Effects of amino acids and sugars on zoospore taxis, encystment and cyst germination in Pythium aphanidermatum (Edson) Fitzp., P. catenulatum Matthews and P. dissotocum Drechs.

Donaldson, S. P.; Deacon, J.W.

doi:10.1111/j.1469-8137.1993.tb03738.x

Cited by 52 publications

(29 citation statements)

References 27 publications

(21 reference statements)

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“…In particular, zoospores tend to accumulate at the elongation zone and wound sites. This accumulation is thought to be due primarily to chemotaxis but may involve other tactic responses such as electrotaxis, geotaxis and rheotaxis (Carlile, 1983(Carlile, , 1986 Deacon & Donaldson, 1993;Gow, 1993). The relative importance of these responses to root infection has yet to be determined.…”

Section: Current Flow Establishes Voltage Ionic and Ph Gradientsmentioning

confidence: 99%

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Tactic response of zoospores of the fungus Phytophthora palmivora to solutions of different pH in relation to plant infection

1995

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Zoospores of the plant pathogen Phytophthora palmivora use a number of tactic responses to target specific infectible regions of host roots. Although the dominant one is believed to be chemotaxis, it has been shown that zoospores of oomycetes may also use the exogenous protonlelectrical currents generated by plant roots for guidance. Since these proton currents also generate significant pH gradients in the rhizosphere, the tactic response of zoospores to changes in pH was examined. Using 'swim-in' capillary tests, zoospores of P. palmiwora were found to be repelled by solutions of high pH and attracted to solutions of low pH, relative to a control at neutrality. This in vitro tactic response was generally consistent with the measured pH a t sites of zoospore accumulation around intact and wounded roots. However, the endogenous pH gradient around host roofs could be abolished with buffers and this treatment did not affect the extent or pattern of zoospore accumulation. Therefore, detection of root-generated pH gradients is unlikely to have a major role in the homing response of zoospores towards plant roots.

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Section: Current Flow Establishes Voltage Ionic and Ph Gradientsmentioning

confidence: 99%

“…Here we examine the tactic response of a population of Plytopbtbora palmivora zoospores to media of differing pH using a 'swim-in' test (Cameron & Carlile, 1978;Donaldson & Deacon, 1993). A high rate of encystment could result in zoospore accumulation due to entrapment.…”

Section: Current Flow Establishes Voltage Ionic and Ph Gradientsmentioning

confidence: 99%

Tactic response of zoospores of the fungus Phytophthora palmivora to solutions of different pH in relation to plant infection

1995

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“…'PEKcougel' and R. 'Lifirane', which were resistant roses against crown gall disease, secreted less acetosyringone derivatives than the susceptible roses, and one of the resistance mechanisms to crown gall disease was related to acetosyringone derivative exudation (Tan et al, 2004). In Pythium, amino acids, polysaccharides, or volatile compounds were demonstrated to stimulate chemotaxis of zoospores (Donaldson and Deacon, 1993;Jones et al, 1991). Although we had not identified the component of root extracts from 'Matsushima No.…”

Section: Guidance Of Zoospores By Chemo-attractants and Encystment Anmentioning

confidence: 99%

“…The infection process of Pythium in diseased plants was reported by some papers, involving the guidance of zoospores to the root surface by chemo-attractants, attachment, and encystment of zoospores on the root surface, germ tube germination (early infection process), and penetration of the germ tube to the root epidermis, cortex, endodermis, and vascular stele (later infection process) (Deacon and Donaldson, 1993;Jones et al, 1991;Rey et al, 1998). The tolerance of 'Matsushima No.…”

Section: Introductionmentioning

confidence: 99%

Rosa multiflora with Root Rot Tolerance Has No Tolerance Mechanism on the Root Surface during the Early Infection Process

