Résumé:
The main objective of this investigation is to study the response of different potato explants
Spunta and Kondor to callogenesis and somatic embryogenesis in the presence of
combinations with NAA / BAP and 2,4-D / BAP. We opted from the start for the buds and
internodes as explants. The color and texture of the calli vary according to the nature of the
growth regulators and the presence or absence of light. With the NAA / BAP combination the
Spunta variety develops the best callogenesis in all environments compared to the Kondor
variety depending on the concentration of hormones, there is a range of variations of days
required for callus initiation, the percentage of explants that have developed calluses, texture,
color and degree of its formation. For the combination 2,4-D / BAP the results indicate that
after three weeks of culture, the calli are moist, soft and friable in green and whitish-green and
white with the NAA / BAP combination, and green, light green and brown color for both
explant with all media with of 2,4-D / BAP combination. Callus growth varies according to
culture conditions like light and temperature, callus incubated in the dark give brown colors
and a friable to compact structure, while the calluses incubated in light show varying colors
(green, light green, white and brown) that are due to the action of light on the photosynthetic
pigments. The rate of callogenesis and fresh weight of calli are positively correlated with the
concentration of auxin. The histological study of callus obtained from internodal explants
after 3 and 60 days shows that cell division is produced in the epidermis only after three days
of culture and then spread to the first layer of the cortex. During somatic embryogenesis the
calluses of different explants develop with all media (1-2) buds and dense roots. Exceeding
three months of incubation the calli are larger and begin to brown and lose the green color
after degradation of chlorophyll. A surprising observation in our study which is the formation
of microtubers from the callus of tubercle germs on M1 and M2 medium after 37 to 60 days
of incubation. This research has made it possible to highlight the conditions necessary for
callogenesis and somatic embryogenesis. In the end it is recommended to try to induce
somatic embryogenesis by applying stress (osmotic, with ions, ABA ...), with the addition of
organic and mineral nitrogen source for a period exceeding three months.
