Indoor and Outdoor Disease Potential of Alternaria alternate
The genus Alternaria belongs to the phylum of Ascomycota, order Pleosporales, and family to the Pleosporaceae. These fungi include nearly 300 species, and mostly known as saprophytic or an opportunistic pathogen. The fungi have been reported to infect over 4000 host plants. Among the species, there remain overlapping morphological characteristics, and often it is not easy to differentiate the species microscopically. These pathogens usually appeared in anamorph, or asexual reproductive stage and the sexual reproduction is mostly known. Hyphae are septate and brown to black; conidiophores (17-40 x 3-3.9 µm) are simple or branched, brown and septate. Conidia are ovoid or obclavate, muriform, two to several celled, and pale brown, with an elongated beak-like apical cell, often in chains and or solitary. The dimension of conidia varies from 18-45 x 6.5-15.5 µm and beaks 2.5-35 x 7-7.5 µm. There are very few studies on the genetic structure and evolutionary trajectory of the pathogen populations in the agroecosystems. The spores (conidia) are usually produced on leaf lesions, and often colonize in plant wounds. Asexual spores are larger than other anemophilous pollen and fungal spores, but they are found in high quantities in the air. The spores can disperse through air currents and rainfall. However, they are also known to be an allergenic fungus. A recent study in Europe has shown that Alternaria sp and its aerial asexual spores (conidia) inhalation of patients escalated the allergy by 8.9%. And it has also been pronounced as a risk factor for the development, persistence, and severity of asthma. Therefore, it has become a potential health concern for allergic patients all over the world. Since the genus, includes large species (300), and they have overlapping morphological characteristics. Hence, it is necessary to detect and identify the indoor and outdoor Alternaria species that are particularly involved in allergenic or asthma reactions.