Identification and characterization of a new branching mutant of Neurospora intermedia from nature

Abstract

Neurospora has been studied extensively to understand various phenomenon of fungal growth and morphogenesis. Fungal morphogenesis is a complex process which includes important aspects like polarized extension of the hyphal tip and hyphal branching. Observations at the tip have shown that growth vesicles arrive at the tip from proximal locations, and then seem to be distributed into the tip dome by the spitzenkorper. No specific mechanism has been defined for branching. Several theories have been proposed for branching that can be broadly divided into two groups. One group supports the mechanism involving origin of branch initiation factors at the hyphal tips (Bachewich and Heath, 1997; Kaminskyj and Heath, 1996; Riquelme and Bartnicki-Garcia, 2004; Watters and Griffiths, 2001). Other group suggests that the signals for branch initiation originate from within the colony or mycelial body (Prosser and Trinci, 1979; Trinci, 1974; Watters, 2006). Watters et al., (2000) proposed that the branching initiation is not completely controlled by the tip but, to some extent by factors occurring at previous branch point. Trinci (1974) proposed that mutation or factor which reduces the maximum rate of tip extension without disturbing the rate of vesicle production would results in an increase in the frequency of branch initiation without reducing the overall rate of hypha formation. Recently it has been found that the fungal growth rate show relationship with the frequency of hyphal branching (Watters et al., 2008, 2011). In this paper we describe a naturally occurring mutant of N. intermedia which shows defect in branching and the inheritance of this defect in the progeny.