Anastomosis and Heterokaryon Formation

Signal exchange and integration during self-fusion in filamentous fungi

“…Analysis of the subcellular dynamics of two proteins essential for germling/hyphal fusion in N. crassa resulted in a working model termed "ping pong signaling" or "cell dialog", which offers a solution for this conundrum [10][11][12]. The mitogen-activated protein kinase MAK-2 and the SO protein alternately concentrate at the growing cell tips of interacting conidial germlings.…”

“…Similar to germling fusion, the biological role of this prevalent growth feature is only insufficiently understood. The ability to fuse is not essential since numerous fusion-deficient by viable mutants of various fungal species have been isolated [6,12]. It has long been proposed that hyphal anastomoses allow for an efficient and even distribution of water, nutrients, signaling compounds and general cellular constituents throughout the mycelium, thereby enabling growth and development in heterogeneous habitats [23,24].…”

“…However, these factors adopt unusual subcellular dynamics and are wired with other conserved and fungal-unique constituents into an intricate signaling network. Complete overviews of the involved genes and proteins have recently been provided elsewhere [6,12]. In this article, we strive to describe the main signaling hubs and their interactions within this network and to illustrate the current "cell dialog" working model.…”

Two genomes are better than one: history, genetics, and biotechnological applications of fungal heterokaryons

“…Studies of hyphal fusion in N. crassa have primarily involved conidial anastomosis tubes (CATs), structures that arise from germinating spores or germ tubes and fuse with each other. Several genes and proteins involved in CAT induction, chemotropism, and fusion have been identified [ 3 , 59 ]. A particularly interesting aspect of CAT chemotropism is the oscillatory recruitment of proteins to the tips of plasma membranes of homing tubes.…”

“…Heterokaryosis also occurs during vegetative growth as a component of the parasexual cycle, a mechanism for increasing genotypic diversity in predominantly asexual fungi (Fig. 1 ) [ 3 ]. In this paper, the term “predominantly asexual” is used to refer to fungi that historically were not known to have a sexual cycle and those that only rarely undergo sexual recombination.…”