|Authors: ||J. Kolarič, I. Mavrič-Ple¿ko, M. Stopar|
|Keywords: ||abscission, gene expression, MdACO1, ethylene, apple|
The expression of the ethylene-related genes MdACO1, MdACS5A and MdACS5B were followed in the fruit cortex (FC) and abscission zone (AZ) tissue of king and lateral fruitlets of the 'Golden Delicious' apple (Malus × domestica Borkh.) at 0, 1, 4 and 7 days after treatment (DAT) with 15 mg L-1 naphthaleneacetic acid (NAA), 150 mg L-1 6-benzyladenine (BA), 500 mg L-1 ethephon, and 3days of 96% shading, all applied at a mean 10-mm fruitlet diameter. MdACO1 was the most abundant expressed gene and a positive relation was found between the amounts of transcript in FC tissue and actual abscission.
Higher MdACO1 expression in FC accelerate abscission process of KF and LF. In the FC tissue of KF, ethephon treatment significantly increased the expression of MdACO1 4 DAT and at the same time a strong abscission of ethephon-treated KF was determined at 10 DAT. In the case of LF, ethephon and shading treatment significantly increased MdACO1 expression 4 DAT and consequently the abscission by these two treatments started 8 DAT while the fruitlets of the control, NAA and BA treatments started to abscise 3 days later.
LF were more subjected to abscission compared to KF and started to abscise at least 3-days earlier than KF.
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