Coffee

C. arabica is a tetraploid (44 chromosomes) and is self-pollinating. There are two distinct botanical varieties: arabica (typica) and bourbon. Historically, typica was cultivated in Latin America and Asia, whereas bourbon arrived in South America and, later, East Africa via the French colony of Bourbon (Reunion). Because C. arabica is self-pollinating, these varieties tended to remain genetically stable. However, spontaneous mutations showing desirable characteristics have been cultivated in their own right, as well as being exploited for cross-breeding purposes. Some of these mutants and cultivars are described below.

Mutants: Caturra - a compact form of bourbon Maragogipe - a mutant typica with large beans San Ramon - a dwarf typica Purpurascens - purple leaved forms

Cultivars have been developed to give the maximum economic return under specific regional conditions such as climate, soil, methods of cultivation and the prevalence of pests and diseases. Some of the better known cultivars are:

Blue Mountain - grown in Jamaica and Kenya

Mundo Novo - a cross between typica and bourbon, originally grown in Brazil

Kent - originally developed in India, showing some disease resistance

Catuai - developed as a hybrid of Mundo Novo and Caturra, characterized by either yellow or red cherries: Catuai-amarelo and Catuai-vermelho respectively.


Coffea canephora
C. canephora is diploid and self-sterile, producing many different forms and varieties in the wild. The identification of cultivars is confused, but two main forms are recognised:

'Robusta' - upright forms
'Nganda' - spreading forms

Arabica / robusta hybrids
Coffee has been selectively bred to improve characteristics of: growth and flowering, yield, bean size and shape, cup quality, caffeine content, disease resistance, drought resistance.

Crosses between arabica and robusta aim to improve arabica by confering disease resistance and vigour or to improve on the cup quality of robusta.

Hibrido de Timor is a natural hybrid of arabica x robusta which resembles arabica coffee and has 44 chromosomes.

Catimor is a cross between Caturra and Hibrido de Timor and is resistant to coffee leaf rust (Hemileia vastatrix).

A new dwarf hybrid called Ruiru Eleven, developed at the Coffee Research Station at Ruiru in Kenya, was launched in 1985. Ruiru 11 is resistant to coffee berry disease and to coffee leaf rust. It is also high yielding and suitable for planting at twice the normal density.

Icatu hybrids are the result of repeated backcrossing of interspecific arabica x robusta hybrids to arabica cultivars Mundo Novo and Caturra.

Arabusta hybrids are fertile interspecific Fl hybrids from crosses between arabica and induced auto-tetraploid robusta coffee.

Techniques used in coffee breeding
1. Controlled pollination and multiplication by seed
2. Vegetative (clonal) propagation
* Traditional methods: grafting, taking cuttings
* New methods (tissue culture): micropropagation, somatic embryogenesis

In recent years the potential of genetic manipulation of Coffea using recombinant DNA technology and tissue culture techniques has been investigated. By introducing new genes for characteristics such as resistance to pests or to herbicides, or genes coding for desirable cup quality attributes, it may be possible to produce plants with any combination of features required.

source:http://www.ico.org/coffee_story.asp