Effect of Bacillus subtilis on antioxidant enzyme activities in tomato grafting

Maria D Arias Padró; Emilia Caboni; Karla Azucena Salazar Morin; Marco Antonio Meraz Mercado; Víctor Olalde-Portugal

doi:10.7717/peerj.10984

Effect of Bacillus subtilis on antioxidant enzyme activities in tomato grafting

PeerJ. 2021 Mar 12:9:e10984. doi: 10.7717/peerj.10984. eCollection 2021.

Authors

Maria D Arias Padró¹, Emilia Caboni², Karla Azucena Salazar Morin¹, Marco Antonio Meraz Mercado¹, Víctor Olalde-Portugal¹

Affiliations

¹ Departamento de Biotecnología y Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN, Irapuato, Guanajuato, Mexico.
² Consiglio per la Ricerca in Agricoltura e l 'Analisi dell'Economia Agraria (CREA), Olivicoltura, Frutticoltura e Agrumicoltura (OFA), Rome, Italy.

Abstract

Grafting generally means stress to a plant and this triggers antioxidant defense systems. An imbalance in reactive oxygen species may negatively affect the grafting success. Several research projects have studied the association with plant growth-promoting rhizobacteria (PGPR) and it has been documented that they enhance nutrient acquisition, regulate hormone levels, and influence the antioxidant response in crops. However, little is known about the strategy of inoculating grafted herbaceous plants with PGPR and its effect on the antioxidant response. The effects of inoculating a strain of Bacillus subtilis on the antioxidant metabolism of grafted tomato were evaluated. In this study, two different rootstocks were used for tomato (Solanum lycopersicum L. var. Rio Grande (RG)): [S. lycopersicum L. var. cerasiforme (Ch)] and eggplant [(Solanum melanogena L. (Ber)] to establish a compatible graft (RGCh) and a semicompatible graft (RGBer). Enzyme activities involved in the antioxidant defense system: superoxide dismutase (SOD), catalase (CAT), phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), peroxidase (POD), and total phenols were measured during 4 weeks after grafting. The results show that for RGCh, during the first two weeks after grafting, the tendency was a decrease of the enzyme activity for SOD, CAT, PAL when inoculated with B. subtilis; while in the semicompatible graft RGBer, PPO and PAL decreased their activity after inoculation. For both combinations, the quantity of total phenols varied depending on the day. In both graft combinations, applications of B. subtilis resulted in 86 and 80% callusing compared with the uninoculated control where the percentages were 74 and 70% for RGCh and RGBer, respectively. The highest significant graft success (95%) was recorded 28 days after grafting for inoculated RGBer. These findings imply that B. subtilis induced antioxidant mechanisms in grafted plants and suggest that inoculation with this growth-promoting bacterium can represent a biotechnological approach to improve success in tomato grafting.

Keywords: Antioxidants; B. subtilis; Grafting; Solanum lycopersicum.

Grants and funding

Maria D. Arias Padró’s work was supported by a doctoral scholarship from Consejo Nacional de Ciencia y Tecnología (CONACYT, Mexico). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.