Comparative pathways of ancient and modern plant domestication processes: purposes, tools, and expectations
Agriculture – the control of plants for human consumption – is believed to have appeared and developed during the paleolitic/neolitic period, ~ 10,000 years ago . The first agriculture had no single or simple origin since a wide variety of plants and animals have been independently domesticated at different times and different places [1-4]. The origin of agriculture and crops domestication is intertwined. Plant domestication involves changes in the plant’s genetic makeup and morphological appearance following successive selections within wild plants and based upon on the variations that are best suitable for humans needs . Domestication is therefore an artificial selection process conducted by humans for the production of plants showing fewer undesirable traits compared to its wild related plants, and making them more dependent on the new artificial environments for their continued survival and development. The concept of selection assumes the existence of a population or group of individuals from which choices can be made. Thus, the diversity of morphotypes or genetic diversity is considered as the backbone for plant domestication and crop improvement. Nonetheless, the way this genetic diversity was probed across time has constantly evolved while being a continuum from the first day. Moreover, while the selection criteria for the desired traits and purposes in the ancient domestication process were certainly exclusively based on morphology (size, color, shape of leaves and fruits, easiness for identification) and to satisfy man’s energy supply needs (taste and flavour, satiety potential), today, the required traits and purposes for plant domestication (seen as continuum) have been refined and expanded. Indeed, new technologies have been developed for probing the genetic diversity whereas human needs have increased to include health and wellbeing. As a consequence more specific and defined traits such as a targeted and defined ingredient or metabolite are sought. To date, the pace of plant domestication has slowed down mainly due to the loss of biodiversity but also because of our ability to satisfy our current food needs. Nevertheless, few new crops species are still being introduced into farming system to fill the growing gaps in the need of humans and pets. Although domestication, as a concept, is not the main focus of this chapter (reader can refer to [3, 4, 6-9]), this review will look at some aspects of plant domestication in the 21st century as compared with ancient domestication process, the extent of genetic diversity within North American roses, the challenges associated with the domestication and agronomy of Atlantic Canada wild rose species taken as an example, and how the current biotechnology tools can contribute to an economic crop production.
2. Domestication as a science
Domestication was defined by De Wet  as "changes in adaptation that insure total fitness in habitats especially prepared by man for his cultigens". Van Raamsdonk  refined this definition by taking into account Simmond’s  observations on plant domestication syndrome because a considerable number of crop plants are dependent on man for establishing new generations due to non-dehiscence, non-shattering, and absence of seed dormancy. Domestication was thus better defined by van Raamsdonk as a process leading to characteristics that are beneficial to humans but generally unprofitable for plants in natural habitats and in the decrease or total lack of capability to disseminate viable offspring . As such defined, the goal for crop domestication appears obvious: setting plant for human’s benefits. However, the paths and process followed, and the tools used towards developing a new crop from its wild related plant can greatly vary (Table 1).
2.2. Domestication process and goal
An artificial selection results in a phenotypic evolution . In fact, agriculture started ~10,000 years ago by probing the diversity present within wild plant species and by planting the selected specimens, first in the garden and then in the field setting, a process known as domestication. Although all crops and plant varieties known to man today did not undergo through this classic process (case of known semi-domesticates) , the vast majority did go through, and thus being fully or super domesticated , depending on era, needs and advances in technology. Domestication is generally considered to be the end-point of a continuum that starts with exploring wild plants, continues through cultivation of plants selected from the wild but not yet genetically different from wild plants, and terminates in the fixation (at some extent), through human selection, of morphological and hence genetic differences distinguishing a domesticate from its wild progenitor. Wild and cultivated populations differ statistically in various characters targeted by human selection, although the cultivated plants may be morphologically indistinguishable from the wild plants . Therefore, cultivated populations are not genetically fixed for any characters distinguishing them from wild populations, but the frequencies of alleles governing the characters subjected to human selection presumably differ . Casas et al.  considered that changes in allele frequencies resulting from human selection constitute at least an incipient domestication, i.e. a nascent domestication. These authors analyzed the morphological variations in wild, managed
