The status of cacao (Theobroma cacao, sterculiaceae) in the western hemisphere

Hunter, J. Robert

doi:10.1007/bf02859775

Cited by 38 publications

(21 citation statements)

References 15 publications

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“…For most tropical tree crops, average yields over large areas are much lower than the maximum recorded yields. The gap between maximum attainable cacao yields (>8 metric tons/ha) under perfect conditions, and even those achieved routinely on experiment stations (3.5-4 metric tons/ha under ideal conditions), is in stark contrast to the average yields obtained by most growers (300-400 kg/ha) (67). The reasons for this yield gap include pests and diseases, poor soil and water management, low commodity prices, markets that fail to provide an incentive to growers, and a shortage of skilled and productive labor needed for improved management because of poor community health and nutrition (60).…”

Section: Impact Of Plant Pathogens In Tropical Tree Fruit Cropsmentioning

confidence: 74%

Fungal and Oomycete Diseases of Tropical Tree Fruit Crops

Drenth

Guest

2016

Annu. Rev. Phytopathol.

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The tropics produce a range of fruit from tree crops that cannot be grown in colder climates. Bananas, mangos, several nuts, spices, coffee, and cacao are widely traded and much sought after around the world. However, the sustainable production of these tropical tree fruit crops faces significant challenges. Among these, losses due to pests and diseases play a large part in reducing yields, quality, and profitability. Using bananas and cacao as key examples, we outline some of the reasons fungal and oomycete diseases cause such significant losses to tropical tree crops. Cultivation of monocultures derived from limited genetic diversity, environmental conditions conducive for disease development, high levels of disease incidence and severity, a lack of disease resistance in planting materials, shortages of labor, and inadequate infrastructure and investment pose significant challenges, especially for smallholder producers. The expansion of travel and trade has given rise to emerging infectious plant diseases that add further insecurity and pressure. We conclude that holistic actions are needed on multiple fronts to address the growing problem of disease in tropical fruit tree crops.

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Section: Impact Of Plant Pathogens In Tropical Tree Fruit Cropsmentioning

confidence: 74%

Fungal and Oomycete Diseases of Tropical Tree Fruit Crops

Drenth

Guest

2016

Annu. Rev. Phytopathol.

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“…Cacao (Theobroma cacao L.) is native to the South American rainforest, although it is thought to have been domesticated in Southern Mexico and Central America (Cuatrecasas 1964;Gómez-Pompa et al 1990;Henderson et al 2007;Hunter 1990). The hypothesized center of genetic diversity is located in the upper Amazonian regions of Peru, Ecuador, Colombia, and Brazil, which has a series of major river systems flowing into the Marañón and the Amazon (Cheesman 1944;Dias 2001;Bartley 2005).…”

Section: Introductionmentioning

confidence: 98%

Molecular characterization of an earliest cacao (Theobroma cacao L.) collection from Upper Amazon using microsatellite DNA markers

Zhang¹,

Boccara

Motilal

et al. 2009

Tree Genetics & Genomes

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Cacao (Theobroma cacao L.) is indigenous to the Amazon region of South America. The river basins in the Upper Amazon harbor a large number of diverse cacao populations. Since the 1930s, several numbers of populations have been collected from the present-day Peruvian Amazon and maintained as ex situ germplasm repositories in various countries, with the largest held in the International Cacao Genebank in Trinidad. The lack of information on population structure and pedigree relationship and the incorrect labeling of accessions are major concerns for efficient conservation and use of cacao germplasm. In the present study, we assessed the individual identity, sibship, and population structure in cacao populations collected from the present-day Loreto Region, Peru in the 1930-1940s. Using a capillary electrophoresis genotyping system, we analyzed the simple sequence repeat variation of 612 cacao accessions collected from the Marañon, Nanay, and Ucayali river systems. A total of 180 cases of mislabeling were identified using a Bayesian clustering method for admixture detection. Using maximum likelihood-based methods, we reconstructed 78 full-sib families nested in 48 half-sib families, indicating that the pods collected in the 1930s were from 48 mother trees, maximum. Likelihood simulation also identified eight probable parents that are responsible for 117 pairs of mother-offspring relationships in this collection. Principal coordinate analysis (PCoA) and the Bayesian clustering method cohesively demonstrated a pronounced structure of genetic diversity, stratified by the river systems of the Peruvian Amazon. Our results also show that, in spite of the high level of allelic diversity in this collection, it was composed of a large number of related family members collected from a relatively small area, including a couple of sites in the Ucayali and Nanay rivers, as well as the lower Marañon river near Iquitos. The vast majority of the Peruvian Amazon, especially the upper Marañon River and its tributaries, have not been sampled by collecting expeditions. The improved understanding of the individual identities, genealogical relationships, and geographical origin of cacao germplasm in this collection will contribute to more efficient conservation and utilization of these germplasm. Additionally, this study also provides more baseline information to help guide future collecting expeditions in the Peruvian Amazon.

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“…Most planted cultivars are mixed hybrid varieties that have been reproduced in seed gardens. Their pedigree and genotype may be uncertain or unknown (Hunter 1990). Finally, disease resistance in T. cacao is multigenic, making the discovery of individual genes responsible for resistance unlikely (Pires et al 1996).…”

Section: Introductionmentioning

confidence: 98%

“…Breeding programs have been supported at many national institutes in the Western Hemisphere. However, except for a few selected clones, very little superior planting material is available for farmers (Hunter 1990). Cacao poses a challenge in regard to improvement through traditional breeding methods.…”

Section: Introductionmentioning

confidence: 98%

Resistance gene homologues in Theobroma cacao as useful genetic markers

Kuhn

Heath²,

Wisser³

et al. 2003

Theor Appl Genet

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Resistance gene homologue (RGH) sequences have been developed into useful genetic markers for marker-assisted selection (MAS) of disease resistant Theobroma cacao. A plasmid library of amplified fragments was created from seven different cultivars of cacao. Over 600 cloned recombinant amplicons were evaluated. From these, 74 unique RGHs were identified that could be placed into 11 categories based on sequence analysis. Primers specific to each category were designed. The primers specific for a single RGH category amplified fragments of equal length from the seven different cultivars used to create the library. However, these fragments exhibited single-strand conformational polymorphism (SSCP), which allowed us to map six of the RGH categories in an F(2) population of T. cacao. RGHs 1, 4 and 5 were in the same linkage group, with RGH 4 and 5 separated by less than 4 cM. As SSCP can be efficiently performed on our automated sequencer, we have developed a convenient and rapid high throughput assay for RGH alleles.

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The status of cacao (Theobroma cacao, sterculiaceae) in the western hemisphere

Cited by 38 publications

References 15 publications

Fungal and Oomycete Diseases of Tropical Tree Fruit Crops

Fungal and Oomycete Diseases of Tropical Tree Fruit Crops

Molecular characterization of an earliest cacao (Theobroma cacao L.) collection from Upper Amazon using microsatellite DNA markers

Resistance gene homologues in Theobroma cacao as useful genetic markers

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