| Chemical induction of systemic acquired resistance (SAR) against Rotylenchulus reniformis, and Meloidogyne javanica, in Ananas comosus was determined. A. comosus plants were treated with single foliar spray of SAR inducing compounds in the greenhouse. The result showed that acibenzolar reduced egg production of R. reniformis by 51% in six months. Acibenzolar, DL-beta-amino-n-butyric acid (BABA), and riboflavin reduced reproduction of M. javanica by 59, 62, and 69%, respectively. In the next series of experiments, acibenzolar was tested at different concentrations to determine a rate response for eliciting SAR in A. comosus. Twelve months after application, acibenzolar at 100 mg/L suppressed M. javanica and R. reniformis reproduction by 30% compared to untreated control. Greater concentrations caused stunting of the plants.; Various behavioral aspects of the nematodes on acibenzolar-treated plant were investigated. High concentrations did not affect movement or penetration of R. reniformis or M. javanica. However, on average, 50% of second-stage juveniles (J2) that penetrated acibenzolar-treated plants developed into mature females with eggs, whereas the other 50% exhibited arrested development. In addition, the number of eggs/egg mass produced in acibenzolar-treated plants was about 50% fewer than that in water-treated plants.; The induction of the SAR marker gene PR-1 was examined in A. comosus. RT-PCR was performed using degenerate primers designed from PR-1 genes of several monocots and dicots. A 266 bp cDNA band was evident only in plants treated with acibenzolar. This 266 bp cDNA was sequenced and found to be highly homologous to a number of PR-1 genes from monocots. In addition, the amino acid sequence deduced from the 266 bp cDNA showed a high identity to PR-1 proteins from both monocots and dicots. Therefore, it was highly likely that this cloned fragment was part of A. comosus PR-1 gene, indicating that A. comosus has a SAR pathway. In addition, time course of PR-1 expression showed that PR-1 induction was initiated as early as one day after acibenzolar application and continued through 3 weeks thereafter.; SAR induction in A. comosus provides some control. This level of control is inadequate by itself, but could be used as a supplemental treatment. |
