Infection Cushion Development by<i>Rhizoctonia solani</i>on Cotton

Armentrout, V. N.; Downer, A. James

doi:10.1094/phyto-77-619

Cited by 51 publications

(33 citation statements)

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“…The early observation of the different steps in the infection process is in concordance with previous studies concerning pathogenic Rhizoctonia AGs on several hosts [9,18,31,32] and the faster and more abundant stomatal penetration of the AG 1-1B and AG 1-1C isolates is probably correlated with the aerial nature of these AGs [33], since isolates from foliage have been reported to penetrate stomata more frequently [10]. During these pathogenic interactions, pectin degrading enzymes seemed important and diffused ahead of the fungus, as pathogen ingress was coupled with extensive host cell deformation and pectin breakdown at locations not in direct contact with hyphae.…”

Section: Discussionsupporting

confidence: 90%

Interactions between cauliflower and Rhizoctonia anastomosis groups with different levels of pathogenicity

Pannecoucque

Höfte

2009

BMC Plant Biol

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Background: The soil borne fungus Rhizoctonia is one of the most important plant pathogenic fungi, with a wide host range and worldwide distribution. In cauliflower (Brassica oleracea var. botrytis), several anastomosis groups (AGs) including both multinucleate R. solani and binucleate Rhizoctonia species have been identified showing different levels of aggressiveness. The infection and colonization process of Rhizoctonia during pathogenic interactions is well described. In contrast, insights into processes during interactions with weak aggressive or non-pathogenic isolates are limited. In this study the interaction of cauliflower with seven R. solani AGs and one binucleate Rhizoctonia AG differing in aggressiveness, was compared. Using microscopic and histopathological techniques, the early steps of the infection process, the colonization process and several host responses were studied.

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Section: Discussionsupporting

confidence: 90%

Interactions between cauliflower and Rhizoctonia anastomosis groups with different levels of pathogenicity

Pannecoucque

Höfte

2009

BMC Plant Biol

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“…Such a contact induced the formation of short hyphal internodes and short perpendicular lateral branches in the pathogenic isolate before appressorium formation. These branches frequently formed feet along the grooves (Armentrout et al 1987). The pathogenic isolate also degraded outer epidermal cell walls in the pre-penetration stages, as previously observed (Weinhold and Motta 1973), though other authors (Christou 1962) suggest that penetration can be induced by mechanical pressure.…”

Section: Discussionsupporting

confidence: 75%

“…The interactions between pathogenic Rhizoctonia spp. strains and several hosts have been described at an ultrastructural level (Dodman 1970, Armentrout andDowner 1987). A comparative study between virulent and hypovirulent isolates of R. solani colonizing cotton hypocotyls and roots pointed out many differences in the anatomy of colonization (Sneh et al 1989), but the information in his regard is still scanty.…”

Section: Introductionmentioning

confidence: 99%

Morphogenetic effects induced by pathogenic and non pathogenicRhizoctonia solaniKühn strains on tomato roots

2007

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-The effects of two Rhizoctonia solani Kü hn isolates on root colonization and morphology of in vitro grown tomato plants were compared. Pathogenic hyphae (R1556) penetrated and filled all the parenchyma cells of the cortex and of the central cylinder; the vessel elements underwent a significant degradation. Several brownish sclerotia and cushion formations were observed. Roots colonized by the non-pathogenic strain showed phytoplane non-pathogenic growth: hyphae occurred in the external root portion and in a few cortical parenchyma cells; a number of hyphal tips grew along the ridges of adjacent epidermal cells or in the intercellular spaces. Morphometric values were significantly lower in the roots of plants infected by the pathogenic isolate than in those infected by the non-pathogenic one compared to the controls. Root growth was described by a logistic model in infected plants and by a linear one in the controls.

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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%

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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Infection Cushion Development byRhizoctonia solanion Cotton

Cited by 51 publications

References 0 publications

Interactions between cauliflower and Rhizoctonia anastomosis groups with different levels of pathogenicity

Interactions between cauliflower and Rhizoctonia anastomosis groups with different levels of pathogenicity

Morphogenetic effects induced by pathogenic and non pathogenicRhizoctonia solaniKühn strains on tomato roots

Fusarium graminearum forms mycotoxin producing infection structures on wheat

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