Cell‐wall lysing enzymes and products of cell‐wall digestion elicit ethylene in citrus

Baldwin, Elizabeth A.; Biggs, R. H.

doi:10.1111/j.1399-3054.1988.tb09193.x

Cited by 31 publications

(19 citation statements)

References 38 publications

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“…These diplodia-produced enzymes could contribute to fruit abscission directly by degrading the cell wall and middle lamella in the abscission zone, and they may also indirectly impact fruit abscission by inducing the fruit to produce ethylene, which in turn induces the plant abscission zone to produce cell wall-degrading enzymes. It has been reported that the fungal pectolytic enzymes and their products induce ethylene in citrus (63) and tomato (64,65) fruits.…”

Section: Figmentioning

confidence: 99%

High Incidence of Preharvest Colonization of Huanglongbing-Symptomatic Citrus sinensis Fruit by Lasiodiplodia theobromae (Diplodia natalensis) and Exacerbation of Postharvest Fruit Decay by That Fungus

Zhao

Bai

McCollum

et al. 2015

Appl Environ Microbiol

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Huanglongbing (HLB), presumably caused by the bacterium "Candidatus Liberibacter asiaticus," is a devastating citrus disease associated with excessive preharvest fruit drop. Lasiodiplodia theobromae (diplodia) is the causal organism of citrus stem end rot (SER). The pathogen infects citrus fruit under the calyx abscission zone (AZ-C) and is associated with cell wall hydrolytic enzymes similar to plant enzymes involved in abscission. By means of DNA sequencing, diplodia was found in "Ca. Liberibacter asiaticus"-positive juice from HLB-symptomatic fruit (S) but not in "Ca. Liberibacter asiaticus"-negative juice. Therefore, the incidence of diplodia in fruit tissues, the impact on HLB-related postharvest decay, and the implications for HLB-related preharvest fruit drop were investigated in Hamlin and Valencia oranges. Quantitative PCR results (qPCR) revealed a significantly (P < 0.001) greater incidence of diplodia in the AZ-C of HLB-symptomatic (S; "Ca. Liberibacter asiaticus" threshold cycle [C T ] of <30) than in the AZ-C of in asymptomatic (AS; "Ca. Liberibacter asiaticus" C T of >30) fruit. In agreement with the qPCR results, 2 weeks after exposure to ethylene, the incidences of SER in S fruit were 66.7% (Hamlin) and 58.7% (Valencia), whereas for AS fruit the decay rates were 6.7% (Hamlin) and 5.3% (Valencia). Diplodia colonization of S fruit AZ-C was observed by scanning electron microscopy and confirmed by PCR test and morphology of conidia in isolates from the AZ-C after surface sterilization. Diplodia C T values were negatively correlated with ethylene production (R ‫؍‬ ؊0.838 for Hamlin; R ‫؍‬ ؊0.858 for Valencia) in S fruit, and positively correlated with fruit detachment force (R ‫؍‬ 0.855 for Hamlin; R ‫؍‬ 0.850 for Valencia), suggesting that diplodia colonization in AZ-C may exacerbate HLB-associated preharvest fruit drop. C itrus huanglongbing (HLB; also known as citrus greening) is one of the most devastating diseases of citrus and has spread throughout the major citrus-producing regions in Asia, Africa, and the Americas, causing great losses for the citrus industry worldwide (1). HLB is associated with "Candidatus Liberibacter" spp., which are Gram-negative, phloem-limited bacteria (2, 3). The Asian form of HLB is currently present in the United States, and the causal pathogen, bacterium "Candidatus Liberibacter asiaticus," was first confirmed in Southeast Florida in 2005 (1) and now is prevalent in all Florida citrus-growing areas in the state. HLB disease causes substantial economic loss by debilitating the productive capacity and shortening the life span of infected trees, promoting fruit drop and reducing fruit quality (4). Yield reduction can reach 30 to 100%, depending on the proportion of the canopy affected and the age of the trees during inoculation (1, 5).HLB-diseased citrus plants develop a multitude of symptoms. Leaf symptoms include chlorosis, which commonly appears in an asymmetric pattern referred to as "blotchy mottle" (4). Chlorosis may typically appear on a single branch and subse...

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Section: Figmentioning

confidence: 99%

High Incidence of Preharvest Colonization of Huanglongbing-Symptomatic Citrus sinensis Fruit by Lasiodiplodia theobromae (Diplodia natalensis) and Exacerbation of Postharvest Fruit Decay by That Fungus

Zhao

Bai

McCollum

et al. 2015

Appl Environ Microbiol

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“…Ethylene biosynthesis, one common response of plant tissues to pathogen attack (21), is stimulated by a variety of plant-and pathogen-derived polysaccharides and proteins (4,26,28). Ethylene has been suggested to play a role in activating certain defense responses in some plant tissues (9).…”

Section: Introductionmentioning

confidence: 99%

Ethylene Biosynthesis-Inducing Xylanase

Dean¹,

Anderson²

1991

Plant Physiol.

