Transcriptomic Analysis of a Susceptible African Maize Line to <i>Fusarium verticillioides</i> Infection

• Main Authors: Humaira Lambarey, Naadirah Moola, Amy Veenstra, Shane Murray, Mohamed Suhail Rafudeen
• Format: Article
• Language: English
• Published: MDPI AG 2020-08-01
• Series: Plants
• Subjects: maize transcriptome; <i>Fusarium verticillioides</i>; phytoalexins; kauralexins
• Online Access: https://www.mdpi.com/2223-7747/9/9/1112

Maize (<i>Zea mays</i> L.) is a staple crop providing food security to millions of people in sub Saharan Africa. <i>Fusarium verticillioides</i>, an important fungal pathogen, infects maize causing ‘<i>Fusarium</i> Ear Rot’ disease, which decreases maize kernel yield and the quality of the crop harvested. Currently, no African maize line is completely resistant to infection by <i>F. verticillioides</i>. This study investigated an African maize line, <i>Zea mays</i> CML144, infected with <i>F. verticillioides</i>. Analysis of morphological characteristics showed significant differences between mock-infected and infected plants. RNA-sequencing (RNA-seq) was conducted on plants 14 days post-inoculation to identify differentially expressed genes (DEGs) involved in <i>F. verticillioides</i> infection. Analysis of RNA-seq data revealed DEGs that were both significantly up- and down-regulated in the infected samples compared to the mock-infected control. The maize <i>TPS1</i> and <i>cytochrome P450</i> genes were up-regulated, suggesting that kauralexins were involved in the CML144 defense response. This was substantiated by kauralexin analyses, which showed that kauralexins, belonging to class A and B, accumulated in infected maize tissue. Gene ontology terms relating to response to stimulus, chemical stimulus and carbohydrate metabolic processes were enriched, and the genes belonging to these GO-terms were down-regulated. Quantitative real-time PCR was performed on selected DEGs and measurement of phytoalexin accumulation validated the RNA-seq data and GO-analysis results. A comparison of DEGs from this study to DEGs found in <i>F. verticillioides</i> (ITEM 1744) infected susceptible (CO354) and resistant (CO441) maize genotypes in a previous study, matched 18 DEGs with 17 up-regulated and one down-regulated, respectively. This is the first transcriptomic study on the African maize line, CML144, in response to <i>F. verticillioides</i> infection.