**Abstract**

Bananas and plantains (*Musa* spp.) represent the fourth most important crop in the world. In 2017, an area of 5,637,508 hectares and a production of 153 million tons were reported. Fusarium wilt caused by the fungus *Fusarium oxysporum* f. sp. *cubense* (Foc), is considered one of the most destructive diseases of bananas and plantains worldwide. The pathogen *Foc* causes a typical wilt syndrome on infected plants, it has a saprophytic and parasitic phase in its life cycle. Fusarium wilt is a "polycyclic" disease. This pathogen shows a relatively diverse population genetic structure for a fungus apparently of asexual reproduction and is composed of different evolutionary lineages, which has 24 groups of vegetative compatibility (VCGs), two clades and nine clonal linage. Foc is a genetically diverse pathogen, although the available evidence so far indicates that it does not use the mechanisms of sexual reproduction, such as recombination, to increase its genetic diversity. Furthermore, the population of this fungus in Southeast Asia shows a high degree of variation, suggesting that Foc lineages evolved together with their hosts in Southeast Asia. Alternatively, it has been suggested that Foc has multiple independent evolutionary origins, both within and outside of the Musaceae origin center.

**Keywords:** genetics, diversity, fusarium wilt disease, banana

## **1. Introduction**

Bananas and plantains (*Musa* spp.) represent the fourth most important crop in the world, since only rice, wheat and corn surpass it [1]. The fruit has a high content of carbohydrates, potassium, phosphorus, magnesium, vitamins A and C, folic acid and tannins [2]. This fruit is produced throughout the year. Therefore, we can always consume bananas, regardless of the month we are in.

These crops are produced in 135 countries in the tropical and subtropical regions. India contributes 31% of the total, followed by China with 10% and the Philippines with 9% of world production. In 2017, an area of 5,637,508 hectares and a production of 153 million tons were reported, with the main exporting countries being Ecuador, Costa Rica, the Philippines, Guatemala and Colombia, who ship their products to the United States, Canada, Europe, Russia, and the Asian Pacific region. The commercialization of this fruit represents an important source of income for the Latin American region. Most of the producers are farmers who grow it for domestic consumption or for local markets and only 15 percent of production is for export [3].

The production of bananas and plantains is seriously affected by various phytopathogenic agents, such as fungi, nematodes, viruses, bacteria, and insects. Some of the pathogens spread during the distribution of Musaceae germplasm native to Southeast Asian occurred in the 20th century to new agricultural areas (Latin America and the Caribbean), since by nature their spread occurs on a smaller scale and hardly at long distances [1].

Fusarium wilt caused by the fungus *Fusarium oxysporum* f. sp. *cubense* (Foc), is considered one of the most destructive diseases of bananas and plantains worldwide [4, 5]. The disease greatly hinders the production mainly of the genotypes of *Musa acuminata*, *M. balbisiana*, *M. schizocarpa* and *M. textilis* and their hybrids [4, 6].

Once Foc enters the fields, it is difficult to control; this is due to the fact that the pathogen persists in the soil for long periods. This is the reason because the use of plants derived from tissue culture have been considered as one of the disease management strategies, this in order to avoid the introduction of Foc in pathogenfree fields; as well as the implementation of safety practices to avoid its dispersion [5]. However, the most effective means of controlling the disease is the replacement of susceptible cultivars by those who are resistant, although today the main markets demand the 'Giant Dwarf' clone from the Cavendish subgroup.

History indicates that the pathogen probably originated in Southeast Asia; however, the first report was in Australia in 1876 affected by the cultivar 'Silk', also known as ʻManzano' (AAB) [4] and in 1890 it occurred in plantations in Costa Rica and Panama. About 30,000 hectares were lost in this country between 1940 and 1960 [4]. In total, it was estimated that more than 40,000 hectares of bananas were lost in a 50-year period in Central and South America [4, 7]. Also, epidemics have been reported on other continents. For example, in Bali, banana production decreased from 134,000 to 54,000 tons in 1997, due to the disease [8].

