her phytoalexins (Nicholson and Hammerschmidt, 1992; Hammerschmidt, 1999). Moreover, quite a few on the O-methylflavonoids detectedin fungus-elicited maize, for example genkwanin or 7-O-methylscutellarein (Figure 1; Supplemental Table S8), have previously been shown to possess antimicrobial activity (Martini et al., 2004; Balmer et al., 2013; Zhanzhaxina et al., 2020), suggesting that the maize flavonoid blend contributes to plant defense against pathogens. Interestingly, xilonenin, by far the most prominent FOMT item within the investigated maize lines (Figure 1; Supplemental Table S8), and also other abundant O-methylated and non-O-methylated flavonoids exhibited contrasting effects on the development of unique maize pathogenic fungi in our experiments. Even though xilonenin had substantial antifungal activity against two Fusarium species but didn’t inhibit the growth of B. maydis and R. microsporus, genkwanin affected the development of R. microsporus and F. verticillioides but not F. graminearum and B. maydis (Figure 7). This HSP90 Antagonist Compound suggests that the complex flavonoid blend comprising additional than 35 distinct compounds may possibly provide a defense barrier against a multitude of diverse maize pathogens. In addition, additive and synergistic effects could mediate or perhaps boost the activity of single blend elements. Nonetheless, the mixed antifungal properties observed in our bioassays may well also indicate that the maize pathogen defense response relies on a number of CB2 Modulator medchemexpress biochemical layers. For example, flavonoids may not be the predominant antifungal compounds, but might induce signaling pathways that trigger the formation of other antifungal defenses by, as an example, acting as scavengers for reactive oxygen species (Zhang et al., 2015). Alternatively, some maize pathogens might have adapted to the toxic arsenal of their host plant by detoxifying their phytoalexins as will be the case for other plant pathogens (Pedras and Ahiahonu, 2005), and this may possibly clarify the mixed antifungal effects seen in our bioassays. Recently, two rice pathogenic fungi have already been reported to detoxify and tolerate 7-methoxynaringenin (sakuranetin) by hydroxylation, O-demethylation or glycosylation (Katsumata et al., 2017, 2018). Maize might still respond to fungal attack using the accumulation of flavonoid phytoalexins even if they are not effective since we demonstrated that flavonoid induction happens in response to a broad range of necrotrophic and hemibiotrophic pathogens (Figure 5B). Maize has been previously reported to biosynthesize complicated mixtures of other pathogen-induced defense compounds which includes BXs, sesquiterpenoids, and diterpenoids (Oikawa et al., 2004; Rostas, 2007; Ahmad et al., 2011; Huffaker et al., 2011; Mafu et al., 2018; Ding et al., 2019, 2020). These substances have already been demonstrated to minimize fungal illnesses in experiments with defined biosynthetic mutants on the BX, kauralexin, and zealexin pathways (Ahmad et al., 2011; Ding et al., 2019, 2020). Right here we highlight the role of another class of fungal-induced metabolites, the O-methylflavonoids, in innate immune responses that probably contribute to pathogen resistance in maize. Further investigation is essential to know if these various groups of phytoalexins have separate or joint roles in maize defense.Formation of O-methylflavonoids in maizePLANT PHYSIOLOGY 2022: 188; 167|Components and methodsPlants and development conditionsSeeds of maize (Z. mays) inbred line W22 (NSL 30053), B73 (PI 550473), B75 (PI 608774), and Nested association mapping (NAM;
