Moniliophthora roreri
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''Moniliophthora roreri'' is a
basidiomycete Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Ba ...
fungus that causes frosty pod rot disease, one of the most serious problems for cacao (''
Theobroma cacao ''Theobroma cacao'', also called the cacao tree and the cocoa tree, is a small ( tall) evergreen tree in the family Malvaceae. Its seeds, cocoa beans, are used to make chocolate liquor, cocoa solids, cocoa butter and chocolate. The largest pr ...
''— the source of
chocolate Chocolate is a food made from roasted and ground cacao seed kernels that is available as a liquid, solid, or paste, either on its own or as a flavoring agent in other foods. Cacao has been consumed in some form since at least the Olmec civ ...
) production in
Latin America Latin America or * french: Amérique Latine, link=no * ht, Amerik Latin, link=no * pt, América Latina, link=no, name=a, sometimes referred to as LatAm is a large cultural region in the Americas where Romance languages — languages derived f ...
. This disease and together with witches’ broom disease (caused by ''M. perniciosa'') and black pod rot (caused by ''Phytophthora'' sp.) constitute the cacao disease trilogy. It causes serious losses in southwestern parts of South America; spores are dry and powdery and are spread easily by water movement, wind, or movement of pods; disease spread is highest during periods of high rainfall.


The fungus


Taxonomy

Originally, ''M. roreri'' was described as an anamorphic ascomycete, ''Monilia roreri'' Cif., due to the absence of a recognizable fruiting body or a sexual stage and other similarities to species of ''Monilia''. Later on it was noticed that the septa of the pathogen contained dolipores and septal pore caps, which are features of basidiomycete fungi. Consequently, ''Monilia roreri'' was reclassified and given its current name, ''Moniliophthora roreri'' (Cif.) H.C. Evans, Stalpers, Samson & Benny. More recently, it was shown that ''M. roreri'' and the causal agent of witches’ broom of cacao, ''M. perniciosa'', are sister species within the mushroom family
Marasmiaceae The Marasmiaceae are a family of basidiomycete fungi which have white spores. They mostly have tough stems and the capability of shrivelling up during a dry period and later recovering. The widely consumed edible fungus ''Lentinula edodes'', th ...
.


Host range

The main hosts of ''M. roreri'' are plants in the
Malvaceae Malvaceae, or the mallows, is a family of flowering plants estimated to contain 244 genera with 4225 known species. Well-known members of economic importance include okra, cotton, cacao and durian. There are also some genera containing familiar ...
that belong to the genus ''Theobroma'', such as ''T. cacao'', ''T. gileri'', ''T. bicolor'', and ''T. grandiflorum'', as well as plants in the closely related genus ''Herrania''. In contrast, the sister species ''M. perniciosa'' has a much broader host range, including hosts in the Solanaceae, Malpighiaceae, and
Bignoniaceae Bignoniaceae is a family of flowering plants in the order Lamiales commonly known as the bignonias or trumpetvines.Vernon H. Heywood, Richard K. Brummitt, Ole Seberg, and Alastair Culham. ''Flowering Plant Families of the World''. Firefly Book ...
.


Infection process and symptomatology

''M. roreri'' is a hemibiotrophic fungus that forms swollen irregularly shaped intercellular mycelia. The infection process starts when conidia of ''M. roreri'' land on the surface of the pods. Then they germinate and penetrate the pod directly through the epidermis, causing internal damage in the early stages of the disease. The initiation of the necrotrophic phase begins when asexual spore masses are produced on the pod surface. External symptoms like dark spots on the surface of pods can be seen only after 40 to 80 days post infection; thus infected pods during the early stages appear asymptomatic, which is one factor that has led to the unwitting movement of infected pods by humans. One week after the appearance of dark lesions, the characteristic white powder of the disease appears on the surface of infected pods. The powdery appearance is due to the presence of millions of conidia that can reach up to 44 million per square centimeter with a mature infected pod capable of producing more than seven billion spores.


History of the disease


First report

The first verified report of frosty pod rot is from
Ecuador Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ' ...
in 1895; some years later in the region of
Quevedo, Ecuador Quevedo is a city in Ecuador located in the Los Ríos Province. It is the seat of Quevedo Canton, a vibrant community founded in 1943. According to the latest census, Quevedo's population is 173,000. Located at 237 km SW of Quito (Ecuador's ...
in 1918, the most famous outbreak in the history of the disease was reported, causing abandonment of most of the cacao plantations over a period of three years. However, an earlier disease in Colombia may have also been caused by ''M. roreri''. In 1817 in the region of Santander, Colombia, a disease with symptomology that matches that of frosty pod rot was reported; therefore, many researchers believe the first known report of frosty pod rot of cacao was in Colombia around one century before the famous outbreak in Ecuador.


Spread

Before the 1950s, ''M. roreri'' was confined to Ecuador, Colombia, and western
Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...
. However, during the last 50 years, the disease has spread southward into
Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...
(in 1988), and northward into all cacao-growing areas of Central America ( Costa Rica, 1978;
Nicaragua Nicaragua (; ), officially the Republic of Nicaragua (), is the largest country in Central America, bordered by Honduras to the north, the Caribbean to the east, Costa Rica to the south, and the Pacific Ocean to the west. Managua is the countr ...
, 1979; Honduras, 1997; Guatemala, 2002;
Belize Belize (; bzj, Bileez) is a Caribbean and Central American country on the northeastern coast of Central America. It is bordered by Mexico to the north, the Caribbean Sea to the east, and Guatemala to the west and south. It also shares a wate ...
, 2004 and
Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
, 2005), in many cases resulting in abandonment of the entire plantation by farmers. The presence of the disease was confirmed in El Salvador and Bolivia in 2009 and 2012, respectively, where the fungus probably arrived some years before. This invasive behavior of the disease represents a threat to cacao growers from Brazil and also to areas outside of Latin America where the majority of the world cocoa is currently produced.


Economic impact of the disease

In Colombia, specifically in the Santander region, average annual losses are of 40% of dry cacao equivalent to US$33 million due to the disease. In Ecuador, during the 1918 outbreak, cacao exportation was reduced from 46,000 to 37,700 tons due to frosty pod rot. In Peru, around 16,500 ha of cacao were abandoned mostly as a result of frosty pod rot, with a final result that Peru went from being an exporter of
chocolate Chocolate is a food made from roasted and ground cacao seed kernels that is available as a liquid, solid, or paste, either on its own or as a flavoring agent in other foods. Cacao has been consumed in some form since at least the Olmec civ ...
to a net importer. In
Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
, in the state of
Tabasco Tabasco (), officially the Free and Sovereign State of Tabasco ( es, Estado Libre y Soberano de Tabasco), is one of the 32 Federal Entities of Mexico. It is divided into 17 municipalities and its capital city is Villahermosa. It is located in ...
, the first report of the disease was in April 2005, and by 2007, frosty pod rot had invaded all cacao areas of the state, becoming the major limiting factor to cacao production there, as well as in Nicaragua and Honduras.


References


External links


Index Fungorum

USDA ARS Fungal Database
* * {{DEFAULTSORT:Moniliophthora Roreri Fungal plant pathogens and diseases Cacao diseases Tricholomataceae Fungi described in 1933