Abstract
The infestation of boktor (Xystrocera festiva Pascoe) stem borer in Sengon (Falcataria falcata) tree plantations in Indonesia, especially in Java, has caused severe losses by damaging the stems, decreasing wood quality, and potentially leading to mortality. To digest the woods, the X. festiva larvae's gut has at least two digestive enzymes, which are trypsin and α-amylase. Former studies have shown that F. falcata produces inhibitors of these two enzymes as part of its defense mechanisms. This research aimed to analyze trypsin inhibitor (TI) and α-amylase inhibitor (AAI) transcripts, as well as their expression, in X. festiva-infested and resistant F. falcata trees. We found 19 contigs encoding the TI gene and 29 contigs encoding AAI. The results were able to predict the sequence of the DNA that produced the TI and AAI transcriptomes, which proved that one gene could be expressed differently due to alternative splicing. The DEG analysis and RT-PCR confirmed that mostly the TI and AAI activity was heavily induced by the X. festiva larvae attacks. The expression of the TI gene was upregulated 0.78 times, while the AAI gene expression was upregulated 2.44 times in infested samples. The findings from this study are fundamental in understanding the mechanism of F. falcata resistance against X. festiva infestation and selecting the resistant trees.