Identification and Functional Verification of Differences in Phenolic Compounds Between Resistant and SusceptiblePopulusSpecies

Abstract

Poplar canker, mainly caused by Botryosphaeria species, is a serious disease that has resulted in the reduced productivity and death of poplar worldwide. Different Populus species have varied resistance levels to poplar canker; however, whether phenolic compounds in poplar are involved in this resistance remains uncertain. Here, we determined the concentrations of phenolic compounds and their antifungal activities in canker-resistant P. tomentosa and canker-susceptible P. beijingensis. We identified 29 phenolic compounds with significantly different concentrations between the two species. Salicylic acid (SA), tremuloidin, salicin, and poplin were dominant in P. tomentosa, while benzoic acid (BA) and catechol were dominant in P. beijingensis. These six phenolic compounds were further tested for antifungal activities. SA, BA, and catechol showed significant antifungal activities against Botryosphaeria dothidea, while the other three compounds showed no activity. As BA or catechol can be converted in plants to SA, which is a remote signaling molecule that plays an important role in plant defenses, we presumed that the resistance of P. tomentosa was initiated by SA, while the susceptibility of P. beijingensis resulted from the absence of SA. Further studies are required to confirm this hypothesis. These results provide a foundation for future research on the disease-resistance mechanisms of poplar.

Priming of Resistance-Related Phenolics: A Study of Plant-Associated Bacteria and Hymenoscyphus fraxineus

“…Several studies have reported that 1-5% of European ash genotypes may possess a durable, high, but partial resistance to H. fraxineus [11,[22][23][24][25][26][27]. Tree resistance to pathogens is related to their ability to synthesize and mobilize secondary metabolites (SMs) [2,[28][29][30][31], since these SMs (ex. phenolics) may perform numerous protective functions and their amount is related to general or specific plant pathogenic resistance [2,28,32,33].…”

Impact of Plant-Associated Bacteria on the In Vitro Growth and Pathogenic Resistance against Phellinus tremulae of Different Aspen (Populus) Genotypes

“…Plant growth promoting bacteria are being more widely used in agriculture, as an eco-friendly alternative to chemical fertilizers and pesticides [7,12]; however, the potential application of such beneficial bacteria in forestry has not yet been sufficiently explored [13]. Tree resistance to pathogens is related to the general viability of trees and their ability to synthesize and mobilize secondary metabolites (SMs) [4,[14][15][16][17]. Modern technologies for the improvement of forest tree planting material include quantitation of phenolic compounds, since these SMs perform numerous protective functions and their amount is related to general or specific plant pathogenic resistance [4,14,18,19].…”

“…Tree resistance to pathogens is related to the general viability of trees and their ability to synthesize and mobilize secondary metabolites (SMs) [ 4 , 14 , 15 , 16 , 17 ]. Modern technologies for the improvement of forest tree planting material include quantitation of phenolic compounds, since these SMs perform numerous protective functions and their amount is related to general or specific plant pathogenic resistance [ 4 , 14 , 18 , 19 ].…”

“…Endophytic bacteria were proven to have an effect on plants’ secondary metabolism [ 16 , 20 , 21 ]; however, overall, little is known about the mechanisms of how this happens [ 16 ]. Moreover, studies show that the ability of different plant genotypes to synthesize SMs and mobilize them against pathogens is variable; therefore, genetic selection is appropriate in this respect [ 4 , 14 , 15 , 18 ].…”

“…Eurasian aspen ( Populus tremula L.) are common pioneer trees in the Northern Hemisphere [ 15 , 22 , 23 , 24 , 25 , 26 ]. Furthermore, aspen and its hybrids are extensively grown for various commercial enterprises [ 14 , 15 , 25 , 27 , 28 ], as well as being used as a model species for not only woody plant experiments [ 28 ], but also plant–microbe interaction studies [ 29 ]. Even so, aspen trees suffer from fungal pathogens throughout their habitat range [ 15 , 30 , 31 ].…”