A novel species of Botrytis isolated from peony in Alaska, USA, and grape in Trento District, Italy, was identified based on morphology, pathogenicity, and sequence data. The grape and peony isolates share sequence homology in the glyceraldehyde-3-phosphate dehydrogenase (G3PDH), heat shock protein 60 (HSP60), DNA-dependent RNA polymerase subunit II (RPB2), and necrosis- and ethylene-inducing protein 1 and 2 (NEP1 and NEP2) genes that place them in a distinct group closely related to B. aclada, a globally distributed pathogen of onions. Genetic results were corroborated with morphological and pathogenicity trials that included two isolates of B. cinerea and two isolates of B. paeoniae from peony in Alaska and one isolate of B. aclada. The authors observed differences in colony and conidia morphology and ability to cause lesions on different host tissues that suggest that the grape and peony isolates represent a distinct species. Most notably, the grape and peony isolates did not colonize onion bulbs, whereas B. aclada readily produced lesions and prolific sporulation on onion tissue. The new species Botrytis euroamericana is described herein.

Hemp (Cannabis sativa L.) has recently become an important crop due to the growing market demands for products containing cannabinoids. Unintended cross-pollination of C. sativa crops is one of the most important threats to cannabinoid production and has been shown to reduce cannabinoid yield. Ploidy manipulation has been used in other crops to improve agronomic traits and reduce fertility; however, little is known about the performance of C. sativa polyploids. In this study, colchicine was applied to two proprietary, inbred diploid C. sativa inbred lines, ‘TS1-3’ and ‘P163’, to produce the tetraploids ‘TS1-3 (4x)’ and ‘P163 (4x)’. The diploid, triploid, and tetraploid F1 hybrids from ‘TS1-3’ × ‘P163’, ‘TS1-3 (4x)’ × ‘P163’, and ‘TS1-3 (4x)’ × ‘P163 (4x)’ were produced to test their fertilities, crossing compatibilities, and yields. The results indicated a reduction in fertility in the triploids and the tetraploids, relative to their diploid counterparts. When triploids were used as females, seed yields were less than 2% compared to when diploids were used as females; thus, triploids were determined to be female infertile. The triploids resulting from the crosses made herein displayed increases in biomass and inflorescence weight compared to the diploids created from the same parents in a field setting. Statistical increases in cannabinoid concentrations were not observed. Lastly, asymmetric crossing compatibility was observed between the diploids and the tetraploids of the genotypes tested. The results demonstrate the potential benefits of triploid C. sativa cultivars in commercial agriculture.

The regulation of cannabinoid synthesis in Cannabis sativa is of increasing research interest as restrictions around the globe loosen to allow the plant’s legal cultivation. Of the major cannabinoids, the regulation of cannabigerolic acid (CBGA) production is the least understood. The purpose of this study was to elucidate the inheritance of CBGA dominance in C. sativa and describe a marker related to this chemotype. We produced two crossing populations, one between a CBGA dominant cultivar and a tetrahydrocannabinolic acid (THCA) dominant cultivar, and one between a CBGA dominant cultivar and a cannabidiolic acid (CBDA) cultivar. Chemical and genotyping analyses confirmed that CBGA dominance is inherited as a single recessive gene, potentially governed by a non-functioning allelic variant of the THCA synthase. The “null” THCAS synthase contains a single nucleotide polymorphism (SNP) that may render the synthase unable to convert CBGA to THCA leading to the accumulation of CBGA. This SNP can be reliably used as a molecular marker for CBGA dominance in the selection and breeding of C. sativa.

Botrytis is one of the most well-studied, economically-important, and oldest fungal taxa. Nonetheless, many species in this genus have remained obscured for nearly 300 years due to the difficulty in distinguishing these species by conventional mycological methods. Aided by the use of phylogenetic tools, the genus is currently undergoing a taxonomic revolution. The number of putative species in the genus has nearly doubled over the last 10 years and more species are likely to be discovered into the future. The implementation of phylogenetic species recognition concepts in genus Botrytis is providing for more resolution on the relatedness among species than ever before and has helped to overcome issues in historical species recognition using morphology, sexual crosses, and pathogenicity trials. Meanwhile, the use of genetic tools is helping to reveal surprising insight into this archetypal necrotroph’s behavior, making these approaches increasingly important in species recognition and identification. As Botrytis taxonomy continues to evolve at a rapid pace, researchers should be encouraged to continue to employ the powerful tool of phylogenetics while considering how it fits into a larger framework of classical Botrytis species recognition. Starting points for discussion on how to move forward with Botrytis species recognition are included herein, with an emphasis on the implications and utility of new species descriptions.

