Scottish scientists have made a huge breakthrough in the quest to speed up the development of raspberry varieties resistant to root rot virus.
The team at Invergowrie’s Scottish Crop Research Institute have developed new techniques to cut years off the time it takes to identify plants that are immune to what is the biggest disease scourge affecting commercial raspberry growers and gardeners globally.
Raspberry breeder Nikki Jennings said the molecular marker technology invented by award-winning SCRI research scientist Julie Graham was the most exciting development for many years.
It allows scientists to almost immediately identify those plants that carry the root rot resistance gene from the scores of raspberry variety crosses the institute breeds annually.
The results allow the breeding team to focus their efforts on plants with immunity so they can produce the seedlings needed to test their actual resistance in ground deliberately infected with the virus which is difficult and very expensive to control using fungicides.
Few of the new rasp varieties that have been developed in recent years have root rot resistance, leaving growers with the expense of regularly having to replace plants.
Ms Jennings said the new variety screening process previously took up to five years from identifying possible crosses to producing seedlings.
The marker technology has already been used on plant material and the hope is seedlings will be in the ground soon. Candidate varieties for further work are likely to be identified as early as next summer.
Ms Jennings said: “It (the market technology) allows us to start assessments for good agronomic traits straight away. The process is simple and quick in the laboratory where plants are screened for resistance. If the marker gene is within the plant then it shows up. It will help cut years off the breeding programme as we can go through the screening process within a year of making the crosses.”
Ms Jennings said the focus for breeders after satisfying demands for root rot resistance would be in evaluating candidate varieties for good fruit quality and flavour.
She added: “To breed rasps is a lengthy process. Glen Ample took 18 years and Glen Doll 16 years. Anything we can do to reduce the breeding timescale is a huge advantage. That the work has been done here is tremendous. It is world leading and it’s fantastic news for raspberry growers.”
The markers developed by SCRI can also identify other desirable traits including pest resistance as well as flavour and appearance, both of which are important to consumers.