Investigation of different slow-growth inducing treatments for in vitro conservation of potato genotypes from national plant-gene bank of Iran

Conservation of potato germplasm (Solanum tuberosum L.) is of great importance due to its role in providing food security. Considering high heterozygosis of potato and severe segregation in the progeny obtained from sexual reproduction, it is necessary to use asexual propagation to maintain selected genotypes. Although in vitro culture is an efficient method for maintaining potato genotypes, rapid growth of plants under optimum growth conditions, makes multiple subcultures necessary to be done. The later leads to increased costs and an increase in the probability of somaclonal variation. Therefore, it seems to be necessary to induce slow growth in plants maintained under in vitro conditions. In the current research the aim was to find out the best in vitro treatment for reducing the growth of potato shoots with the least negative effect on them. To approach the aim, two types of agar (including agar-agar and confectionery agar) and two osmotic agents (including sorbitol and mannitol) were evaluated on three potato genotypes in 6℃. The traits of shoot length, number of possible buds and microplant condition were recorded after 9 months. The results of data analysis showed that in all the three investigated genotypes, sorbitol osmotic agent (in combination with agar-agar or confectionery agar) at the temperature of 6 ℃ was the best treatment for medium-term storage of potato germplasm. It was mainly due to having the least shoot length, good microplant condition and also having enough buds for subsequent subcultures.