Fenhexamid Resistance in the Botrytis Species Complex, Responsible for Grey Mould Disease

International audience1.1 Chemical control of grey mould in French vineyardsThe three major fungal pests of grapevine, powdery and downy mildew and grey mould aremostly controlled through the application of fungicides. Some of those are particularlyactive against the grey mould agent Botrytis cinerea. The panel of fungicides authorized inFrance comprise since many years anilinopyrimidines, benzimidazoles, dithiocarbamates,dicarboximides, phenylpyrroles and pyridinamines. Lately, the panel has been completedby fenhexamid, a sterol biosynthesis inhibitor (SBI) and the pyridine boscalid, a succinatedehydrogenase inhibitor (SDHI). In addition, a biofungicide based on the Bacillus subtilisstrain QST 713 (Serenade) has been authorized in 2010 against grey mould in vineyards. Thecompounds authorized against grey mould in French vineyards are listed in Table 1.Since grey mould may infect grapevine from flowering until harvest, optimal protectionneeds to be obtained during this period. Nowadays up to three treatments per season arerecommended in vineyards, corresponding to the stages A-C (A: flower cap falling – B:bunch closure – C: veraison). To reduce pesticide applications along with the general trendof reduction of chemical inputs in agriculture chemical treatments against grey mould arepositioned according to epidemiological and meteorological parameters. Grey mould notonly affects quantity of harvest but also the wine quality. Therefore, treatments also dependon the economic value of the wine. The number of treatments is variable between regionsand years according to the factors cited above.In those regions with regular applications of anti-Botrytis fungicides, especially in theNorthern regions, resistant strains have been selected which can ultimately lead totreatment failure. In order to reduce the risk of specific resistance development each antiBotrytis mode-of-action is limited to one application/season in France since the 90’s,involving alternations of different chemical families to combat grey mould in the vineyards

SiOx/SiNy multilayers for photovoltaic and photonic applications

Microstructural, electrical, and optical properties of undoped and Nd3+-doped SiOx/SiNy multilayers fabricated by reactive radio frequency magnetron co-sputtering have been investigated with regard to thermal treatment. This letter demonstrates the advantages of using SiNy as the alternating sublayer instead of SiO2. A high density of silicon nanoclusters of the order 1019 nc/cm3 is achieved in the SiOx sublayers. Enhanced conductivity, emission, and absorption are attained at low thermal budget, which are promising for photovoltaic applications. Furthermore, the enhancement of Nd3+ emission in these multilayers in comparison with the SiOx/SiO2 counterparts offers promising future photonic applications

Phylogenetic Distribution of Fungal Sterols

BACKGROUND: Ergosterol has been considered the "fungal sterol" for almost 125 years; however, additional sterol data superimposed on a recent molecular phylogeny of kingdom Fungi reveals a different and more complex situation. METHODOLOGY/PRINCIPAL FINDINGS: The interpretation of sterol distribution data in a modern phylogenetic context indicates that there is a clear trend from cholesterol and other Delta(5) sterols in the earliest diverging fungal species to ergosterol in later diverging fungi. There are, however, deviations from this pattern in certain clades. Sterols of the diverse zoosporic and zygosporic forms exhibit structural diversity with cholesterol and 24-ethyl -Delta(5) sterols in zoosporic taxa, and 24-methyl sterols in zygosporic fungi. For example, each of the three monophyletic lineages of zygosporic fungi has distinctive major sterols, ergosterol in Mucorales, 22-dihydroergosterol in Dimargaritales, Harpellales, and Kickxellales (DHK clade), and 24-methyl cholesterol in Entomophthorales. Other departures from ergosterol as the dominant sterol include: 24-ethyl cholesterol in Glomeromycota, 24-ethyl cholest-7-enol and 24-ethyl-cholesta-7,24(28)-dienol in rust fungi, brassicasterol in Taphrinales and hypogeous pezizalean species, and cholesterol in Pneumocystis. CONCLUSIONS/SIGNIFICANCE: Five dominant end products of sterol biosynthesis (cholesterol, ergosterol, 24-methyl cholesterol, 24-ethyl cholesterol, brassicasterol), and intermediates in the formation of 24-ethyl cholesterol, are major sterols in 175 species of Fungi. Although most fungi in the most speciose clades have ergosterol as a major sterol, sterols are more varied than currently understood, and their distribution supports certain clades of Fungi in current fungal phylogenies. In addition to the intellectual importance of understanding evolution of sterol synthesis in fungi, there is practical importance because certain antifungal drugs (e.g., azoles) target reactions in the synthesis of ergosterol. These findings also invalidate use of ergosterol as an indicator of biomass of certain fungal taxa (e.g., Glomeromycota). Data from this study are available from the Assembling the Fungal Tree of Life (AFTOL) Structural and Biochemical Database: http://aftol.umn.edu

Glutaredoxin regulation of primary root growth is associated with early drought stress tolerance in pearl millet

Seedling root traits impact plant establishment under challenging environments. Pearl millet is one of the most heat and drought tolerant cereal crops that provides a vital food source across the sub-Saharan Sahel region. Pearl millet’s early root system features a single fast-growing primary root which we hypothesize is an adaptation to the Sahelian climate. Using crop modeling, we demonstrate that early drought stress is an important constraint in agrosystems in the Sahel where pearl millet was domesticated. Furthermore, we show that increased pearl millet primary root growth is correlated with increased early water stress tolerance in field conditions. Genetics including genome-wide association study and quantitative trait loci (QTL) approaches identify genomic regions controlling this key root trait. Combining gene expression data, re-sequencing and re-annotation of one of these genomic regions identified a glutaredoxin-encoding gene PgGRXC9 as the candidate stress resilience root growth regulator. Functional characterization of its closest Arabidopsis homolog AtROXY19 revealed a novel role for this glutaredoxin (GRX) gene clade in regulating cell elongation. In summary, our study suggests a conserved function for GRX genes in conferring root cell elongation and enhancing resilience of pearl millet to its Sahelian environment