Morphogenic determinants as Exemplified by the Crown-gall Disease

Lippincott, James A.; Lippincott, Barbara B.

doi:10.1007/978-3-642-66279-9_14

Cited by 9 publications

(5 citation statements)

References 123 publications

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“…The reappraisal of the host-range studies on Agrobacterium [3,4,7] suggested a positive correlation between polyphenolic content and susceptibility for crown gall and hairy-root. This observation agrees very well both with Lippincott's hypothesis of the central role of a monophenoldiphenol-peroxidase system in regulating plant cell division [57], and with Clark's results [34], described above. Fig.…”

Section: Resultssupporting

confidence: 91%

“…It is commonly accepted that these compounds act as competitive inhibitors of IAA-oxidase [54]. It is known that auxin is an important factor during crown gall transformation: the conversion of competent host cells to rapidly dividing cells is considered to involve at least two steps, the second requiring auxin [56,57]. It has also been demonstrated that Agrobacterium strains can synthetize fl-indoleacetic acid [35,58,59] and actually produce this plant-growth regulator in the host plant [60].…”

Section: Auxin Protection Certain Phenolics Showmentioning

confidence: 99%

“…Not only crown gall tumours, but also embryonic and juvenile plant tissues show an increased level of auxin protectors and of auxin and a change in redox potential to a more reduced state. According to Lippincott and Lippincott [57] "These results point to a possible central role for a monophenol-diphenol-peroxidase system in regulating cell division in both tumor and meristematic tissues".…”

Section: Auxin Protection Certain Phenolics Showmentioning

confidence: 99%

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The susceptibility of plants to Agrobacterium: A discussion of the role of phenolic compounds

Cleene¹

1988

FEMS Microbiology Letters

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Section: Resultssupporting

confidence: 91%

Section: Auxin Protection Certain Phenolics Showmentioning

confidence: 99%

Section: Auxin Protection Certain Phenolics Showmentioning

confidence: 99%

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The susceptibility of plants to Agrobacterium: A discussion of the role of phenolic compounds

Cleene¹

1988

FEMS Microbiology Letters

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“…Although most parts ofmany plants are susceptible to experimental inoculation, A. tumefaciens normally infects through wounds in roots and at the rootshoot interface, the crown (18). Crown gall is among the major disease problems in fruit tree and ornamental nurseries and vineyards (25,26).…”

Section: Bacterial Strains and Culturementioning

confidence: 99%

Use of a Root Tumorigenesis Assay to Detect Genotypic Variation in Susceptibility of Thirty-four Cultivars of Pisum sativum to Crown Gall

Hawes¹,

Robbs²,

Pueppke³

1989

Plant Physiol.

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We developed a quantitative assay to measure tumorigenesis on roots and root crowns, the natural sites of Agrobacterium tumefaciens infection. Efficiency of tumor formation and tumor weight on seedlings of Pisum sativum 'Little Marvel' were directly proportional to the logarithm of inoculum concentration. Depth of wounding prior to inoculation also significantly influenced tumor weight but not efficiency. Mean weight of tumors that developed in response to inoculation with strain B6 varied significantly among 34 different commercial cultivars. Tumors on the most susceptible cultivar, Target, were more than tenfold heavier than those formed on the least susceptible cultivar, Sweet Snap. Efficiency of tumorigenesis on 'Sweet Snap' was also relatively low: only 64% of inoculated seedlings developed tumors compared with 89 to 100% efficiencies for all other cultivars. evaluate resistance and susceptibility in Pisum sativum L., a well characterized diploid species that is a known host of A. tumefaciens (16). To initiate studies of crown gall resistance in pea, we established a reproducible quantitative assay for tumorigenesis on roots of intact plants and used it to survey genotypic variation among 34 commercial cultivars of pea. MATERIALS AND METHODS Bacterial Strains and CultureSingle colony cultures of bacterial strains were maintained at -70C in 50:50 (v/v) glycerol:yeast extract-mannitol (YEM) medium. Strain B6 was a gift from J. A. Lippincott (Northwestern University). For assays, cultures were grown overnight on YEM solidified with 0.7% agar and were suspended in water. Inoculum concentrations were estimated turbidimetrically and confirmed by dilution plating.Agrobacterium tumefaciens is a soil-borne bacterial pathogen that causes crown gall on most dicots and some gymnosperms and monocots (5). Although most parts ofmany plants are susceptible to experimental inoculation, A. tumefaciens normally infects through wounds in roots and at the rootshoot interface, the crown (18). Crown gall is among the major disease problems in fruit tree and ornamental nurseries and vineyards (25,26 Plant Inoculation and AssayPisum sativum L. seeds were surface-sterilized by consecutive 5-min immersions in 95% ethanol and 50% commercial bleach and then washed 4x in at least 50 mL of sterile water. Seeds were germinated on water agar overlaid with filter paper for 2 to 3 d or until the radicles were approximately 1 to 3 cm in length. Each seedling was wounded either by stabbing the root with a marked scalpel blade to a depth of 1 mm or by pushing the blade through the root to a depth of approximately 3 mm. Three wounds were made on each plant at approximately 5-mm intervals from the crown to the root tip. Seedlings were immersed into 5 mL of inoculum for 5 min and were then placed into moistened growth pouches (Northrup King, Minneapolis, MN), with 4 or 5 seedlings per pouch. Pouches were moistened daily with approximately 5 mL of water and were incubated at 250C day/230C night for 2 weeks.

