Susan S. Martin Research Collins CO ABSTRACT. lesions isoflavone flavanone detected. The to

Transcription

1 72 Journal of Sugar Beet Research Vol 27 No3 &4 Susan S. Martin Research Collins CO ABSTRACT lesions isoflavone flavanone detected. The to PrE~sumed to malin1:en.an<:e of

2 July-December 1990 Flavonoid Phytoalexins 'VICU.'-,I>.J.J.<'" are low molecular antimicrobial and accumulated in studies have 7nllfT/17t",", lines to SYlltllleS:lze CLS infection. 1. Structures of be1:agann et BETAVULGARIN 2'-hydroxy-5-methoxy-6,7-methylenedioxyisoflavone BETAGARIN 5,2'-dimethoxy-6,7-methylenedioxyflavanone The spe,cles 711JUtflV1C in the broad sense includes a of diverse Dn,enOnlD(~S are believed to have been rldr",,,",,, human sellectlon table achieved

3 74 Journal of Sugar Beet Research Vol 27 No 3 &4 maritima the Asia and westward to the Coast of to the is reasonable the Mediterranean ancestors of the cultivated had a close associahon with which is that in when he sp4~clm ~ns at herbaria in lithe were almost II If B or BV is involved,""..~,,,-u.a,,-, which is n1"':'c01'lt should be diseased forms disease evaluation gel~mljla:5m collection of the Introcluc:tIOifi Station at "Y'o""",...M,n'T'tT for such a MATERIALS AND METHODS Because of this work was to determine whether flavonoid was absent in line were odt:alrlea at various times and under various circumstances. In the SarnpJlea

4 July-December 1990 Flavonoid Phytoalexins were lac~nlculea which were obtained on-line from a phot()dllodle de"tector and recorded. The chlrornal:og;raltn each was recorded at 280 nm and areas were determined with an electronic were at a detector of absorbance unit full and an mtegj~at()r attenuation of X 512. Table RESULTS AND DISCUSSION salnr:>le(l, and the presence lines were C111rn"r'I':>"t'"U results are listed in Band BV in each it ",,,,>,,,,1-,i-,,,.i-,",'7'" OJmlpanSon of lesions of years, as were tpe sainp>1es of 1ag;mamn and Gnset:)aCJn, Band BV do not identical so a direct conversion of the flavanone B to the isoflavone BV cannnot be 1-'''-'''><''''''-'''''''-'-'-, but the lack of B in some smnples cll">'1nl'it indicate that it has been transformed to other n1",'-'''l1(,i"c

5 76 Journal of Sugar Beet Research Vol 27 No 3 &4 O>J','()C1VU'I1'n V'~H'~V"'" tested and numbers are from the USDA- Iowa State IA. Line or PI Number Presence of BV B tr 2 U.S. Collins) 3 PI roots 4 India PI table type; red leaves, roots 5 India PI annual 6 PI table red leaves, roots 7 Yugoslavia PI-3S7360 'Ohridska Z01ta'; Fodder type 8 Australia PI 'Fordhook Master'; Chard tr 9 Yugoslavia PI 'Domasne'; erect annual nd 10 Poland I Har'; fodder type; nd roots 11 Poland PI Iran white or 13 USSR type 14 Gr. Britain Red table-beet 15 U.S. inbred; LSR 16 U.S. 17 U.S. Smooth root x table) 18 'Monohikari' (commercial 19 U.S. Yellow leaf mutant (Ft. Collins ) 20 China CH China 22 China PI feng 6';

