التشخيص الجزيئي لعزلة من فايروس موزائيك الخيار و مقاومته باستخدام بعض عوامل المقاومة الاحيائية والكيميائية والتراكيب الوراثية لنبات الخيار(Cucumis sativus L)

Molecular identification of an isolate of cucumber mosaic virus and its control using some biological and chemical control factors and genotypes

This study aimed to control of Cucumber mosaic virus, CMV) on cucumber
plants (Cucummis sativus L.) using some biological control factors and some
chemicals (amino acids, seaweed extracts (Oligo X), the biofungicide of
Trichoderma spp., the biostimulant (Bio Health WSG), glutathione, and hydrogen
peroxide), which have a role in inducing systemic resistance (ISR) in the plants, as
well as testing the response of some cucumber genotypes (AH- 38, HA-37, HA-
2160, HA2114, HA-2122, HA-12, HA-16, HA-41, CU-O719, and CU-2102) against
CMV. This study also conducted to determine the effect of CMV infection on some
plant contents of some mineral elements (calcium, magnesium, sodium, potassium,
manganese, nitrogen, and protein) as well as some chemical compounds (phenols,
flavonoids, and tannins), and some hormones (Gibberellin, cytokinin, and
indoleacetic acid). All the experiments mentioned in this study were carried out in
the Laboratory of Plant Viruses and Greenhouses of the Plant Protection Department
at the College of Agriculture/ University of Kerbala.
Results showed that the virus isolated in this study was molecularly diagnosed
as CMV with a similarity of 100% with some CMV isolates previously registered at
the National Center for Biotechnology Information (NCBI) including those isolated
and diagnosed in Hungary (AJ517802), Australia (U22821), and Slovenia
(OL142046). However, the results of testing the response of the cucumber genotypes
against CMV showed that all the genotypes tested in this study are susceptible to
CMV infection with different degrees of susceptibility. The genotypes HA-2114,
CU-O719, and HA-2160 showed a lower susceptibility to the virus compared with
the other genotypes, in which the severity of infection ranged between 15-20%,
respectively. Whereas, it was found that the genotypes HA-37, HA2122, and HA41
are the most susceptible to the virus among the other genotypes, whose infection
severity ranged between 80 and 100%, respectively.
The results also demonstrated that the viral infection had a clear effect in
reducing the content of the CMV-infected genotypes of calcium, magnesium, and
manganese, and the genotypes HA37 and HA-41 were the most affected and
significantly different from their content in uninfected plants of the same genotypes.
It was also observed that CMV infection had a clear effect in raising the plant mineral
content of sodium and potassium, and the plants of the genotypes HA-2114 and HA-37, respectively, were the most high and significantly different from their content in
uninfected plants. It was also noticed a clear effect in reducing the plant nitrogen and
protein content in the genotypes infected with the virus (CMV), and the genotype
2122-HA was the most affected with a significant difference from its content in the
control plants (uninfected). It was also found a high content of CMV-infected plants
of chemical compounds (phenols, flavonoids, and tannins), and the most high
content was in the genotypes HA-2122, HA-12, and HA-41 that significantly
different from their content in the uninfected plants.
However, it was observed that the plant content of gibberellin hormone was
significantly decreased in the genotypes infected with CMV, and the genotype HA-
37 was the most affected in reducing the level of this hormone (1.72) μg/ml) with a
significant difference from its content in the uninfected plants, which was 2.80
µg/ml. It was also found that there was a significant increase in the plant content of
the hormone cytokinin and indole acetic acid in the CMV-infected genotypes. The
HA-41 genotype gave the highest rates (5.68 µg/ ml and 4. 65 µg/ ml, respectively)
with a significant difference from its content in uninfected plants which was 2.14
µg/ ml and 1.95 µg/ ml, respectively.
CMV infection produced a clear decrease in the dry weight and productivity
of the genotype plants with a significant difference from those weights obtained from
the non-infected plants. It was also shown that the treatment with amino acids,
seaweed extracts (Oligo X), the biofungicide containing different Trichoderma spp.
and the biostimulant (Bio Health WSG), glutathione (Glutathione), and hydrogen
peroxide (H2O2) had a clear effect in reducing the disease symptoms caused by
CMV, which indicates that these biological and chemical factors have a good role in
inhibiting the replication and movement of the virus inside the plant cells. The results
also proved that the use of the biofungicide containing different Trichoderma spp.
before infection and during infection gave better results than its use after CMV
infection.