2.3. Domestication tools
2.3.1. Ancient tools
The oldest cultivated garden rose was
22.214.171.124. Probing the genetic diversity
During ancient times, botanists such as Linnaeus  have played a crucial role in probing rose genetic diversity and defining boundaries between species. Linaeus  was one of the first botanists to acknowledge the complexity of the genus
126.96.36.199. Process and goal for probing the genetic diversity (food and ornamentals)
During the Middle Ages, dogroses were cultivated at monasteries as a medicinal plant and, all parts including rosehips, seeds, petals, leaves and roots were virtually used. Later on in the 19th century, dogroses served as rootstocks to graft modern rose cultivars either as frost or soil born disease resistance sources . They have also been used as a rustic and hardly living fence for fields and public spaces. In the twentieth century, roses have become important horticultural and cosmetic crops receiving much attention from geneticists, breeders, and general public. Hybrid Tea varieties of roses (
The Centre for Variety Research, the Netherlands, has submitted more than 2,800, predominantly Hybrid Tea varieties, for Plant Breeders Rights. This number is increasing annually with 80 applications on average each year. This registration and protection process is based on morphological and physiological characteristics as described by the UPOV (Union Internationale pour la Protection des Obtentions Végétales) guidelines . Wild roses, semi-domesticated and commercial varieties, serve as breeding materials for creating new genetic stocks. These breeding materials generally selected as seed or pollen parents, for flowers that are often flagrant, commonly rose-colored flowers although white or more rarely yellow flowers can be observed in some species  are used in crosses. Hence, seedlings of interest with differences in flagrance, colour, shapes, disease resistance genes are selected through extensive field trials and advanced in the registration process . Among the many wild rose species, the selection was obviously based on easy availability, attractiveness of characters, seed set potential, but also the plant morphology such as dwarfness and small size of flowers . During these times less emphasis was made on the wild rose fruit characteristics.
2.3.2. Modern tools
In modern times, these classical methods become less and less efficient as the number of varieties to be tested increases and the genetic distances between varieties becomes smaller . As well, because the needs, objectives, and challenges associated with the rose industry are now changing both in terms of flower and fruit production, combination of morphological, cytological, conventional breeding and biotechnological methods are being widely used for the determination of
188.8.131.52. Probing the genetic diversity
Domestication and crop improvement involve the selection of specific alleles at genes controlling key morphological and agronomic traits, resulting in reduced genetic diversity relative to unselected genes . This artificial selection process that operates also in almost all agro-systems, including agroforestry, favours abundance of the preferred targeted phenotypes, and acts with more intensity in household gardens . In the 20th century, probing for crops and their wild relative’s genetic diversity has been the focus of extensive investigations. In roses in particular, morphometric [13, 30-34], cytological characters [25, 35] were the most used in the
184.108.40.206. Process and goal (life quality)
One of the main current questions is whether the process and goal for probing rose genetic diversity has changed over time. Although crop domestication and improvement process is a continuum, it evolves constantly with the available technologies in order to meet and fulfill the societal needs. In the present global economy, the scale of demands for any good has increased and the trade has become multidirectional (selling in all part of globe) with multiple layers (one product could be found in many other products as additive or supplement) (Table 1). Thus, probing the genetic diversity of a plant species which end-product would satisfy these new needs both in terms of quality, quantity, sustainability and stability has become the new challenge for plant products developers. Hence, the need for well characterized germplasm with stable and preserved genetic identity is becoming the landmark for todays and tomorrow’s natural product designers and developers. Therefore, sophisticated molecular tools [51, 52] as well as mass tissue culture and plant propagation tools are being employed to insure stability and sustainability.
