Submitted to: Bemisia International Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 10/6/2006
Publication Date: 12/3/2006
Citation: McKenzie, C.L., Sinisterra, X., Albano, J.P., Powell, C., Dowd, S.E., Shatters, R.G. 2006. Determining the role of ethylene biosynthesis in the development of tomato irregular ripening disorder using microarray technology and rt-real time PCR [abstract]. Bemisia International Workshop Proceedings. Interpretive Summary:
Technical Abstract: Whiteflies, Bemisia tabaci biotype B, are associated with a plant physiological disorder termed tomato irregular ripening. Symptoms of tomato irregular ripening disorder do not appear on tomato foliage where whitefly feed, but appear as an uneven fruit color development during ripening in tomato. This disorder is characterized externally by incomplete reddening of the fruit exhibited by longitudinal white or yellow streaks that typically start as a star at the blossom end of the fruit which can become more pronounced with the points radiating up the fruit. Color often develops along locule walls with intermediate areas remaining green or yellow, producing a star-burst appearance. Internally, fruit exhibit white or yellow tissues. The mechanism(s) of symptom development and the physiological bases of this disorder are not completely understood although altered gibberellin metabolism and suppression of ethylene biosynthesis in tomato fruit as a result of whitefly feeding have been indicated. In order to determine the underlying causes of tomato irregular ripening disorder associated with whitefly feeding, microarray hybridization analysis followed by reverse transcription (rt) real time PCR validation were used to determine gene regulation in young and old leaf tissue, stems, flowers, roots, and fruits over time. Tomato plants infested with whitefly had higher N levels (18.5%); were taller, wider, produced more leaves, flowers (2,998 vs. 2,443) & fruit (871 vs. 828), however significantly fewer fruit ever became ripened (48 vs. 272). Based on sequence similarity analysis we determined that selected genes were likely to be involved with ethylene biosynthesis production. Microarray analysis results of the first harvest (21 days after whitefly infestation) indicated a total of 68 genes involved in ethylene biosynthesis and were up or down-regulated in response to whitefly feeding after 21 days exposure. Seven genes involved in ethylene biosynthesis responded to whitefly feeding in new leaf tissue (3 up-regulated, 4 down regulated); 18 genes in old leaf tissue (10 up-regulated, 8 down-regulated); 4 genes in stem tissue (all up-regulated); 13 genes in root tissue (all up-regulated); 15 genes in flower tissue (10 up-regulated, 5 down-regulated); and 11 genes responded in fruit tissue (8 up-regulated, 3 down-regulated). After 3 weeks of whitefly infestation, the highest fold changes were in old leaf tissue (4.78) and fruit (-8.58). Genes with the highest fold changes were chosen for validation using rt-Real Time PCR and changes in gene regulation were monitored over time (21, 45, and 65 days after whitefly infestation). Results will be presented and ethylene’s role in the development of tomato irregular ripening disorder will be discussed.