Updated: Feb 18, 2020
In our September newsletter we announced the introduction of an elite winter wheat variety, RGT Wolverine, with resistance to barley yellow dwarf virus that will offer farmers an alternative to chemical control for the first time.
In this article we take a look at how this remarkable breakthrough came about.
Twenty years ago, researchers at Plant Breeding International Cambridge started work on incorporating BYDV resistance into UK wheat germplasm.
One source, the resistance gene Bdv2 originating from a distant relative of wheat, Thinopyrum intermedium, proved the most interesting.
However, due to the absence of modern molecular marker technology and effective screening methods, the introduction of the trait into truly competitive germplasm for the UK market proved technically very challenging.
Work continued, but at a fundamental experimental level because it was perceived there was little demand for the trait at the time, not least because insecticide seed treatments offered cheap and reliable control.
“We knew the trait was viable from that early work, along with other research carried out at a similar time by Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO),” says Richard Summers, head of cereal breeding and research at RAGT Seeds.
“The CSIRO work did succeed in the commercialisation of BYDV-resistant wheat, one of the very few breeding programmes in the world to have done so to this day.”
CSIRO did this by translocating a genetic segment from Thinopyrum containing Bdv2 onto a wheat chromosome, via a research line known as TC14.
“It is interesting to note that the two CSIRO varieties, Manning and Mackellar, introduced 16 years ago, have maintained significantly higher yields compared with BYDV-susceptible varieties when BYDV pressure is high, outperforming all other varieties in this situation.”
A few years after RAGT bought PBIC, RAGT wheat breeder, Célia Bequain and her team, in collaboration with pathologists and molecular marker specialists within RAGT, recommenced work on introducing Bdv2 into commercially acceptable material.
“The rapid development of marker systems and other technologies that identify sequences of DNA code in the intervening years greatly simplified the selection of key traits in breeding programmes, such as BYDV resistance,” says Richard.
“Of course, we had no idea at the time that neonicotinoid seed treatments would soon be banned. But, as a company, we aim to deliver varieties not just with improved yield and quality but also better resistances that take account of environmental and other farming issues, including the withdrawal of useful chemistry.”
In 2013, the team produced the cross that became RGT Wolverine, Europe’s first BYDV resistant wheat.
In the three years before National List entry the cross performed very well. It was in the bracket of RAGT’s best feed wheats, proving that the team had succeeded in getting the trait into top-performing material.
Two years in NL trials against competitor material have confirmed that success. With its competitiveness becoming apparent, RAGT tested RGT Wolverine’s performance against BYDV, and the results speak for themselves (see below).
RAGT is the first breeder in Europe to offer a BYDV-resistant wheat, marking a major breakthrough in European winter wheat development.
The variety is capable of delivering exceptional yields and growers will not be penalised for choosing it in the absence of BYDV.
RGT Wolverine, which is aimed at the Group 4 sector, has been put forward for RL Candidate selection this autumn. Farmers will be able to try the variety in autumn 2020 following RAGT’s decision to fast-track seed production.
Trials confirm stand-out BYDV resistance
The effectiveness of the Bdv2 resistance trait in RGT Wolverine has been clearly demonstrated in a range of laboratory and field experiments carried out by RAGT.
In the laboratory, RGT Wolverine was compared against a widely grown, fully recommended UK variety as a control. In addition, two of RAGT’s French lines were tested to provide additional confirmation, one with the Bdv2 trait and one without.
When plants reached the second-leaf stage, BYDV-infected aphids were transferred to each plant. After 42 days of incubation, leaf tissue samples were sent for ELISA testing to detect virus presence.
The resistant lines consistently showed a lower level of virus compared with the susceptible ones.
Subsequent field trials at Cambridge, Lincolnshire and Yorkshire mirrored the ELISA tests and confirmed the effectiveness of the Bdv2 gene.
Three BYDV strains were also confirmed at all three sites by ELISA tests (PAV, MAV and RPV), suggesting the resistance is also broad spectrum.