Sclerotial Morphogenesis in Fungi

None or very few sclerotia of Rhizoctonia solani (AG-1, IA) were formed on Hopkins agar medium without KH2PO4, though hyphae developed in some extent. While, the number and weight of sclerotia were decreased when MgSO4 was absent. As KH2PO4 in the basal medium was replaced with other phosphates different in cation, sclerotia were well formed. The optimal concentration of phosphate as KH2PO4 for the sclerotium formation, in number and weight, and hyphal development was in the region of 100ppm.The addition of magnesium resulted in the increase of the number and weight of sclerotia proportionally with the amount of the magnesium compound.The results indicate that phosphorus ion is indispensable to the sclerotium formation, whereas magnesium ion is promotive.The absence of phosphorus at the maturing stage resulted in the formation of few sclerotia, even though phosphorus was presented at the hyphal and initial phases. While defficiency of phosphorus in the early stage of sclerotium development showed no effect on the number and weight of sclerotia formed, if the phosphorus was supplied in subsequent periods. The branching internodes of hyphae grown on the phosphorus free medium were longer than those of on the medium containing phosphorus. This decrease of the hyphal branching will lead to the decrease of interweaving hyphae and will result in the scarce sclerotium formation.A large accumulation of 32P to sclerotia was strikingly observed in this experiment.

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“…The sclerotium morphogenesis of fungi was affected by nutrients and physical factors1, 2,5,6,[8][9][10]14,16,18,[20][21][22][23][24][25] …”

Section: Discussionmentioning

confidence: 99%

“…It is well known that fungal sclerotium production is affected by various physical and chemical factors2, 5,9,10,14,15,17,18,25).…”

Section: Introductionmentioning

confidence: 99%

The Effects of Phosphorus and Magnesium on Sclerotium Formation in Rhizoctonia solani Kuehn.

Moromizato

Ishizaki²,

Takara

et al. 1991

Jpn. J. Phytopathol.

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“…It is expressed by four main types of sclerotia (compact bodies of aggregated hyphae), which are loose, terminal, lateral-chained and lateral-simple. These types are represented mainly, but not solely, by Rhizoctonia solani, Sclerotinia sclerotiorum, Sclerotium rolfsii and Sclerotinia minor, respectively (Chet et al, 1967(Chet et al, , 1969Chet & Henis, 1975;Le Tourneau, 1979;Willetts, 1971Willetts, , 1978Willetts, , 1997Willetts & Wong, 1980). These fungi are of great agricultural interest because they cause stem-rot diseases in a wide variety of economically important agricultural crops.…”

Section: Introductionmentioning

confidence: 99%

Superoxide radical induces sclerotial differentiation in filamentous phytopathogenic fungi: a superoxide dismutase mimetics study

Papapostolou

Georgiou

2010

Microbiology

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This study shows that the superoxide radical (O 2˙" ), a direct indicator of oxidative stress, is involved in the differentiation of the phytopathogenic filamentous fungi Rhizoctonia solani, Sclerotinia sclerotiorum, Sclerotium rolfsii and Sclerotinia minor, shown by using superoxide dismutase (SOD) mimetics to decrease their sclerotial differentiation. The production rate of O 2˙" and SOD levels in these fungi, as expected, were significantly lowered by the SOD mimetics, with concomitant decrease of the indirect indicator of oxidative stress, lipid peroxidation. INTRODUCTIONSclerotial differentiation is a primitive form of differentiation exhibited by certain phytopathogenic filamentous fungi. It is expressed by four main types of sclerotia (compact bodies of aggregated hyphae), which are loose, terminal, lateral-chained and lateral-simple. These types are represented mainly, but not solely, by Rhizoctonia solani, Sclerotinia sclerotiorum, Sclerotium rolfsii and Sclerotinia minor, respectively (Chet et al., 1967(Chet et al., , 1969Chet & Henis, 1975;Le Tourneau, 1979;Willetts, 1971Willetts, , 1978Willetts, , 1997Willetts & Wong, 1980). These fungi are of great agricultural interest because they cause stem-rot diseases in a wide variety of economically important agricultural crops. Therefore, elucidating the mechanisms of sclerotium biogenesis of these fungi may lead to the development of non-toxic ways to combat plant diseases, which could be used as alternatives to the traditional toxic fungicides. Moreover, understanding sclerotial differentiation is very important because it will help to understand more complex forms of differentiation in other organisms as well as whether their mechanisms share common biochemical pathways.It has been proposed that sclerotial differentiation is related to high oxidative stress (Georgiou, 1997), based on the finding that sclerotium biogenesis in S. rolfsii was accompanied by the accumulation of high levels of lipid peroxidation products. This finding has been supported by other studies that developed into a theory of oxidative stress as an inducer of sclerotial metamorphosis (Georgiou et al., 2006). Specifically, hydroxyl radical scavengers, vitamin C and b-carotene (both also acting as endogenous fungal antioxidants), decreased sclerotial differentiation in S. rolfsii, S. minor, S. sclerotiorum and R. solani. In more recent studies, we demonstrated a strong relationship between the thiol redox state of these fungi and their sclerotial differentiation (Patsoukis & Georgiou, 2007a, b, 2008a. Specifically, in R. solani, S. rolfsii and S. minor, there was a decrease in the total amount of reduced thiols during transformation of the undifferentiated mycelium into sclerotium, which, for S. sclerotiorum was accompanied by an increase in the total oxidized components. Moreover, the antioxidant thiol redox state modulator N-acetylcysteine inhibited sclerotial differentiation in S. rolfsii, R. solani and S. sclerotiorum.Until now, our studies have associated only indirect indicators ...

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“…A recurrent argument is that generally sclerotia do not form in culture until mycelial growth has been restricted in some way. Despite the importance of this view in stimulating research, some of which has led to some contrary results (Chet & Henis, 1975), there seems to be nothing in the S . roljsii literature about the use of abrupt, brief lowtemperature treatment as a tool to study the connection of growth restriction to sclerotial formation.…”

Section: Introductionmentioning

confidence: 99%

“…in culture have been reviewed (Aycock, 1966;Chet & Henis, 1975 ;Willetts, 1978 ;Punja, 1985). A recurrent argument is that generally sclerotia do not form in culture until mycelial growth has been restricted in some way.…”

Section: Introductionmentioning

confidence: 99%

Induction of sclerotia in Sclerotium rolfsii by short low-temperature treatment

Rawn

1991

Journal of General Microbiology

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When grown on two agar media in Petri dishes a Sclerotium rovsii Sacc. isolate produced sclerotia in different patterns, predominantly at the colony centre on one medium (glucose/yeast extract) but at the dish wall on the other (glucose/ammonium nitrate). However, on both media a short cold treatment (3 h at 5 "C) of colonies grown at 24 "C temporarily interrupted growth and induced subsequent sclerotial formation in a ring where the colony margin was at the time of the cold shock. A second cold treatment 1 d after the first induced a sclerotial ring but negated the effect of the first treatment. The results support the view that interruption of hyphal growth triggers sclerotial formation.

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Sclerotial Morphogenesis in Fungi

Cited by 172 publications

References 4 publications

The Effects of Phosphorus and Magnesium on Sclerotium Formation in Rhizoctonia solani Kuehn.

The Effects of Phosphorus and Magnesium on Sclerotium Formation in Rhizoctonia solani Kuehn.

Superoxide radical induces sclerotial differentiation in filamentous phytopathogenic fungi: a superoxide dismutase mimetics study

Induction of sclerotia in Sclerotium rolfsii by short low-temperature treatment

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