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Samantha Lung

Bio: Samantha Lung is a academic researcher at Simon Fraser University who has co-authored 3 publication(s) receiving 43 citation(s). The author has an hindex of 2. The author has done significant research in the topic(s): Pith & Explant culture.

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Open accessJournal ArticleDOI: 10.3389/FPLS.2019.01120
Zamir K. Punja1, Danielle Collyer1, Cameron Scott1, Samantha Lung1  +2 moreInstitutions (1)
Abstract: Plant pathogens infecting marijuana (Cannabis sativa L.) plants reduce growth of the crop by affecting the roots, crown and foliage. In addition, fungi (molds) that colonize the inflorescences (buds) during development or after harvest, and which colonize internal tissues as endophytes, can reduce product quality. The pathogens and molds that affect C. sativa grown hydroponically indoors (in environmentally controlled growth rooms and greenhouses) and field-grown plants were studied over multiple years of sampling. A PCR-based assay using primers for the internal transcribed spacer region (ITS) of ribosomal DNA confirmed identity of the cultures. Root-infecting pathogens included Fusarium oxysporum, F. solani, F. brachygibbosum, Pythium dissotocum, P. myriotylum and P. aphanidermatum, which caused root browning, discoloration of the crown and pith tissues, stunting and yellowing of plants, and in some instances, plant death. On the foliage, powdery mildew, caused by Golovinomyces cichoracearum, was the major pathogen observed. On inflorescences, penicillium bud rot (caused by P. olsonii and P. copticola), botrytis bud rot (B. cinerea) and fusarium bud rot (F. solani, F. oxysporum) were present to varying extents. Endophytic fungi present in crown, stem and petiole tissues included soil-colonizing and cellulolytic fungi, such as species of Chaetomium, Trametes, Trichoderma, Penicillium and Fusarium. Analysis of air samples in indoor growing environments revealed that species of Penicillium, Cladosporium, Aspergillus, Fusarium, Beauvaria, and Trichoderma were present. The latter two species were the result of the application of biocontrol products for control of insects and diseases, respectively. Fungal communities present in unpasteurized coconut fibre (coco) growing medium are potential sources of mold contamination on cannabis plants. Swabs taken from greenhouse-grown and indoor buds pre- and post-harvest revealed the presence of Cladosporium and up to five species of Penicillium, as well as low levels of Alternaria species. Mechanical trimming of buds caused an increase in the frequency of Penicilllium species, presumably by providing entry points through wounds or spreading endophytes from pith tissues. Aerial distribution of pathogen inoculum and mold spores and dissemination through vegetative propagation, are important methods of spread, and entry through wound sites on roots, stems and bud tissues facilitates pathogen establishment on cannabis plants.

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Topics: Cladosporium (58%), Fusarium oxysporum (58%), Trichoderma (55%) ...read more

38 Citations


Journal ArticleDOI: 10.1080/07060661.2021.1954695
Abstract: Cannabis (Cannabis sativa L., marijuana) plants with symptoms of crown rot, root decay, wilting and plant death were sampled during 2018 and 2019 from seven production greenhouses. Affected tissues...

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Topics: Pythium (57%), Root rot (56%), Wilting (52%)

5 Citations


Open accessJournal ArticleDOI: 10.3389/FPLS.2021.732344
Abstract: Tissue culture approaches are widely used in crop plants for the purposes of micropropagation, regeneration of plants through organogenesis, obtaining pathogen-free plantlets from meristem culture, and developing genetically modified plants. In this research, we evaluated variables that can influence the success of shoot growth and plantlet production in tissue cultures of drug-type Cannabis sativa L. (marijuana). Various sterilization methods were tested to ensure shoot development from nodal explants by limiting the frequency of contaminating endophytes, which otherwise caused the death of explants. Seven commercially grown tetrahydrocannabinol (THC)-containing cannabis genotypes (strains) showed significant differences in response to shoot growth from meristems and nodal explants on Murashige and Skoog (MS) medium containing thidiazuron (1 μM) and naphthaleneacetic acid (0.5 μM) plus 1% activated charcoal. The effect of Driver and Kuniyuki Walnut (DKW) or MS basal salts in media on shoot length and leaf numbers from nodal explants was compared and showed genotype dependency with regard to the growth response. To obtain rooted plantlets, shoots from meristems and nodal explants of genotype Moby Dick were evaluated for rooting, following the addition of sodium metasilicate, silver nitrate, indole-3-butyric acid (IBA), kinetin, or 2,4-D. Sodium metasilicate improved the visual appearance of the foliage and improved the rate of rooting. Silver nitrate also promoted rooting. Following acclimatization, plantlet survival in hydroponic culture, peat plugs, and rockwool substrate was 57, 76, and 83%, respectively. The development of plantlets from meristems is described for the first time in C. sativa and has potential for obtaining pathogen-free plants. The callogenesis response of leaf explants of 11 genotypes on MS medium without activated charcoal was 35% to 100%, depending on the genotype; organogenesis was not observed. The success in recovery of plantlets from meristems and nodal explants is influenced by cannabis genotype, degree of endophytic contamination of the explants, and frequency of rooting. The procedures described here have potential applications for research and commercial utility to obtain plantlets in stage 1 tissue cultures of C. sativa.

