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Poster: Biology & Disease Mgmt: Biological Control


Analysis of IAA and ABA in HLB diseased citrus trees
Z. PANG (1), H. Wang (1), N. Wang (1) (1) citrus research and educational center, U.S.A.

HLB, caused by Candidatus Liberibacter asiaticus (Las), is a disastrous disease resulting in defoliation, twig dieback, root decline and fruit drop. Among these symptoms, preharvest fruit drop directly poses a disastrous threat to the citrus industry by decreasing yield. At early developmental stage of fruit, dropping always occur at AZ-A zone which is between branch and peduncle. Here, different hormones level at peduncle area were dynamically monitored both in healthy and HLB infected trees during the fruit maturation to find if hormone imbalance in HLB infected peduncles caused preharvest fruit drop. Indole-3-acetic acid (IAA) level was lower in HLB infected trees at the early stage of fruit ripening compared to healthy trees. Level of abscisic acid (ABA), which promote fruit mature and abscission, was higher in Las infected trees. Expression analysis of hormone related genes also matched the hormone detection. We will also report our results in preventing preharvest fruit drop using different hormones.