Influence of Temperature and Humidity on the Growth of Pseudomonas Citri and Its Host Plants and on Infection and Development of the Disease

Peltier, George L.

doi:10.1175/1520-0493(1920)48<718c:iotaho>2.0.co;2

Cited by 12 publications

(24 citation statements)

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“…In C. sinensis epicarp the proximal quarters exhibited the greatest change in sugars both during accumulation and subsequent loss, whereas the distal quarters exhibited the least change, suggesting that translocation from and to the tree was responsible for the observed changes. At temperatures as low as 5°C, photosynthesis in C. sinensis leaves can be as much as 50% their maximum photosynthetic rate (16), yet growth of C. sinensis trees nearly ceases at temperatures below 13C (7,15). Thus, during the months of October through January there is virtually no growth of C. sinensis trees while the fruit do continue to enlarge (5 In addition to components of sugar metabolism, components of nitrogen metabolism also affect interconversions between the two plastid forms.…”

Section: Discussionmentioning

confidence: 99%

Sugar Regulation of Plastid Interconversions in Epicarp of Citrus Fruit

Huff¹

1984

Plant Physiol.

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In a previous paper (9) it was demonstrated that transformation between chloroplasts and chromoplasts in citrus epicarp could be controlled in vitro by manipulating sugar and nitrogen supplies in agar media upon which pericarp segments were cultured. High concentrations of sucrose in media usually promoted degreening and inhibited regreening, whereas nitrogen as nitrate and certain amino acids acted in opposition to sucrose by inhibiting degreening and promoting regreening. In the presence ofincreasing nitrogen concentrations, the sucrose effect was much reduced and, when nitrogen supplies were sufficiently high, high concentrations of sucrose sometimes promoted regreening.In addition to promoting loss ofChl, high sugar concentrations in media increased epicarp sugar concentrations, and in media lacking nitrogen high concentrations of sugars caused a marked reduction in epicarp amino acid concentrations. In those in vitro experiments there was a significant negative correlation between Chl and the molar ratio of sugars to amino acids in the epicarp.Based on these observations, it is hypothesized that most citrus fruit degreen in response to a reduced flux in nitrogen to the fruit accompanied by increased concentrations of sugars in the epicarp, both usually induced by cool temperatures. Regreening of late season citrus fruit in the spring and summer could be attributed to renewed nitrogen flux and a reduction in sugar concentrations. Degreening of species such as C. madurensis Lour., could also be attributed to elevated sugar concentrations and reduced nitrogen content, but cool temperatures would not be the causative factor.To further examine the relationship between plastid transformations and sugar and nitrogen status, Chl, sucrose, reducing sugars, total nitrogen, and amino acids were monitored in the epicarp of C. sinensis (L.), Osbeck cv Valencia and pericarp of C. madurensis Lour. fruit degreening in situ, and in the epicarp of regreening C. sinensis fruit. Also, pericarp sections from C. sinensis fruit at different stages of development were tested for their response to sugars and nitrate in vitro. The results, reported here, suggest that accumulation ofsugars in the epicarp is indeed a major factor regulating plastid metamorphosis in citrus fruit, and that while the abundance of nitrogen is an influential factor, nitrogen flux is not a major factor in seasonal changes in plastid form. MATERIALS

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Section: Discussionmentioning

confidence: 99%

Sugar Regulation of Plastid Interconversions in Epicarp of Citrus Fruit

Huff¹

1984

Plant Physiol.

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“…Early studies suggest a temperature range of 20-30°C is necessary for citrus canker development (Peltier 1920;Koizumi 1977). However, a recent study showed citrus canker develops best at 30-35°C ).…”

Section: Introductionmentioning

confidence: 99%

“…In addition, temperature influences the symptom expression and length of incubation period, reducing or increasing it (Koizumi 1976;Dalla Pria et al 2006). In each citrus species, the bacterium can express unique behaviour under the same environmental conditions (Peltier 1920). Free moisture is essential for bacterial dissemination and initiation of an infection process.…”

Section: Introductionmentioning

confidence: 99%

Modelling the progress of Asiatic citrus canker on Tahiti lime in relation to temperature and leaf wetness

et al. 2008

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“…According to the literature (Peltier, 1920;Koizumi, 1977;Timmer et al, 1991;Pruvost et al, 2002;Bock et al, 2005), the quantity of Xanthomonas citri subsp. citri cells dispersed in rain splash depends on various factors, such as the age of the lesions and the ambient temperature.…”

Section: Dr Gottwald Et Al's Answer (12)mentioning

confidence: 99%

Statement in response to the comments submitted by the US phytosanitary authorities on a previous EFSA opinion (EFSA Journal 2011;9(12):2461) regarding the export of Florida citrus fruit to the EU

2013

EFS2

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The European Food Safety Authority (EFSA) has been asked to address the comments submitted in April 2012 by the US phytosanitary authorities on the EFSA scientific opinion on the US request related to the export of Florida citrus fruit. The EFSA Panel on Plant Health acknowledges the responses provided by the United States Department of Agriculture (USDA) and considers that the USDA misinterpreted the conclusions made by the Panel in its previous opinion (EFSA Panel on Plant Health (PLH), 2011). The Panel considers that the extrapolations of the data provided by Shiotani et al. (2009) andGottwald et al. (2009) were not supported by sound evidence. The Panel considers that both the responses provided by Dr Shiotani and by Dr Gottwald and colleagues do not lead to any major change in the set of scientifically sound information related to citrus canker and Xanthomonas citri pv. citri. The Panel, after evaluating the response provided by the USDA regarding the previous EFSA scientific opinion on citrus canker, considers that the removal of mandatory mitigation measures in field and packinghouse facilities increases the risk of contamination of fruit during the growing season and thus the bacterial load and frequency of infected fruit in consignments. Permitting the trade of citrus fruit originating from infected orchards increases the probability of the presence of X. citri pv. citri on fruit in consignments from those sites. The Panel considers that citrus fruit is a pathway for introduction of X. citri pv. citri into the European Union and the related risk is being evaluated in a separate EFSA opinion under preparation on the plant health risk of citrus canker for the EU. The Panel, after evaluating the response provided by the USDA regarding its previous pest risk assessments and risk management analyses, further considers that:removing mandatory mitigation measures in the field increases the risk of contamination of fruit during the growing season and thus the bacterial load and frequency of infected fruit in consignments;removing mandatory mitigation measures in packinghouse facilities contributes to increasing the bacterial load and frequency of infected fruit in consignments;allowing the trade of citrus fruit originating from infected orchards increases the probability of the presence of Xanthomonas citri pv. citri on fruit in consignments from those sites.The Panel considers that citrus fruit is a pathway for the introduction of X. citri pv. citri to the European Union and the related risk is being evaluated in a separate EFSA opinion under preparation on the plant health risk of citrus canker for the EU, addressing another question from the same terms of reference.Statement in response to the comments submitted by the US phytosanitary authorities EFSA Journal 2013;11(10):3374 3

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Influence of Temperature and Humidity on the Growth of Pseudomonas Citri and Its Host Plants and on Infection and Development of the Disease

Cited by 12 publications

References 0 publications

Sugar Regulation of Plastid Interconversions in Epicarp of Citrus Fruit

Sugar Regulation of Plastid Interconversions in Epicarp of Citrus Fruit

Modelling the progress of Asiatic citrus canker on Tahiti lime in relation to temperature and leaf wetness

Statement in response to the comments submitted by the US phytosanitary authorities on a previous EFSA opinion (EFSA Journal 2011;9(12):2461) regarding the export of Florida citrus fruit to the EU

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