Given the damage caused by Fusarium wilt, there is a probability that the pathogen could be distributed through the planting material (corms or suckers) of 'Gros Michel', since this was used for use in new plantations [4, 9]. At that time, large shipments of suckers and rhizomes may also have been transported between countries by transnational companies to supplement local stocks of commercial cultivars, thereby promoting the spread of disease. The stage was set for a major epidemic to emerge [10].

#### **2. Banana importance**

Banana and plantain (*Musa* spp.) are believed to have originated in Southeast Asia and are cultivated in a wide variety of environments in the tropics and subtropics regions of the world. *Musa*, including the dessert banana and the cooking types or plantains are produced in 155 countries.

Throughout history *Musa* has provided humans with food, medicine, clothing, tools, shelter, furniture, paper, and handicrafts. *Musa* are rich in vitamin C, B6, minerals (particularly potassium), and dietary fiber. They are also a rich energy source, with carbohydrates accounting for 22% and 32% of fruit weight for banana and plantain, respectively. It is cholesterol free, high in fiber, and low in sodium.

In terms of total fruit crops production, the banana ranks after oranges, grapes, and apples, but when plantain production is added, it becomes the world's number one fruit crop. According to the Food and Agriculture Organization of the United Nations (FAO), in 2018 more than 11.3 million hectares of banana and plantain were harvested worldwide and were produced a total of 155.2 million tonnes:

**129**

**(Foc)**

**Table 1.**

plant species [12].

*Genetic Diversity of Fusarium Wilt Disease of Banana DOI: http://dx.doi.org/10.5772/intechopen.94158*

115.7 million tonnes under their bananas crop item (75%) and 39.5 million tonnes under their plantains crop item (25%). However, the estimated production for the same year published by [11] is 139.5 million tonnes: 79.6 million tonnes of Cavendish (57%), 17.5 million tonnes of other dessert bananas (13%), 20.9 million tonnes of

**Rank Country/territory Production (tonnes)** India 30,808,000 China 11,221,700 Philippines 9,358,785 Colombia 7,287,997 Indonesia 7,264,383 Ecuador 7,157,603 Brazil 6,752,171 Cameroon 5,144,258 Congo, Democratic Republic of the 5,066,203 Uganda 4,337,747 Guatemala 4,294,121 Ghana 4,264,258 Tanzania 4,045,568 Angola 3,492,184 Nigeria 3,093,872 Costa Rica 2,633,788 Mexico 2,354,479 Peru 2,329,480 Cote d'Ivoire 2,280,368 Dominican Republic 2,224,403

In the **Table 1**, the list of top 20 of banana-producing countries and overseas

**3. Fusarium wilt caused by the fungus** *Fusarium oxysporum* **f. sp.** *cubense*

*Fusarium* is a genus comprises several species of filamentous ascomycetes, including pathogenic and non-pathogenic species for agricultural crops. One of the best known is *F. oxysporum*, this causes vascular wilt and root rot in more than 100

In the *Fusarium* system, Foc belongs to the *Fusarium oxysporum* species complex (FOSC), four clades have been identified from this, using the translational elongation factor 1-alpha (tef1) and the rDNA of the mitochondrial subunit (mtssu), in

Plantain (15%), and 21.4 million tonnes of other cooking bananas (15%).

plantains categories into, according FAO statistics.

*Source: http://www.promusa.org/Banana-producing+countries+portal*

*Top 20 of banana-producing countries and overseas territories.*

Foc isolates, which were grouped as baseline lineage [13].

territories and the number of tonnes they each produced in 2018 is showed. Production is measured in tonnes and represent the total of the bananas and


#### *Genetic Diversity of Fusarium Wilt Disease of Banana DOI: http://dx.doi.org/10.5772/intechopen.94158*

#### **Table 1.**

*Genetic Variation*

production is for export [3].

epidemic to emerge [10].

