Background: Tomato (Solanum lycopersicon) is affected by many biotic and abiotic stresses which
became major limiting factors for growth, fruit yield quality and quantity. Tomato ringspot virus
(ToRSV) is considered one of the most devastating members of the genus Nepovirus and distributed in
most parts of the world and can infect herbaceous, ornamental and woody species including tomato,
tobacco, grape, apple, peach, cherry, apricot and raspberry. Both of sodium azide (NaN3) and ethyl
methanesulfonate (EMS) are known as chemical mutagens.
Objective: Study the effect of chemical mutagens (NaN3and EMS) on the resistance of (ToRSV) on
two different tomato cultivars and characterization induction mutagens by ISSR molecular method.
Methods: ToRSV was isolated from infected tomato, grapevine and pelargonium plants and detected
using double antibody sandwich-enzyme linked immunosorbent assay (DAS-ELISA). Host range study
was carried out using mechanical inoculation into fourteen different diagnostic host plant species and
cultivars belonging to 6 families. Tomato seeds were treated with four different concentration of
NaN3and EMS (1.0, 2.0, 3.0 and 4.0 mM) and (0.3%, 0.4%, 0.5%and 0.6%) respectively, then planted
into a tissue culture media, induced plants were checked for resistance to ToRSV by ELISA. ISSR
reaction was used to confirm the DNA variations.
Results: ToRSV was transmitted mechanically into11 plant species and cvs., belonging to 6 families
while 3 plant species and cvs. from 2 families gave negative results with DAS-ELISA and were
symptomless. Treated plant with different concentrations of NaN3and EMS showed that high
concentrations of both chemicals led to death of plantlets while, concentrations 3.0 and 4.0 mM of
NaN3 and EMS 0.4%, 0.5% showed no symptoms of ToRSV in spite of concentrations 1mM and 2mM
of NaN3 and 0.3% of EMS were showing symptoms and gave positive results with ELISA. EMS
(0.40%) treated tomato cv. CR and 3mM NaN3 treated tomato cv. SSB revealed 3 unique fragments
with 98-A ISSR primer, 3 unique fragments appeared in SSB cv. treated with 3mM NaN3 with 98-B
ISSR primer, and E-9 ISSR primer revealed 6 fragments in EMS (0.40%) treated CR cv. and 5
fragments in 3mM NaN3 treated SSB cv. Indicting changes in the genetic make-up of the treated
tomato plants. No similar fragments were observed in the control samples.
Conclusion: NaN3 at 3mM concentration and EMS at 0.4% concentration gave the highest effect in
resistance to ToRSV on tomato and revealed in different unique fragments in ISSR PCR reaction,
without harmful effect on the produced plants.