantain, Silk, Iholena, Maia Maoli/Popoulu, Pisang Raja, Pome, and Mysore, to Foc TR4 under both greenhouse and field conditions. Genotypes from the Silk and Iholena subgroups were highly susceptible to Foc TR4. Pome and Mysore showed resistance and intermediate resistance, respectively. However, Pisang Raja ranged from susceptible to intermediate resistance. One cultivar from the Maia Maoli/Popoulu subgroup was highly susceptible, while the other displayed significant resistance. Most Plantain cultivars exhibited high resistance to Foc TR4, except two French types of cultivar, 'Uganda Plantain' and 'Njombe N°2', which were susceptible. The susceptibility to Foc TR4 of some of the AAB genotypes evaluated, especially Plantain and other cooking bananas, indicates that growers dependent on these varieties need to be included as part of the prevention and integrated Foc TR4 management strategies, as these genotypes play a crucial role in food security and livelihoods. [ABSTRACT FROM AUTHOR]

Fusarium oxysporum f.sp. cubense, causal agent of Panama disease, is one of the biggest threats to global banana production, particularly the Cavendish competent tropical race 4 (Foc TR4). It continues to spread globally with detections occurring in regions of the Middle East and new continents such as Africa and South America in the last decade. As the search was on for new management strategies and resistant cultivars to combat the disease, a banana cultivar-screening trial took place in the Northern Territory of Australia, which examined the responses of 24 banana cultivars to the soil borne fungus. These cultivars included material from TBRI, FHIA and selections from Thailand, Indonesia and Australia and evaluated for their resistance to tropical race 4 for two cropping cycles. Several cultivars displayed considerable resistance to Foc TR4, including several FHIA parental lines and hybrids, the Cavendish (AAA) selections GCTCV 215 and GCTCV 247 from TBRI and an Indonesian selection CJ19 showed either very little to no plant death due to the disease. [ABSTRACT FROM AUTHOR]

The socio‐economic impact of Fusarium odoratissimum, which is colloquially called tropical race 4 (TR4), is escalating as this fungal pathogen spreads to new banana‐growing areas. Hence, the development of simple, reliable and rapid detection technologies is indispensable for implementing quarantine measures. Here, a versatile loop‐mediated isothermal amplification (LAMP) assay has been developed that is applicable under field and laboratory conditions. DNA markers unique to TR4 isolates were obtained by diversity arrays technology sequencing (DArTseq), a genotyping by sequencing technology that was conducted on 27 genotypes, comprising 24 previously reported vegetative compatibility groups (VCGs) and three TR4 isolates. The developed LAMP TR4 assay was successfully tested using 22 TR4 isolates and 45 non‐target fungal and bacterial isolates, as well as on infected plants under greenhouse and field conditions. The detection limit was 1 pg µL−1 pure TR4 DNA or 102 copies plasmid‐localized TR4 unique sequence (SeqA) per reaction, which was not affected by background DNA in complex samples. The LAMP TR4 assay offers a powerful tool for the routine and unambiguous identification of banana plants infected with TR4, contributing to advanced diagnosis in field situations and monitoring of fusarium wilt. [ABSTRACT FROM AUTHOR]

The expression profile of pathogenesis related genes are signatures of an infection response in plant cells. Pathogenic infections can increase or reduce gene expression in a plant system in a relatively specific pattern. These expression patterns can be used as standards in pathogenicity studies and, where phenotypic expression is normally used to gauge a plants response to infection, it could additionally present a more rapid and early screening reference tool. Three genes: catalase (CAT), pathogen related protein (PR10), and phenylalanine ammonia (PAL) all implicitly implicated in the plant disease response pathway were targeted for analysis during the infection of Fusarium oxysporum f. sp. cubense tropical race 4 (FOCR4) in banana Musa acuminata cv. Berangan seedlings after a standard challenge under growth room conditions. Distinct patterns of gene expression were observed at three infection time points by real time expression analysis. There was a sequential 10-fold reduction in expression for the PR gene while, the PAL and CAT genes were both upregulated. These results present a set of reference genes that could be used for screening of a plant's response to Fusarium before the onset of symptoms. [ABSTRACT FROM AUTHOR]

