Architecture and Florogenesis in Female Cannabis sativa Plants

The inflorescence is the main product of medical cannabis. Hundreds of specialized metabolites with potential bioactivity are produced and accumulated in the glandular trichomes that are highly abundant mainly on female inflorescences. Understanding the morphophysiological and genetic mechanisms governing flower and inflorescence development is therefore of high scientific and practical importance. However, in-depth investigations of cannabis florogenesis are limited. Cannabis producers and researchers consider long photoperiod to be “non-inductive” or “vegetative,” but under these growth conditions, the development of solitary flowers and bracts in shoot internodes clearly indicates that the plant cannot be defined as vegetative or non-inductive in the classical sense. Most probably, induction of solitary flowers is age-dependent and controlled by internal signals, but not by photoperiod. Short photoperiod induces intense branching, which results in the development of a compound raceme. Each inflorescence consists of condensed branchlets with the same phytomer structure as that of the larger phytomers developed under long day. Each phytomer consists of reduced leaves, bracts, one or two solitary flowers, and an axillary shoot (or inflorescence). Therefore, the effect of short photoperiod on cannabis florogenesis is not flower induction, but rather a dramatic change in shoot apex architecture to form a compound racemose inflorescence structure. An understanding of the morphophysiological characteristics of cannabis inflorescence will lay the foundation for biotechnological and physiological applications to modify architecture and to maximize plant productivity and uniformity in medical Cannabis

Ongoing Evolution in the Genus Crocus: Diversityof Flowering Strategies on the Way to Hysteranthy

[EN] Species of the genus Crocus are found over a wide range of climatic areas. In natural habitats, these geophytes diverge in the flowering strategies. This variability was assessed by analyzing the flowering traits of the Spanish collection of wild crocuses, preserved in the Bank of Plant Germplasm of Cuenca. Plants of the seven Spanish species were analyzed both in their natural environments (58 native populations) and in common garden experiments (112 accessions). Differences among species observed in the native habitats were maintained under uniform environmental conditions, suggesting a genetic basis for flowering mechanisms. Two eco-morphological types, autumn- and spring-flowering species, share similar patterns of floral induction and differentiation period in summer. The optimal temperature for this process was 23 degrees C for both types. Unlike Irano-Turanian crocuses, spring-flowering Spanish species do not require low winter temperatures for flower elongation. Hysteranthous crocuses flower in autumn prior to leaf elongation. We conclude that the variability in flowering traits in crocuses is related to the genetic and environmental regulation of flower primordia differentiation and elongation prior to emergence above the soil surface. The elucidation of the physiological differences between eco-morphological types of crocuses: synanthous with cold requirements and synanthous and hysteranthous without cold requirements, unlocks a new approach to the flowering evolution of geophytes in Mediterranean regions. Crocus species can serve both as a new model in the study of the molecular basis of hysteranthy and for the purposes of developing the molecular markers for desirable flowering traits.The collection activities of plant materials included in this study were mainly supported by successive Spanish research projects funded by the "Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria" [INIA RF2004-00032-C03, INIA RF2008-00012-C03, INIA RF2011-00005-C03], co-funded by the European Regional Development Fund (ERDF-FEDER), and also by means of the European Action 018 Agri Gen Res (CrocusBank). The activities of PhD. TPF were supported by a pre-doctoral grant from the "Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria" within the framework of the project INIA RF2011-0005-C03-01. The preservation of these materials in the facilities of the Bank of Plant Germplasm of Cuenca (CIAF Albaladejito -IRIAF), as part of the Spanish Germplasm Collection of Saffron and other Crocus, is currently supported by the Spanish National Program for Conservation and Utilization of Plant Genetic Resources for Agriculture and Food (action INIA RFP2014-00012). Some activities have been also funded by the "Ministerio de Ciencia, Innovacion y Universidades de Espana" [AGL2016-77078-R].Pastor-Férriz, T.; De-Los-Mozos-Pascual, M.; Renau-Morata, B.; Nebauer, SG.; Sanchís, E.; Busconi, M.; Fernández, J.... (2021). Ongoing Evolution in the Genus Crocus: Diversityof Flowering Strategies on the Way to Hysteranthy. Plants. 10(3):1-18. https://doi.org/10.3390/plants1003047711810

Herbaceous peony in warm climate: Modelling stem elongation and growers profit responses to dormancy conditions

We analysed the data collected for herbaceous peony cultivated in a warm climate region and stored in winter under three constant chilling temperatures. We used the quadratic regression model to describe the stem elongation responses to winter dormancy conditions, and the logistic function to describe the weekly stems elongation. The predicted maximal stem length from the first model was used as the input parameter for the second model. More than 4000 data for various (a) chilling constant temperatures during dormancy, (b) dormancy duration, and (c) germination duration, were used. The models were applied to determine the optimal number of chill units. For this purpose, two criteria were used in different versions of the model: the maximal stem length and the maximal profit of farmers. For the two chilling temperatures of 2 °C and 6 °C, the optimal values of chill units (in the models of a maximal stem length and maximal profit of farmers) are close to one another, and the values of a maximal stem length and maximal profit are significantly different. In the case of the third chilling temperature of 10 °C, the model failed to determine the optimal number of chill units. The method of inverse confidence intervals for testing the significance of the optimal number of chill units was used

Micropropagation of Grapevine and Strawberry from South Russia: Rapid Production and Genetic Uniformity

