Changes in the content of phenolic compounds in sunflower leaves after inoculation with the causal agent of downy mildew

Abstract

Two nearly isogenic lines of sunflower, resistant and susceptible to downy mildew, due to the presence/absence of the Pl6 gene, were used in this study. Inoculation with the suspension of Plasmopara halstedii zoospores, was done on the plants in the phase of first pair of leaves. In the samples taken from 2nd to 96th h after inoculation, content of phenolic compounds in methanolic extracts from frozen leaves were analyzed (UV-VIS and HPLC analysis). A constitutive level of phenolic compounds, as well as, their accumulation after the inoculation were higher in the susceptible than in the resistant isogenic line. Chlorogenic, ferulic acid and esculin had the highest contribution to the phenolic compound accumulation 24 h after the inoculation in the susceptible line, while only the chlorogenic acid and eculin accumulated in the resistant line. Also, there was a trend of scopoletin accumulation in the resistant line.

U ovom radu korišćene su dve izogene linije suncokreta koje se razlikuju po prisustvu Pl6 gena za otpornost prema plamenjači. U fazi prvog para listova izvršena je inokulacija biljaka suspenzijom zoospora Plasmopara halstedii. U uzorcima uzetim od dva do 96 h nakon inokulacije, analiziran je sadržaj fenolnih jedinjenja u metanolnim ekstraktima iz zamrznutih listova suncokreta (UV-VIS i HPLC analiza). Konstitutivni nivo fenolnih jedinjenja, kao i njihova akumulacija nakon inokulacije su veći kod osetljive nego kod otporne izogene linije. Najveći doprinos akumulaciji fenolnih jedinjenja 24 h nakon inokulacije kod osetljive linije imaju hlorogena, ferulična kiselina i eskulin, a kod otporne linije hlorogena kiselina i eskulin. Kod otporne linije postoji trend akumulacije skopoletina.