Kageyama

et al. 2007

Engei Gakkai Zasshi

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Rosa multiflora 'Matsushima No. 3' shows tolerance to root rot disease caused by Pythium helicoides Drechsler. However, there has been no report on the tolerance mechanism of 'Matsushima No. 3'. The infection process of Pythium in diseased plants was divided broadly into two stages, as early and later infection processes. This study focused on the early infection process: chemotaxis, attachment, and encystment of zoospores and germ tube germination on the root surface, in order to clarify the tolerance of 'Matsushima No. 3' in comparison with a susceptible rose. 'Matsushima No. 3' and R. 'Fashion Parade', which were estimated as showing tolerance and susceptibility to root rot disease in the field, respectively, were used as plant materials. Rooted cuttings of 'Matsushima No. 3' and 'Fashion Parade' were inoculated by zoospore suspension of P. helicoides, and root rot symptoms of these roses were evaluated at 7 days after inoculation. From the results of inoculation, we concluded that 'Matsushima No. 3' was tolerant, and 'Fashion Parade' was susceptible to root rot disease. Visual observation showed that zoospores of P. helicoides aggregated at the end of capillaries filled with root extract agar of 'Matsushima No. 3' as well as 'Fashion Parade', and zoospores encysted on the root surface of 'Matsushima No. 3' too. Therefore, 'Matsushima No. 3' didn't inhibit the chemotaxis and encystment of zoospores. From SEM observations, most cystospores germinated on the root surface in 'Matsushima No. 3' and 'Fashion Parade', and the percentages of germ tube penetration to the epidermis in 'Matsushima No. 3' and 'Fashion Parade' were 55.0 and 71.2, respectively. The result that no differences were recognized between the two roses during the early infection process indicated that the tolerance mechanism in 'Matsushima No. 3' was not active in the early but in the latter infection process, that is, some tolerance mechanism might inhibit hyphae from expanding to the cortical tissue.

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“…Fungi, having mechanisms of chemotaxis and chemotropism and sensing root exudates such as sugars, amino acids, organic acids and fatty acids, can move or grow in response to gradients of these compounds Donaldson and Deacon, 1993;Ruttledge and Nelson, 1997;Tyler, 2002). Electrostatic charge may also be an important sensory stimulus for swimming zoospores (Van West et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Infection Mechanism of Pathogenic Exduate by Soil-Borne Fungal Pathogens : A Review

Lim¹,

Kim²,

Song³

et al. 2012

Korean Journal of Soil Science and Fertilizer

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The processes to determine the composition, dynamics, and activity of infection mechanisms by the rhizosphere microflora have attracted the interest of scientists from multiple disciplines although considerable progress of the infection pathways and plant-pathogen interactions by soil borne fungal pathogens have been made. Soilborne pathogens are confined within a three-dimensional matrix of mineral soil particles, pores, organic matter in various stages of decomposition and a biological component. Among the physical and chemical properties of soils soil texture and matric water potential may be the two most important factors that determine spread exudates by soil borne fungal pathogens, based on the size of the soil pores. Pathogenic invasion of plant roots involves complex molecular mechanisms which occur in the diffuse interface between the root and the soil created by root exudates. The initial infection by soilborne pathogens can be caused by enzymes which breakdown cell wall layers to penetrate the plant cell wall for the fungus. However, the fate and mobility of the exudates are less well understood. Therefore, it needs to develop methods to control disease caused by enzymes produced by the soilborne pathogens by verifying many other possible pathways and mechanisms of infection processes occurring in soils.

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Effects of amino acids and sugars on zoospore taxis, encystment and cyst germination in Pythium aphanidermatum (Edson) Fitzp., P. catenulatum Matthews and P. dissotocum Drechs.

Cited by 52 publications

References 27 publications

Tactic response of zoospores of the fungus Phytophthora palmivora to solutions of different pH in relation to plant infection

Tactic response of zoospores of the fungus Phytophthora palmivora to solutions of different pH in relation to plant infection

<i>Rosa multiflora</i> with Root Rot Tolerance Has No Tolerance Mechanism on the Root Surface during the Early Infection Process

Infection Mechanism of Pathogenic Exduate by Soil-Borne Fungal Pathogens : A Review

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