Document Type : Original Article
Grades of microtubers of four potato cultivars (Hermes, Charlotte, Inova and Maris Peer) under two concentrations of Si-NPs (200 and 400 ppm) exposed to drought stress, induced by polyethylene glycol (PEG 10%) were evaluated. Si-NPs at low concentration-treated explants gave the maximum number and weight (7 and 0.89 g, respectively) of grade 1 of microtubers in Hermes cv. Shoots and microtubers of Hermes cv. showed presence or absence of specific isoenzymes of peroxidase (POD), polyphenol oxidase (PPO) and amplification of specific amplicons with different base pairs using 5 different SCoT primers. Isoenzyme of POD1 was present in microtubers and both isoenzyme of PPO 8 in microtubers and PPO10 isoenzyme in shoot were absent. The highest number of total monomorphic and polymorphic bands (23) in microtubers amplified with different 5 SCoT primers were recorded. Absence of amplicons with 700 and 460 bp amplified using SCoT 1 and 510bp with SCoT11 and presence of both amplicons 645 and 280 bp with SCoT11in microtubers were also detected. The same concentration of Si-NPs gave the maximum number and weight (7 and 0.17 g, respectively) of grade 2 of microtubers in Inova cv. Isoenzyme of POD10 was absent in shoot and isoenzymes of PPO 8, 9 in shoot and isoenzyme of PPO8 in microtubers were absent. Amplicons with 375 bp with SCoT 8 in shoots was disappear. It can recommend that, application of 200 ppm of Si-NPs was more effective for large grade microtubers induction in vitro especially in Hermes and Inova cvs.