Barley research promises to improve plant breeding

“Barley is an excellent crop model to understand complex mechanisms like recombination and to develop new protocols and techniques that can be easily transferred to wheat and other cereals.”

Plant breeding relies on ‘recombination’, the cellular process in which genetic material is exchanged between parents to create unique progeny. Recombination is, therefore, key to the improvement of crops. However, in cereal crops there is a problem: in crops like barley and wheat recombination is heavily skewed towards the ends of the chromosomes, a feature not yet understood by scientists. The consequence is that some very important genes (e.g. those conferring disease resistance or environmental tolerance) that are located outwith the regions where recombination occurs frequently are difficult to either separate from, or to combine with, other valuable genes during plant breeding.

A research team from the James Hutton Institute has shed light into recombination in barley by studying subtle alterations to individual components of the recombination machinery, and then directly visualising how chromosomes behave when recombination is taking place. Their results suggest that it may be possible to favourably modify recombination by intervening in the early stages of the process, thereby allowing previously impossible combinations of valuable genes to be assembled in a single cultivar. Their findings may result in improved barley varieties suited to the needs of growers and industry.

Dr Isabelle Colas, a molecular geneticist based at the James Hutton Institute’s Cell and Molecular Sciences Group, said: “Recombination patterns in barley currently exclude around thirty percent of its genes because they rarely, if ever, participate in genetic exchange. The result is that they are excluded from the breeding process.

“By studying a particular barley mutant identified in the 1970s, we showed that recombination is reduced along all of the chromosomes, but also that the timing when recombination is decided is much earlier than previously thought.

“We know that environmental stresses such as temperature can increase recombination in desirable regions. The current study shows that using stress to modify patterns of recombination needs to be done very early in the process and in a short window of time. We now understand where, when and how to apply such treatments and have started to partner breeders to use this approach to improve the barley breeding process.

“Importantly, barley is an excellent crop model to understand complex mechanisms like recombination and to develop new protocols and techniques that can be easily transferred to wheat and other cereals.”

Paper: A spontaneous mutation in MutL-Homolog 3 (HvMLH3) affects synapsis and crossover resolution in the barley desynaptic mutant des10. Colas I, Macaulay M, Higgins JD, Phillips D, Barakate A, Posch M, Armstrong SJ, Franklin FC, Halpin C, Waugh R, Ramsay L. New Phytologist, 2016 Nov.

Layman’s summary: Atlas of Science.