Embryo and callus induction by different factors in ovary culture of cucumber

Abstract

Haploid and doubled haploid lines can be obtained in a short time using in vitro methods. In this study, unfertilized ovaries of cucumber were harvested and placed on semi-solid MS media as explants in Petri dishes. The thermal shock pretreatment, cucumber genotypes, hormonal combinations and AgNO 3 were evaluated as experimental factors in three consecutive experiments. The results of first experiment revealed that the thermal shock pretreatment had a significant influence on embryo induction, and the highest rate of embryogenesis was produced in presence of thermal shock pretreatment and the NAA+2,4-D+KIN+BAP (0.5+0.7+1+1.8) mg/L hormonal combination. The highest rate of callus induction was recorded in combination of absence thermal shock and the NAA+2,4-D+KIN+BAP (1.5+0.7+1+1.8) mg/L hormonal combination. According to the second experiment results, genotypes and the other hormonal combinations in media culture had highly significant effects on embryo and callus induction. The NBDC6 * 6/32441 genotype had the highest effects on these traits. A combination of BAP (4 mg/L) and 2,4-D (1.5 mg/L) was found to be optimal for embryogenesis. In third experiment, the highest level of embryogenesis (24.93%) and callus (24.19%) induction were found in the local Iranian cultivar in comparison to NBDC6 * 6/32441 genotype. Silver nitrate treatment had significant effects on the embryo and callus induction. The highest rate of embryo induction was recorded in presence of silver nitrate; however the absence of AgNO 3 had a positive effect on the callus induction. In conclusion, the thermal shock pretreatment, silver nitrate, genotype and hormonal combination factors could play key roles in embryo and callus production, independently and simultaneously.