|Purposes||Food, medicine clothing, energy, sustainability||Food, clothing, energy, health, life quality, sustainability||[28, 53, 54]|
|Screening methods||Morphology, taste, flavour, energy||Morphology, genetic DNA markers, QTLs, taste, flavour, energy, metabolite profiles,||[20, 41, 51, 52]|
|Production paths||Gathering, yards and small farms sowing and harvesting, human and animal force||Experimental tubes, growth chambers, greenhouse and fields, large commercial fields, high throughput management, human and animal force and mechanization||[28, 53]|
|Yield||Low||High||[28, 55, 56]|
|Value chain||Self, local consumption,||Global, processing, distribution and marketing networks|
3. Plant domestication in the 21st century: A case study with PEI wild rosehips
One of the most recent and successful domestication of a wild species is that of the North American ginseng . Similar to ginseng, interests in wild rosehip products are increasing worldwide due to its nutraceutical and natural health products properties . With aging and changing eating lifestyles, the incidence of chronic diseases is increasing worldwide. Despite success achieved in fighting these diseases, prevention measures have become top priorities for citizens and public health systems. Recently, increasing interest has been expressed in plant natural products as preventative agents. Hence, plant product preparations such as those from rosehip have been used as food and medicine for centuries. The genus
3.1. Introduction to the genus
Rosaspecies phylogeny and biodiversity
Rosaspecies biodiversity and phylogeny
The taxonomy and breeding system of the genus
3.2.2. North American
Rosaspecies biodiversity and phylogeny
Biodiversity of the North American wild roses has been investigated by botanists in the early 1900’s. Watson , Crepin [69, 70], Erlanson MacFarlane [71, 72] have described and defined 13 - 22
3.2.3. Genetic and Metabolite diversity within the Prince Edward Island’s field collection
Using SSR markers  and single nucleotide polymorphisms analysis, our group has assessed the genetic diversity within 30 ecotypes under cultivation and identified three major clusters, with cluster 2 and 3 showing 2 and 3 sub-clusters, respectively [65, 73]. The metabolite profiles in the flesh, seed, and fuzz for anthocyanins, flavonols, tilirosides which is a potent antidiabetic compound, tannins and fatty acids were also determined from the 30 ecotypes [65, 73]. The level of anthocyanin was very low in all ecotypes, with only one ecotype showing a level that was 30-40 % higher compared to the average. A large diversity was observed for flavonols and tiliroside among ecotypes. Only 4 ecotypes had a high content for both flavonols and tiliroside in the analyzed tissues (Ghose et al, submitted). One ecotype showed 18:3 level as high as 41.2%. The data suggests that it is possible to select and propagate a given ecotype for its unique metabolite profile for commercial and drug production [65, 73].
3.3. Domestication and end uses
Roses have been domesticated by man first for the beauty of their flower and incorporated in many cultural and political practices  and are now encountered on all continents, climates, and market places. Nonetheless, the medicinal uses of rose leaves, flowers and fruits were also widespread in human history [13, 54, 75-78].
3.3.1. Flower roses
The best known uses for roses are their flowers as ornamental on tables, in home backyards, public gardens and spaces. Historically, only very few wild rose species (at most 5 to 11 species) have been involved as parents in the today flower roses. One example of using native rose species in North America is related to the Parkland Rose series developed at AAFC in Morden, Manitoba. These flower roses are hardy, winter resistant and some of these rose varieties involve in their pedigree
3.3.2. Wild rosehips
The fruits of roses, the hips, have been highly regarded as important food and medicinal sources [13, 54, 79]. Rosehip is appreciated as traditional vitamin C rich soup in Sweden where the demand is particularly high . Its flesh and seeds have been used in concoctions and tonics for various ailments, including the use as laxative and diuretic, against common cold, gastroinstestinal disorders, gastric ulcers [77, 81, 82], and anti-inflammatory diseases such as arthritis . A review on the major chemical components of dogrose hips from was recently made by Werlemark . However, a marked variation in chemical composition is associated with species, genotypes, and environments in which the plants evolve. For example, Melville and Pyke  found a weak correlation between latitude and vitamin C content of British rosehip populations from Scotland and England. Similarly, Werlemark  hypothesised that rosehips produced in a colder climate, especially with colder summer, may have higher vitamin C content compared to those that have been maturing in a warmer climate and also anticipated that local variations in precipitations and temperatures during summer may affect the chemical content of rosehips. It is reasonable to assume that, with different species and cooler summer and fall (Table 2), the Canadian Maritime wild rose species would show different chemical composition, especially in terms of relative amount when compared to their European and South American counterparts. By comparing some rosehip samples from Prince Edward Island, Denmark, Chile and South Africa, our group observed differences between origins, especially with regards to total oil content and fatty acid profiles (Figure 2). Nonetheless, sample preparation (harvesting time and conditioning) can also be a major source of variation. It will be of interest to compare the chemical composition of rosehips collected in each of these regions during the same summer or fall for obtaining factual and conclusive answers to these assumptions.
Rosehip seed contains pretty well balanced omega-6 (18:2) / omega-3 (18:3) fatty acid ratio and also shows relatively high level of oleic acid as compared to olive and canola oils that are rich in oleic acid but low in both linoleic and linolenic acids (Figure 3). As genetic variability for fatty acid composition has been observed in PEI wild roses (Ghose et al, submitted) and the seed oil content is relatively low, breeding efforts could contribute to increase the oil content.
