Production of virus-tested planting
materials from genetically stablished fruit trees.
Feeding the growing world population
faces with several challenges including the limitation of appropriate
agricultural land, climate change and social demands for healthy food and
environment preservation. According to the FAO reports, more than one billion people
around the world are currently suffering from starvation and malnutrition. It
is now stablished that plant pathogens, pests and weeds are of the most
important factors that affect the agricultural crop yield and quality
worldwide. Perhaps the
climate change and particularly global warming and increasing level of the
greenhouse gas, CO2, are the biggest challenges for the agriculture
of todays and future. It enhances soil erosion, shortage of sufficient water,
loose of agricultural lands, pooleward movement of plant pests and the
emergence and/or re-emergence of plant pathogens and pests. It is commonly
accepted that plant pests and diseases and weeds play important negative roles
in agricultural production and human feeding.
Damages to the quality and quantity
of crops could be decreased by application of agricultural practices and other
control measures including synthetic pesticides and biological agents. However,
application of pesticides, as the most prominent control strategy, is not
accepted in green agriculture and is useless in controlling vascular pathogens
including viruses and phytoplasmas. For the latter pathogens, prevention from
infection and control of insect vectors are the only known control strategies.
However, as these pathogens transmit in grafting materials, the original
planting materials (e.g. nuclear stocks) should be virus-free before further
multiplication.
Sanitation of planting materials to
obtain “virus-free” clones could be achieved by several methods including heat
therapy, cryotherapy, meristem tip culture alone or in combination with
chemotherapy. Co-application of tissue culture technologies with one or several
therapy means is commonly accepted as they result in more success in terms of
sanitation and regeneration. However, this method (s) suffers from somatic
mutations and maintain of some viral pathogens in planting materials after
treatment.
Here in our institute, we used an
alternative strategy to produce “virus-tested” planting materials. First,
candidate true-to-type fruit tree plants and vegetative stocks were checked for
vascular pathogens according to national health standards of fruit trees using
serological and molecular approaches. The healthy materials were used for
grafting and the infected ones were removed. The resulted saplings were kept in
insect-proof screen house for two years and tested for systemic pathogens by
several techniques and the suspected plants were removed. The plants that fully
passed detection methods and revealed as virus-tested, were delivered to
producers for multiplication. This strategy were successfully applied for local
cultivars including appricot (19), peach (3), nectarin (2) and olive (7). As
none of the above mentioned sanitation processes used, no somatic variation are
happened and are fully free from the vascular pathogens that tested for.