Functional distinction of hyphal compartments

Abstract

Hyphae of higher fungi grow at their tips and are compartmentalized by porous septa that enable inter-compartmental cytoplasmic streaming. Woronin bodies discontinue cytoplasmic streaming by plugging the septal pores. Here, it was assessed whether apical compartments of Aspergillus niger sustain their own growth or whether their growth depends on subapical compartments. Hyphae of wildtype and the ΔhexA strain, lacking Woronin bodies, had a similar morphology and growth rate. A total of 58% and 17% of the hyphae continued growing, respectively, after dissecting the 2nd compartment. Extension rate of the apical compartments that continued growing was not affected, even when the carbon or nitrogen source was limiting. Thus, apical compartments are self-sustaining in growth. It was also shown that the first 8 subapical compartments of the wildtype, but not of the ΔhexA strain, function as a backup system for growth by forming new branches when their apical neighbouring compartment has been damaged. This backup system is pivotal in nature because of the life style of fungi to continuously explore their surrounding substrate that may prove hostile.

Seeking the Roles for Fungal Small-Secreted Proteins in Affecting Saprophytic Lifestyles

“…In spite of widespread cytoplasmic continuity present in many filamentous fungi, both environmental changes as well as inherent developmental factors can confer phenotypic heterogeneity along different sections of an integral colony (Tegelaar and Wösten, 2017;Op De Beeck et al, 2020;Tegelaar et al, 2020). Is it possible that SSPs are "self-effectors", which are involved in the regulation of the mentioned heterogeneity?…”

The PoV mycovirus affects extracellular enzyme expression and fruiting body yield in the oyster mushroom, Pleurotus ostreatus

“…These results indicate that colony radial extension in the virus-infected strain was delayed, partly due to the short and agglomerative hyphal branching, which was visible under a microscope, suggesting that PoV may have a decisive effect on organizing and/or regulating the apical elongation process. In several studies of the mechanism of hyphal growth in fungi, fungal hyphae continuously grow and elongate in a specific direction with the aid of lysis of the cell wall at the tip of the hypha 26 . The vesicles of the cell migrate towards the tip of the hypha, where they secrete various enzymes and other compounds during apical elongation.…”

Multiscale heterogeneity in filamentous microbes

“…This 409 was concluded from the finding that the growth rate in these compartments remains unaffected 410 when they are mechanically detached from the rest of the hypha. Interestingly, the first 411 subapical compartments (up to eight) function as a backup system for growth by forming new 412 branches upon damage of the apical compartment (Tegelaar and Wösten, 2017). This backup 413 system appears crucial in nature considering the fact that fungal colonies continuously explore 414 substrates that may locally be hostile for growth.…”