Abstract
BackgroundGibberella ear rot (GER) is one of the most economically important fungal diseases of maize in the temperate zone due to moldy grain contaminated with health threatening mycotoxins. To develop resistant genotypes and control the disease, understanding the host-pathogen interaction is essential.ResultsRNA-Seq-derived transcriptome profiles of fungal- and mock-inoculated developing kernel tissues of two maize inbred lines were used to identify differentially expressed transcripts and propose candidate genes mapping within GER resistance quantitative trait loci (QTL). A total of 1255 transcripts were significantly (P ≤ 0.05) up regulated due to fungal infection in both susceptible and resistant inbreds. A greater number of transcripts were up regulated in the former (1174) than the latter (497) and increased as the infection progressed from 1 to 2 days after inoculation. Focusing on differentially expressed genes located within QTL regions for GER resistance, we identified 81 genes involved in membrane transport, hormone regulation, cell wall modification, cell detoxification, and biosynthesis of pathogenesis related proteins and phytoalexins as candidate genes contributing to resistance. Applying droplet digital PCR, we validated the expression profiles of a subset of these candidate genes from QTL regions contributed by the resistant inbred on chromosomes 1, 2 and 9.ConclusionBy screening global gene expression profiles for differentially expressed genes mapping within resistance QTL regions, we have identified candidate genes for gibberella ear rot resistance on several maize chromosomes which could potentially lead to a better understanding of Fusarium resistance mechanisms.
Highlights
Gibberella ear rot (GER) is one of the most economically important fungal diseases of maize in the temperate zone due to moldy grain contaminated with health threatening mycotoxins
The reference genome B73 version 2 was used for read alignment and transcripts per million (TPM) was used for estimation of gene expression levels [21]
The current study characterized the plant response to Gibberella ear rot disease in maize using gene expression profiling of two inbred lines with contrasting levels of resistance and identified fungal responsive genes mapping within chromosomal regions associated with GER resistance. This information helped us to identify candidate genes that are possibly relevant in the defense response to help understand GER resistance mechanisms
Summary
Gibberella ear rot (GER) is one of the most economically important fungal diseases of maize in the temperate zone due to moldy grain contaminated with health threatening mycotoxins. To develop resistant genotypes and control the disease, understanding the host-pathogen interaction is essential. Gibberella ear rot (GER) is a fungal disease of maize ears caused by Fusarium graminearum. The pathogen causes stalk and root rot of maize and has a wide range of other cereal crop hosts such as wheat, barley, rice, and oats, Development of GER resistant genotypes is the most recommended method of disease control since the use Kebede et al BMC Genomics (2018) 19:131 of fungicides and cultural practices are less effective [1]. Breeding progress or selection gains had been slow due to the requirement of intensive field work and multi-environment testing
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