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“…The fact that crown gall host systems differ with respect to the degree of bacterial virulence shown by a given strain, the time it takes for tumor formation, and the size and number of tumors formed has been well established (1,6,7).…”

mentioning

confidence: 99%

Agrobacterium tumefaciens Site Attachment as a Necessary Prerequisite for Crown Gall Tumor Formation on Potato Discs

Glogowski

Galsky²

1978

Plant Physiol.

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The infectivity of Agrobacterium tumefaciens strain B6 was inhibited about 50% when these bacteria were inoculated on potato discs with equal viable cell counts of a weakly virulent strain of A. tumefaciens (B-48) The fact that crown gall host systems differ with respect to the degree of bacterial virulence shown by a given strain, the time it takes for tumor formation, and the size and number of tumors formed has been well established (1, 6, 7).The necessity for bacterial attachment to a specific site as a prerequisite for the formation of crown gall tumors on the primary leaves of Pinto beans and the time it takes for such attachment have been shown (5). Studies as to whether a similar type of attachment is necessary in other crown gall host systems have been limited due to the lack of another suitable quantitative bioassay for tumor formation, although the necessity for site attachment has been established for some nonquantitative host systems (8,10). With the recent development of the potato disc bioassay by Anand and Heberlein (1). we have undertaken studies which show that attachment to a specific site, which occurs in a short period of time, is a necessary prerequisite for tumor formation on potato discs.With the recent discovery that infectivity is due to the presence of a plasmid (11) found within tumor-inducing strains of Agrobacterium tumefaciens, experiments to determine the biochemical nature of the transformation process should increase in number. The need to understand more completely the nature of specific host systems for studying tumor formation takes on great importance. 2To whom reprint requests should be sent. MATERIALS AND METHODSof Northwestern University. The bacterium and yeast (which was obtained from the culture collection at the USDA Lab in Peoria) were grown for 48 hr in a medium containing 0.8% (w/v) nutrient broth, 0.1% (w/v) yeast extract, and 0.5% (w/v) sucrose on a New Brunswick Scientific Shaker at 27 C.Tumors were induced on potato discs by the method first described by Anand and Heberlein (1), and modified slightly in our laboratory (3). Red potatoes (Solanum tuberosum var. Red Russett) were purchased from the local market and soaked in 20%o Clorox (v/v) for 20 min. Potato discs were then obtained by placing a sterilized cork borer (20-mm diameter) through the potato and cutting 5-mm discs from the resulting plug. Five potato discs were then placed on Petri dishes containing 1.5% (w/v) agar and inoculated with 0.5 ml of bacterial suspension containing a known quantity of viable cells. The Petri dishes were placed at 27 C and exposed to 15 hr of room light and 9 hr of darkness daily. Twelve days following inoculation the tumors were counted with the aid of a dissecting scope. The tumors at this time, however, were clearly visible with the human eye. Each experimental sample consisted of three Petri dishes which contained five potato discs. Sterile techniques were employed throughout the above procedure.In order to insure that a maximum competition for attachment site...

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Morphogenic determinants as Exemplified by the Crown-gall Disease

Cited by 9 publications

References 123 publications

The susceptibility of plants to Agrobacterium: A discussion of the role of phenolic compounds

The susceptibility of plants to Agrobacterium: A discussion of the role of phenolic compounds

Use of a Root Tumorigenesis Assay to Detect Genotypic Variation in Susceptibility of Thirty-four Cultivars of Pisum sativum to Crown Gall

Agrobacterium tumefaciens Site Attachment as a Necessary Prerequisite for Crown Gall Tumor Formation on Potato Discs

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