The process Reference: employed to obtain healthy …The process employed to obtain healthy citrus...
Transcript of The process Reference: employed to obtain healthy …The process employed to obtain healthy citrus...
The process employed to obtain healthy citrus plants
Step 3: Establishment of the cell culture and plant regeneration
In this phase, the explants are dissected, the
female reproductive parts are removed and placed
onto a nutrient medium which stimulates cell
division. Cell division transforms the female
reproductive parts to a clump of unorganised
cells, called a ‘plant callus’. The plant callus is then
transferred to a different nutrient medium with
different growth hormones that stimulate the
development of a plant embryo and later to a plantlet
with roots, a shoot and leaves.
Step 4: Transfer to soil and acclimatisation
Once the regenerated plantlet reaches an ideal size, it is
either planted into sterilised soil in plastic pots or mini-
grafted onto certified disease-free rootstock seedlings.
The regenerated plantlets are then allowed to
acclimatise slowly, in order to grow and adapt to
external environments.
Reference: LEONE GANADO, C., 2014. A study on citrus somatic
embryogenesis: A protocol for use in citrus sanitation. Master of
Science, Malta: University of Malta, Institute of Earth Systems.
Photography: Chris Leone Ganado
Step 2: Sterilisation of all equipment and biological material
The successful execution of sanitation and
micro-propagation techniques strictly require a clean
environment free from bacteria and fungi, since
these can contaminate the explants. The collected
explants are sterilised using alcohol, distilled water
and bleach under controlled conditions, the nutrient
medium and vessels for plant growth are sterilised
in an autoclave, while the tools are sterilised in a dry
heat steriliser.
Plant callus with developing embryo
PLANT HEALTH DIRECTORATE
The resilience of the local citrus industry is
dependent on the maintenance of a healthy
citrus tree population. This can be achieved by the
conservation and promotion of old local varieties
of citrus trees and by adopting preventive
measures to control the introduction of devastating
diseases, such as the Citrus Tristeza Virus.
The conservation of old local varieties of citrus
trees is important as these have been selected
by farmers for their desirable characteristics
that make them adaptable and resistant to the
local environment. Having been cultivated for
hundreds of years, they also form part of our
living traditional heritage and may serve as a
source of useful genetic material for the future.
Through the EAFRD Project on the Study and Sustainable
Conservation of Varieties of Local Plants, the Plant
Health Directorate has embarked upon activities to
identify local varieties of citrus trees through clonal
selection, which were then sanitised via a technique
called ‘Somatic embryogenesis’, as a means of
ensuring the continued existence of such varieties
which are at risk of extinction. This technique is ideal
because it produces disease-free plants that are
genetically identical to the parent tree.
Sanitation via somatic embryogenesis involves a number of steps:
Step 1: Selection and collection of plant material
Traditional knowledge from experts and farmers is
essential to identify local citrus varieties. During
the project, three orange and three lemon varieties,
suspected to be of local origin, were studied.
These trees were found in the old citrus groves
at San Anton Gardens and in private gardens
bearing old trees in Santa Venera and Siġġiewi.
The plant material collected for sanitation,
which are referred to as ‘explants’, were closed
flower buds.
Address:
Plant Health Directorate, Plant Biotechnology Centre,
Annibale Preca Str, Lija LJA 1915, Malta.
Website: www.planthealth.gov.mt
Telephone: 22926535
Email: [email protected]
Regenerated plantlets during acclimatisation
Parliamentary Secretariat for agriculture,fiSherieS and animal rightS