The role of leitucenin a in lettuce (Lactuca sativa) against pathogen Xanthomonas campestris pv. oryzae

Hong, Chia Yean (2007) The role of leitucenin a in lettuce (Lactuca sativa) against pathogen Xanthomonas campestris pv. oryzae. Universiti Malaysia Sabah. (Unpublished)


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Lettucenin A is the major phytoalexin produced by lettuce after elicited by biotic or abiotic elicitors. The production of lettucenin A in leaves can be induced by 5% CUS04 (w/v) and 1 % AgNO₃ (w/v). A clear inhibition zone where the fungus Aspergillus niger failed to grow on TLC bioassay after the chromatogram was developed in hexane: ethyl acetate (1:1 , v/v) at Rf 0.45 was observed. Lettucenin A was detected at a retention time of approximately 5.3 min when analyzed with HPLC in isocratic solvent system with water: acetonitrile (60:40, v/v). In vitro antibacterial study with Xanthomonas campeslris pv. oryzae showed that this pathogen had different sensitivity to all tested concentrations of lettucenin A. The bacterium was more sensitive to higher concentration of lettucenin A (333, 533 and 667 μg mrl�¹) than in lower concentration such as 67 μg mrl�¹. Thus, the relationship between the bacterial growth rate and lettucenin A concentration was negatively correlated. However, the bacterial growth rate was continuing to increase after two hours of incubation time. Hence, it is suggested that X campestris pv. oryzae might had the ability to detoxify the lettucenin A. It is also suggested that the success or failure of X campestris pv. oryzae to invade lettuce depends on a balance between accumulation and degradation of lettucenin A at the invading site of lettuce. In summary, lettucenin A may play an important role in the resistance of lettuce against microbial infection.

Item Type: Academic Exercise
Uncontrolled Keywords: lettucenin, phytoalexin, microbial infection, growth rate, HPLC
Subjects: S Agriculture > SB Plant culture
Divisions: SCHOOL > School of Science and Technology
Date Deposited: 13 Mar 2014 06:57
Last Modified: 12 Oct 2017 06:13

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