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Silverleaf whitefly stress impairs sugar export from cotton source leaves
Author(s) -
Lin TongBao,
Wolf Shmuel,
Schwartz Am,
Saranga Yehoshua
Publication year - 2000
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.2000.100310.x
Subject(s) - sugar , whitefly , chemistry , horticulture , botany , biology , food science
Silverleaf whitefly (SLW), Bemisia argentifolii Bellows and Perring, is one of the most noxious pests of numerous field and vegetable crops, causing billions of dollars worth of damage throughout the world. SLW is a phloem feeder whose feeding is likely to interfere with phloem transport. The aim of this study was to test the hypothesis that SLW infestation impairs carbohydrate export from source leaves, and consequently increases their carbohydrate content. The youngest fully expanded leaves of cotton ( Gossypium hirsutum L., cv. Siv'on), grown under SLW‐infested and noninfested conditions, were characterized for their diurnal changes in carbohydrate content and photoassimilate export. SLW infestation induced a considerable reduction in net photosynthetic rate (P n ), coupled with increased sucrose, glucose and fructose and decreased starch concentrations. Export rate was determined after CO 2 pulse‐labeling both by in situ monitoring of leaf radioactivity and by analyzing the content and radioactivity of the major carbon metabolites. Radioactive counting indicated a lower rate of C efflux for the infested plants. A similar trend was found for the specific activities of sucrose and the three soluble sugars combined (sucrose, glucose and fructose). A single exponential decay function with asymptote was fitted to the above efflux curves. All the calculated exponential coefficients demonstrated lower export rates after SLW injury. These results indicate that SLW impairs photoassimilate export, suggesting possible down‐regulation of P n due to increased foliar soluble sugar contents.

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