Grapes and strawberries are major fruit crops with a dynamic, fast-growing global market. In addition to conventional techniques, biotechnological tools allow the preservation of valuable genotypes of both crops and the large-scale propagation of high-quality material. We have developed new protocols for expeditious and reliable micropropagation of grapes and strawberries cultivated in south Russia. In vitro cultivation on semisolid media was combined with rapid propagation in bioreactors. A six-week cycle of propagation in a bioreactor resulted in a 300-fold increase in fresh mass, with a propagation rate of ~5 in grapes and ~20 in strawberries. Genetic analysis using the inter simple sequence repeat (ISSR) DNA fingerprinting technique confirmed the full uniformity of the regenerants. The results of this research will support the local horticultural industry with fast and efficient propagation systems of new breeding lines, introduced varieties, and elite cultivars

Variability in the Chemical Composition of a New Aromatic Plant <i>Artemisia balchanorum</i> in Southern Russia

Lemon wormwood Artemisia balchanorum was recently introduced to southern Russia as a new aromatic plant. Based on biological and chemical characteristics, several populations with dominant citral, linalool, and geraniol production were selected for further development and maintained by seed propagation. Chemical analysis of five outstanding populations at three stages of annual development: vegetative, flower buds, and full flowering, confirmed that the seed populations retain the distinct dynamics of the dominant and minor components during the annual cycle and can be used for the commercial production of citral, linalool, and geraniol. Micropropagation in vitro allows for efficient clonal micropropagation and mass reproduction of elite cultivars and promising forms of A. balchanorum on a commercial scale but cannot serve as a source of direct and efficient production of secondary metabolites

ToBRFV Infects the Reproductive Tissues of Tomato Plants but Is Not Transmitted to the Progenies by Pollination

Tomato brown rugose fruit virus (ToBRFV), a newly identified Tobamovirus, has recently emerged as a significant pathogen of tomato plants (Solanum lycopersicum). The virus can evade or overcome the known tobamovirus resistance in tomatoes, i.e., Tm-1, Tm-2, and its allele Tm-22. ToBRFV was identified for the first time only a few years ago, and its interactions with the tomato host are still not clear. We investigated ToBRFV’s presence in the reproductive tissues of tomato using fluorescent in situ hybridization (FISH) and RT-PCR. In infected plants, the virus was detected in the leaves, petals, ovary, stamen, style, stigma, and pollen grains but not inside the ovules. Fruits and seeds harvested from infected plants were contaminated with the virus. To test whether the virus is pollen transmitted, clean mother plants were hand pollinated with pollen from ToBRFV-infected plants and grown to fruit. None of the fruits and seeds harvested from the pollinated clean mother plants contained ToBRFV. Pollen germination assays revealed the germination arrest of ToBRFV-infected pollen. We concluded that ToBRFV might infect reproductive organs and pollen grains of tomato but that it is not pollen transmitted

Garlic Potyviruses Are Translocated to the True Seeds through the Vegetative and Reproductive Systems of the Mother Plant

Garlic lost its ability to produce true seeds millennia ago, and today non-fertile commercial cultivars are propagated only vegetatively. Garlic viruses are commonly carried over from one generation of vegetative propagules to the other, while nematodes and arthropods further transmit the pathogens from infected to healthy plants. A recent breakthrough in the production of true (botanical) garlic seeds resulted in rapid scientific progress, but the question of whether viruses are transmitted via seeds remains open and is important for the further development of commercial seed production. We combined morpho-physiological analysis, fluorescence in situ hybridization (FISH), and PCR analysis to follow potyvirus localization and translocation within garlic fertile plants and seeds. Spatial distribution was recorded in both vegetative and reproductive organs. We conclude that garlic potyviruses are translocated to the seeds from the infected mother plant during flower development and post-fertilization, while pollen remains virus-free and does not contribute to seed infection. Therefore, the main practical goal for virus-clean seed production in garlic is the careful maintenance of virus-free mother plants. Although garlic pollen is free of potyviral infection, the male parents&rsquo; plants also need to be protected from contamination, since viral infection weakens plants, reducing flowering ability and pollen production

Pathogen Eradication in Garlic in the Phytobiome Context: Should We Aim for Complete Cleaning?

Global food production is challenged by plant pathogens that cause significant crop losses. Fungi, bacteria, and viruses have long threatened sustainable and profitable agriculture. The danger is even higher in vegetatively propagated horticultural crops, such as garlic. Currently, quarantine, rouging infected plants, and control of natural vectors are used as the main means of disease and pest control in garlic crops. Agricultural biotechnology, meristem-tip culture, and cryotherapy offer solutions for virus eradication and for the multiplication of ‘clean stocks’, but at the same time, impact the symbiotic and beneficial components of the garlic microbiome. Our research involves the first metatranscriptomic analysis of the microbiome of garlic bulb tissue, PCR analyses, and a biological assay of endophytes and pathogens. We have demonstrated that in vitro sanitation methods, such as shoot tip culture or cryotherapy can alter the garlic microbiome. Shoot tip culture proved ineffective in virus elimination, but reduced bacterial load and eliminated fungal infections. Conversely, cryotherapy was efficient in virus eradication but demolished other components of the garlic microbiome. Garlic plants sanitized by cryotherapy exhibited a lower survival rate, and a longer in vitro regeneration period. The question arises whether total eradication of viruses, at the expense of other microflora, is necessary, or if a partial reduction in the pathogenic load would suffice for sanitized garlic production. We explore this question from both scientific and commercial perspectives