The role of genetic variation in Zea mays response to beneficial endophytes

Abstract

Growth-promoting endophytes have great potential to boost crop production and sustainability. There is, however, a lack of research on how differences in the plant host affect an endophyte’s ability to promote growth. We set out to quantify how different maize genotypes respond to specific growth-promoting endophytes. We inoculated genetically diverse maize lines with three different known beneficial endophytes: Herbaspirillum seropedicae (a Gram-negative bacteria), Burkholderia WP9 (a Gram-negative bacteria), and Serendipita vermifera Subsp. bescii (a Basidiomycota fungi). Maize seedlings were grown for 3 weeks under controlled watering and limited nutrient conditions in the greenhouse and assessed for various growth-promotion phenotypes. We found Herbaspirillum seropedicae to increase chlorophyll content (p = 0.02), plant height (p = 0.012), root length (p = 0.057), and root volume (p = 0.044) significantly in different maize genotypes, while Burkholderia WP9 did not promote growth in maize genotypes under these conditions. Serendipita bescii significantly increased plant height (p = 0.0041), root (p = 0.0004) and shoot biomass (p = 0.0046) for different maize genotypes, and shoot mass growth promotion correlated (r = 0.58, p = 1.97e−09) with measured fungal abundance. Although plant genetic variation by itself had a strong effect on phenotype, its interaction with the different endophytes was weak, and the endophytes rarely produced consistent effects across different genotypes. This genome-by-genome interaction indicates that the relationship between a plant host and beneficial endophytes is complex, and it may partly explain why many microbe-based growth stimulants fail to translate from laboratory settings to the field. Detangling these interactions will provide a ripe area for future studies to understand how to best harness beneficial endophytes for agriculture.