**2. Banana importance**

types or plantains are produced in 155 countries.

smaller scale and hardly at long distances [1].

demand the 'Giant Dwarf' clone from the Cavendish subgroup.

decreased from 134,000 to 54,000 tons in 1997, due to the disease [8].

who grow it for domestic consumption or for local markets and only 15 percent of

The production of bananas and plantains is seriously affected by various phytopathogenic agents, such as fungi, nematodes, viruses, bacteria, and insects. Some of the pathogens spread during the distribution of Musaceae germplasm native to Southeast Asian occurred in the 20th century to new agricultural areas (Latin America and the Caribbean), since by nature their spread occurs on a

Fusarium wilt caused by the fungus *Fusarium oxysporum* f. sp. *cubense* (Foc), is considered one of the most destructive diseases of bananas and plantains worldwide [4, 5]. The disease greatly hinders the production mainly of the genotypes of *Musa acuminata*, *M. balbisiana*, *M. schizocarpa* and *M. textilis* and their hybrids [4, 6]. Once Foc enters the fields, it is difficult to control; this is due to the fact that the pathogen persists in the soil for long periods. This is the reason because the use of plants derived from tissue culture have been considered as one of the disease management strategies, this in order to avoid the introduction of Foc in pathogenfree fields; as well as the implementation of safety practices to avoid its dispersion [5]. However, the most effective means of controlling the disease is the replacement of susceptible cultivars by those who are resistant, although today the main markets

History indicates that the pathogen probably originated in Southeast Asia; however, the first report was in Australia in 1876 affected by the cultivar 'Silk', also known as ʻManzano' (AAB) [4] and in 1890 it occurred in plantations in Costa Rica and Panama. About 30,000 hectares were lost in this country between 1940 and 1960 [4]. In total, it was estimated that more than 40,000 hectares of bananas were lost in a 50-year period in Central and South America [4, 7]. Also, epidemics have been reported on other continents. For example, in Bali, banana production

Given the damage caused by Fusarium wilt, there is a probability that the pathogen could be distributed through the planting material (corms or suckers) of 'Gros Michel', since this was used for use in new plantations [4, 9]. At that time, large shipments of suckers and rhizomes may also have been transported between countries by transnational companies to supplement local stocks of commercial cultivars, thereby promoting the spread of disease. The stage was set for a major

Banana and plantain (*Musa* spp.) are believed to have originated in Southeast Asia and are cultivated in a wide variety of environments in the tropics and subtropics regions of the world. *Musa*, including the dessert banana and the cooking

Throughout history *Musa* has provided humans with food, medicine, clothing, tools, shelter, furniture, paper, and handicrafts. *Musa* are rich in vitamin C, B6, minerals (particularly potassium), and dietary fiber. They are also a rich energy source, with carbohydrates accounting for 22% and 32% of fruit weight for banana and plantain, respectively. It is cholesterol free, high in fiber, and low in sodium. In terms of total fruit crops production, the banana ranks after oranges, grapes, and apples, but when plantain production is added, it becomes the world's number one fruit crop. According to the Food and Agriculture Organization of the United Nations (FAO), in 2018 more than 11.3 million hectares of banana and plantain were harvested worldwide and were produced a total of 155.2 million tonnes:

**128**

*Top 20 of banana-producing countries and overseas territories.*

115.7 million tonnes under their bananas crop item (75%) and 39.5 million tonnes under their plantains crop item (25%). However, the estimated production for the same year published by [11] is 139.5 million tonnes: 79.6 million tonnes of Cavendish (57%), 17.5 million tonnes of other dessert bananas (13%), 20.9 million tonnes of Plantain (15%), and 21.4 million tonnes of other cooking bananas (15%).

In the **Table 1**, the list of top 20 of banana-producing countries and overseas territories and the number of tonnes they each produced in 2018 is showed. Production is measured in tonnes and represent the total of the bananas and plantains categories into, according FAO statistics.
