Generation of Rubus arcticus L. haploids through in vitro microspore culture technique

Arctic raspberry ( Rubus arcticus L.) is a valuable small-fruit crop used as a plantation crop for a relatively short time. R. arcticus is a remontant donor in interspecific hybridization with Rubus idaeus L., though conditioning low yields to hybrids. So R. arcticus is primarily bred for yield enhancement; therefor, the acceleration of the breeding process is of great importance. This can be achieved using plants with a doubled haploid set of chromosomes. This paper is the first to describe the technique of production haploid plants of R. arcticus via in vitro microspore culture. In the experiments we used Finnish cultivars Pima and Mespi and Swedish cultivar Astra. To obtain donor explants, the method of forcing generative shoots was used throughout the year. Microspores were isolated from anthers with the use of manual homogenizer into a 1.5 ml micro test Eppendorf tube. The homogenate was added with 0.5 ml sterile water containing 30 g/l glucose, centrifuged at 4500 rpm, and the microspores were transferred with a microdoser to nutrient medium for morphogenesis initiation...