The expression profile of pathogenesis related genes are signatures of an infection response in plant cells. Pathogenic infections can increase or reduce gene expression in a plant system in a relatively specific pattern. These expression patterns can be used as standards in pathogenicity studies and, where phenotypic expression is normally used to gauge a plants response to infection, it could additionally present a more rapid and early screening reference tool. Three genes: catalase (CAT), pathogen related protein (PR10), and phenylalanine ammonia (PAL) all implicitly implicated in the plant disease response pathway were targeted for analysis during the infection of Fusarium oxysporum f. sp. cubense tropical race 4 (FOCR4) in banana Musa acuminata cv. Berangan seedlings after a standard challenge under growth room conditions. Distinct patterns of gene expression were observed at three infection time points by real time expression analysis. There was a sequential 10-fold reduction in expression for the PR gene while, the PAL and CAT genes were both upregulated. These results present a set of reference genes that could be used for screening of a plant's response to Fusarium before the onset of symptoms. [ABSTRACT FROM AUTHOR]

Fusarium wilt or Panama disease poses a great risk to banana production worldwide and is caused by Fusarium oxysporum f. sp. Cubense (Foc). Its tropical race 4 (TR4) is a major problem for Cavendish banana growing areas. Basrai (Dwarf Cavendish) is the major cultivated variety in Pakistan and now recently been reported to be affected by Foc TR4 in certain areas in the Sindh province. To genetically characterize, three independent isolates (P.TH1, P.TH2 and P.Th3) were sampled from different fields in district Thatta and fungus was isolated on potato dextrose agar. The pure fungal isolates were used to establish Koch's postulates by testing their pathogenicity on tissue cultured Cavendish banana. A diagnostic PCR assay was optimized and used to sequence a reported molecular marker for specific detection of Foc TR4 and to sequence 28S-18S ribosomal RNA intergenic spacer region (IGS) from these local isolates. The phylogenetic of Pakistani isolates suggests that they belong to previously characterized lineage V of tropical race 4 of F. oxysporum cubense with 99% bootstrap support and show close relationship with Indonesian and Malaysian Foc TR4 isolates. The rapid spread of this disease in different banana growing areas of the Sindh is alarming and necessitates effective control of this through chemical and biocontrol, if remains unchecked, Foc TR4 can raise havoc to banana industry in Pakistan and would be devastating economically. [ABSTRACT FROM AUTHOR]

Fusarium wilt of banana (Musa spp.), caused by Fusarium oxysporum f. sp. cubense (Foc), is one of the most important banana diseases. Three races (1, 2, 4) of Foc have been identified worldwide, but race 4 (especially tropical race 4, TR4) is the most destructive pathogen and has significant impacts on banana production in Taiwan and Southern China. To characterize the genetic relationship of Foc in these two regions, 55 isolates of Foc, including 18 from Taiwan and 37 from Hainan and Guangdong Provinces, were subjected to pathogenicity tests, race 4-specific polymerase chain reaction (PCR) diagnosis, and amplified fragment length polymorphism (AFLP) analysis. One race 4 isolate from Australia, one race 1 isolate from Philippines, and 10 non-banana F. oxysporum isolates were also included in the study for comparison. Pathogenicity tests indicated that 16 and 21 isolates of Foc from Taiwan and Southern China, respectively, were pathogenic on Cavendish banana and classified as race 4, and the remaining isolates were identified as race 1. PCR amplification with race 4 and tropical race 4-specific primers confirmed that all of the race 4 isolates from Taiwan and Southern China were TR4. AFLP analysis with eight EcoRI-MseI primer combinations clustered the 67 F. oxysporum isolates analyzed into two major groups, one containing all race 4 isolates and the other consisting of race 1 isolates along with the non-banana F. oxysporum isolates. No significant divergence was observed among TR4 isolates from Southern China and Taiwan, suggesting that the TR4 isolates from Southern China might share the same lineage as those from Taiwan. [ABSTRACT FROM AUTHOR]