The occurrence of virus of the family
on maize and annual grasses was studied in the south region of the Czech Republic during three years. On maize and annual weed grasses no BYDV-MAV and CYDV-RPV pathogens were found in test samples. Out of 246 maize samples taken, BYDV-PAV was found in 50 of them. The occurrence of this pathogen on maize varied with the locality and the year of sampling. In the test annual weed grasses BYDV-PAV was found in
Echinochloa crus-galii, Setaria pumila
plants. The occurrence of this pathogen was also dependent on the locality and the year of sampling. This pathogen was not found in
.The present results suggest that maize and some species of annual weed grasses in the territory of southern Moravia may serve as a major source of BYDV-PAV for winter cereals because these species are a „green bridge“ for this virus species
The heritability of maize resistance to one Czech isolate of
Sugarcane mosaic virus
(SCMV) was determined. Parental maize lines with different degree of resistance or susceptibility, their F
progeny were mechanically inoculated by this virus and symptom development were observed during 63 days. The analysis of resistance of F
hybrids, derived from resistant lines and lines with a different degree of susceptibility, suggests that there was no hybrid found which would not exhibit any symptom of infection induced by SCMV, but the symptoms appeared one or two weeks later, compared with the susceptible line, the onset of infection was very gradual and the percentage of infection never reached 100 percent. Heritability of this trait, determined on the basis of the variances of parents, F
hybrids, and the development of infection in F
populations was relatively high and ranged from 0,70 to 0,91. From these results we can assume that the resistance of tested lines to SCMV detected in the greenhouse is not inherited completely dominantly but it may be controlled partially dominantly or polygenically.
The movement of
Sugarcane mosaic virus
(SCMV) in the leaves and entire plants of three maize lines was studied under greenhouse conditions. One line was considered resistant and the other two showed a different level of susceptibility. The effect of the growth stage at which the maize plants were inoculated on SCMV movement was also examined. None of the lines tested was fully immune, even in the resistant line the inoculated leaves were infected. Nevertheless, SCMV was detected in the inoculated leaves 7 days later than in the susceptible lines and did not spread into the newly developed leaves. In the lines with the different level of susceptibility SCMV moved into the newly developed leaves at a different rate and in the less susceptible line the spread was also affected by the development stage of maize at inoculation. The spread of the virus from the inoculated parts of the leaves into the non-inoculated ones was also considerably faster in the highly susceptible line, compared with the susceptible and the resistant line, whereas in these two lines the rate of spread was dependent on the development stage of the plants under inoculation and also on the position of the leaf on the plant.