Articles
Xylem hydraulic conductance in southern highbush blueberry genotypes with different levels of field resistance to bacterial leaf scorch
Article number
1440_39
Pages
281 – 288
Language
English
Abstract
Xylella fastidiosa causes bacterial leaf scorch of southern highbush blueberry (Vaccinium corymbosum interspecific hybrids) in the southeastern US. The bacterium colonizes and occludes the xylem of affected plants, causing drought-like symptoms and plant death.
Here, we investigate host xylem functionality in response to natural infection by X. fastidiosa in blueberry cultivars differing in field resistance to the disease.
Using a high-pressure flow meter, hydraulic conductance per stem cross-sectional area (Ksa) was measured on field-collected stem sections from 5- to 6-year-old plants of genotypes FL 86-19 (highly susceptible), ‘Star’ (intermediate), and ‘Emerald’ (field-resistant) in the fall of two years.
In asymptomatic plants, Ksa values were typically greater for ‘Emerald’ than for ‘Star’ or FL 86-19 for all tissue types tested (lignified stems, partially lignified stems, green shoots, and petioles) across both years, with differences being statistically significant for lignified and partially lignified stems.
This shows the overall greater capacity for water flow in the xylem system of ‘Emerald.’ When Ksa of sections having <20% foliar leaf scorch severity was compared with that of more severely affected sections (≥20% foliar leaf scorch severity) in ‘Star’ and FL 86-19, Ksa was higher in the less severely affected sections for all tissue types except the current-season green shoots.
Consistently across both years, petiole Ksa was reduced considerably and significantly in severely affected sections of the highly susceptible FL 89-16. Loss of xylem function in the petiole may help explain the greater propensity for plant death in FL 86-19 compared with Star in response to infection by X. fastidiosa.
Here, we investigate host xylem functionality in response to natural infection by X. fastidiosa in blueberry cultivars differing in field resistance to the disease.
Using a high-pressure flow meter, hydraulic conductance per stem cross-sectional area (Ksa) was measured on field-collected stem sections from 5- to 6-year-old plants of genotypes FL 86-19 (highly susceptible), ‘Star’ (intermediate), and ‘Emerald’ (field-resistant) in the fall of two years.
In asymptomatic plants, Ksa values were typically greater for ‘Emerald’ than for ‘Star’ or FL 86-19 for all tissue types tested (lignified stems, partially lignified stems, green shoots, and petioles) across both years, with differences being statistically significant for lignified and partially lignified stems.
This shows the overall greater capacity for water flow in the xylem system of ‘Emerald.’ When Ksa of sections having <20% foliar leaf scorch severity was compared with that of more severely affected sections (≥20% foliar leaf scorch severity) in ‘Star’ and FL 86-19, Ksa was higher in the less severely affected sections for all tissue types except the current-season green shoots.
Consistently across both years, petiole Ksa was reduced considerably and significantly in severely affected sections of the highly susceptible FL 89-16. Loss of xylem function in the petiole may help explain the greater propensity for plant death in FL 86-19 compared with Star in response to infection by X. fastidiosa.
Publication
Authors
R.M. Holland, J. Yin, R.O. Teskey, H. Scherm
Keywords
bacterial leaf scorch, blueberry, hydraulic conductance, Vaccinium corymbosum, Xylella fastidiosa, xylem function
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