The Australian banana industry’s search for new varieties resistant to diseases such as Panama tropical race 4 (TR4) and Panama disease race 1 is looking brighter than ever, thanks to major inroads being made by a national plant protection project. 

Most recently, the project has managed to access five Cavendish selections and one Dwarf Ducasse selection from Taiwan, all with reported resistance to TR4.

By Stewart Lindsay, Department of Agriculture and Fisheries, South Johnstone, Queensland.

The project “Improved Plant Protection for theAustralian Banana Industry” (BA16001) is now a little over halfway completed and is achieving major goals for the banana industry. The five-year project is funded by Horticulture Innovation via the banana industry research and development levy, with coinvestment from the Department of Agriculture and Fisheries, NT Department of Primary Industries and Resources, NSW Department of Primary Industries and contributions from the Australian Government.

The project combines a full range of activities from identifying, importing and screening new banana varieties for disease resistance to undertaking research activities into the highest priority pest and disease issues. These activities are grouped as theme areas, and some of the key activities and outcomes from the program so far are outlined below.

Theme 1 – Accessing and screening banana varieties for pest and disease resistance
This aspect of the project aims to access plant varieties from overseas breeding programs and then conduct research trials to screen for disease resistance against Panama disease Race 1 and Tropical Race 4 (TR4), Yellow Sigatoka leaf spot and to assess yield and performance characteristics.

With the increasing spread of TR4 around the world, many overseas banana breeding programs are restricting access to their material to try and maximise the opportunity to commercialise the intellectual property in the varieties they have produced.

Accessing new varieties

The project has been successful in negotiating access to 35 new varieties, primarily from breeding programs focusing mainly on breeding dessert banana types familiar to the Australia market – selections of Cavendish and Lady Finger, and hybrids of Lady Finger and Silk/Sugar bananas.

The project has managed to access five Cavendish selections and one Dwarf Ducasse selection from
Taiwan with reported resistance to TR4, which entered the quarantine tissue culture laboratory in mid-July 2020. From Brazil the project has successfully negotiated access to 25 varieties, mostly Lady Finger and Silk/Sugar hybrids with reported resistance to Panama disease Race 1, with 12 of these arriving in April 2020 and entering the quarantine screening system. In 2018 the project was able to access four varieties from the French breeding program, including two novel hybrids and two hybrids reported as similar to the Silk/Sugar banana variety, with reported Panama disease and leaf spot resistance. These lines successfully cleared the quarantine screening process and will be available for the next round of research screening trials.

Screening new varieties

The project has provided a network of field screening trials in New South Wales, north Queensland and Northern Territory to assess for:

• Panama disease Race 1 resistance and cold tolerance, and agronomic performance and consumer acceptance for selected varieties – Duranbah, New South Wales
• Agronomic performance and Yellow Sigatoka leaf spot resistance – South Johnstone, Queensland
• Panama disease TR4 resistance and agronomic performance – Coastal Plains Research Farm, Northern Territory

At the Duranbah site, 19 varieties were planted in February 2018 and have been assessed for their Panama disease Race 1 resistance, with a number of varieties showing promise. The site was also used to assess the production performance and consumer acceptance of PKZ and FHIA17, resistant varieties identified from the previous plant protection program. The consumer acceptance assessments compared FHIA-17 and PKZ with Cavendish sourced from North Queensland and northern New South Wales, with the consumer tasting revealing that while PKZ and FHIA-17 possess some desirable agronomic attributes and disease resistance, they did not appeal to consumers when compared to Cavendish bananas sourced from NQ and NNSW. As a result it was not recommended that PKZ or FHIA-17 be pursued for commercialisation. The trial site at Duranbah has now been closed with the cessation of the lease, and a new site is being planned for the NSW DPI facility at Alstonville.

At South Johnstone, 32 varieties were planted in September 2018, with harvest for the plant crop spreading from May to December 2019. The trial is assessing a range of mostly Cavendish varieties,
including all the selections in Australia from Taiwan with reported TR4 resistance. The first ratoon
harvest is progressing well with more than 60% of the varieties harvested so far. The results of the
plant crop assessments were presented in an article in the previous edition of the Australian Bananas
magazine.

The trials at Coastal Plains Research Farm in the Northern Territory are proceeding well with disease
assessment and agronomic data for the plant crop completed and analysed. There are two trials being
undertaken, the main trial assessing 19 commercial varieties and a sub-trial investigating resistance
in 14 important breeding lines. The results from the plant crop of both trials are presented in an article in this Australian Bananas edition. There are promising results so far with four new Cavendish
selections, along with three hybrids from the French breeding program showing good resistance in the
plant crop. The two cooking bananas Dwarf French Plantain and Tonga have also performed well.

Pre-commercialisation trials on farms

Once varieties have been screened in the research trials, those candidates with promising performance
are then assessed under commercial production conditions on farms. These trials are supervised by
DAF with restrictions around plant propagation and marketing to maintain the intellectual property of
the originating breeding program. Between 100 and 300 plants of up to three Cavendish varieties with
good TR4 resistance have been established on four properties across the North Queensland production
districts between October 2019 and May 2020.

A trial is also planned for planting later this year in the NT as well. These trials aim to gather some data and assessments by growers of the important commercial characteristics. These assessments will then be shared with the broader banana industry via extension activities and magazine articles.

Theme 2 – Managing the variety importation process, and providing access to clean planting material

The project provides for the registration and management of the only post-entry quarantine facilities in Australia for importing banana varieties. New varieties identified and received by the project are managed and assessed through these facilities to ensure they are clear of the many different exotic banana pests and diseases. This process takes between 1.5-2 years and has ensured that Australia has maintained its freedom from devastating new diseases and pests while still being able to import new banana varieties to test. 

DAF has recently increased the size of the post-entry quarantine facilities at both the EcoSciences Precinct in Brisbane and at the Maroochy Research Facility at Nambour, successfully passing the auditing and registration for both sites. This component of the project is also responsible for managing the Australian banana germplasm collection. The collection continues to be used to support banana research trials and to supply plants for grower evaluation, where they are not restricted due to Material Transfer Agreements or research agreements. Between April 2019 and May 2020, a total of 5575 plantlets were provided and different accessions accessed 127 times. The collection and tissue culture laboratory are playing an important role in multiplying and providing the plants required for the next round of variety screening trials at South Johnstone and the Northern Territory.

New activities coming up

The variety screening efforts are continuing with new trial plantings planned in the Northern Territory and North Queensland later this year. These trials will continue screening activities for agronomic performance and TR4 resistance. The project is also continuing the assessment and selection of improved Goldfinger and Cavendish types developed through the mutation breeding efforts undertaken in the recently completed project “Fusarium wilt TR4 research program” (BA14014).

In that project 20 selections of Goldfinger with improved eating characteristics, and 27 selections of TR4 resistant Cavendish varieties with improved bunch and plant characteristics have been made. These selections need to undergo more rigorous assessment to identify the outstanding performers for their disease resistance, agronomic characteristics and consumer acceptability. Currently the Cavendish selections are only present in the Northern Territory, and the project team in Theme 2 has been busy developing a safe and effective protocol with biosecurity authorities in Queensland and the Northern Territory to allow for tissue-cultured plantlets of each selection to be imported safely back into Queensland.
So exciting times ahead for the banana industry investment in the search for new, disease resistant
banana varieties.