ABSTRAK
Telah dilakukan penelitian yang bertujuan untuk menginduksi responspertahanan tanaman tembakau oleh lipopolisaakrida (LPS). LPS diekstraksi daribakteri Pseudomonas syringae pv. tabaci (Pta) dan P. syringae pv. glycinea (Pgl).Respons pertahanan tanaman yang diamati adalah deposisi callose dan ekspresigen terkait pertahanan (PAL, HIN 1 dan HSR 203J). Untuk pengamatan deposisicallose, daun tembakau diinfiltrasi dengan LPS Pta dan Pgl (400 µg/ml dan 800µg/ml) serta diinkubasi selama 24 dan 48 jam. Selanjutnya, klorofil daundiluruhkan menggunakan larutan laktofenol dan diwarnai dengan aniline blue.Deposisi callose diamati dibawah mikroskop fluoresensi. Hasil pengamatanmenunjukkan LPS bakteri Pgl menginduksi deposisi callose lebih banyakdibandingkan LPS bakteri Pta. Pengamatan ekspresi gen-gen terkait pertahanandilakukan pada daun tembakau yang diinfiltrasi dengan 400 µg/ml LPS bakteriPta and Pgl, serta diinkubasi selama 6 jam. Hasil RT-PCR terhadap dauntembakau menunjukkan LPS bakteri Pta dan Pgl mampu menginduksi ekspsresigen HIN 1, tetapi tidak mampu menginduksi ekspresi gen PAL dan HSR 203J.Gen HIN 1 terekspresi lebih kuat pada daun tembakau yang diinduksi oleh LPSbakteri Pgl daripada LPS Pta. Hasil penelitian mengindikasikan bahwa LPSbakteri Pgl menginduksi respons pertahanan daun tembakau lebih baik daripadaLPS bakteri Pta.

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Abstract
The aim of this study is to know the induction of tobacco defenseresponses by using lipopolysaccharides (LPS) which extracted from twophytopathogen, Pseudomonas syringae pv. tabaci (Pta) and P. syringae pv.glycinea (Pgl). The plant defense responses that observed are callose depositionand expression of defense-related genes (PAL, HIN 1 and HSR 203J). To detectcallose deposition, tobacco leaves were infiltrated with 400 µg/ml and 800 µg/mlLPS Pta and Pgl, then incubated for 24 or 48 hr. Tobacco leaves were cleared inlactophenol solution, stained with aniline blue, then visualized by fluorescencemicroscopy. The result showed that LPS from Pgl induced more callosedeposition than that from Pta in tobacco leaves. To investigate defense-relatedgenes expression, tobacco leaves were infiltrated with 400 µg/ml LPS extractedfrom Pta and Pgl, then incubated for 6 hr. Analysis of defense-related genesexpression were conducted by RT-PCR and visualized by electrophoresis on a1.8% agarose gel. The result showed LPS Pta and Pgl can induce expression ofHIN 1 gene in tobacco leaves, but can not induce the PAL and HSR 203J genes.The HIN 1 gene was highly expressed in tobacco leaves induced by LPS Pgl. Theresult indicates that tobacco could effectively recognize LPS of nonhost pathogenPgl but not in host pathogen Pta.