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Topics: Plantlet (59%), Micropropagation (56%), Kinetin (54%) ...read more
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Open access
25 Sep 1980-

28 Citations


Open accessJournal ArticleDOI: 10.3390/MICROORGANISMS8020290
20 Feb 2020-
Abstract: Cannabis legalization has occurred in several countries worldwide. Along with steadily growing research in Cannabis healthcare science, there is an increasing interest for scientific-based knowledge in plant microbiology and food science, with work connecting the plant microbiome and plant health to product quality across the value chain of cannabis. This review paper provides an overview of the state of knowledge and challenges in Cannabis science, and thereby identifies critical risk management and safety issues in order to capitalize on innovations while ensuring product quality control. It highlights scientific gap areas to steer future research, with an emphasis on plant-microbiome sciences committed to using cutting-edge technologies for more efficient Cannabis production and high-quality products intended for recreational, pharmaceutical, and medicinal use.

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15 Citations


Open accessJournal ArticleDOI: 10.3389/FPHAR.2020.571832
Abstract: For nearly a century, Cannabis has been stigmatized and criminalized across the globe, but in recent years, there has been a growing interest in Cannabis due to the therapeutic potential of phytocannabinoids. With this emerging interest in Cannabis, concerns have arisen about the possible contaminations of hemp with pesticides, heavy metals, microbial pathogens, and carcinogenic compounds during the cultivation, manufacturing, and packaging processes. This is of particular concern for those turning to Cannabis for medicinal purposes, especially those with compromised immune systems. This review aims to provide types of contaminants and examples of Cannabis contamination using case studies that elucidate the medical consequences consumers risk when using adulterated Cannabis products. Thus, it is imperative to develop universal standards for cultivation and testing of products to protect those who consume Cannabis.

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Topics: Cannabis (53%)

14 Citations


Open accessJournal ArticleDOI: 10.3389/FPLS.2020.00718
Zamir K. Punja1, Janesse E. Holmes1Institutions (1)
Abstract: Cannabis sativa L (hemp, marijuana) produces male and female inflorescences on different plants (dioecious) and therefore the plants are obligatory out-crossers In commercial production, marijuana plants are all genetically female; male plants are destroyed as seed formation reduces flower quality Spontaneously occurring hermaphroditic inflorescences, in which pistillate flowers are accompanied by formation of anthers, leads to undesired seed formation; the mechanism for this is poorly understood We studied hermaphroditism in several marijuana strains with three objectives: (i) to compare the morphological features of this unique phenotype with normal male flowers; (ii) to assess pollen and seed viability from hermaphroditic flowers; and (iii) to assess the effect of hermaphroditism on progeny male:female (sex) ratios and on genetic variation using molecular methods The morphological features of anthers, pollen production and germination in hermaphroditic flowers and in staminate inflorescences on male plants were compared using light and scanning electron microscopy Seeds produced on hermaphroditic plants and seeds derived from cross-fertilization were germinated and seedlings were compared for gender ratios using a PCR-based assay as well as for the extent of genetic variation using six ISSR primers Nei's index of gene diversity and Shannon's Information index were compared for these two populations The morphology of anthers and pollen formation in hermaphroditic inflorescences was similar to that in staminate flowers Seedlings from hermaphroditic seeds, and anther tissues, showed a female genetic composition while seedlings derived from cross-fertilized seeds showed a 1:1 male:female sex expression ratio Uniquely, hermaphroditic inflorescences produced seeds which gave rise only to genetically female plants In PCR assays, a 540 bp size fragment was present in male and female plants, while a 390 bp band was uniquely associated with male plants Sequence analysis of these fragments revealed the presence of Copia-like retrotransposons within the C sativa genome which may be associated with the expression of male or female phenotype In ISSR analysis, the percentage of polymorphic loci ranged from 44 to 72% in hermaphroditic and cross-fertilized populations Nei's index of gene diversity and Shannon's Information index were not statistically different for both populations The extent of genetic variation after one generation of selfing in the progeny from hermaphroditic seed is similar to that in progeny from cross-fertilized seeds

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Topics: Selfing (55%), Inflorescence (53%), Pollen (52%) ...read more

12 Citations


Open accessJournal ArticleDOI: 10.1080/07060661.2020.1836026
Cameron Scott1, Zamir K. Punja1Institutions (1)
Abstract: Powdery mildew on cannabis (Cannabis sativa L., marijuana), caused by Golovinomyces cichoracearum, reduces plant growth and overall quality. To investigate disease management options, biological, c...

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Topics: Powdery mildew (62%), Cannabis (53%)

9 Citations


Performance
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Author's H-index: 2

No. of papers from the Author in previous years
YearPapers
20212
20191

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Author's top 2 most impactful journals