Tag: Breeding

*The inheritance of chemical phenotype in Cannabis sativa L. (II): Cannabigerol predominant plants

E. P. M. de Meijer & K. M. Hammond
Euphytica (2005) 145: 189–198
DOI: 10.1007/s10681-005-1164-8

This paper aims to clarify the genetic mechanism that is responsible for the accumulation of cannabigerol (CBG) in certain phenotypes of Cannabis sativa L. CBG is the direct precursor of the cannabinoids CBD, THC and CBC. Plants strongly predominant in CBG have been found in different fibre hemp accessions. Inbred offspring derived from one such individual were crossed with true breeding THC predominant- and CBD predominant plants, respectively. The segregations in the cross progenies indicate that CBG accumulation is due to the homozygous presence of a minimally functional allele, tentatively called B0, at the single locus B that normally controls the conversion of CBG into THC (allele BT) and/or CBD (allele BD). The fact that CBG accumulating plants have so far been found in European fibre hemp populations that are generally composed of BD/BD plants, and the observation that the here investigated B0 allele possesses a residual ability to convert small amounts of CBG into CBD, make it plausible that this B0 is a mutation of normally functional BD. Therefore, B0 is considered as a member of the BD allelic series encoding a CBD synthase isoform with greatly weakened substrate affinity and/or catalytic capacity.
Abstract

*The Inheritance of Chemical Phenotype in Cannabis sativa L. (I)

Etienne P. M. de Meijer, Manuela Bagatta, Andrea Carboni, Paola Crucitti,
V. M. Cristiana Moliterni, Paolo Ranalli and Giuseppe Mandolino
Genetics. 2003 Jan; 163(1): 335–346.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1462421/

Four crosses were made between inbred Cannabis sativa plants with pure cannabidiol (CBD) and pure Delta-9-tetrahydrocannabinol (THC) chemotypes. All the plants belonging to the F(1)’s were analyzed by gas chromatography for cannabinoid composition and constantly found to have a mixed CBD-THC chemotype. Ten individual F(1) plants were self-fertilized, and 10 inbred F(2) offspring were collected and analyzed. In all cases, a segregation of the three chemotypes (pure CBD, mixed CBD-THC, and pure THC) fitting a 1:2:1 proportion was observed. The CBD/THC ratio was found to be significantly progeny specific and transmitted from each F(1) to the F(2)’s derived from it. A model involving one locus, B, with two alleles, B(D) and B(T), is proposed, with the two alleles being codominant. The mixed chemotypes are interpreted as due to the genotype B(D)/B(T) at the B locus, while the pure-chemotype plants are due to homozygosity at the B locus (either B(D)/B(D) or B(T)/B(T)). It is suggested that such codominance is due to the codification by the two alleles for different isoforms of the same synthase, having different specificity for the conversion of the common precursor cannabigerol into CBD or THC, respectively. The F(2) segregating groups were used in a bulk segregant analysis of the pooled DNAs for screening RAPD primers; three chemotype-associated markers are described, one of which has been transformed in a sequence-characterized amplified region (SCAR) marker and shows tight linkage to the chemotype and codominance.
Abstract

The Derivation of Modern Cannabis Varieties

Bailey Rahn, Brian J. Pearson, Robert N. Trigiano & Dennis J. Gray
Critical Reviews in Plant Sciences, 
DOI: 10.1080/07352689.2016.1273626

Considering the ancient importance of cannabis and the current trend toward its deregulation worldwide, it is imperative to develop best management practices to legitimize the crop. The genetic backgrounds of commercially-sold varieties must be determined in order to standardize the products produced from them and to efficiently improve them for future needs. Currently the genetic backgrounds of most cannabis varieties are unknown or suspect. It is possible that some are merely clones of other varieties. By utilizing modern tools of genetic analyses, the identities of all or most existing varieties, as well as their parentages, will be determined. As with all major crops, understanding varietal identity is a crucial step required to modernize the cannabis industry. This article describes and explores the derivation of 601 modern varieties in order to provide a fundamental point of reference for scientists to study cannabis genetics in the future.
Abstract

Targeted mutation of Δ12 and Δ15 desaturase genes in hemp produce major alterations in seed fatty acid composition including a high oleic hemp oil

Monika Bielecka, Filip Kaminski, Ian Adams, Helen Poulson, Raymond Sloan, Yi Li, Tony R. Larson, Thilo Winzer, Ian A. Graham
February 2014 Plant Biotechnology Journal 12(5)
DOI: 10.1111/pbi.12167

