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The FTF (Fusarium Transcription Factor) gene family is composed of two members (FTF1 and FTF2) with high sequence homology. Both genes encode Zn(II)2Cys6 binuclear zinc finger transcription factors involved in the modulation of virulence in the F. oxysporum species complex (FOSC). While FTF1 is a multicopy gene exclusive of highly virulent strains of FOSC and is located in the accessory genome, FTF2 is a single copy gene, located in the core genome, and well conserved in all filamentous ascomycete fungi, except yeast. The involvement of FTF1 in the colonization of the vascular system and regulation of the expression of SIX effectors has been stablished. To address the role of FTF2 we generated and characterized null FTF2 mutants in a F. oxysporum f. sp. phaseoli weakly virulent strain and analyzed them together with the equivalent mutants formerly obtained in a highly virulent strain. The results obtained highlight a role for FTF2 as a negative regulator of the production of macroconidia and demonstrate that it is required for full virulence and positive regulation of SIX effectors. In addition, gene expression analyses provide compelling evidence that FTF2 is involved in the regulation of hydrophobins likely required for plant colonization.

Resumen del trabajo presentado a la 29th Fungal Genetics Conference, celebrada en Pacific Grove, California (US) del 14 al 19 de marzo de 2017., Nitric oxide (NO) is a highly reactive molecule with fundamental roles in the biology of all living systems. The participation of NO in developmental processes has been described in several fungal species. However, the nature of the mechanisms and factors being affected by NO in fungi is poorly characterized. Botrytis cinerea is a plant pathogenic fungus which has attracted much attention given its wide host range and its necrotrophic life style. The production of NO by the fungus has been demonstrated as well as its detoxification by means of a flavohemoglobin enzyme encoded by gene Bcfhg1. It has been suggested that the physiological functions of the flavohemoglobin could be related to its involvement in the modulation of endogenous NO levels produced by the fungus during specific developmental stages. Pharmacological studies in which germinating spores and mature mycelium were exposed either to NO donors or to NO scavengers indicate that NO affects germination. From the data obtained, in combination with the results derived from the analysis of the response of ΔBcfhg1 germinating spores to NO, it can be concluded that NO exerts and inmediate and transitoy effect on germination efficiency, on germ tube elongation and on nuclear division rate. Global expression analysis of ΔBcfhg1 in these conditions detected major changes in the expression pattern with about one third of the genes predicted in the B. cinerea genome responding to exposition to NO. Functional enrichment analysis allowed to identify links between exposition to NO, growth arrest and down-regulation of “DNA replication”, “nucleolus” and “cell cycle” genes., This work was supported by grants AGL2012-39876-C02-01 and AGL2015-66131-C2-1-R, from MINECO (Spain).

Plants and fungi use light and other signals to regulate development, growth, and metabolism. The fruiting bodies of the fungus Phycomyces blakesleeanus are single cells that react to environmental cues, including light, but the mechanisms are largely unknown [1]. The related fungus Mucor circinelloides is an opportunistic human pathogen that changes its mode of growth upon receipt of signals from the environment to facilitate pathogenesis [2]. Understanding how these organisms respond to environmental cues should provide insights into the mechanisms of sensory perception and signal transduction by a single eukaryotic cell, and their role in pathogenesis. We sequenced the genomes of P. blakesleeanus and M. circinelloides and show that they have been shaped by an extensive genome duplication or, most likely, a whole-genome duplication (WGD), which is rarely observed in fungi [3, 4, 5, 6]. We show that the genome duplication has expanded gene families, including those involved in signal transduction, and that duplicated genes have specialized, as evidenced by differences in their regulation by light. The transcriptional response to light varies with the developmental stage and is still observed in a photoreceptor mutant of P. blakesleeanus. A phototropic mutant of P. blakesleeanus with a heterozygous mutation in the photoreceptor gene madA demonstrates that photosensor dosage is important for the magnitude of signal transduction. We conclude that the genome duplication provided the means to improve signal transduction for enhanced perception of environmental signals. Our results will help to understand the role of genome dynamics in the evolution of sensory perception in eukaryotes. The work by the US Department of Energy Joint Genome Institute, a DOE Office of Science User Facility, is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The project was supported by European funds (European Regional Development Fund, ERDF), the Spanish Ministerio de Economía y Competitividad (BIO2005-25029-E, BIO2015-67148-R), and the Regional Government (Junta de Andalucía, P06-CVI-01650) to L.M.C.; Conacyt (Mexico) (FORDECYT-2012-02-193512) to A.H.-E.; the US National Science Foundation (MCB-0920581) to A.I.; and the Czech Science Foundation (13-33039S) to M.E.

Resumen del trabajo presentado en el 4th International Neotyphodium/Grass Interactions Symposium, celebrado en Soest (Alemania), del 27 al 29 de septiembre de 2000, Festuca rubra is a very common grass in natural grasslands known as dehesas in Westem Spain. In these ecosysterns, about 70% of the F. rubra plants are infected by the fungal endophyte Epichloe festucae. In E. festucae cultures obtained frorn F. rubra plants, two double-stranded RNA (dsRNA) elernents have been found. The major elernent has a size of 5 kbp, and it is encapsidated. This dsRNA elernent is tought to be the genorne of a virus of the farnily Totiviridae. We call this virus Epichloe festucae virus (EN). The other dsRNA element, (refered as M) has a size of 2.5 kbp, it is not encapsidated, and has no nucleotide sequence homology with EfV. The presence of these dsRNAs cause no obvious symptorns in their fungal hosts. Efv and M are persistent in their host, and both elernents have been rnaintained in an isolate through succesive passes in laboratory media for more than two years. AIso, both elements are efficiently transrnitted frorn rnicelium to conidia by the process of conidiogenesis. When the incidence of endophytes and viruses in a natural population of Festuca rubra was studied, it was found that 78% (n=32) of the plants analized were infected by Epichloe festucae. Most isolates of E. festucae (82%) were infected by dsRNA viruses. However, some isolates were infected by both EfV and M while others were infected only by M. This suggests that the M elernent is not dependent upon EfV for its replication, and it is an autonomous replicon. The high incidence of these viruses in a population may indicate that all plants are infected by the same fungal genotype, or that in this population there is physical contact between different fungal genotypes. The dsRNA/Epichloe association mirrors the F. rubra/Epichloe association. In both cases ínfected hosts occur at a high frequency in natural populations and they do not show obvious symptoms.

32 p.-3 fig., The molecular dialog between fungal pathogens and their plant hosts is governed by signals from the plant, secreted pathogen effectors and enzymes, and the plant immune system. There is an increasing awareness that nutritional factors are also central to fungal-plant interactions. Nutritional factors include carbon and nitrogen metabolism, local pH and redox state, and manipulation of host metabolism by secreted pathogen effectors. A diverse combination of approaches from genetics, biochemistry and fungal and plant cell biology addresses these questions, and a workshop whose abstracts accompany this note was held in 2018 to bring these together. Questions were asked about how the lifestyles and nutritional strategies of eukaryotic filamentous phytopathogens are related to the metabolic architectures and pathogenic processes affecting both plant hosts and their pathogens. The aim for future work will be to provide metabolism-based strategies for pathogen control., We thank the US-Israel Binational Agricultural Research and Development Fund (BARD) for funding the workshop (number W-104-17).