Novel Trichomeristogenous Development of Pycnidium in Truncatella angustata BPF5 (Coelomycete)

Abstract

Morphogenesis of pycnidium of Truncatella angustata BPF5 has been studied under in vitro culture on l-arabinoze medium. A single stalked, lemon shaped and papillate initial cell seems to take part in the formation of pycnidium. The apical papilla of initial cell elongates so as to give the initial a central position flanked by hyphae. This single initial by successive divisions becomes an oval pycnidial primordium (trichomeristogenous). Further enlargement of pycnidium seems to take place due to mechanical force exerted by successive conidial formation. At maturity, the pycnidium is melanized. Some primordia abort leaving behind ghost pycnidia in the central disc. The minimal supplemented media like l-arabinoze medium reduce vegetative growth but induce early pycnidial formation thus requiring less teasing operations during microscopy. This in turn avoids damage of fragile young structures and facilitates study of developmental stages. This is the first report of early stages of pycnidial development under in vitro condition in any of the Coelomycetous fungus.