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Abstract
This study was carried out during the period from 2005 to 2008 at the Kaha Research Station and Tissue Culture Research Laboratory, Horticulture Research Institute, A.R.C. The purpose of this work was to produce cucumber tolerant to Fusarium wilt using tissue culture. In vitro regeneration was achieved in four inbred lines of cucumber (Cucumis sativus L.), namely Alagy, K-40, K-43 and K-44. Cucumber explants including at least the cotyledon a short section of hypocotyl and the apical bud were cultured on Murashige and Skoog (MS) medium
supplemented with 0.25 or 0.50 mg/l 6-benzladenine (BA). Among the tested lines the K-40 and K-43 lines were superior to Alagy and K-44 lines for regeneration capacity and genetic stability under tissue culture conditions.
The better shoot regeneration was observed on medium with 0.50 compared to 0.25 mg/l BA. Shoot elongation and rooting were achieved in one step by culturing of small shoots on full-strength MS medium without BA. Plantlet length which originated from medium
contained 0.25 mg/l BA was higher than the other plantlets originated at
0.50 mg/l BA. Moreover, the number of roots per plantlet of the K-40 and
K-43 lines recorded the highest values than the other tested lines.
Acclimatization and evaluation of regenerated plants were performed.
The fungal culture filtrate concentration affected the regeneration and inducing resistance curve, the best shoot regeneration per explant was
observed on medium contained 10% of fungal culture filtrate than the
other concentrations. The best shoot length was observed on medium
contained 0, 5, and 10% of fungal culture filtrate than that contained 20%.
The plantlet length which originated from media contained 0% of fungal
culture filtrate was superior to plantlets which observed from medium
contained 5 or 10% of fungal culture filtrate. On the other hand, 20% of
fungal culture filtrate gave the shortest plantlet length. The highest
number of roots per plantlet were exhibited from shoots originated from
20% of fungal culture filtrate, while, the moderately values were obtained
from 5 and 10%. On the contrary, the lowest number of roots per plantlet
was obtained from 0% of fungal culture filtrate. Root length of plantlets at
0, 5 and 10% of fungal culture filtrate was superior to 20% of fungal culture filtrate.
Evaluation of regenerated plants was performed through susceptibility test and estimation of some morphological characters.
It could be noticed that the plants which originated from medium without
fungal culture filtrate exhibited the highest percentage of infection while,
the other fungal culture filtrate concentrations exhibited the highest
tolerant to Fusarium pathogen. As for morphological characters the taller
main shoot length was observed from plants of K-40 line compared to those of K-43. Also the plants proliferated from medium without fungal culture filtrate gave the highest value of main shoot length than plants produced from media included 5, 10 and 20% of fungal culture filtrate.
Evaluation of some morphological characteristic could be utilized in
predicting plant ploidy.
This method could quickly and safely produce resistant cucumber plants from susceptible lines, which would shorten the period of time needed to induce disease resistance.