We used expressed sequence tag library and whole genome sequence mining to identify a suite of putative desaturase genes representing the four main activities required for production of polyunsaturated fatty acids in hemp seed oil. Phylogenetic-based classification and developing seed transcriptome analysis informed selection for further analysis of one of seven Δ12 desaturases and one of three Δ15 desaturases that we designate CSFAD2A and CSFAD3A, respectively. Heterologous expression of corresponding cDNAs in Saccharomyces cerevisiae showed CSFAD2A to have Δx+3 activity, while CSFAD3A activity was exclusively at the Δ15 position. TILLING of an ethyl methane sulphonate mutagenized population identified multiple alleles including non-sense mutations in both genes and fatty acid composition of seed oil confirmed these to be the major Δ12 and Δ15 desaturases in developing hemp seed. Following four backcrosses and sibling crosses to achieve homozygosity, csfad2a-1 was grown in the field and found to produce a 70 molar per cent high oleic acid (18:1Δ9) oil at yields similar to wild type. Cold-pressed high oleic oil produced fewer volatiles and had a sevenfold increase in shelf life compared to wild type. Two low abundance octadecadienoic acids, 18:2Δ6,9 and 18:2Δ9,15, were identified in the high oleic oil, and their presence suggests remaining endogenous desaturase activities utilize the increased levels of oleic acid as substrate. Consistent with this, CSFAD3A produces 18:2Δ9,15 from endogenous 18:1Δ9 when expressed in S. cerevisiae. This work lays the foundation for the development of additional novel oil varieties in this multipurpose low input crop.
Abstract

*Statistical genetic considerations for maintaining germ plasm collections

Note: This paper is not cannabis related but has demonstrated to be a Must-Read.

J. Crossa , C. M. Hernandez , P. Bretting , S. A. Eberhart , S. Taba
Theor Appl Genet (1993) 86:673-678
DOI: 10.1007/BF00222655

One objective of the regeneration of genetic populations is to maintain at least one copy of each allele present in the original population. Genetic diversity within populations depends on the number and frequency of alleles across all loci. The objectives of this study on outbreeding crops are: (1) to use probability models to determine optimal sample sizes for the regeneration for a number of alleles at independent loci; and (2) to examine theoretical considerations in choosing core subsets of a collection. If we assume that k-1 alleles occur at an identical low frequency of p0 and that the k(th) allele occurs at a frequency of 1-[(k-1)p0], for loci with two, three, or four alleles, each with a p0 of 0.05, 89-110 additional individuals are required if at least one allele at each of 10 loci is to be retained with a 90% probability; if 100 loci are involved, 134-155 individuals are required. For two, three, or four alleles, when p0 is 0.03 at each of 10 loci, the sample size required to include at least one of the alleles from each class in each locus is 150-186 individuals; if 100 loci are involved, 75 additional individuals are required. Sample sizes of 160-210 plants are required to capture alleles at frequencies of 0.05 or higher in each of 150 loci, with a 90-95% probability. For rare alleles widespread throughout the collection, most alleles with frequencies of 0.03 and 0.05 per locus will be included in a core subset of 25-100 accessions.
Abstract

Sequence heterogeneity of cannabidiolic- and tetrahydrocannabinolic acid-synthase in Cannabis sativa L. and its relationship with chemical phenotype

Chiara Onofri, Etienne P.M. de Meijer, Giuseppe Mandolino
Phytochemistry. 2015 Aug;116:57-68. 
doi: 10.1016/j.phytochem.2015.03.006

Sequence variants of THCA- and CBDA-synthases were isolated from different Cannabis sativa L. strains expressing various wild-type and mutant chemical phenotypes (chemotypes). Expressed and complete sequences were obtained from mature inflorescences. Each strain was shown to have a different specificity and/or ability to convert the precursor CBGA into CBDA and/or THCA type products. The comparison of the expressed sequences led to the identification of different mutations, all of them due to SNPs. These SNPs were found to relate to the cannabinoid composition of the inflorescence at maturity and are therefore proposed to have a functional significance. The amount of variation was found to be higher within the CBDAS sequence family than in the THCAS family, suggesting a more recent evolution of THCA-forming enzymes from the CBDAS group. We therefore consider CBDAS as the ancestral type of these synthases.
Abstract

Selection for low Δ 9-tetrahydrocannabinol content in Thai hemp cultivars

Weerapun Kunkaew, S. Julsrigival, S. Pinmanee, Prapatsorn Tipparat
January 2011 SABRAO journal of breeding and genetics 43(1):1-14
https://www.researchgate.net/publication/287843199_Selection_for_low_D_9-tetrahydrocannabinol_content_in_Thai_hemp_cultivars

