Induced resistance to Fusarium oxysporum in mechanically stressed Acacia koa A. Gray seedlings

A nonpathogenic isolate of Fusarium oxysporum, 618-12, added to soil prior to the pathogen, suppressed fusarium wilt (F. o. f.sp. dianthi race 2) in a susceptible cultivar of carnation by 80% compared with the treatment with the pathogen only. The possibility of systemically induced resistance by the nonpathogenic isolate was assessed by inoculating antagonist and pathogen at different locations (stem versus soil, soil versus stem, and in a split-root system). No significant disease suppression was found with any of these spatially separated inoculations. However, inoculation of antagonist and pathogen at the same location within the stem (i.e., mixed stem inoculation) resulted in significant and reproducible disease reductions compared with stem inoculation with the pathogen alone. This reduction was found for different inoculum densities and different cultivars. Several other nonpathogenic Fusarium isolates could also reduce wilt symptoms in the susceptible carnation cultivar after mixed stem inoculation with the pathogen. This disease-suppressive effect after mixed stem inoculations may be caused by locally induced resistance or competition between isolates within the stem. Plants showed vascular browning around the inoculation point following inoculation with nonpathogenic isolates. Disease suppression, as well as vascular browning, were absent when dead conidia of the isolate 618-12 were used. After its addition to soil, the isolate was recovered from 44–78% of carnation stems. Spread of the nonpathogenic isolate within the stem occurred only in the first 4 days after stem inoculation, and it remained confined to limited distances from the inoculation point between 4 and 59 days after inoculation. The pathogenic isolate could be isolated at increasingly greater distances from the inoculation point during this period. These data suggest that the nonpathogenic isolate is not actively spread through the plant by growth of the fungus. Keywords: biological control, competition, induced resistance, wilt.

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DETEKSI PENGIMBASAN KETAHANAN PISANG TERHADAP PENYAKIT LAYU FUSARIUM DENGAN ASAM FUSARAT (INDUCED RESISTANCE DETECTION OF BANANA AGAINST FUSARIUM WILT USING FUSARIC ACID)

Jurnal Perlindungan Tanaman Indonesia ◽

10.22146/jpti.16345 ◽

2016 ◽

Vol 19 (1) ◽

pp. 40

Author(s):

Christanti Sumardiyono ◽

Suharyanto Suharyanto ◽

Suryanti Suryanti ◽

Putri Rositasari ◽

Yufita Dwi Chinta

Keyword(s):

Salicylic Acid ◽

Phenolic Compounds ◽

Fusarium Oxysporum ◽

Induced Resistance ◽

Cross Section ◽

Fusarium Wilt ◽

Fusaric Acid ◽

Banana Plant ◽

Water Stream ◽

Soil Nutrition

Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc) is the most destructive disease of banana. Until today this disease has not been successfully controlled. Fusaric acid is a toxin produced by Foc. Tyloses produced inxylem that caused wilting and yellowing of banana plants, inhibit soil nutrition and water stream. The study carried out previously showed that enriched fusaric acid in banana culture induced the resistance of banana seedlings against Foc. The signal of induced resistance increased the phenolic compounds. One of the phenolic compounds is salicylic acid. The aim of this study was to detect induced resistance of banana plant from tissue cultured enriched with fusaric acid. The experiment was done in the field highly infected with Foc. Observation of resistance was done by measuring disease percentage of yellowing and wilting leaves.Tyloses produced in xylem was observed microscopically from cross section of root. Root damage intensity was counted using tyloses score. Salicylic acid content of root was analyzed with phenolic compounds method using HPLC. The results showed that banana plants from enriched tissues culture with 1.165 ppm of fusaric acid increased the resistance against Foc, but salicylic acid was not detected. Salicylic acid was only detected at low concentration (2 ppb) in moderate resistant banana roots from induced plants with 9.32 ppm of fusaric acid. The chromatogram showed three peaks of unknown phenolic compounds. Tyloses intensity was not related with induced resistance of banana against fusarium wilt. Advanced research is needed with more plants samples. It was suggested to identify the phenolic compounds which were detected in induced resistant plant.Keywords: banana, fusaric acid, fusarium wilt, induced resistance, salicylic acidLayu fusarium yang disebabkan oleh Fusarium oxysporum f. sp. cubense (Foc) adalah penyakit yang sangat merusak pada pisang dan belum dapat dikendalikan secara tuntas. Gejala berupa kelayuan daun karena tersumbatnya xilem karenapembentukan tilosis yaitu pertumbuhan sel dalam jaringan xilem. Pengimbasan ketahanan diharapkan dapat menjadi salah satu cara pengendalian penyakit layu fusarium. Penelitian sebelumnya menunjukkan penambahan asam fusaratdalam kultur jaringan dapat mengimbas ketahanan bibit pisang terhadap penyakit layu fusarium. Asam salisilat adalah salah satu signal ketahanan yang akan meningkat kandungannya bila terjadi peningkatan ketahanan akibat pengimbasan. Penelitian ini bertujuan untuk mendeteksi hasil pengimbasan ketahanan pisang dengan asam fusarat dalam kultur jaringan. Tanaman telah ditanam di lapangan yang terinfeksi berat oleh Foc. Intensitas penyakit di lapang diamati dengan menghitung persentase daun menguning dan atau layu. Intensitas kerusakan akar diamati dengan pembuatan irisan tipis dan pengamatan tilosis dengan cara skoring. Analisis asam salisilat dalam akar dilakukan dengan metode analisis senyawa fenol menggunakan HPLC. Hasil penelitian tanaman dari bibit yang diimbas dengan 1,165 ppm asam fusarat dalam kultur jaringan menunjukkan peningkatan ketahanan di lapang. Intensitas tilosis lebih rendah pada tanaman yang diimbas ketahanannya dibandingkan yang tidak diimbas. Asam salisilat dalam tanaman yang diimbas ketahannnya denganasam fusarat 9,32 ppm terdeteksi pada konsentrasi yang sangat rendah yaitu 2 ppb, dengan ketahanan moderat. Pada tanaman hasil pengimbasan yang menunjukkan kriteria tahan asam salisilat tidak terdeteksi, namun terdeteksi tigapuncak senyawa fenol yang belum teridentifikasi. Intensitas tilosis pada tanaman yang diimbas ketahanannya tidak menunjukkan penurunan dibandingkan dengan tanaman yang tidak diperlakukan. Penelitian ini perlu dilanjutkan dengan sampel yang lebih banyak. Identifikasi jenis senyawa fenol perlu dilakukan dalam penelitian lanjutan.Kata kunci: asam fusarat, asam salisilat, layu fusarium, pengimbasan ketahanan, pisang

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