Biokimia Adaptasi 2013 Oleh: Pauline D. Kasi (PBI/1032) S. Hafidhawati A. (PBI/1044) PPS Biologi UGM

PHYTOALEXINS Phytoalexins : low molecular weight, anti-microbial compounds that are both synthesized and accumulated in plants after exposure to microorganisms or abiotic agents (Mert-Türk, 2002) Phytoalexins are compounds synthesized by plants in response to extrinsic stress such as microbial attack and physical injury (Ejike et.al., 2013) Phytoalexins  secondary metabolites by phenylpropanoid, mevalonic acid, and polymalonic acid pathway

Inducer & signaling of phytoalexin  Microbial attack  Elicitors : Induce phytoalexin by mimicking a pathogen attack or other stress.  Signaling to camalexin :  Jasmonic acid, Salysilic acid, ROS  Microbial attack  Elicitors : Induce phytoalexin by mimicking a pathogen attack or other stress.  Signaling to camalexin :  Jasmonic acid, Salysilic acid, ROS

Phytoalexin toxicity Phytoalexin was involved in defense against netrophic but not biotrophic pathogens, also resistance against hemibiotrophy Ex: Camalexin play a role in resistance to the necrotophic fungi Alternaria brassicicola (black spot), but adapted to biotrophic Golovinomyces orontii (powdery mildew) Phytoalexin was involved in defense against netrophic but not biotrophic pathogens, also resistance against hemibiotrophy Ex: Camalexin play a role in resistance to the necrotophic fungi Alternaria brassicicola (black spot), but adapted to biotrophic Golovinomyces orontii (powdery mildew)

Camalexin biosynthesis and regulatory mechanisms (Ahuja et.al., 2012)

Structures of selected phytoalexins

(Ahuja et.al., 2012)

…(continued)

Arachidins, Resveratrol in peanut seed Großkinsky et al., 2012

(Ahuja et.al., 2012)

Phytoalexins application Some phytoalexins have attracted relevant in human health promotion  peanut phytoalexin as anticancer, antidiabetic and vasodilator effects (Boue et al., 2009; Holland & O'Keefe, 2010) Food preservatives in cereal foods crop (Ejike et al., 2013) Phytoalexin from grapevine has anti-carcinogenic and anti-inflammatory (Smoliga, 2011)

References  Ahuja, I., Kissen, R. & Bones, A.M. (2012). Phytialexins in defense against pathogens. Trends in Plant Science 17(2) :  Boue, S.M., Cleveland, T. E., Carter-Wientjes, C., Shih, B. Y., Bhatnagar, D.,McLachlan, J.M., et al. (2009). Phytoalexin-enriched functional foods. Journal of Agricultural and Food Chemistry, 57: 2614–2622.  Großkinsky, D.K, Graaff, E. & Roitsch, T. (2012). Phytoalexin transgenics in crop protection—Fairy tale with a happy end?. Plant Science 195 : 54– 70  Holland, K. W., & O'Keefe, S. F. (2010). Recent applications of peanut phytoalexins. Recent Patents on Food, Nutrition & Agriculture, 2 : 221– 232.  Smoliga, J.M. et al. (2011) Resveratrol and health – a comprehensive review of human clinical trials. Mol. Nutr. Food Res. 55 :1129–1141

Diskusi 1.Pada organ apa fitoalexin disentesis? (Darussalam) Fitoaleksin disintesis pada hampir semua organ tanaman, dimana ada serangan patogen yang terjadi. Semakin dekat dengan tempat terjadinya serangan patogen, konsentrasi fitoaleksin semakin besar.

Diskusi 2.Apakah ada perbedaan signal dari pathogen dengan signal dari Jasmonic Acid? (Nurul) Ada. Serangan dari patogen yang akan memicu terbentuknya jasmonic acid. Jasmonic acid merupakan salah satu signaling bagi camalexin pada Arabidopsis.

Diskusi 3.Bagaimana mekanisme pertahanan jika terjadi serangan dari virus? Apakah sama dengan bakteri? (Darussalam) Mekanisme pertahanan terhadap virus berbeda dengan patogen lainnya. Virus mampu menduplikasi asam nukleat yang terdapat pada sel tumbuhan. Beberapa tumbuhan mampu membentuk vaksin untuk menangkal virus tersebut. Namun mekanisme pembentukan vaksin tersebut berbeda dengan biosintesis fitoaleksin.