Carbohydrate and nutritional responses to stem girdling and drought stress with respect to understanding symptoms of Huanglongbing (HLB) in Citrus

Riccardo Lo Bianco, Giuseppe Cimo', Wije Bandaranayake, Edgardo Etxeberria, James P. Syvertsen, Pedro Gonzalez

Risultato della ricerca: Article

15 Citazioni (Scopus)

Abstract

The most important worldwide problem in citrus production is the bacterial disease Huanglongbing (HLB; citrus greening) caused by phloem-limited bacterium Candidatus Liberibacter asiaticus. The earliest visible symptoms of HLB on leaves are vein yellowing and an asymmetrical chlorosis referred to as “blotchy mottle”, thought to be the result of starch accumulation. We tested the hypothesis that such visible symptoms are not unique to HLB by stem girdling 2-yr-old seedlings of two citrus rootstocks with and without drought stress in the greenhouse. After 31 d, girdling had little effect on shoot growth but girdling increased the relative growth rate of shoots in drought stressed trees. Starch content in woody roots of non-girdled trees was 3 – 19 times higher than in girdled trees. In non-girdled trees, drought stress induced some starch accumulation in roots, but there were no effects of drought stress on root starch or sucrose in girdled trees. Girdling induced 4-fold greater starch content in leaves on well-watered trees but leaf sucrose content was not affected. Girdling reduced leaf transpiration in well-watered trees but net assimilation of CO2 was not affected by girdling or leaf starch accumulation. Leaves on girdled trees clearly had visible blotchy mottle symptoms but no symptoms developed on non-girdled trees. The increase in leaf starch, up to 50% dry weight (DW), resulted in an increase in leaf DW per leaf area (LA) and an artificial reduction of many leaf nutrients on a DW basis. Most of these differences disappeared when expressed on a LA basis. Leaf B, however, was inversely related to leaf starch when both were expressed on a LA basis. In the absence of HLB, girdling increased in leaf starch, decreased in root starch, duplicated the asymmetric blotchy mottled visual leaf symptoms that have been associated with HLB-infected trees. This supports our contention that such symptoms generally attributed to HLB are not uniquely related to HLB infection, but rather are directly related to starch accumulation and secondarily to nutrient deficiencies in leaves.
Lingua originaleEnglish
pagine (da-a)920-928
Numero di pagine9
RivistaHORTSCIENCE
Volume48
Stato di pubblicazionePublished - 2013

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greening disease
girdling
signs and symptoms (plants)
Citrus
water stress
carbohydrates
starch
leaves
leaf area
sucrose
Candidatus Liberibacter asiaticus
shoots
plant veins
nutrient deficiencies
chlorosis
phloem

All Science Journal Classification (ASJC) codes

  • Horticulture

Cita questo

Carbohydrate and nutritional responses to stem girdling and drought stress with respect to understanding symptoms of Huanglongbing (HLB) in Citrus. / Lo Bianco, Riccardo; Cimo', Giuseppe; Bandaranayake, Wije; Etxeberria, Edgardo; Syvertsen, James P.; Gonzalez, Pedro.

In: HORTSCIENCE, Vol. 48, 2013, pag. 920-928.

Risultato della ricerca: Article

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title = "Carbohydrate and nutritional responses to stem girdling and drought stress with respect to understanding symptoms of Huanglongbing (HLB) in Citrus",
abstract = "The most important worldwide problem in citrus production is the bacterial disease Huanglongbing (HLB; citrus greening) caused by phloem-limited bacterium Candidatus Liberibacter asiaticus. The earliest visible symptoms of HLB on leaves are vein yellowing and an asymmetrical chlorosis referred to as “blotchy mottle”, thought to be the result of starch accumulation. We tested the hypothesis that such visible symptoms are not unique to HLB by stem girdling 2-yr-old seedlings of two citrus rootstocks with and without drought stress in the greenhouse. After 31 d, girdling had little effect on shoot growth but girdling increased the relative growth rate of shoots in drought stressed trees. Starch content in woody roots of non-girdled trees was 3 – 19 times higher than in girdled trees. In non-girdled trees, drought stress induced some starch accumulation in roots, but there were no effects of drought stress on root starch or sucrose in girdled trees. Girdling induced 4-fold greater starch content in leaves on well-watered trees but leaf sucrose content was not affected. Girdling reduced leaf transpiration in well-watered trees but net assimilation of CO2 was not affected by girdling or leaf starch accumulation. Leaves on girdled trees clearly had visible blotchy mottle symptoms but no symptoms developed on non-girdled trees. The increase in leaf starch, up to 50{\%} dry weight (DW), resulted in an increase in leaf DW per leaf area (LA) and an artificial reduction of many leaf nutrients on a DW basis. Most of these differences disappeared when expressed on a LA basis. Leaf B, however, was inversely related to leaf starch when both were expressed on a LA basis. In the absence of HLB, girdling increased in leaf starch, decreased in root starch, duplicated the asymmetric blotchy mottled visual leaf symptoms that have been associated with HLB-infected trees. This supports our contention that such symptoms generally attributed to HLB are not uniquely related to HLB infection, but rather are directly related to starch accumulation and secondarily to nutrient deficiencies in leaves.",
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T1 - Carbohydrate and nutritional responses to stem girdling and drought stress with respect to understanding symptoms of Huanglongbing (HLB) in Citrus

