The first bananas were harvested in a Wageningen Greenhouse,
according to the Wageningen World Magazine. Researchers have been growing them
above ground in order to trying to outsmart the Panama disease caused by Fusarium Wilt, which is threatening the banana population
around the world.
From all sides researchers are looking for approaches, e.g.,
genetics and growing conditions, to making global cultivation more sustainable.
New methods to efficiently monitor Panama disease, also known as Fusarium wilt, caused by Fusarium species in bananaswere developed during the PhD research of Fernando Garcia-Bastidas at Wageningen University and Research. These new methods and trials enabled a close monitoring of the international and intercontinental dissemination of the so-called Tropical Race 4 (TR4) strain of Fusarium odoratissimum, a new species originating from Indonesia that devastates banana plantations of Cavendish as well as many other local varieties around the world.
Fernando Garcia-Bastidas defended his
dissertation entitled ‘Panama disease in banana: Spread, screens and genes’ on
March 19, 2019 at Wageningen University. The thesis describes the developing
pandemic of a Fusarium species, which
causes Panama disease in banana. He focused his research on the genetic
diversity for resistance towards a panel of Fusarium strains representing
global pathogenic diversity and aspects of the molecular interaction between
the fungus and the host.
The thesis further explores the resistance
to TR4 in a wide panel of banana accessions and the possible use of a
resistance gene from a wild banana ancestor by genetically transforming Cavendish
bananas, thereby providing a potential solution for sustainable disease
management. Lasting disease management, however, relies on genetic diversity
and the research described in this thesis is the basis for developing such new
varieties.
Researchers from Wageningen University & Research are harvesting the first Dutch bananas this week. Boerenhart, a supplier of fresh and local products will offer the bananas as ‘regional product’ to restaurants and hospitals in the region of Wageningen. The cultivation took place on two types of substrates: coco peat and rock wool. This allows the growth of banana without the settlement of aggressive fungi.
In the greenhouses of the experimental farm Unifarm in Wageningen a unique research experiment has been carried out since January. Bananas grow in the greenhouse in pots and on a substrate, both artificial media for plant growth. “For the 100th anniversary of WUR, we developed this plan together with the local cooperation Boerenhart: the cultivation of a regional banana in the Wageningen greenhouses,” says Professor of Tropical Plant Pathology Gert Kema. “With this experiment we will investigate whether this cultivation offers prospects for further research into mastering Fusarium wilt. This is due to a soil borne fungal pathogen that threatens the banana production throughout the world. So we took the banana out of the soil.”
A leading strategy for managing the ongoing pandemic of Fusarium wilt in bananas is the generation of resistant banana varieties. To gain insight into the diversity of the causal fungi, Nani Maryani Martawi looked to the Indonesian archipelago, where hundreds of wild and cultivated banana varieties are grown. As part of her PhD research, she studied the diversity of the isolated pathogens that cause Fusarium wilt and their co-evolution with the banana hosts.
Fusarium wilt, also known as Panama disease, has wiped out thousands of hectares of banana crops around the world. It is caused by a soil-borne fungal pathogen Fusarium oxysporum f.sp. cubense (Foc), which can best be managed by developing resistant banana varieties. In her dissertation, Nani Maryani Martawi introduces comprehensive studies on the genetic diversity and phylogeny of Foc strains associated with Fusarium wilt. Using cluster analyses of Indonesian and global isolates, she revealed the widest genotypic diversity ever reported for Fusarium wilt of bananas. More than half of the genotypes ever identified were present in Indonesia, suggesting that these banana pathogens co-evolved with the local banana varieties. Martawi also provides convincing evidence that the Foc Tropical Race 4 (TR4) strain, which kills the Cavendish cultivar, likely emerged from Indonesia and is still evolving alongside local varieties.
Nani Maryani Martawi defended her dissertation entitled ‘A complex relationship: banana and Fusarium wilt in Indonesia’ on 29 October 2018 at Wageningen University. For information about Fusarium wilt in general, click here.
Gene identified for full virulence of the Fusarium wilt towards Cavendish banana
In an article in the PLOS One journal researchers identified a gene and protein that is required for full virulence of the fungus that causes Furasium wilt in Cavendish banana. A mutant of the Fusarium oxysporum f.sp. cubense (Focub) SIX1a gene was tested in the banana plant. This mutant was found to be severely compromised in its virulence. When the gene was reintroduced virulence was restored to wild type levels.
PhD defence on insights into the global genetic diversity of Fusarium
banana plant
On October 17th 2018 Nadia Ordóñez defended her PhD entitled ‘A global genetic diversity analysis of Fusarium oxysporum f.sp. cubense (Foc)’ at Wageningen University. In her research the genetic and geographically diversity of Tropical race 4 (TR4) strain of Foc was mapped out using DNA sequencing methods.
Bananas are an essential staple food and a significant income for agricultural-based economies in developing countries. Fusarium wilt of bananas, popularly known as Panama disease, is one of the most threatening fungal diseases of banana production. Foc is the causal fungal agent of this disease. The TR4 strain of this fungus affects many local banana varieties as well as the Cavendish cultivar, which accounts for 85% of world trade in bananas. Since all Cavendish bananas are clones of each other and there is little variation, they are highly susceptible to TR4, making the sector extremely vulnerable.
