Towards eco-friendly crop protection: natural deep eutectic solvents and defensive secondary metabolites

Plant science

Biochemical components of wild relatives of chickpea confer resistance to pod borer, Helicoverpa armigera

Efforts are being made to develop chickpea varieties with resistance to the pod borer, Helicoverpa armigera for reducing pesticide use and minimizing the extent of losses due to this pest. However, only low to moderate levels of resistance have been observed in the cultivated chickpea to this polyphagous pest. Hence, it is important to explore wild relatives as resistance sources to develop insect-resistant cultivars. Therefore, we studied different biochemical components that confer resistance to H. armigera in a diverse array of wild relatives of chickpea. Accessions belonging to wild relatives of chickpea exhibited high levels of resistance to H. armigera as compared to cultivated chickpea genotypes in terms of lower larval survival, pupation and adult emergence, decreased larval and pupal weights, prolonged larval and pupal developmental periods and reduced fecundity of the H. armigera when reared on artificial diet impregnated with lyophilized leaf powders. Amounts of proteins and phenols in different accessions of chickpea wild relatives were significantly and negatively correlated with larval weight, pupation and adult emergence. Phenols showed a negative correlation with pupal weight and fecundity, but positive correlation with pupal period. Total soluble sugars showed a negative correlation with larval period, but positive correlation with pupation and pupal weight, while tannins showed a positive correlation with larval weight, pupation and adult emergence. The flavonoid compounds such as chlorogenic acid, ferulic acid, naringin, 3,4-dihydroxy flavones, quercetin, naringenin, genistein, biochanin-A and formononetin that were identified through HPLC fingerprints, exhibited negative effects on survival and development of H. armigera reared on artificial diet impregnated with lyophilized leaf powders. The wild relatives with diverse mechanisms of resistance conferred by different biochemical components can be used as sources of resistance in chickpea breeding programs to develop cultivars with durable resistance to H. armigera for sustainable crop production

Luteolin and quercetin affect aphid feeding behavior

AbstractThe flavone luteolin and the flavonol quercetin naturally occur in plants, providing some resistance against herbivores. However, despite suggesting the potential use of these compounds for plant protection, research on their relationship with aphids is limited. The aim of our study was to assess the effect of applying two flavonoids, quercetin and luteolin, at different concentrations, in vitro on the feeding behavior of the black bean aphid Aphis fabae Scopoli (Hemiptera: Aphididae). In most events associated with stylet activity, differences in probing behavior did not vary between the control gel and those with flavonoids. Higher concentrations of quercetin increased the number of penetrations, while lower concentrations of luteolin prolonged the first probing. The addition of flavonoids to the gels reduced passive ingestion. At a concentration of 0.1%, luteolin completely stopped salivation, and at 0.01%, it shortened the average duration of this activity. In events associated with active ingestion, differences in feeding behavior were observed between the control gel and those with quercetin at lower concentrations, affecting the time to the first stylet activity and the average time of active ingestion. Lower concentrations of luteolin prolonged the time to the first active ingestion, the duration of the first active ingestion, and the average time of this activity. Increased concentrations of quercetin and luteolin negatively affected aphid feeding behavior. Quercetin was better tolerated by A. fabae. A more noticeable effect was observed with an increase in luteolin concentration on the feeding behavior of A. fabae. These findings could be applied in biotechnological projects aiming to develop plants resistant to aphids and other herbivores

Analiza zawartości flawonoidów w lucernie

Flavonoid glycosides constitute important group of plant secondary metabolites. This class of natural products play significant role in different physiological processes. Liquid chromatography (HPLC) was used to determine the flavonoid profiles and their concentration in aerial parts of three alfalfa (Medicago sativa L.) cultivars. It was shown that flavonoids of alfalfa are glycosides of four flavone aglycones: apigenin, luteolin, tricin and chrysoeriol. Ali flavonoid glycosides possesed glucuronid acid in sugar chain. Some of them were acylated with ferulic, coumaric or sinapic acids. It was shown that dominant flavonoids of alfalfa were the flavones: tricin and apigenin glycosides (65-72 % of total). The concentration of luteolin and chrysoeriol glycosides did not exceed 30 % of the total. The dominant flavonoid in Radius and Sapko cultivars was glucoside of tricin, in Sitel cultivar glycoside of apigenin. Thus, tricin and apigenin glycosides were the major flavones found in alfalfa aerial parts.Wobec doniesień literaturowych ukazujących różne aspekty interakcji roślina-owad celowe wydaje się poszukiwanie roślinnych substancji chemicznych biorących udział w obronie roślin przed negatywnym wpływem biotycznych czynników środowiskowych. Przykładowo, flawonoidy oddziałują jako deterenty pokarmowe, inhibitory trawienia, a także bezpośrednie toksykanty w stosunku do owadów. Lucerna z uwagi na bogactwo struktur flawonów jest dobrym modelem do prowadzenia prac związanych z tym zagadnieniem. Wiedza na temat występowania flawonoidów w lucernie siewnej, będącej jedną z głównych roślin pastewnych, nie jest pełna, dlatego celem przeprowadzonych badań było zidentyfikowanie i porównanie zawartości flawonoidów w powszechnie użytkowanych odmianach lucerny siewnej (Medicago saliva L.). Badaniom poddano trzy odmiany lucerny: Radius, Sapko i Sitel. Ekstarkcję flawonoidów przeprowadzono z 6-miesięcznych roślin za pomocą metanolu. Rozdział i identyfikację flawonoidów wykonano metodą wysokosprawnej chromatografii cieczowej (HPLC) sprzężonej ze spektrometrią mas. Stwierdzono, że flawonoidy badanych odmian lucerny to glikozydy czterech aglikonów flawonów: apigeniny, luteoliny, trycyny i chryzoeriolu. W łańcuchu cukrowym wszystkich glikozydów występował kwas glukuronowy, a niektóre z nich były acylowane kwasem ferulowym, kumarowym bądź synapinowym. Wykazano, że dominującymi związkami były pochodne trycyny i apigeniny. Łączna zawartość glikozydów apigeniny i trycyny wahała się w granicach 65 do 72 % sumy flawonów badanych lucern. Zawartość glikozydów luteoliny i chryzoeriolu nie przekraczała 30 % sumy flawonów. Dla odmian Radius i Sapko związkiem dominującym był glikozyd trycyny, którego maksymalne stężenie (2.49 mg/ g s.m.) odnotowano w tkankach odmiany Radius. W przypadku odmiany Sitel w największych ilościach występował glikozyd apigeniny (1.31 mg/ g s.m.)