Identifikasi Molekuler Patogen Penyebab Bercak dan Hawar Daun serta Potensi Cendawan Endofit Mahoni (Swietenia spp.) sebagai Agen Hayati

Abstract

Penyakit bercak dan hawar daun masih menjadi salah satu kendala dalam pembibitan mahoni karena dapat menurunkan kualitas serta kelangsungan hidup bibit di persemaian. Pengendalian penyakit yang masih bergantung pada fungisida kimia sintetis berpotensi menimbulkan resistensi patogen serta berdampak negatif terhadap lingkungan. Oleh karena itu, diperlukan pendekatan pengendalian yang lebih efektif dan ramah lingkungan melalui pemanfaatan cendawan endofit sebagai agen pengendali hayati. Penelitian ini bertujuan mengidentifikasi cendawan patogen penyebab penyakit bercak dan hawar daun berdasarkan karakter molekuler, menganalisis keragaman cendawan endofit, serta mengevaluasi potensi cendawan endofit sebagai agen pengendali hayati secara in vitro. Penelitian dilakukan melalui identifikasi molekuler cendawan patogen menggunakan Basic Local Alignment Search Tool (BLAST) dan analisis filogenetik berdasarkan daerah Internal Transcribed Spacer (ITS), analisis keragaman cendawan endofit, serta uji antagonis, senyawa volatil, dan aktivitas enzimatik secara in vitro. Hasil identifikasi molekuler menunjukkan bahwa keenam isolat cendawan patogen memiliki kemiripan yang tinggi dengan Corynespora cassiicola, Pseudopestalotiopsis theae, Colletotrichum fructicola, C. gloeosporioides, dan Bipolaris setariae. Sebanyak 68 isolat berhasil diisolasi dari jaringan daun, ranting, dan akar. Dari 68 isolat tersebut, dapat dikategorikan menjadi 9 morfospesies dengan keanekaragaman yang relatif rendah. Namun, terdapat 4 morfospesies nonpatogen yang berpotensi dikembangkan sebagai agen pengendali hayati. Pengujian in vitro menunjukkan bahwa empat isolat cendawan endofit nonpatogen, yaitu M1, M4, M6, dan M7, mampu menghambat pertumbuhan C. cassiicola, P. theae, Colletotrichum sp., dan B. setariae melalui berbagai mekanisme antagonisme. Isolat M6 menunjukkan kemampuan penghambatan tertinggi pada uji antagonis dan uji senyawa volatil, sedangkan M1, M4, dan M7 menghasilkan enzim protease dan kitinase dengan aktivitas yang tergolong rendah. Penelitian ini menghasilkan informasi mengenai spesies cendawan patogen penyebab penyakit bercak dan hawar daun pada mahoni, keragaman cendawan endofit yang berasosiasi dengan mahoni, serta potensi beberapa isolat cendawan endofit sebagai agen pengendali hayati. Informasi yang diperoleh diharapkan dapat menambah koleksi mikroba bermanfaat serta menjadi acuan penting bagi penelitian lanjutan di bidang perlindungan tanaman dan bioteknologi kehutanan.

Leaf spot and leaf blight are among the major constraints in mahogany seedling production because they reduce seedling quality and survival in nurseries. Disease management still relies heavily on synthetic chemical fungicides, which may lead to pathogen resistance and adverse environmental impacts. Therefore, environmentally friendly disease management strategies are needed, including the use of endophytic fungi as biological control agents. This study aimed to identify fungal pathogens causing leaf spot and leaf blight based on molecular characteristics, analyze the diversity of endophytic fungi, and evaluate the potential of endophytic fungi as biological control agents through in vitro assays. The study was conducted through the molecular identification of pathogenic fungi using the Basic Local Alignment Search Tool (BLAST) and phylogenetic analysis based on the Internal Transcribed Spacer (ITS) region, analysis of endophytic fungal diversity, and in vitro evaluation of antagonistic activity, volatile compound production, and enzymatic activity. The molecular identification revealed that the six pathogenic fungal isolates showed high sequence similarity to Corynespora cassiicola, Pseudopestalotiopsis theae, Colletotrichum fructicola, C. gloeosporioides, and Bipolaris setariae. A total of 68 isolates were successfully isolated from leaf, twig, and root tissues. These 68 isolates could be categorized into 9 morphospecies, representing relatively low diversity. Nevertheless, four nonpathogenic morphospecies were identified as having potential for development as biological control agents. The in vitro assays demonstrated that four nonpathogenic endophytic fungal isolates, namely M1, M4, M6, and M7, inhibited the growth of C. cassiicola, P. theae, Colletotrichum sp., and B. setariae through multiple antagonistic mechanisms. Isolate M6 exhibited the highest inhibitory activity in both dual culture and volatile compound assays, whereas isolates M1, M4, and M7 produced protease and chitinase with low enzymatic activity. This study provides information on the fungal species causing leaf spot and leaf blight in mahogany, the diversity of endophytic fungi associated with mahogany, and the potential of several endophytic fungal isolates as biological control agents. The findings are expected to enrich beneficial microbial collections and serve as a reference for future studies in plant protection and forest biotechnology.