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"Lipopolysaccharide (LPS) is a major component of outer-membrane gram-negative bacteria, and it can act as aPathogen-Associated Molecular Pattern (PAMP) for perception of pathogens by plants. LPS can be recognized byplants, triggering certain plant defense-related responses, including callose deposition. This study investigated inductionof callose deposition by bacterial LPS in tobacco. Tobacco leaves were infiltrated with 400 μg/mL and 800 μg/mL LPSextracted from Pseudomonas syringae pv. tabaci (Pta) and Pseudomonas syringae pv. glycinea (Pgl) and incubated for24 h or 48 h. To detect callose deposition, tobacco leaves were cleared in lactophenol solution, stained with aniline blue,and visualized by fluorescence microscopy. Results showed that LPS from Pgl induced more callose deposition intobacco leaves than did that from Pta. In addition, a Pearson correlation test revealed that incubation period was themost significant factor in callose deposition, followed by the type of LPS bacteria. However, LPS concentration was notsignificantly corelated to callose deposition in tobacco leaves.Induksi Deposisi Callose pada Tanaman Tembakau (Nicotiana tabacum) oleh Lipopolisakrida BakteriPseudomonas syringae pv. tabaci dan Pseudomonas syringae pv. glycinea. Lipopolisakarida (LPS) adalah komponenutama permukaan sel bakteri gram negatif. LPS dapat berperan sebagai Pathogen-Associated Molecular Pattern(PAMP), yaitu molekul yang menjadi target pengenalan patogen oleh tanaman. Pengenalan LPS oleh tanaman dapatmenginduksi respon pertahanan tanaman, termasuk deposisi callose. Penelitian bertujuan untuk mengetahui induksideposisi callose pada tanaman tembakau oleh LPS bakteri yang diekstraksi dari bakteri Pseudomonas syringae pv.tabaci (Pta) dan P. syringae pv. glycinea (Pgl). Untuk pengamatan deposisi callose, daun tembakau diinfiltrasi LPS Ptadan Pgl, dengan konsentrasi 400 μg/ml dan 800 μg/ml, diinkubasi selama 24 dan 48 jam. Selanjutnya, klorofil daundiluruhkan menggunakan larutan laktofenol dan diwarnai dengan aniline blue. Deposisi callose diamati menggunakanmikroskop fluoresen. Hasil pengamatan menunjukkan LPS bakteri Pgl menginduksi deposisi callose lebih banyakdibandingkan LPS bakteri Pta. Lebih lanjut, berdasarkan uji korelasi pearson diketahui bahwa waktu inkubasi adalahfaktor yang berkorelasi paling signifikan terhadap deposisi callose, diikuti oleh jenis bakteri LPS. Namun, konsentrasiLPS tidak berkorelasi signifikan dengan deposisi callose pada daun tembakau."

"The hypersensitive reaction (HR) jn plants is a plant defense system against pathogen attack. HR is characterized by the rapid death of infected cells accompanying the formation of necrotic lessions in which pathogens are thought to be enclosed. Following the early signaling events activated by pathogen attack, the elicitor signals are often amplified through the generation of secondary signal molecules such as salicylic acid (SA) and Jasmonate acid (JA). Some studies have shown thai SA- and JA-signaling pathways are interconnected in complicated ways and it is still not clear how defense response is modulated by SA and JA. To understand better the involvement of JA. the action of MeJA on harpin-induced HR was investigated by using tobacco plant (wildtype and transgenic carrying a chimeric gene of PSPAL2 promoter and GUS gene. Leaves of of tobacco were infiltrated with harpin and MeJA. The results from HR assay and GUS histochemical staining showed that induction of HR by harpin (250 ug/ml) seems to be modulated by 100 uM MeJA. These results suggest that exogenenously application of MeJA will affect the endogenous concentration in plant that will become a switching point for MeJA to lead the potentiation or suppression of defense response."