Effects of Endophytic Bacillus Subtilis and Salicylic Acid on Postharvest Diseases (Phytophthora infestans, Fusarium oxysporum) Development in Stored Potato Tubers

Abstract

Postharvest diseases of potato lead to significant food and economic losses worldwide. The exogenous application of eco-friendly methods plays an important role in the control of postharvest decay. In this work the effects of endophytic bacteria B. subtilis (10-4, 26D) were studied in the context of two application parameters: concentration, with a range between 103–108 CFU/mL tested, and synergistic effects of the signal molecule salicylic acid (SA) (0.05 mM) on potato tubers’ resistance to Phytophthora infestans and Fusarium oxysporum during storage. The experiments were carried out on hydroponically grown potato (Solanum tuberosum L.) mini-tubers. This study demonstrates the suppressive effect of B. subtilis (10-4, 26D) on diseases of potato during storage and reveals that this effect happens in a dose-dependent manner, both individually and in combination with SA. The most effective concentrations of B. subtilis for suppression of both Ph. infestans and F. oxysporum are 108 CFU/mL (10-4 and 26D), 107 CFU/mL (10-4 + SA) and 106 CFU/mL (26D + SA). The ability of B. subtilis (10-4, 26D) to effectively penetrate and colonize the internal tubers’ tissues when applied immediately prior to storage, and the ability of SA to accelerate these processes, have been proven. B. subtilis (10-4, 26D), individually and in compositions with SA, increased ascorbic acid content and decreased pathogen-induced proline accumulation and lipid peroxidation in tubers. This indicates a protective effect conferred to cells against reactive oxygen and an extension of aging processes, manifested by a prolonged shelf life and extended preservation of fresh appearance.

Occurrence of Sweetpotato (Ipomoea batatas) Wilt and Surface Rot Disease and Determining Resistance of Selected Varieties to the Pathogen in Korea

“…On the basis of symptoms, a disease severity index was established and categorized using a 0-to-5 scale. Categories were as follows: 0 = seedlings grew normally without visible symptoms; 1 =~5% browning and cracking in vascular bundle length; 2 =~25% browning and cracking, 3 =~25% browning and cracking in vascular bundle length and yellowing of the bottom leaves; 4 = browning of the entire vascular and discoloration of all the leaves; 5 = seedling collapsed and died [49]. The final disease index (DI) was calculated using the following formula:…”

The Effect of Endophytic Bacteria Bacillus subtilis and Salicylic Acid on Some Resistance and Quality Traits of Stored Solanum tuberosum L. Tubers Infected with Fusarium Dry Rot

“…With that, Bacillus efficiency might depend on various factors, including strain characteristics (epiphytes or endophytes), application methods (before or after harvest/storage), type of pathogens/hosts, etc. [9,16]. Additionally, there is interest in the co-application of B. subtilis alongside other biological agents in an integrated vision of disease management due to the lack of individual strains with broad spectrum activity against a wide range of pathogens.…”

“…Numerous studies have indicated the potential of SA postharvest application for reducing chilling injury and decay, delaying ripening, and enhancing the health benefits of fruit and vegetable consumption by increasing antioxidant capacity [17]. However, there is little information regarding the influence of the joint application of endophytic B. subtilis with SA on plant growth, development, and postharvest physiology of healthy and pathogens-infected potatoes during long-time storage [16,18,19]. In our recent work, we generated data about endophytic B. subtilis (strains 10-4, 26D), alone or in compositions with SA, increasing the resistance of potato tubers to Phytophthora infestans and Fusarium oxysporum during long-time storage, which was accompanied with prolonging shelf-life of potatoes and preserving their appearance [16].…”

“…However, there is little information regarding the influence of the joint application of endophytic B. subtilis with SA on plant growth, development, and postharvest physiology of healthy and pathogens-infected potatoes during long-time storage [16,18,19]. In our recent work, we generated data about endophytic B. subtilis (strains 10-4, 26D), alone or in compositions with SA, increasing the resistance of potato tubers to Phytophthora infestans and Fusarium oxysporum during long-time storage, which was accompanied with prolonging shelf-life of potatoes and preserving their appearance [16]. The findings suggest B. subtilis decrease as disease incidence in potato due to colonizing internal tissues and protect cells inside against pathogen development and stress-induced cell damages, therewith, controlling aging processes [16].…”

“…In our recent work, we generated data about endophytic B. subtilis (strains 10-4, 26D), alone or in compositions with SA, increasing the resistance of potato tubers to Phytophthora infestans and Fusarium oxysporum during long-time storage, which was accompanied with prolonging shelf-life of potatoes and preserving their appearance [16]. The findings suggest B. subtilis decrease as disease incidence in potato due to colonizing internal tissues and protect cells inside against pathogen development and stress-induced cell damages, therewith, controlling aging processes [16]. However, the mechanisms underlying B. subtilis actions both alone and in compositions with SA on potato under postharvest pathogen's infection are largely unknown and they require further detailed investigations to fully realize their potential in agricultural/food industries.…”