In the research of Nadia a molecular detection tool to monitor the spread of TR4 was developed. This assay enables rapid, routine and unambiguous detection of TR4 in the field and is therefore of immense value for charting the progression of its spread. That this is urgently needed, the results provide an image that all TR4 isolates, regardless of the year of isolation and country of origin, were highly infectious on both ‘Gros Michel’ and ‘Grand Naine’ banana varieties , underpinning the risk for banana plantations that only rely on these cultivars.
Recent research on improving banana cultivation is bundled in the new publication ‘Achieving sustainable cultivation of bananas Volume 1’. Both the banana research community as well as banana producers will find information from all over the world about the current challenges in banana production, improving cultivation practice across the value chain, from propagation to harvesting, packaging and ripening, and ways of measuring and improving the environmental impact of banana cultivation.
Throughout the book attention is paid to pests and diseases affecting bananas, including Fusarium wilt. Highlights of the book include: the latest research on banana domestication and genetic diversity; new research on the limitations of current good agricultural practices and how areas such as soil health can be improved; and summaries of best practice in neglected but critical areas such as harvesting and ripening operations.
More information and the opportunity to order the book at the publishers website.
The Biomedical Science Journal for Teens has put research into banana Black Sigatoka disease in the spotlight. The disease is threatening commercial Cavendish banana crops worldwide, as the fungus that causes it has developed resistance to the chemicals that are supposed to control them. Researchers also detected a specific protein in the fungus, that triggers the resistance mechanism of the plant. These yet unknown disease resistance genes could be used to save the banana industry.
In order to further support the sustainable production of bananas researchers wanted to find out more about the genetic basis of disease resistance to Pseudocercospora fijiensis strains, which cause theBlack Sigatoka or “black leaf streak disease” (BLSD). Researchers isolated the DNA of the fungus, sequenced its whole genome and built a genetic map to complete the genome picture to better understand the relationship between the banana and its pathogen.
Also, they found a gene that is coding a protein, a so-called effector protein, which triggers a resistance mechanism in wild bananas. Upon recognition, the plant kills the infected cells and surrounding cells, thereby stopping the spread of the infection. Bananas recognizing this protein most likely possess a resistance gene. This could greatly help banana breeding and production.
Less bananas due to reduced photosynthesis
When bananas are affected by BLSD, the fungus destroys the leaf tissue which reduces photosynthesis and thus, crop yields. Farmers can control BLSD only through fungicides, and this greatly increases the economic and environmental costs to produce bananas. Moreover, the frequent use of fungicides leads to strains that are increasingly resistant to these chemicals.
Further reading
Read the whole article in Science Journal for Kids
The article is based on the PLOS genetics article: ‘Combating a Global Threat to a Clonal Crop: Banana Black Sigatoka Pathogen Pseudocercospora fijiensis (Synonym Mycosphaerella fijiensis) Genomes Reveal Clues for Disease Control’ http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1005876
On June 6th Caucasella Diaz, Mexico, defended her PhD thesis titled “Functional genetics and genomics of the banana black Sigatoka pathogen Pseudocercosporafijiensis” at Wageningen University.
Her thesis describes the completion of the genome sequencing of this devastating fungus that threatens banana exports worldwide, as well as the development of a genetic transformation protocol that was used to discover a new resistance mechanisms to fungicides in the fungus.
All students are writing their PhD books! Hence, we are in harvest time. We expect dozens of new exciting papers that will move the front forward and together form a solid foundation for a new phase in Panama disease research.
Jaye de la Cruz, first INREF PhD student graduated
On October 23rd, 2017, Jaye de la Cruz successfully defended her PhD thesis titled “Panama disease in banana and neoliberal governance: towards a political ecology of risk”. Jaye was supervised by Dr Kees Jansen and her promotor was Prof. Philip McNaughton. Her thesis casts a different light on a major plant disease in a major crop and underscores the complexity of international action to reduce its risk, particularly by illuminating the power relationships in the sector.
Forthcoming PhD graduations
We fixed the dates for three students, most other will fix their dates soon likely for graduation in November and December 2018.
On June 6th, Ms. Caucasella Diaz Trujillo, Mexico, will defend her PhD thesis titled “Functional genetics and genomics of the banana black Sigatoka pathogen Pseudocercospora fijiensis”. The ceremony is at the Wageningen University and Research auditorium, Building 362, General Foulkesweg 1, 6703 BG Wageningen, and start at 13:30.
On October 16th, Ms. Nadia Ivone Ordóñez Román, INREF PhD student, will defend her thesis titled “A global genetic diversity analysis of Fusariumoxysporum f.sp. cubense, the Panama disease pathogen of banana”. The ceremony is at the Wageningen University and Research auditorium, Building 362, General Foulkesweg 1, 6703 BG Wageningen, and start at 16:00.
On October 29th, Ms. Nani Maryani Martawi, KNAW-SPIN student, will defend her thesis titled “Fusarium wilt of banana in Indonesia: genetic diversity and phylogeny of causal fungi”. The ceremony is at the Wageningen University and Research auditorium, Building 362, General Foulkesweg 1, 6703 BG Wageningen, and start at 11:00.
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