Allelochemicals Biologica... - Name

ALLELOCHEMICALS FROM AGERATUM CONYZOIDES AND ORYZA SATIVA 201
R=-(CH 2 ) 12 CH 3 , -(CH 2 ) 14 CH 3 , -(CH 2 ) 16 CH 3 , -(CH 2 ) 7 CH=CH(CH 2 ) 5 CH 3 , -
(CH 2 ) 7 CH=CH(CH 2 ) 7 CH 3 , -(CH 2 ) 7 CH=CHCH 2 CH=CH(CH 2 ) 4 CH 3
Figure 6. Alkylresorcinols.
3.2. Diterpene and flavone phytoalexins from rice
Allelochemicals play an important role in rice disease resistance (Bailey and Mansfield,
1982). Antifungal allelochemicala, phytoalexins produced by rice in response to injury,
physiological stimuli or in the presence of infectious agents (Hammerschmidt, 1999).
In particular, phytoalexins can be induced and accumulated by rice after fungal
infection. Phytoalexins from rice mainly involve two types of diterpenes and flavones,
including momilactones A and B, oryzalexins A-F and S, phytocassanes A-E and
sakuranetin (Figures 7, 8).
Momilactone A Momilactone B Sakuranetin
Oryzalexin A: R 1 =OH, R 2 =CH 3 Oryzalexin E: R=CH 3 Oryzalexin S
Oryzalexin B: R 1 =O, R 2 =OH Oryzalexin F: R=CH 2 OH
Oryzalexin C: R 1 =O, R 2 =O
Oryzalexin D: R 1 =OH, R 2 =O
Figure 7. Typical diterpene and flavone phytoalexins from rice.