Genetic chromosome and Factor mutations in Coffee plants

For professional baristas, please follow the coffee workshop (Wechat official account cafe_style)

The heredity of Coffea

The heredity of the genus Coffee is very complex, and its chromosome number is mostly 2n=22 except that Arabica coffee is 2n=4x=44 (heterotetrad). Medium-grain coffee (Coffea canephora, 2n=2x = 22) grows well and can be used as a genetic research material. All of the above mutations are a pair of factors, while many other pairs of factor mutations have not been found.

The chromosomes in the Prophase of meiosis are heterochromic, the staining near the centrosome is darker, and the staining of other parts is lighter.

With the exception of Arabica coffee from the Ethiopian highlands, 90% of Arabica coffee is self-compatible, and all other types of coffee are self-infertile. After several generations of self-breeding, the growth potential and yield of Elaraby coffee were not affected.

Arabica coffee has more mutations, which may be due to its easy selfing and recessive mutations.

The chromosome mutations in Arabica coffee are

a. Six elements (2n=66) Bullata form. The leaf is thicker and wider than the quaternary, with fewer stomata and less fruit.

b. Octet (2n=88) Bullata form.

Leaves are smaller, thicker and tougher than hexagons, with fewer pores and stronger.

And less.

c. Binary (2n=22) Monosperma form.

The leaf is thinner and narrower than the binary, with more stomata and less fruit.

Only one seed per fruit.

d. Chromosome variation of somatic cells.

The factor mutations of Arabica coffee are

a. About 1/3 of the known mutations are dominant, 1/3 are incomplete dominant and 1/3 are recessive.

b. There are also good offspring in recessive mutation: Typica → bourbon Bourbon → Laurina Bourbon → Semperflorens.

c. Dominant mutations such as maragogype and Caturra.

d. Most mutations have the power to affect the whole plant (Pleiotropic), such as narrow leaf mutation, deformed mutation A, deformed mutation B, wrinkled leaf mutation, brown leaf mutation, short branch leaflet mutation, purple leaf mutation, calyx mutation, multi-flower mutation, large calyx mutation, dwarf mutation, yellow endosperm mutation, orthophytic mutation, tufted mutation, large mutation, small mutation, yellow fruit mutation, Lloyd's coffee. Normal coffee and so on.

e. All the factors were very stable, only the abrupt change of short branch and leaflet showed the appearance of intermediate type, but it was also very obvious.

f. Factor epistasis and interaction have been found.

g. The study of mutations is of great value, and some mutations have been bred into economic varieties.

h. This kind of study can explore the source of cultivated varieties. For example, bourbon is from typica.