AU - Lo Bianco, Riccardo

AU - Cimo', Giuseppe

AU - Bandaranayake, Wije

AU - Etxeberria, Edgardo

AU - Syvertsen, James P.

AU - Gonzalez, Pedro

PY - 2013

Y1 - 2013

N2 - The most important worldwide problem in citrus production is the bacterial disease Huanglongbing (HLB; citrus greening) caused by phloem-limited bacterium Candidatus Liberibacter asiaticus. The earliest visible symptoms of HLB on leaves are vein yellowing and an asymmetrical chlorosis referred to as “blotchy mottle”, thought to be the result of starch accumulation. We tested the hypothesis that such visible symptoms are not unique to HLB by stem girdling 2-yr-old seedlings of two citrus rootstocks with and without drought stress in the greenhouse. After 31 d, girdling had little effect on shoot growth but girdling increased the relative growth rate of shoots in drought stressed trees. Starch content in woody roots of non-girdled trees was 3 – 19 times higher than in girdled trees. In non-girdled trees, drought stress induced some starch accumulation in roots, but there were no effects of drought stress on root starch or sucrose in girdled trees. Girdling induced 4-fold greater starch content in leaves on well-watered trees but leaf sucrose content was not affected. Girdling reduced leaf transpiration in well-watered trees but net assimilation of CO2 was not affected by girdling or leaf starch accumulation. Leaves on girdled trees clearly had visible blotchy mottle symptoms but no symptoms developed on non-girdled trees. The increase in leaf starch, up to 50% dry weight (DW), resulted in an increase in leaf DW per leaf area (LA) and an artificial reduction of many leaf nutrients on a DW basis. Most of these differences disappeared when expressed on a LA basis. Leaf B, however, was inversely related to leaf starch when both were expressed on a LA basis. In the absence of HLB, girdling increased in leaf starch, decreased in root starch, duplicated the asymmetric blotchy mottled visual leaf symptoms that have been associated with HLB-infected trees. This supports our contention that such symptoms generally attributed to HLB are not uniquely related to HLB infection, but rather are directly related to starch accumulation and secondarily to nutrient deficiencies in leaves.

AB - The most important worldwide problem in citrus production is the bacterial disease Huanglongbing (HLB; citrus greening) caused by phloem-limited bacterium Candidatus Liberibacter asiaticus. The earliest visible symptoms of HLB on leaves are vein yellowing and an asymmetrical chlorosis referred to as “blotchy mottle”, thought to be the result of starch accumulation. We tested the hypothesis that such visible symptoms are not unique to HLB by stem girdling 2-yr-old seedlings of two citrus rootstocks with and without drought stress in the greenhouse. After 31 d, girdling had little effect on shoot growth but girdling increased the relative growth rate of shoots in drought stressed trees. Starch content in woody roots of non-girdled trees was 3 – 19 times higher than in girdled trees. In non-girdled trees, drought stress induced some starch accumulation in roots, but there were no effects of drought stress on root starch or sucrose in girdled trees. Girdling induced 4-fold greater starch content in leaves on well-watered trees but leaf sucrose content was not affected. Girdling reduced leaf transpiration in well-watered trees but net assimilation of CO2 was not affected by girdling or leaf starch accumulation. Leaves on girdled trees clearly had visible blotchy mottle symptoms but no symptoms developed on non-girdled trees. The increase in leaf starch, up to 50% dry weight (DW), resulted in an increase in leaf DW per leaf area (LA) and an artificial reduction of many leaf nutrients on a DW basis. Most of these differences disappeared when expressed on a LA basis. Leaf B, however, was inversely related to leaf starch when both were expressed on a LA basis. In the absence of HLB, girdling increased in leaf starch, decreased in root starch, duplicated the asymmetric blotchy mottled visual leaf symptoms that have been associated with HLB-infected trees. This supports our contention that such symptoms generally attributed to HLB are not uniquely related to HLB infection, but rather are directly related to starch accumulation and secondarily to nutrient deficiencies in leaves.

UR - http://hdl.handle.net/10447/95889

M3 - Article

VL - 48

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EP - 928

JO - Hortscience: A Publication of the American Society for Hortcultural Science

JF - Hortscience: A Publication of the American Society for Hortcultural Science

SN - 0018-5345

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