Fungal Spores

Abstract Many heterotrophic eukaryotic organisms belong to the monophyletic kingdom Fungi. Because of their stationary life style, fungi reproduce by forming spores, cells that are specialised for dispersal to new locations by air, water or animals. Flagellated zoospores are produced by simple aquatic fungi. Most fungi are terrestrial, growing as hyphae and producing thick‐walled nonmotile spores. Asexual spores include sporangiospores and conidia, whereas sexual spores include zygospores, ascospores and basidiospores. Ascospores and basidiospores often are forcibly ejected into the air. Sporulation requires favourable nutritional and environmental conditions such as light and temperature, and involves cellular signalling and metabolic responses. As spores mature, their walls thicken, energy reserves such as lipid are acccumulated, and their metabolism decreases as they prepare for dormancy. Mature spores may undergo either exogenous or constitutive dormancy before germination. Upon germination, metabolic acitivity increases and a germ tube emerges from the spore. Key Concepts: Fungal spores have a unique role in fungal life cycles as they provide the genetic link between one generation and another. Spores can be part of asexual or sexual reproductive cycles, and are sometimes borne by multicellular sporocarps. Spores in part owe their success to their thick walls, reserve energy source, low metabolic rate and ability to withstand environmental stress that enables them to survive during dispersal. Some fungi coevolved with insects, establishing mutualistic symbiotic relationships, and depend upon them for spore dispersal. Sporulation occurs within a narrow range of special nutritional and environmental conditions, and involves signal transduction, gene activation and metabolic turnover. Sporulation and spore germination of some fungi are coordinated with light and temperature changes marking day and night cycles, the seasons or with life cycles of their hosts. Conditions required for germination reflect the particular biological adaptations and requirements of the fungus, and ensure that further somatic growth will be successful. Scientists should understand spore biology so that they may better control animal, plant and human diseases; to better utilise fungi for industrial purposes, or to utilise them more effectively in the laboratory.