The Effect of Myco-Biocontrol Based Formulates on Yield, Physiology and Secondary Products of Organically Grown Basil

The development of organic farming as a result of increasing consumer preference for organic food has led to the development and registration of new pest-control products for certified organic production. In this study, the effects of three biocontrol products containing spores and mycelium of Arthrobotrys oligospora—Artis®, Beauveria bassiana—Bora®, and Coniothyrium minitans—Öko-ni® were tested on four basil (Ocimum basilicum L.) cultivars: ‘Aromat de Buzau’, ‘Serafim’, ‘Macedon’ and ‘Cuisoare’. The application of Öko-ni® increased basil yields by 8% relative to Control. The application of Bora® increased chlorophyll content of basil leaves by 2% and the activity of photosynthesis by 66% relative to the Control. Basil essential oil (EO) content was increased by 18% with the application of Artis® and by 34% with the application of Bora® and Öko-ni®, respectively. The content of phenolic compounds analyzed by HPLC varied; caffeic acid concentration was higher in the plants treated with Öko-ni®, hyperoside, isoquercitrin and rutin concentrations were higher in those treated with Artis®, while the quercitrin content was higher in Bora®-treated plants. The two main EO constituents that were identified were linalool and methyl chavicol in ‘Aromat de Buzau’, linalool and eugenol in ‘Serafim’, neral and geranial in ‘Macedon’, also linalool and eugenol in ‘Cuisoare’. The investigated myco-biocontrol products had positive effects on basil fresh biomass and EO content and also influenced the content of phenolic compounds.

Genome Sequence of the Biocontrol Agent Coniothyrium minitans strain Conio (IMI 134523)

Coniothyrium minitans (synonym, Paraphaeosphaeria minitans) is a highly specific mycoparasite of the wide host range crop pathogen Sclerotinia sclerotiorum. The capability of C. minitans to destroy the sclerotia of S. sclerotiorum has been well recognised and it is available as a widely used biocontrol product Contans® WG. We present the draft genome sequence of C. minitans strain Conio (IMI 134523), which has previously been used in extensive studies that formed part of a registration package of the commercial product. This work provides a distinctive resource for further research into the molecular basis of mycoparasitism to harness the biocontrol potential of C. minitans.

Genome-Wide Identification and Expression Analysis of the bZIP Transcription Factors in the Mycoparasite Coniothyrium minitans

The basic leucine zipper (bZIP) proteins family is one of the largest and most diverse transcription factors, widely distributed in eukaryotes. However, no information is available regarding the bZIP gene family in Coniothyrium minitans, an important biocontrol agent of the plant pathogen Sclerotinia sclerotiorum. In this study, we identified 34 bZIP genes from the C. minitans genome, which were classified into 8 groups based on their phylogenetic relationships. Intron analysis showed that 28 CmbZIP genes harbored a variable number of introns, and 15 of them shared a feature that intron inserted into the bZIP domain. The intron position in bZIP domain was highly conserved, which was related to recognize the arginine (R) and could be treated as a genomic imprinting. Expression analysis of the CmbZIP genes in response to abiotic stresses indicated that they might play distinct roles in abiotic stress responses. Results showed that 22 CmbZIP genes were upregulated during the later stage of conidial development. Furthermore, transcriptome analysis indicated that CmbZIP genes are involved in different stages of mycoparasitism. Among deletion mutants of four CmbZIPs (CmbZIP07, -09, -13, and -16), only ΔCmbZIP16 mutants significantly reduced its tolerance to the oxidative stress. The other mutants exhibited no significant effects on colony morphology, mycelial growth, conidiation, and mycoparasitism. Taken together, our results suggested that CmbZIP genes play important roles in the abiotic stress responses, conidial development, and mycoparasitism. These results provide comprehensive information of the CmbZIP gene family and lay the foundation for further research on the bZIP gene family regarding their biological functions and evolutionary history.

CmAim24 Is Essential for Mitochondrial Morphology, Conidiogenesis, and Mycoparasitism in Coniothyrium minitans

ABSTRACT Coniothyrium minitans is an important mycoparasite of the notorious phytopathogenic fungus Sclerotinia sclerotiorum. The mycoparasitism system of C. minitans-S. sclerotiorum is unique and important in probing fungi and fungal interactions. Here, we report a conidiation-deficient mutant, ZS-1TN1961, which was screened from a transfer DNA (T-DNA) insertional library of C. minitans. A single-copy gene, encoding a protein with high sequence similarity to Aim24 (altered inheritance of mitochondria protein 24) in Saccharomyces cerevisiae, was disrupted by T-DNA insertion in this mutant. Gene replacement and complementation experiments confirmed that mutants lacking CmAim24 exhibited significantly reduced conidial production and germination as well as reduced sclerotial mycoparasitic ability. Furthermore, cellular localization assays showed that CmAim24 localized to mitochondria, and abnormal mitochondria were observed in the ΔCmAim24 mutant. The ΔCmAim24 mutant exhibited significant accumulation of reactive oxygen species (ROS) and a reduced ATP content in mycelia. In summary, our results suggest that CmAim24 plays a key role in mitochondrial architecture and function, conidiogenesis, and mycoparasitism in C. minitans. IMPORTANCE Aim24 proteins are involved in mitochondrial biogenesis and accumulate between the two membranes of a mitochondrion. Their function in prokaryotes and filamentous fungi is as yet unknown. In the present study, we characterized an Aim24 protein, CmAim24, in the mycoparasite Coniothyrium minitans and proved its critical role in mitochondrial morphology and function, conidiogenesis, conidial germination, and mycoparasitism to S. sclerotiorum.