A new study has compared genomes across 18 strains of the septoria leaf blotch fungus zymoseptoria tritici.
The work has revealed a core set of genes that may offer clues for improved control of this important disease.
These ‘core biology’ gene sets are present and functional in all strains of the fungus, unlike other ‘flexible biology’ sections which appear to mutate and evolve rapidly.
The core set comprised 9,807 sequences which were present, more-or-less, unchanged in all samples.
That left a large accessory genome, consisting of 45% of the total genes where the sequences could be highly variable.
Wheat septoria genomes
The wheat-pathogenic fungus zymoseptoria is one of the most rapidly evolving threats to global food security. Like many crop diseases, it can quickly adapt making it resistant to pesticides.
Severe epidemics of this type of septoria have decreased wheat yields by up to 50%.
The core set coded for proteins required for essential functions including virulence. Both core and accessory genomes encoded many small proteins that likely interact with plant immunity.
However, the researchers were unable to identify the genes that induced the characteristic brown patches that are typical of the disease.
“We also identified a non-pathogenic strain lacking five of the core genes. Just by restoring a single carefully chosen gene full virulence was regained,” Dr. Jason Rudd of Rothamsted Research said, who led the study.
“This hints at the huge potential for using genomic techniques to control crop diseases that can evolve rapidly, making them quickly resistant to herbicides or other treatments.”
Insects
Rothamsted has also been involved in compiling a database of 19 insect genomes, encompassing some of the most damaging pests of crops worldwide.
The work was made public recently.
Included are genomes from some of the most common pest threats faced by farmers around the world, including wireworm, cabbage stem flea beetle and pollen beetle.
It is hoped that the new database will help speed up the development of novel pest control approaches that can overcome resistance and create more nature friendly solutions to crop protection.
The four-year ‘pest genome initiative’, a consortium of Rothamsted Research and the agri-science companies Syngenta and Bayer, firstly sequenced the genomes, and then assembled them into their constituent chromosomes before adding information about what individual genes code for.
The team said their efforts will help in the development of crop protection products that are more species-specific and overcome the problem of resistance.
The information now being made available should also help develop non-chemical pest control method.
These include the manipulating of insect behaviour, focusing on the genes that control how insects find mates and host plants and hence shepherd them away from crops.