Although a high value was recognized to rosehip throughout centuries, it is only recently that the wild roses are being domesticated and cultivated for their fruits and to develop agronomic practices that ensure an economic production of the hips [28, 51, 52, 56, 77, 85]. However, due to the diversity of species, genotypes, soils and climates, different agronomic practices are being implemented and tested in different regions, including Denmark, Turkey, Bulgaria, Chile and Canada. Whereas Chilean started their trials by developing a nursery built on the "Tunnel" greenhouse model with a capacity to accommodate 15.000 cuttings, under an irrigation system with nebulizers to reduce temperature and humidification before a developmental stage in the fields, the Danish, Swedish and Canadian choose to established field trials using wild cutting, spacing, density and nutrient management trials [28, 55]. In Sweden, the germplasm used were mostly concentrated on the Scandinavian
220.127.116.11.1. Soils and climates
Although originally native to temperate regions of the globe, roses have adapted to warmer regions and grow well now in very diversified habitats and soil types [13, 79]. The soil should be well drained though and not heavy. Species preference for soil type has nonetheless been reported.
|PEI Canada||16 – 22||7 – 18||270||300||Orthic humo-ferric Podzol with sandy loam||46.04 – 46.57|
|Denmark||17||9||170||150||Typic Fragiudalf||55 – 57.4|
|Sweden||13||5||180||120- 140||Aeric Endoaquept||55 – 68 N|
|Turkey||17 – 29||6 – 7||50||70||Typic Haploxeroll||36 – 42 N|
|Bulgaria||25||14||180||120||pseudopodzolic- podzolic||41 – 43 N|
|Chile||17 – 28||8 - 20||350- 500||200 -300||Andisol - Ultisol||18 – 58 S|
Barry et al  described the first time the establishment of field trial for North American wild roses belonging to the
18.104.22.168.3. Pests and diseases management
Traditionally, fungal diseases such as black spot caused by
Insects such aphids (
22.214.171.124.4. Yield and storage
Rosehip yield vary considerably depending on the plant material, cultivation procedures, age of orchard, and harvesting methods. Werlemark and Nybom  reported that up to 8 kg of rosehips per bush could be harvested by hand in commercial planting of dogrose hybrid PiRo 3. Similarly up to 3 t/ha could be obtained from
One of the shortcoming issues for the establishment of commercial rosehip production orchard is the availability plant materials for large acreages. So far, all established fields are based on cuttings or seedlings obtained from wild selections. Because of the genetic diversity within the genus
126.96.36.199.1. Regeneration and propagation
The use of plant regeneration from seed for commercial production has been reported [85, 101]. It ensures the production of higher number of plants for field planting in a relatively short period of time. However, the mating system of
Cuttings and explants are currently the materials of choice in commercial wild rose production [64, 86, 101], and most, if not all, of these explants (Figure 6) are derived from wild plants. Wild rose plants grow in the nature as populations that can involve different species, interspecific and intraspecifc hybrids, parental and sibling all growing in a confined area. Collecting cuttings in such an environment, even from the same patch, does not ensure the genetic integrity of the collected material for propagation. Once collected, the material should be well characterized and identified. Now, remains our ability to get enough characterized plant materials for large field planting. We believe that the well characterized plant material should be used as starting point for plant regeneration and mass production in the form of rooted seedling or cuttings. This is the approach we pursue in Canada for commercial wild rose production (Figure 7).
Tissue protocols have been developed and available for flower roses [102-104] and could be applied to rosehip production. Once elite genotypes such as those reported by Sanderson and Fillmore  are identified, tissue culture should be able to ensure a sustainable plant production or field planting by growers (Figure 7).
188.8.131.52.2. Cell culture
Similar to tissue culture, rose plants can be regenerated by cell culture. Contrary to tissue culture however, the new plants are obtained from callus generated from sterile explants. This method leads to pure line but can also create new lines different from the mother plant from which the explant was obtained because of somaclonal variations that may occur during the induction of callus and regeneration processes. Thus, for the production of mass plant production from a selected elite wild ecotype, tissue culture appears more appropriate as it minimizes the risk of somaclonal variations while showing high rate of plant multiplication.
With the increasing demands for natural heath products, plant biodiversity is being thoroughly revisited. The genus