Selective Induction Infection Cushions by Rhizoctonia solani Relation to Host Responses

El-Samra, I. A.; El-Faham, Y. M.; Kamara, A. M.

doi:10.1111/j.1439-0434.1981.tb03371.x

Cited by 7 publications

(4 citation statements)

References 5 publications

(4 reference statements)

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“…Abundant literature suggests that infection cushion formation by R. solani is induced by host exudates (Dodman & Flentje, 1970;Marshall & Rush, 1980a;El-Samara et al, 1981), In our experiments we observed that more infection cushions were formed on collodion membranes placed over soybean leaves of susceptible than resistant cultivars. Only the isolates of AG-1 I A, IB, and IC formed infection cushions on collodion membranes placed over soybean leaves.…”

Section: Discussionsupporting

confidence: 53%

Factors affecting infection cushion development by Rhizoctonia solani AG‐1 IA and IB on soybean leaves

1994

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Infection cushions were formed by isolates of Rhizoctonia solani, anastomosis group 1 IA (AG-I I A, aerial blight) and AG-1 IB (web blight) on leaves ofall 10 soybean cullivars tested. Isolates of AG-1 IA and IB did not form infection cushions on soybean leaf surface replicas of either resistant or susceptible cultivars. More infection cushions were formed by isolates of AG-1 IA and IB on collodion membranes placed over leaves of susceptible cultivars compared with resistant cultivars. Isolates of AG-1 IC. AG-4 and AG-5, also formed infection cushions on soybean leaves. However, the isolates of other anastomosis groups did not form infection cushions on soybean leaves. Differential induction of infection cushion formation by the leaves of various plant species was observed, AG-1 IA formed infection cushions on more graminaceous hosts than AG-1 IB, Our results suggest that a chemical stimulus is needed for infection cushion formation. Glucose and 3-O-methylglucose repressed disease severity caused by AG-1 IA and IB isolates to the same extent. Disease severity and the number of infection c^shions formed on leaves of ten soybean cultivars were correlated. Fewer infection cushions were formed on resistant cultivars than on susceptible cultivars.

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Section: Discussionsupporting

confidence: 53%

Factors affecting infection cushion development by Rhizoctonia solani AG‐1 IA and IB on soybean leaves

1994

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“…Large infection cushions were formed by highly branched and agglomerated hyphae (Figure 1B). Additionally, smaller infection structures similar to lobate appressoria (Figure 1C) and foot structures (Figure 1D) were observed, as described for Rhizoctonia solani [40,42,43,51-53]. Trichothecenes are potent phytotoxins that can evoke symptoms like necrosis in a wide variety of plants at very low concentrations [7].…”

Section: Resultsmentioning

confidence: 96%

“…Additionally, the results exclude a dependence of compound appressoria formation on certain topographical features, because the epidermal architecture of bracts and caryopses is fundamentally different. Topographical features of the inoculated surface [ 40 ], the availability of nutrients [ 40 , 57 ] and plant exudates [ 40 , 43 , 57 - 59 ] were discussed to be influencing factors for development and morphology of compound appressoria from R. solani . Several abiotic factors which influence fungal growth and development, like humidity, temperature, exposure to light, and nutrient availability will probably influence the development of compound appressoria.…”

Section: Discussionmentioning

confidence: 99%

Fusarium graminearum forms mycotoxin producing infection structures on wheat

2011

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BackgroundThe mycotoxin producing fungal pathogen Fusarium graminearum is the causal agent of Fusarium head blight (FHB) of small grain cereals in fields worldwide. Although F. graminearum is highly investigated by means of molecular genetics, detailed studies about hyphal development during initial infection stages are rare. In addition, the role of mycotoxins during initial infection stages of FHB is still unknown. Therefore, we investigated the infection strategy of the fungus on different floral organs of wheat (Triticum aestivum L.) under real time conditions by constitutive expression of the dsRed reporter gene in a TRI5prom::GFP mutant. Additionally, trichothecene induction during infection was visualised with a green fluorescent protein (GFP) coupled TRI5 promoter. A tissue specific infection pattern and TRI5 induction were tested by using different floral organs of wheat. Through combination of bioimaging and electron microscopy infection structures were identified and characterised. In addition, the role of trichothecene production for initial infection was elucidated by a ΔTRI5-GFP reporter strain.ResultsThe present investigation demonstrates the formation of foot structures and compound appressoria by F. graminearum. All infection structures developed from epiphytic runner hyphae. Compound appressoria including lobate appressoria and infection cushions were observed on inoculated caryopses, paleas, lemmas, and glumes of susceptible and resistant wheat cultivars. A specific trichothecene induction in infection structures was demonstrated by different imaging techniques. Interestingly, a ΔTRI5-GFP mutant formed the same infection structures and exhibited a similar symptom development compared to the wild type and the TRI5prom::GFP mutant.ConclusionsThe different specialised infection structures of F. graminearum on wheat florets, as described in this study, indicate that the penetration strategy of this fungus is far more complex than postulated to date. We show that trichothecene biosynthesis is specifically induced in infection structures, but is neither necessary for their development nor for formation of primary symptoms on wheat.

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“…Penetration of the epidermis occurred after formation of appressorium-like structures and infection cushions. On roots of cabbage seedlings, no formation of infection structures was observed, possibly because the cuticle composition or the absence of specific root exudates did not induce infection structure formation [ 44 , 45 , 46 ]. On tomato seedlings S. cepivorum formed infection structures similar to those on onion seedlings, although they did not result in successful invasion of the tomato-root system.…”

Section: Discussionmentioning

confidence: 99%

Visualization of Three Sclerotiniaceae Species Pathogenic on Onion Reveals Distinct Biology and Infection Strategies

Steentjes

Tonn

Coolman

et al. 2021

IJMS

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Botrytis squamosa, Botrytis aclada, and Sclerotium cepivorum are three fungal species of the family Sclerotiniaceae that are pathogenic on onion. Despite their close relatedness, these fungi cause very distinct diseases, respectively called leaf blight, neck rot, and white rot, which pose serious threats to onion cultivation. The infection biology of neck rot and white rot in particular is poorly understood. In this study, we used GFP-expressing transformants of all three fungi to visualize the early phases of infection. B. squamosa entered onion leaves by growing either through stomata or into anticlinal walls of onion epidermal cells. B. aclada, known to cause post-harvest rot and spoilage of onion bulbs, did not penetrate the leaf surface but instead formed superficial colonies which produced new conidia. S. cepivorum entered onion roots via infection cushions and appressorium-like structures. In the non-host tomato, S. cepivorum also produced appressorium-like structures and infection cushions, but upon prolonged contact with the non-host the infection structures died. With this study, we have gained understanding in the infection biology and strategy of each of these onion pathogens. Moreover, by comparing the infection mechanisms we were able to increase insight into how these closely related fungi can cause such different diseases.

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Selective Induction Infection Cushions by Rhizoctonia solani Relation to Host Responses

Cited by 7 publications

References 5 publications

Factors affecting infection cushion development by Rhizoctonia solani AG‐1 IA and IB on soybean leaves

Factors affecting infection cushion development by Rhizoctonia solani AG‐1 IA and IB on soybean leaves

Fusarium graminearum forms mycotoxin producing infection structures on wheat

Visualization of Three Sclerotiniaceae Species Pathogenic on Onion Reveals Distinct Biology and Infection Strategies

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