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However, asci in some genera or species can occur in numbers of one (e.g. Monosporascus cannonballus), two, four, or multiples of four. In a few cases, the ascospores can bud off conidia that may fill the asci (e.g. Tympanis ) with hundreds of conidia, or the ascospores may fragment, e.g. some Cordyceps , also filling the asci with smaller cells.
The species of Sordaria are similar morphologically, producing black perithecia containing asci with eight dark ascospores in a linear arrangement. These species share a number of characteristics that are advantageous for genetic studies. They all have a short life cycle, usually 7–12 days, and are easily grown in culture. Most species are ...
The cup of the apothecium is lined with asci, in which the ascospores are contained. When the ascospores are released from the asci, they are carried by the wind until they land on a suitable host. The ascospores of S. sclerotiorum infect aboveground plant host tissue [14] and begin to invade the host's tissues via mycelium, causing infection.
Naked asci: these occur in simple ascomycetes; asci are produced on the organism's surface. Perithecia: Asci are in flask-shaped ascoma (perithecium) with a pore (ostiole) at the top. Cleistothecia: The ascocarp (a cleistothecium) is spherical and closed. Apothecia: The asci are in a bowl shaped ascoma (apothecium). These are sometimes called ...
As an ascomycete, Ceratocystis coerulescens produces ascospores encased as groups of eight in asci. The asci are protected by a perithecium, a flask-shaped ascocarp, in which the pathogen overwinters. Ascospores are the sexual spores and are far less common than the asexual spores known as conidia.
The asci produce four ascospores each by sexual reproduction. Ascospores are forcibly released from the asci at the end of a rain event following a dry period and are splashed by water or carried by wind to host leaves and flower stems. [3] When the ascospores reach the host plant, the infection cycle begins.
The bitunicate asci are thick-walled, with an outer and inner layer. The outer and inner layer of the ascus wall are called exotunica and endotunica, and they separate during ascospore release. [6] The asci usually contains eight ascospores, while the shape and separation of the ascospores are more variating. [13]
An analysis of 939 asci in which the genotypes of all meiotic products (ascospores) could be determined found 11 asci with an exceptional segregation pattern. These included six asci in which there was one wild-type meiotic product but no expected reciprocal double-mutant (B5B3) product.