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Azospirillum brasilense Sp7 x Gibberella zeae interactions in early growth stages of high carotenoid corn

Sarah Boyd Lade: University of Lleida

<div>High-carotenoid (HC) corn has clear benefits for human health. It is rich in pro-vitamin A and other nutritionally important carotenoids and represents a cost-effective intervention particularly in developing countries. In addition to safety and efficacy studies, HC must be tested to determine fitness to interact with a diverse array of environmental stresses pests, and pathogens. <i>Gibberella zeae</i> (anamorph <i>Fusarium graminearum</i>) (GZ) has devastating effects on corn when infection takes place early in the plant's lifecycle. Priming seeds with plant growth-promoting rhizobacteria (PGPR) can promote seedling survival and reduce posterior detrimental effects of this pathogen. The aims of this study were to compare HC with its near isogenic white corn inbred line (M37W), and to test how the PGPR <i>Azospirillum brasilense </i>Sp7 (Sp7) interacts with HC to offset symptoms caused by GZ. HC seedlings were co-inoculated with Sp7 and GZ and grown under controlled conditions. Four weeks after planting, the seedlings were tested for disease severity, moisture accumulation, ferric reducing antioxidant power (FRAP), total phenolic content (TPC), and hormone assemblage of the plant immune system. Co-inoculation decreased disease severity in HC, and increased both FRAP and TPC. Results showed that co-inoculation has a synergistic effect with HC, promoting seedling survival and a non-antagonistic relationship between significantly increased (p<0.05) levels of jasmonic and salicylic acids.</div>