6 July-December 1990 Flavonoid Phytoalexins 77 ID Country Line or Presence of Nr of Origin PI Number Description or comment BV B 23 China PI 'Shuang feng 304'; sugarbeet 24 Iran PI 'Choghondar' 25 Poland PI 'Poly Mono Ihar' 26 China PI 'Tzu Lo Pu Tou'; most roots red tr 27 Turkey PI Some roots red; some bolters tr J I Manchuria PI Iran PI Most roots red 'Choghondar' ' 30 Iran PI 'Choghondar'; some roots red; bolter nd 31 Iran PI 'Chaghonda'; most roots red tr 32 Turkey PI 'Cicla'; 'Pazi'; some roots red; annual tr 33 Turkey PI tr 34 U.s. FC502-3 CMS Hybrid; LSR X FC U.s. SP Sclerotium rolfsii resistant inbred with beta garin, represent all possible combinations of methoxy or hydroxy substitution at the 5 and 2' positions (Fig. 1; i.e., 5,2' dihydroxy; 5-hydroxy-2' -methoxy; 2' -hydroxy-5-methoxy; and 5,2'-dimethoxy). Thus, small amounts of the flavanone equivalent of betagarin may be detectable on occasion, although normally it is converted to the isoflavone. Structural characterization of the three unknown flavanones is in progress. Isoflavonoids such as BV are well-known as phytoalexins, although they are produced most commonly by members of the plant family Fabaceae (Leguminosae) (Ingham, 1982, 1983). However, among the hundreds of known isoflavonoids, betavulgarin thus far is unique to members of the genus Beta, as it has not been reported from any other plant taxon, even its botanical relative, spinach (Spinacia), a member of the same plant family (Richardson, 1981). BV, in particular, is effective in limiting the growth of C. beticola in in vitro bioassays (Johnson et al., 1976; Martin, 1977; Ruppel and Martin, unpublished), and amounts of BV accumulated by a single lesion are sufficient to limit fungal expansion (Martin, 1977). Thus, the rapidity and quantity of phytoalexin accumulation may contribute to a complex of responses that together determine the degree of

7 78 Journal of Sugar Beet Research Vo127No3&4 resistance exhibited the host plant. Without exception, the diverse derived Beta and phenotypes I tested produced the flavonoid BV in to Cercospora leaf disease. of BV's involvement in it is a if the compound is to be invoked as a resistance factor. Richardson ) found betavulgarin was synthesized several Beta species after induction by a spore suspension of non-pathogenic (to Beta) fungus Helminthosporium carbonum; however, BV was not detected in a few plants of B. maritima ("from French II Richardson, 1981). leaves of Beta from a botanic in London did not produce BV H. carbonum whereas B. trigyna plants grown from seed of two Russian populations accumulated BY. It is that the short elicitation time or comparatively techniques used of compounds into suspension droplets on leaves, followed by and chromatography) account for the lack of detectable production, or it simply could be that H. carbonum is not as effective as C. beticola in eliciting BV It is also that the populations in question do not have the to produce BV, or that produce an alternative At rate, negative finding will be to continue to explore the ability species to produce Band BV when infected by C. beticola. Harlan (1976) noted that when a defensive strategy a QIE,eaSe-ln(lW:::lng fungus involves the of fungistatic or there is a cost to the host. Thus, continuous selection for production of the secondary compounds is Smith and Gaskill (1970) showed that the genetic of resistance of to C. beticola is complex, involving a minimum of or 5 gene os'vnlthe~t1c sequence to flavonoids also complex, "CI,l111"'~,o- the activation of several major biochemical pathways InCluc:non of enzymes. These observations that there must been considerable selection pressure to maintain this biochemical pathway in sugarbeet. In Beta vulgaris lato), a long relationship with C. beticola appears to have resulted in a balance between host and pathogen, and may be an cause for the maintenance of flavonoid... h"ti~-r'-',u....<.~.i'uh s'vnthe:sls. ACKNOWLEDGEMENTS I thank Drs. Earl and Richard Hecker for allowing me to sample the Cercospora-infected plants from their studies, and David M. Tinnermeier for careful technical assistance.

8 July-December 1990 Flavonoid Phytoalexins 79 LITERATURE CITED G. H The wild of Beta. Proc. Am. Soc. Beet Technol. 8: "-''-''',,",l,''' G. H Int(~rspeC1tlC "'",...,..." 1. and the wild SPE~CH~S Technol. 18(4): F. R. \..;.t-lo't""n"'"t'7 leaves... '-~)'...".."-,.u,v'... M., and H. Grisebach. of flavanone to isoflavone. evolution. isoflavonoids.j"ru,e01acjtl, and G. W. of Accumulation of the flavonoids '-'-"F.,',"',J... l in Beta infected 01'",rl<O""'''1'1> beticola. Plant term redefinition. and

9 80 Journal of Sugar Beet Research Vol 27 No 3 &4 E. C. and J evaluation of beticola in the 16: C. and J. O. 'l.,ju,"'...l.u. leaf Inheritance of resistance J. Amer. Soc. Technol. A Flavonoid Metabolism. CRC Raton FL. 320 pp. Boca