Background

Canola is Canada’s most important oilseed crop, contributing $20 billion to the country’s economy in 2014. Canola crops are threatened by a variety of fungal pathogens, including Leptosphaeria maculans (L. maculans), the causal agent of blackleg disease. Increased canola production in western Canada, in large measure through more frequent cropping in the rotation, has increased the risk that erosion of genetic resistance to blackleg in current varieties is increasing. While genetic resistance has been used to mitigate the disease using traditional breeding strategies, there is little knowledge about the genes facilitating blackleg resistance. Annual losses to crops are in the billions of dollars globally, thus the development of novel and durable technologies that protect the worlds food systems is of critical and immediate importance.

Deployment of genetic resistance in canola varieties against L. maculans has been a successful control strategy in Canada and in other canola or oilseed rape growing regions of the world. However, there are numerous reports of crop losses due to resistance failure. Races of L. maculans can be used to identify specific resistance genes in varieties or breeding material of B. napus and other Brassica spp. Knowledge of host resistance genes and pathogen avirulence genes is beneficial to the development of novel blackleg disease resistant cultivars.

Technology Overview

Researchers at the University of Manitoba have identified unique resistance genes to the fungal pathogen Leptosphaeria maculans, the causal agent of blackleg disease in Brassica napus. To identify defense genes, high throughput next generation RNA was used to examine the transcriptome of a universally susceptible (cv. Westar) and commercially available resistant line carrying LepR1. The cotyledons were treated with water or virulent strains of L. maculans and sequenced using the Illumina Hi-seq 2500 platform.

Sequencing resulted in >475 million high quality sequence reads. Differential gene expression was performed using Cuffdiff, and a dense list of 54 core defense genes that may contribute to host resistance were identified.

To identify these genes further, Arabidopsis mutants containing a T-DNA insertion that disrupts gene activity were screen for defense response against L. maculans or the ability to form a lesion on the leaf surface. This analysis identified several highly susceptible mutants, in which L. maculans asexual reproduction (pycnidia formation) is clearly visible. These data establish the genes as helpful for defense against L. maculans in Arabidopsis. Four of these have been expressed in B. napus and increase the resistance of the plant to the fungal pathogen. Researchers except that the increased expression of one or more of the other 50 genes in B. napus plants susceptible to infection by L. maculans and will increase the resistance of the plant to L. maculans.

Technical Description

The hemibiotrophic fungal pathogen Leptosphaeria maculans is the causal agent of blackleg disease in Brassica napus (canola, oilseed rape) and causes significant yield loss worldwide. While genetic resistance has been used to mitigate the disease using traditional breeding strategies, there is little knowledge about the genes facilitating blackleg resistance. RNA sequencing and a streamlined bioinformatics pipeline identified unique genes and plant defense pathways specific to plant resistance in the B. napus-L. maculans LepR1-AvrLepR1 interaction. Data reveal accelerated activation of the plant transcriptome in resistant host tissues associated with genes coding for extracellular receptors and phytohormone signaling molecules. Functional characterization of Arabidopsis mutants infected with L. maculans provides direct functional support for transcriptome data and identifies novel resistance regulators in the Brassicaceae. Spatial gradients of gene activity were identified in response to L. maculans proximal to the site of infection using a combination of laser microdissection and directed qPCR. Together, this dataset provides unprecedented spatial and temporal resolution of the plant defense response to L. maculans and serves as a valuable resource to those interested in host pathogen interactions. Identification of novel plant resistance genes to fungal pathogens is a priority for plant researchers and addresses global food security challenges.

Stage of Development

Technology Readiness Level (TRL): 4

Benefits

More intensive production of canola through market opportunities and cultivar improvement has lead to increased fungal pressure in the field resulting in sever blackleg epidemics and significant yield loss. An estimated average yield loss of <10% with maximum losses of 30%–50% have been documented as a result of blackleg development in oilseed rape crops. Thus, the development of novel and durable resistant cultivars can mitigate crop losses due to blackleg disease. This technology provides a proactive approach to develop novel cultivars resistant to blackleg to further prevent a more widespread re-emergence of blackleg.

Applications

Resistance of a member of the genus Brassica to infection by Leptosphaeria maculans
Methods of making a transgenic plant with increased resistance to Leptosphaeria maculans

Opportunity

The University of Manitoba is actively seeking a licensee to elicense the patent to move this technology to the market.

Increased Resistance of Canola to L. maculan's and Method of Use

Patents

IP Status

Seeking