Evaluating Rhizobacterial Antagonists for Controlling Cercospora beticola and Promoting Growth in Beta vulgaris

Zakariae El Housni; Said Ezrari; Nabil Radouane; Abdessalem Tahiri; Abderrahman Ouijja; Khaoula Errafii; Mohamed Hijri

doi:10.3390/microorganisms12040668

Evaluating Rhizobacterial Antagonists for Controlling Cercospora beticola and Promoting Growth in Beta vulgaris

Microorganisms. 2024 Mar 27;12(4):668. doi: 10.3390/microorganisms12040668.

Authors

Zakariae El Housni^{1

2}, Said Ezrari³, Nabil Radouane⁴, Abdessalem Tahiri², Abderrahman Ouijja¹, Khaoula Errafii⁴, Mohamed Hijri^{4

5}

Affiliations

¹ Laboratory of Biotechnology and Molecular Biology, Department of Biology, Faculty of Science, Moulay Ismail University, Zitoune, Meknès 50050, Morocco.
² Phytopathology Unit, Department of Plant Protection, Ecole Nationale d'Agriculture de Meknès, BPS 40, Meknès 50001, Morocco.
³ Microbiology Unit, Laboratory of Bioresources, Biotechnology, Ethnopharmacology and Health, Faculty of Medicine and Pharmacy Oujda, University Mohammed Premier, P.O. Box 724 Hay Al Quods, Oujda 60000, Morocco.
⁴ African Genome Center, University Mohammed VI Polytechnic (UM6P), Lot 660, Hay Moulay Rachid, Ben Guerir 43150, Morocco.
⁵ Institut de Recherche en Biologie Végétale (IRBV), Département de Sciences Biologiques, Université de Montréal, Montréal, QC H1X 2B2, Canada.

Abstract

Cercospora beticola Sacc. is an ascomycete pathogen that causes Cercospora leaf spot in sugar beets (Beta vulgaris L.) and other related crops. It can lead to significant yield losses if not effectively managed. This study aimed to assess rhizosphere bacteria from sugar beet soil as a biological control agent against C. beticola and evaluate their effect on B. vulgaris. Following a dual-culture screening, 18 bacteria exhibiting over 50% inhibition were selected, with 6 of them demonstrating more than 80% control. The bacteria were identified by sequencing the 16S rRNA gene, revealing 12 potential species belonging to 6 genera, including Bacillus, which was represented by 4 species. Additionally, the biochemical and molecular properties of the bacteria were characterized in depth, as well as plant growth promotion. PCR analysis of the genes responsible for producing antifungal metabolites revealed that 83%, 78%, 89%, and 56% of the selected bacteria possessed bacillomycin-, iturin-, fengycin-, and surfactin-encoding genes, respectively. Infrared spectroscopy analysis confirmed the presence of a lipopeptide structure in the bacterial supernatant filtrate. Subsequently, the bacteria were assessed for their effect on sugar beet plants in controlled conditions. The bacteria exhibited notable capabilities, promoting growth in both roots and shoots, resulting in significant increases in root length and weight and shoot length. A field experiment with four bacterial candidates demonstrated good performance against C. beticola compared to the difenoconazole fungicide. These bacteria played a significant role in disease control, achieving a maximum efficacy of 77.42%, slightly below the 88.51% efficacy attained with difenoconazole. Additional field trials are necessary to verify the protective and growth-promoting effects of these candidates, whether applied individually, combined in consortia, or integrated with chemical inputs in sugar beet crop production.

Keywords: Cercospora beticola; Cercospora leaf spot; biological control; plant growth-promoting rhizobacteria; sugar beet.

Grants and funding

This study was supported by funds from the Moulay Ismail University, École Nationale d’Agriculture de Meknès, and University Mohammed VI Polytechnic (UM6P), which is gratefully acknowledged.