Field resistance of selected banana cultivars against Tropical Race 4 of Fusarium oxysporum f. sp. cubense in the Philippines

Abstract

Recent epidemics of Fusarium wilt caused by virulent Tropical Race 4 (TR4) of Fusarium oxysporum f. sp. cubense (Foc) posed serious threat to the Philippine banana industry. Based on monoculture cropping of TR-4 susceptible Cavendish varieties, the nation’s multi-million US$ export banana industry is at risk. To develop disease management tactics, selected introduced and local cultivars were studied for their reaction to Foc in a field previously severely affected by TR4. Evaluated were two commercially grown Cavendish, and 2 variants from Taiwan, 3 local cultivars and 1 improved hybrid from Honduras. The experimental plot comprised of 10 tissue-culture derived plants spaced 2.5 × 3 m, replicated 10 times, and arranged in completely randomized block design. Disease incidence was assessed weekly by monitoring any symptom including leaf chlorosis, wilting and/or pseudostem splitting. The 2 commercially grown Cavendish, Grand Naine and Williams, showed susceptible reactions, with incidence of more than 90% before shooting. Lakatan, a popular local cultivar was most susceptible with 100% incidence. GCTCV119, and Formosana, Cavendish variants did not show any infected plants in the first crop, although some symptoms were appearing in the ratoon crop. Saba, an important cooking banana was highly resistant with no disease incidence, even in the ratoon crop. Vegetative Compatibility Group (VCG) analyses confirmed that Foc TR4 VCG1213/16 was associated with the infections.