Selection for reduced Δ 9-tetrahydrocannabinol (THC) content in four Thai hemp cultivars (including V50, Mae Sa Mai, Huay Hoi and Pang Ung) was carried out in highland areas in the northern Thailand. Research work was conducted for two consecutive growing seasons during 2008 to 2009 at Pangda Royal Agricultural Station, Samoeng district, Chiang Mai province, Thailand. Results of selection indicated that after selecting for two successive generations, the average THC content of four Thai hemp cultivars reduced to 18.0-55.0% and cannabidiol (CBD) content increased to 20.0-127.0%. The results of selection also indicated that chemotype classification could be grouped by using the ratio of CBD/THC content as follows: non-drug type (CBD/THC>10.0), intermediate type (1.0≤CBD/THC≤10.0) and drug type (CBD/THC<1.0). Thus, selection for reduced THC content, high ratio of CBD/THC content could be used as alternative criteria for improving low THC content in hemp cultivars. As well, mass selection method was considered as an effective and suitable method for improving these THC and CBD traits.
Abstract

New developments in fiber hemp (Cannabis sativa L.) breeding

Elma M.J. Salentijna, Qingying Zhangb, Stefano Amaduccic, Ming Yangb, Luisa M. Trindadea 
Industrial Crops and Products Vol. 68, June 2015, pages 32-41
DOI: 10.1016/j.indcrop.2014.08.011

Fiber hemp (Cannabis sativa L.) is a sustainable and high yielding industrial crop that can help to meet the high global demand for fibers. Hemp can be grown for fiber, seeds, and/or for dual purpose in a wide range of geographic zones and climates. Currently the main hemp producing regions in the world are China, Europe, and Canada. The number of new cultivars developed for each of these regions has gradually increased, with each region producing its own typical hemp cultivars for different purposes. In this article, the state of the art of fiber hemp breeding programs in Europe, China, and Canada are reviewed. The breeding strategies and tools used in the breeding of hemp cultivars are discussed. We also provide an overview of genetic diversity in hemp for different traits. In addition, the current knowledge of the main breeding goals for fiber hemp, which are an improvement of fiber quality and fiber yield, breeding for specific cannabinoid profiles, control of flowering behavior, male flowering control, and breeding of cultivars for specific environments are evaluated. Lastly, we discuss the inestimable value of next generation technologies to breed new hemp cultivars that are suitable for a biobased economy.
Abstract

Introduction to the Special Issue on Cannabis

Dennis J. Gray, Robert C. Clarke & Robert N. Trigiano
Critical Reviews in Plant Sciences, 2016
DOI: 10.1080/07352689.2016.1267492

…Cannabis is among these most ancient plants to be
genetically modified and domesticated, in this instance,
into two distinct forms: hemp and drug varieties. Based
upon fiber evidence, the earliest records for humankind’s
domestication of cannabis date from 8500 BP in China
(Fleming and Clarke, 1998). Due to its ready availability,
strength, and versatility, cannabis became domesticated
as a fiber crop (hemp) and is ubiquitously used for a
wide array of products, ranging from clothing and rope
to seed oil. Drug forms of cannabis were domesticated
by 3000 BP (Schultes, 1967). It must be concluded that
cannabis has been an integral part of the human experience since the dawn of civilization and continues into
the present.
Introduction

Identification of QTLs for sex expression in dioecious and monoecious hemp (Cannabis sativa L.)

A.-M. Faux . X. Draye . M.-C. Flamand, A. Occre . P. Bertin
Euphytica 209(2), 357-376
DOI 10.1007/s10681-016-1641-2

Abstract Hemp (Cannabis sativa L.) is a diploid species including both dioecious and monoecious cultivars with hetero- and homomorphic sex chromosomes, respectively. It displays a high plasticity of sex expression, i.e., the ratio of female and male flowers. In this study, we investigated the role of sex chromosomes in the genetic determinism of sex expression in dioecious and monoecious hemp. The experimental
materials were three F1 segregating populations, two dioecious (C1 and C2: ‘Carmagnola’ $ 9 ‘Carmagnola’#), and one monoecious (UF: ‘Uso 31’ 9 ‘Fedora17’). A ‘sex’ phenotypic marker was mapped in C1 and C2. In total, 23, 42, and 26 AFLP markers (71 markers in total) were mapped to three, nine, and three co-segregation groups putatively located on sex chromosomes in C1, C2, and UF, respectively. Recombination rates with sex ranged from 0 to 0.5. Five sexlinked markers were detected in UF, revealing homologies between the X chromosomes of monoecious
hemp and the X and Y chromosomes of dioecious hemp. Five QTLs associated with quantitative variations in sex expression were identified in each map. Four markers associated with variations in sex expression in UF segregated with sex or accounted for a putative QTL in C1 or C2. Two QTLs and three of these markers were mapped in UF in a region homologous to the sex-locus region of the dioecious maps. Given these results, conducting further research on the genetic determinism of sex expression in hemp using a quantitative approach appears relevant.
Abstract