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The ethylene biosynthesis-inducing endoxylanase (EIX) from xylan-induced cultures of the fungus, Trichoderma viride, was purified to near homogeneity and compared with the EIX isolated from Cellulysin. Both enzymes migrate as 9.2 kilodalton proteins during gel filtration chromatography under nondenaturing conditions, but the mature polypeptide migrates as a 22 kilodalton band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amino acid composition of the 22 kilodalton polypeptide is enriched by Gly, Ser, Thr, Trp, and Tyr, but depleted in Ala, Glx, Leu, and Lys. Both proteins lack sulfur-containing amino acids. The protein is glycosylated, and inhibition of EIX synthesis by tunicamycin suggests that at least some of the sugar moieties are linked to asparagine residues. EIX appears to be synthesized initially as a 25 kilodalton precursor protein that is processed to 22 kilodalton during secretion.A factor limiting our understanding of plant defense responses in plant-pathogen interactions has been the paucity of elicitors which have been purified and structurally characterized. Ethylene biosynthesis, one common response of plant tissues to pathogen attack (21), is stimulated by a variety of plant-and pathogen-derived polysaccharides and proteins (4,26,28). Ethylene has been suggested to play a role in activating certain defense responses in some plant tissues (9). This laboratory has previously demonstrated that an endo-B-1,4-xylanase (1,4-f3-D-xylan xylanohydrolase; EC 3.2.1.8) purified from a commercial mixture of fungal enzymes, Cellulysin3, is a potent elicitor ofethylene biosynthesis in tobacco (Nicotiana tabacum L. cv Xanthi) ( 1,12).

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“…Baldwin and Biggs (3) reported that Pectolyase induces ethylene production in citrus fruit. We found that the mixture of enzymes in Pectolyase is also effective in inducing ethylene formation in tomatoes.…”

Section: Effects Of the Enzymes On Ethylene Productionmentioning

confidence: 99%

Pectic Enzymes in Pectolyase

Baldwin¹,

Pressey²

1989

Plant Physiol.

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The pectic enzymes in Pectolyase were separated by ion exchange chromatography on Q-Sepharose. Three pectin lyases, two polygalacturonases, and a pectinmethylesterase were resolved. The enzymes were further purified on Mono 0 and/or Mono S columns to remove traces of cellulase. The enzymes had molecular weights ranging from 25,000 to 36,000 daltons. They were optimally active between pH 4.0 and 6.2 and were not greatly affected by ions. The pectin lyases and polygalacturonases were endo-enzymes. They solubilized uronic acids from washed cell wall fragments, but the lyases were much more effective than the polygalacturonases. The mixture of enzymes constituting Pectolyase increased ethylene production 15-to 25-fold when introduced into tomato and orange fruits. The enzymes purified from Pectolyase all increased ethylene production in the fruits but the lyases were generally more effective than the hydrolases.Pectolyase is a commercially available enzyme mixture prepared from culture filtrates of Aspergillus japonicus (8,13). These enzymes in combination with cellulases are very effective in degrading cell walls and thereby liberating protoplasts. For this reason, Pectolyase is widely used to generate protoplasts in cell culture research. There have been several attempts to identify the cell wall degrading enzymes in Pectolyase to explain the effectiveness of this preparation. Ishii and coworkers (10, 11) separated an endo-PG' (EC 3.2.1.15) and an endo-PL (EC 4.2.2.3) from the culture filtrates. They also obtained evidence that the solutions contained a maceration stimulation factor which enhanced the action of both enzymes on cell walls (9). The combination of enzymes able to degrade pectate and pectin plus the enzyme activator appeared to be the basis for the potency of Pectolyase in liberating protoplasts.Our interest in the pectic enzymes in Pectolyase stems from the observation that purified tomato PG induced ethylene production and accelerated ripening when infiltrated into green tomato fruit (4). We wanted to expand these studies to microbial pectic enzymes and selected Pectolyase as a source. Attempts to separate the PL and PG (10, 11) revealed that the Pectolyase contained several isoenzymes of each. This ' Abbreviations: PG, polygalacturonase; PL, pectin lyase; PME, pectinmethylesterase.paper describes the separation and properties of the enzymes and their effectiveness in inducing ethylene production in tomato and orange fruit. MATERIALS AND METHODS SubstratesCitrus pectin (Sigma Chemical Co.) was purified by precipitation from a 1% aqueous solution by the addition of two volumes of ethanol, followed by washing with ethanol and acetone. Polygalacturonic acid was prepared from pectate (Sigma Chemical Co.) by partial hydrolysis as described earlier (15). Cell walls were prepared from the fruits of apple, nectarine, cucumber, and tomato and the roots of carrot and radish by homogenizing 100 g of tissue with 200 mL of0.5 M sodium phosphate (pH 7.0). The insoluble material was collected by centrifuga...

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Cell‐wall lysing enzymes and products of cell‐wall digestion elicit ethylene in citrus

Cited by 31 publications

References 38 publications

High Incidence of Preharvest Colonization of Huanglongbing-Symptomatic Citrus sinensis Fruit by Lasiodiplodia theobromae (Diplodia natalensis) and Exacerbation of Postharvest Fruit Decay by That Fungus

High Incidence of Preharvest Colonization of Huanglongbing-Symptomatic Citrus sinensis Fruit by Lasiodiplodia theobromae (Diplodia natalensis) and Exacerbation of Postharvest Fruit Decay by That Fungus

Ethylene Biosynthesis-Inducing Xylanase

Pectic Enzymes in Pectolyase

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