Влияние абсцизовой кислоты на восприимчивость листьев пшеницы к возбудителю мучнистой росы Blumeria graminis f. sp. tritici

Abstract

Абсцизовой кислоте (АБК) принадлежит важная роль в регуляции защитных процессов при стрессах различной природы. В отличие от абиотических стрессов при взаимодействии растения и патогена этот фитогормон в большинстве случаев является негативным регулятором устойчивости. Однако даже при сходном характере патогенеза активность АБК может быть разнонаправленной. В частности, обработка АБК в разных экспериментах индуцировала как снижение, так и увеличение восприимчивости злаков к мучнистой росе. Целью данной работы явилось изучение иммуномодулирующих свойств экзогенной АБК в зависимости от ее концентрации в патосистеме, включающей растения пшеницы Triticum aestivum L. и возбудитель мучнистой росы Blumeria graminis (DC.) Speer f. sp. tritici (syn. Erysiphe graminis). Исследовали изменение числа колоний патогена на листьях восприимчивой пшеницы (сортов Заря и Тавричанка) при обработке 2-недельных проростков различными концентрациями АБК (0–9 мкМ) до и непосредственно после инфицирования. При обработке целых растений АБК добавляли в раствор Кнопа, в экспериментах с отделенными листьями на плаву в чашках Петри использовали водные растворы фитогормона. Показано, что величина и направленность воздействия экзогенной АБК на число колоний патогена зависят от ее концентрации и времени применения относительно момента инфицирования. Концентрационная зависимость для АБК варьировала по форме, могла иметь минимум (уменьшение восприимчивости) или максимум (увеличение восприимчивости) числа колоний при сходных концентрациях. При этом ингибирование роста патогена было более характерно при предварительной обработке АБК. Немонотонность и варьирование формы зависимости от концентрации, вероятно, могут объяснить имеющуюся в литературе неоднозначность при определении иммуномодулирующих свойств АБК. Сложный характер концентрационной зависимости и обусловленное им варьирование в достаточно широких пределах иммунологического состояния, по-видимому, обеспечивают поддержание равновесия в патосистеме и шансы на выживание как растению-хозяину, так и патогенному организму

Abscisic acid (ABA) plays an important role in the regulation of protective processes under stresses of various nature. In contrast to abiotic stresses, when a plant and a pathogen interact, this phytohormone is in most cases a negative regulator of resistance. However, even with a similar nature of pathogenesis, ABA can produce different effects. For example, ABA treatment in different experiments induced either a decrease or an increase in the susceptibility of cereals to powdery mildew. The aim of this work was to study the immunomodulatory properties of exogenous ABA depending on its concentration in the pathosystem composed of wheat Triticum aestivum L. plants and powdery mildew pathogen Blumeria graminis (DC.) Speer f. sp. tritici (syn. Erysiphe graminis). We studied the change in the number of pathogen colonies on susceptible wheat leaves (Zarya and Tavrichanka varieties) when two-week-old seedlings were treated with various ABA concentrations (0–9 μM) before and immediately after they were infected. When whole plants were used in the experiment, ABA was added to Knop’s solution; in experiments with detached leaves floating in Petri dishes, aqueous solutions of the phytohormone were used. Our results show that the magnitude and direction of the effect of exogenous ABA on the number of colonies of the pathogen depends on its concentration and the time of application relative to the moment of infection. ABA concentration dependence was variable in form: similar concentrations could be inhibitory, resulting in the minimum number of colonies, or stimulating, with the maximum number of colonies. At the same time, the pre-infection use of ABA was more likely to be inhibitory. The non-monotonicity and variation of the form of concentration dependence could probably account for the contradictory literature data on the immunomodulatory properties of ABA. The complex nature of the concentration dependence and the corresponding variation in the immunological state within a fairly wide range seem to ensure the Abscisic acid (ABA) plays an important role in the regulation of protective processes under stresses of various nature. In contrast to abiotic stresses, when a plant and a pathogen interact, this phytohormone is in most cases a negative regulator of resistance. However, even with a similar nature of pathogenesis, ABA can produce different effects. For example, ABA treatment in different experiments induced either a decrease or an increase in the susceptibility of cereals to powdery mildew. The aim of this work was to study the immunomodulatory properties of exogenous ABA depending on its concentration in the pathosystem composed of wheat Triticum aestivum L. plants and powdery mildew pathogen Blumeria graminis (DC.) Speer f. sp. tritici (syn. Erysiphe graminis). We studied the change in the number of pathogen colonies on susceptible wheat leaves (Zarya and Tavrichanka varieties) when two-week-old seedlings were treated with various ABA concentrations (0–9 μM) before and immediately after they were infected. When whole plants were used in the experiment, ABA was added to Knop’s solution; in experiments with detached leaves floating in Petri dishes, aqueous solutions of the phytohormone were used. Our results show that the magnitude and direction of the effect of exogenous ABA on the number of colonies of the pathogen depends on its concentration and the time of application relative to the moment of infection. ABA concentration dependence was variable in form: similar concentrations could be inhibitory, resulting in the minimum number of colonies, or stimulating, with the maximum number of colonies. At the same time, the pre-infection use of ABA was more likely to be inhibitory. The non-monotonicity and variation of the form of concentration dependence could probably account for the contradictory literature data on the immunomodulatory properties of ABA. The complex nature of the concentration dependence and the corresponding variation in the immunological state within a fairly wide range seem to ensure the