Сексуальные кресты и изоляции рекомбинантного потомства являются важным инструментом исследования для нитчатых грибов,<em> Fusarium graminearum</em> Методам необходимо успешно осуществлять эти процессы представлены.
Fusarium graminearum has become a model system for studies in development and pathogenicity of filamentous fungi. F. graminearum most easily produces fruiting bodies, called perithecia, on carrot agar. Perithecia contain numerous tissue types, produced at specific stages of perithecium development. These include (in order of appearance) formation of the perithecium initials (which give rise to the ascogenous hyphae), the outer wall, paraphyses (sterile mycelia which occupy the center of the perithecium until the asci develop), the asci, and the ascospores within the asci14. The development of each of these tissues is separated by approximately 24 hours and has been the basis of transcriptomic studies during sexual development12,8. Refer to Hallen et al. (2007) for a more thorough description of development, including photographs of each stage. Here, we present the methods for generating and harvesting synchronously developing lawns of perithecia for temporal studies of gene regulation, development, and physiological processes. Although these methods are written specifically to be used with F. graminearum, the techniques can be used for a variety of other fungi, provided that fruiting can be induced in culture and there is some synchrony to development. We have recently adapted this protocol to study the sexual development of F. verticillioides. Although individual perithecia must be hand picked in this species, because a lawn of developing perithecia could not be induced, the process worked well for studying development (Sikhakolli and Trail, unpublished).
The most important function of fungal fruiting bodies is the dispersal of spores. In many of the species of Ascomycota (ascus producing fungi), spores are shot from the ascus, due to the generation of turgor pressure within the ascus, driving ejection of spores (and epiplasmic fluid) through the pore in the ascus tip2,7. Our studies of forcible ascospore discharge have resulted in development of a “spore discharge assay”, which we use to screen for mutations in the process. Here we present the details of this assay.
F. graminearum is homothallic, and thus can form fruiting bodies in the absence of a compatible partner. The advantage of homothallism is that crossing is not necessary to generate offspring homozygous for a particular trait, a facet that has facilitated the study of sexual development in this species14,7. However, heterothallic strains have been generated that can be used for crossing5,9. It is also possible to cross homothallic strains to obtain mutants for several genes in one strain1. This is done by coinoculating one Petri dish with 2 strains. Along the meeting point, the majority of perithecia will be recombinant (provided a mutation in one of the parent strains does not inhibit outcrossing). As perithecia age, they exude ascospores en masse instead of forcibly discharging them. The resulting spore exudate (called a cirrhus) sits at the tip of the perithecium and can easily be removed for recovery of individual spores. Here we present a protocol to facilitate the identification of recombinant perithecia and the recovery of recombinant progeny.
Ф. graminearum особенно хорошо приспособлены к изучению плодоношения развитие тела в связи с наличием хорошо аннотированного генома ( mips.helmholtz-muenchen.de/genre/proj/FGDB / 4), а также наличие Affymetrix- основанный микрочипов 6. Это способствовало возможность идентифицировать гены, важные для аскоспор разряда 7,11,3. Методы, представленные здесь, позволяют исследователю сосредоточиться на дискретный набор этапов развития и функций для генетического анализа плодовых тел F. graminearum. Эти методы также легко адаптируется к связанным грибов, которые могут быть вызваны на фрукты в культуре, и может быть использован в качестве стандарта для развития целого ряда других грибковых типов тела плодоношения.
Способность оценивать фенотип стрельбы спор может быть тонким в вид, где споры малого и трудно понять, например, <eм> F. graminearum. Коллекция спор на чистую слайд облегчает и визуальной оценки и количественная оценка, так как споры могут быть смыты слайдов и количественно. Некоторые виды грибов производят слизь, которая окружает их споры и споры не могут быть смывается, но должны учитываться микроскопически они остаются на слайде. Мы нашли, что это верно Sclerotinia sclerotiorum.
The authors have nothing to disclose.
Эта работа была поддержана грантом от Национального научного фонда (MCB-0923794 для FT).
Name of the reagent | Company | Catalogue number |
Fusarium graminearum strain PH-1 | Fungal Genetics Stock Center, Kansas | FGSC 9075 |
Tween 60 | Sigma-Aldrich | P1629 |
Czapek’s Dox Agar | Difco, Becton Dickinson | 233810 |
Potassium Chlorate | Sigma-Aldrich | 255572 |