Full text

Fusarium wilt disease, caused by Fusarium oxysporum f. sp. cubense (Foc), is a major
concern of the global banana industry having wiped out the Gros Michel plantations in
Central America which consequently caused the costly shift to Foc resistant Cavendish
varieties in the 1950s. A virulent strain that attacks Cavendish, the Foc Tropical Race 4
(TR4), has been found causing epidemic on Cavendish in Asia. The recent epidemic of
Fusarium wilt disease in Cavendish plantations in the Philippines (Figure 1) poses a serious
threat to the sustainability of the multi-million dollar Cavendish-based export industry, to
the country as top banana exporter in Asia (Figure 2), and to the local cultivars grown by
small-scale farmers as well.
The use of resistant varieties for a long-term management strategy of Foc has long been
sought for. But breeding programmes failed to produce varieties of equal or better
productivity and quality and those which would satisfy the discriminating standards of the
global market. Some varieties released by the breeding programme of the Fundacion
Hondurena de Investigacion Agricola (FHIA) are high-yielding and resistant to Fusarium wilt
but have low acceptance in the export market. The Taiwan Banana Research Institute (TBRI)
has achieved some successes in the selection and use of disease resistant somaclonal
variants of Cavendish as part of the integrated approach to sustain the banana export
industry in that country. A number of these varieties were shared to Bioversity’s
International Transit Center (ITC) for inclusion in the International Musa Testing Programme
(IMTP). Subsequently, the ITC had distributed the varieties through Bioversity
International’s National Repository Multiplication and Dissemination Center (NRMDC)
programme in Asia for evaluation and adoption.
This paper reports the results of a field trial (under commercial plantation setting) of
introduced somaclonal Cavendish selections from TBRI, comparing them with regular
Cavendish varieties and some non-Cavendish local cultivars. Results of the study would be
of great value in the attempt to mitigate the threat of Foc epidemics in the country.
Figure 1. Farms affected by Fusarium wilt epidemic: (a) the sporadic appearances of
Fusarium wilt disease during the early stage of the epidemic; (b) Foc TR4
infected Cavendish plant; and (c) abandoned area because of extensive
disease incidence
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Figure 2. Top 10 banana exporting countries in 2008 (FAOSTAT, 2011)
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a
a
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a
in10,000tonnes
100
200
300
500
400
600
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Brazil
DomRep
Cameroon
Panama
Honduras
Guatemala
Columbia
Philippines
CostaRica
Ecuador
The trial was established in September 2009 within the plantation of the Lapanday
Agricultural and Development Corporation, Davao del Norte, Philippines. The experimental
field had previously a high level of incidence of Foc. Eight banana varieties (Table 1) were
evaluated. Experimental units were planted with 10 tissue-culture derived seedlings spaced
at 2.5m x 3m, and were replicated 10 times and arranged in a completely randomized
design. A total of 100 plants per cultivar were planted.
Cultural practices such as fertilization, pruning, irrigation and drainage were implemented
as recommended for commercial production. Disease incidence was assessed and recorded
weekly by determining the number of infected plants, showing typical external symptoms of
Fusarium wilt like yellowing of older leaves and/or pseudostem splitting. To confirm
infection, the pseudostem of suspected plants were cut cross sectionally and longitudinally
to examine the confirmatory reddish to dark brown internal vascular tissue discoloration. To
confirm the identity of the pathogen, strands of infected pseudostem tissues were sent to
Stellenbosch University for vegetative compatibility group (VCG) analyses using the protocol
described by Puhalla in 1985.
Agronomic data were also collected wherever possible. Comparative study on yield and fruit
quality parameters were particularly collected and analyzed for the Cavendish varieties.
*PosterpaperpresentedduringtheAmericanPhytopathological
SocietyAnnualMeeting,August6‐
10,2011Honolulu,Hawaii
Table 3. Comparative agronomic and yield data (Primary Crop) and fruit characteristics of Grand Naine
as against the Foc TR4 resistant GCTCV varieties
Disease incidence: The reactions of the different cultivars to Fusarium wilt was assessed in
terms of disease incidence as recorded at different weeks after planting. Results confirm the
high susceptibility of commercial Cavendish varieties (Table 2 and Figures 3, 4). Grand Naine and
Williams succumbed to the disease with almost 100% incidence even before flowering stage in the
first crop, which thwarted the development of a ratoon crop. On the other hand, GCTCV 119 and
GCTCV 219 did not manifest disease symptoms in the first crop, although some infections were
recorded in the ratoon crop (Table 2). Among the local cultivars, the popular cooking cultivar
Cardava showed high resistance as it remained free from Fusarium wilt incidence even for the
ratoon crop. Lakatan was most susceptible with 100% incidence in the primary crop. Latundan
and FHIA 21 showed lower disease incidence compared with Lakatan and the Cavendish, but they
eventually succumbed to the disease at a later stage of plant growth and in the ratoon crop.
Results from the VCG analyses of diseased samples done at Stellenbosch University confirmed
that all infections were caused by the VCG 1213/16, the VCG characterizing TR4.
Plantain-type cooking variety bred by FHIAPlantainAAABFHIA 21
Popular local cooking-type varietySabaABBCardava
Popular local dessert-type varietySilkAABLatundan
Popular local dessert-type variety
Lakatan
AAALakatan
Somaclonal selection from TaiwanCavendishAAAGCTCV 218
Somaclonal selection from TaiwanCavendishAAAGCTCV 119
Popular commercial export varietyCavendishAAAWilliams
Popular commercial export varietyCavendishAAAGrand Naine
DescriptionSub-GroupGenome
Cultivars
Table 1. List of cultivars evaluated for resistance to Foc TR4
Among the Cavendish varieties, GCTCV 119 and 218 were highly resistant to Foc TR4 compared
with two commercial varieties, the Grand Naine and Williams. Agronomic and yield data (Table
3) showed that GCTCV 119 and GCTCV 218 may have comparable yield and fruit quality as the
existing commercial varieties especially for the ratoon crop, although their harvest maturity
are a little bit longer. Chemical analyses showed that the two GCTCVs were sweeter compared
to Grand Naine as shown by their higher total soluble solids and lower titratable acidity,
indicating potential acceptance in the export market. These varieties present great potential as
components for an integrated management approach in managing TR4 for the export banana
industry. Among the local cultivars, Cardava showed strong resistance to TR4.
Table 2. Fusarium incidence on selected banana cultivars, 2009-2011
0.240.1421
410
715274357270
GCTCV 218
0.240.14214
9717274355261
GCTCV 119
0.260.16173
9916262337223
Grand Naine
RipeUnripeRipeUnripe
Ratoon
Crop
Primary
Crop
TTA**TSS*Hand Class
Bunch
Weight
(kg)
Days to
Shooting
Days to
harvest
Plant
height
(inches)
Cultivar
Fruit CharacteristicsAgronomic and Yield Data
* Total soluble solids ** Titratable Acidity
N/A81FHIA 21241GCTCV 218
00Cardava281GCTCV 119
10041LatundanN/A94Williams
N/A100LakatanN/A97Gran Naine
Ratoon CropPrimary CropRatoon CropPrimary Crop
Fusarium wilt incidence
Cultivar
Fusarium wilt incidence
Cultivar
Figure 4. GCTCV 119 vs Grand Naine field trial in a
heavily infested Foc TR4 farm, Philippines,
March 2010
Figure 3. Fusarium wilt incidence of different
banana varieties planted in Davao del
Norte, Philippines (Primary Crop)
0
20
40
60
80
100
1 5 9 13172125293337414549
Gran naine GCTCV 119
GCTCV 218 Williams
Cardava Latundan
FHIA 21 Lacatan
Weeks
100
60
40
20
0
80
FocTR4incidence(%)
Grand Naine
GCTCV 218
Cardava
FHIA 21 Lakatan
Latundan
Williams
GCTCV 119
1517 21
13
937
33
29
25 41 45 49 GCTCV 119 Grand Naine
* N/A – Not applicable to ratoon crop due to high Fusarium wilt incidence
AB Molina1, EG Fabregar2, EB Ramillete2, VGO Sinohin1 and A Viljoen3
1Bioversity International- Asia Pacific, Commodities for L ivelihoods (CfL) – Musa Programme, Los Baños, Laguna, Philippines; 2Lapanday Foods Corporation, Davao
City, Philippines; 3Department of Plant Pathology, Un iversity of Stellenbosch, Matieland, South Africa