What Determines Growth Direction in Fungal Hyphae?

Riquelme, Meritxell; Reynaga-Peña, Cristina G.; Gierz, Gerhard; Bartnicki-García, S.

doi:10.1006/fgbi.1998.1074

Cited by 182 publications

(146 citation statements)

References 33 publications

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“…Previously, based on comparative results with benomyl and cytochalasin, we proposed that the microtubule cytoskeleton was directly involved in maintaining the trajectory of the Spk (Riquelme et al, 1998). Our present observations with the dynein-deficient ropy mutants lend support to the notion that the microtubule cytoskeleton plays a major role in the formation and behaviour of the Spk.…”

Section: Spk Behaviour and Morphogenesissupporting

confidence: 86%

“…For highresolution work, the fungus was grown on a modified slide culture chamber (Lo! pez-Franco, 1992 ;Riquelme et al, 1998) and observed with a phase-contrast 100i oil-immersion objective (n.a. 1n25) and a 25i WF eyepiece (American Optical).…”

Section: Methodsmentioning

confidence: 99%

“…There is mounting evidence that the position of the Spk governs the growth direction of a hypha (Girbardt, 1957 ;Bracker et al, 1997 ;Riquelme et al, 1998). Our previous work with microtubule inhibitors implicated the microtubular cytoskeleton in the positioning and movement of the Spk in hyphae of N. crassa (Riquelme et al, 1998), but its exact role in apical growth has yet to be elucidated.…”

Section: Introductionmentioning

confidence: 98%

“…Our previous work with microtubule inhibitors implicated the microtubular cytoskeleton in the positioning and movement of the Spk in hyphae of N. crassa (Riquelme et al, 1998), but its exact role in apical growth has yet to be elucidated. It has long been proposed that cytoplasmic microtubules participate in the transport of secretory vesicles to the hyphal apex (Howard & Aist, 1977, 1980Howard, 1981 ;Gooday, 1983 ;Gow, 1989 ;Hasek & Bartnicki-Garcı!…”

Section: Introductionmentioning

confidence: 99%

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Dynein and dynactin deficiencies affect the formation and function of the Spitzenkörper and distort hyphal morphogenesis of Neurospora crassa

2000

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The impact of mutations affecting microtubule-associated motor proteins on the morphology and cytology of hyphae of Neurospora crassa was studied. Two ropy mutants, ro-1 and ro-3, deficient in dynein and dynactin, respectively, were examined by video-enhanced phase-contrast microscopy and image analysis. In contrast to the regular, hyphoid morphology of wildtype hyphae, the hyphae of the ropy mutants exhibited a great variety of distorted, non-hyphoid morphologies. The ropy hyphae were slow-growing and manifested frequent loss of growth directionality. Cytoplasmic appearance, including organelle distribution and movement, were ostensibly different in the ropy hyphae. The Spitzenko $ rper (Spk) of wild-type hyphae was readily seen by phase-contrast optics ; the Spk of both ro-1 and ro-3 was less prominent and sometimes undetectable. Only the fast-growing ropy hyphae displayed a Spk, and it was smaller and less phase-dark than the wild-type Spk. Growth rate in both wild-type and ropy mutants was directly correlated with the size of the Spk. Spk efficiency, measured in terms of cell area generated per Spk travelled distance, was lower in ropy mutants. Another salient difference between ropy mutants and wild-type hyphae was in Spk trajectory. Whereas the Spk of wild-type hyphae maintained a trajectory close to the cell growth axis, the Spk of ropy hyphae moved much more erratically. Sustained departures in the trajectory of the ropy Spk produced corresponding distortions in hyphal morphology. A causal correlation between Spk trajectory and cell shape was tested with the Fungus Simulator program. The characteristic morphologies of wild-type or ropy hyphae were reproduced by the Fungus Simulator, whose vesicle supply centre (VSC) was programmed to follow the corresponding Spk trajectories. This is evidence that the Spk controls hyphal morphology by operating as a VSC. These findings on dynein or dynactin deficiency support the notion that the microtubular cytoskeleton plays a major role in the formation and positioning of the Spk, with dramatic consequences on hyphal growth and morphogenesis.

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Section: Spk Behaviour and Morphogenesissupporting

confidence: 86%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Dynein and dynactin deficiencies affect the formation and function of the Spitzenkörper and distort hyphal morphogenesis of Neurospora crassa

2000

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“…The conidial morphology was similar to that of the wild-type A8 (Figure 4). Normal filamentous fungi grow by the delivery of the components for cell wall extension to the hyphal tips (Girbardt 1957; Riquelme et al 1998). Hyphal branching is generated when the biosynthetic capacity or volume of the cytoplasm in a hyphal tip has reached its maximum (Yarden et al 1992).…”

Section: Resultsmentioning

confidence: 99%

Qipgene inFusarium oxysporumis required for normal hyphae morphology and virulence

et al. 2015

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Ribonucleic acid (RNA)-silencing mechanisms exist in many eukaryotes to regulate a variety of biological processes. The known molecular components are related to Dicers, Argonautes and RNA-dependent RNA polymerases. Previous biochemical studies have also suggested that Qip, with an exonuclease domain, facilitates the conversion of duplex small interfering RNAs into single strands. In our study, the Qip gene in Fusarium oxysporum was disrupted using homologous recombination technology. The deletion of the Qip gene resulted in a decrease in colony growth rates but increased the number of branches. Additionally, the ΔQip mutant had a reduced pathogenicity in cabbage. Our results show Qip gene in F. oxysporum is required for normal hyphae morphology and virulence. The mutant will be useful for elucidating the relationship between the RNA-silencing mechanism and hyphal growth and development in F. oxysporum.

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The emerging role of septins in fungal pathogenesis

2023

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Fungal pathogens undergo specific morphogenetic transitions in order to breach the outer surfaces of plants and invade the underlying host tissue. The ability to change cell shape and switch between non‐polarised and polarised growth habits is therefore critical to the lifestyle of plant pathogens. Infection‐related development involves remodelling of the cytoskeleton, plasma membrane and cell wall at specific points during fungal pathogenesis. Septin GTPases are components of the cytoskeleton that play pivotal roles in actin remodelling, micron‐scale plasma membrane curvature sensing and cell polarity. Septin assemblages, such as rings, collars and gauzes, are known to have important roles in cell shape changes and are implicated in formation of specialised infection structures to enter plant cells. Here, we review and compare the reported functions of septins of plant pathogenic fungi, with a special focus on invasive growth. Finally, we discuss septins as potential targets for broad‐spectrum antifungal plant protection strategies.

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What Determines Growth Direction in Fungal Hyphae?

Cited by 182 publications

References 33 publications

Dynein and dynactin deficiencies affect the formation and function of the Spitzenkörper and distort hyphal morphogenesis of Neurospora crassa

Dynein and dynactin deficiencies affect the formation and function of the Spitzenkörper and distort hyphal morphogenesis of Neurospora crassa

Qipgene inFusarium oxysporumis required for normal hyphae morphology and virulence

The emerging role of septins in fungal pathogenesis

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