Summary Zymoseptoria tritici is a filamentous fungus causing Septoria tritici blotch in wheat. The pathogen has a narrow host range and infections of grasses other than susceptible wheat are blocked early after stomatal penetration. During these abortive infections, the fungus shows a markedly different gene expression pattern. However, the underlying mechanisms causing differential gene expression during host and non‐host interactions are largely unknown, but likely include transcriptional regulators responsible for the onset of an infection programme in compatible hosts. MoCOD1, a member of the fungal Zn(II)2Cys6 transcription factor family, has been shown to directly affect pathogenicity in the rice blast pathogen Magnaporthe oryzae. Here, we analyse the role of the putative transcription factor Zt107320, a homologue of MoCOD1, during infection of compatible and incompatible hosts by Z. tritici. We show for the first time that Zt107320 is differentially expressed in host versus non‐host infections and that lower expression corresponds to an incompatible infection of non‐hosts. Applying reverse genetics approaches, we further show that Zt107320 regulates the dimorphic switch as well as the growth rate of Z. tritici and affects fungal cell wall composition in vitro. Moreover, ∆Zt107320 mutants showed reduced virulence during compatible infections of wheat. We conclude that Zt107320 directly influences pathogen fitness and propose that Zt107320 is involved in the regulation of growth processes and pathogenicity during infection.

BACKGROUND Koshu, a hybrid of Vitis vinifera L. and V. davidii Foex, is the most popular indigenous cultivar for wine production in Japan. However, little is known about the potential aroma compounds it contains and how environmental factors affect these. In this study, we obtained comprehensive profiles of the volatile (both glycosidically bound and free) and phenolic compounds that occur in koshu berries, and compared these with similar profiles for V. vinifera cv. chardonnay. We then compared the response of these two cultivars to bunch shading and the ripening‐related phytohormone abscisic acid (ABA). RESULTS Koshu berries contained significantly higher concentrations of phenolic compounds, such as hydroxycinnamic acid derivatives, and some volatile phenols, such as 4‐vinyl guaiacol and eugenol, than chardonnay berries, which are thought to contribute to the characteristics of koshu wine. In addition, koshu berries had a distinctly different terpenoid composition from chardonnay berries. Shading reduced the concentration of norisoprenoid in both cultivars, as well as several phenolic compounds, particularly their volatile derivatives in koshu berries. The exogenous application of ABA induced ripening and increased the concentrations of lipid derivatives, such as hexanol, octanol, 1‐nonanol, and 1‐octen‐3‐ol. Multivariate and discriminant analyses showed that the potential aroma and flavor compounds in the berries could be discriminated clearly based on cultivar and environmental cues, such as light exposure. CONCLUSION The unique secondary metabolite profiles of koshu and their different responses to environmental factors could be valuable for developing various types of koshu wines and new cultivars with improved quality and cultural characteristics. © 2018 Society of Chemical Industry

Background Although grapes accumulate diverse groups of volatile compounds, their genetic regulation in different cultivars remains unelucidated. Therefore, this study investigated the volatile composition in the berries of an interspecific hybrid population from a Vitis labruscana ‘Campbell Early’ (CE) × Vitis vinifera ‘Muscat of Alexandria’ (MA) cross to understand the relationship among volatile compounds and their genetic regulation. Then, a quantitative trait locus (QTL) analysis of its volatile compounds was conducted. Results While MA contained higher concentrations of monoterpenes and norisoprenoids, CE contained higher concentrations of C6 compounds, lactones and shikimic acid derivatives, including volatiles characteristic to American hybrids, i.e., methyl anthranilate, o-aminoacetophenone and mesifurane. Furthermore, a cluster analysis of volatile profiles in the hybrid population discovered ten coordinately modulated free and bound volatile clusters. QTL analysis identified a major QTL on linkage group (LG) 5 in the MA map for 14 monoterpene concentrations, consistent with a previously reported locus. Additionally, several QTLs detected in the CE map affected the concentrations of specific monoterpenes, such as linalool, citronellol and 1,8-cineol, modifying the monoterpene composition in the berries. As for the concentrations of five norisoprenoids, a major common QTL on LG2 was discovered first in this study. Several QTLs with minor effects were also discovered in various volatile groups, such as lactones, alcohols and shikimic acid derivatives. Conclusions An overview of the profiles of aroma compounds and their underlying QTLs in a population of interspecific hybrid grapes in which muscat flavor compounds and many other aroma compounds were mixed variously were elucidated. Coordinate modulation of the volatile clusters in the hybrid population suggested an independent mechanism for controlling the volatiles of each group. Accordingly, specific QTLs with significant effects were observed for terpenoids, norisoprenoids and some volatiles highly contained in CE berries.

formation 19 20 Word count: 6136 21 22 Zt107320 directly influences pathogen fitness and propose that Zt107320 regulates growth processes 38 and pathogenicity during infection. Our results suggest that this putative transcription factor is 39 involved in discriminating compatible and non-compatible infections. 40 41 2018), which may contribute to the genomic variation observed for Z. tritici (Grandaubert et al. 2017; 55 Hartmann et al. 2017). Under experimental conditions, the fungus has a narrow host range infecting 56 wheat and shows abortive infections on closely related non-host grass species like Triticum 57 monococcum (Jing et al. 2008) and Brachypodium distachyon (Kellner et al. 2014; O'Driscoll et al. 58 2015). However, the underlying determinants of host specialisation and host specificity of Z. tritici 59 are largely unknown. 60 A previous study comparing the expression profiles of Z. tritici between early infection (4 days post 61 infection) of the compatible host T. aestivum and the non-host B. distachyon revealed a set of 289 62genes that were similarly expressed in the two hosts, but differentially expressed compared to 63 growth in axenic culture (Kellner et al. 2014). These genes are likely crucial for Z. tritici during 64 stomatal penetration that occurs in same way in both hosts. However, 40 genes showed differential 65 expression between host and non-host infections (Kellner et al. 2014) and are possibly involved in 66 the discrimination of compatible and non-compatible host-pathogen interactions. The signalling and 67 157