Powdery mildew is among the most common diseases of both hemp- and marijuana-type cultivated Cannabis sativa. Despite its prevalence, no documented studies have characterized sources of natural genetic resistance in this pathosystem. Here we provide evidence for the first resistance (R) gene in C. sativa, represented by a single dominant locus that confers complete resistance to an isolate of the powdery mildew pathogen Golovinomyces ambrosiae, found in the Pacific Northwest of the United States. Linkage mapping with nearly 10,000 single nucleotide polymorphism (SNP) markers revealed that this R gene (designated PM1) is located on the distal end of the long arm of one of the largest chromosomes in the C. sativa genome. According to reference whole genome sequences and Sanger sequencing, the marker was tentatively placed in a cluster of R genes of the nucleotide-binding site (NBS) and leucine-rich repeat (LRR) protein type. PM1's dominant behavior, qualitative penetrance, and a co-segregating qPCR marker to track its inheritance were confirmed in two separate genetic backgrounds totaling 185 recombinant F1 plants. The goal of this study is to provide a foundation for the discovery and characterization of additional sources of genetic resistance to pathogens that infect C. sativa.

Genus Botrytis contains approximately 35 species, many of which are economically-important and globally-distributed plant pathogens which collectively infect over 1,400 plant species. Recent efforts to genetically characterize genus Botrytis have revealed new species on diverse host crops around the world. In this study, surveys and subsequent genetic analysis of the glyceraldehyde-3-phosate dehydrogenase ( G3PDH ), heat-shock protein 60 ( HSP60 ), DNA-dependent RNA polymerase subunit II ( RPB2 ), and necrosis and ethylene-inducing proteins 1 and 2 ( NEP1 and NEP2 ) genes indicated that Botrytis isolates collected from peony fields in the United States contained more species diversity than ever before reported on a single host, including up to 10 potentially novel species. Together, up to 16 different phylogenetic species were found in association with peonies in the Pacific Northwest, which is over a third of the total number of species that are currently named. Furthermore, species were found on peonies in Alaska that have been described on other host plants in different parts of the world, indicating a wider geographic and host distribution than previously thought. Lastly, some isolates found on peony share sequence similarity with unnamed species found living as endophytes in weedy hosts, suggesting that the isolates found on peony have flexible lifestyles as recently discovered in the genus. Selected pathogenicity, growth, and morphological characteristics of the putatively new Botrytis species were also assessed to provide a basis for future formal description of the isolates as new species.

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Peonies, Paeonia lactiflora and hybrids, are popular ornamental plants grown in landscapes and as cut flowers. As with many ornamental plants, the information on the etiology of peony diseases is incomplete with varying amounts of detailed descriptive material; sometimes validation of Koch’s postulates is also lacking. In a survey to identify the range of diseases of peony in the United States, samples were obtained from 12 states. Fungal and oomycete plant pathogens recovered from symptomatic, diseased tissue were identified by morphology and BLAST identification of the internal transcribed spacer, glyceraldehyde 3-phosphate dehydrogenase, the 28s large subunit, and/or cytochrome c oxidase subunit 1 gene nucleotide sequences for representative isolates. Ten fungal or oomycete genera were identified, and Koch’s postulates were confirmed for selected plant pathogens found during this survey. New disease reports are generated for several states, including five genera never previously reported on peonies in the United States: a Botryosphaeria sp., multiple Colletotrichum spp., Mycocentrospora acerina, a Phoma sp., and Pilidium concavum. The information gained from this survey will provide plant disease diagnosticians and growers a more comprehensive resource for understanding the regional prevalence of peony diseases and subsequently making better disease management decisions.