Routledge Handbook of Agricultural Biodiversity

Danny Hunter, Luigi Guarino, Charles Spillane, Peter C. McKeown, Danny Hunter, Luigi Guarino, Charles Spillane, Peter C. McKeown

• Publisher: Routledge
• Year: 2017
• eBook ISBN: 9781317753285
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Ecology
• Index: Biological Sciences

The world relies on very few crop and animal species for agriculture and to supply its food needs. In recent decades, there has been increased appreciation of the risk this implies for food security and quality, especially in times of environmental change. As a result, agricultural biodiversity has moved to the top of research and policy agendas.

This Handbook presents a comprehensive overview of our current knowledge of agricultural biodiversity in a series of specially commissioned chapters. It draws on multiple disciplines including plant and animal genetics, ecology, crop and animal science, food studies and nutrition, as well as social science subjects which explore the socio-economic, cultural, institutional, legal and policy aspects of agricultural biodiversity. It focuses not only on the core requirements to deliver a sustainable agriculture and food supply, but also highlights the additional ecosystem services provided by a diverse and resilient agricultural landscape and farming practices. The book provides an indispensable reference textbook for a wide range of courses in agriculture, ecology, biodiversity conservation and environmental studies.

Part 1
Biological resources for agricultural biodiversity

1
Plant Genetic Resources

Robert Henry

Introduction

Plant biodiversity provides the genetic resource base for agriculture, underpinning crop and pasture selection and breeding. Molecular tools have improved understanding of the relationships between plants and provided insights into their potential use in agriculture. Agriculture utilizes a diverse group of plant species, but we rely heavily on a very small number of species for the bulk of our food. Crop wild relatives represent key genetic resources for food and agriculture. Advancing technologies allow access to genes from more diverse plants and facilitate the domestication of new species for agriculture. Plant genetic resources are found in farmers’ fields, gene and seed banks and wild populations, and conservation in situ and ex situ is essential for agricultural sustainability. Productivity gains required to satisfy the growth in food demand will rely on utilization of these resources. Changing global food consumption patterns may influence the utilization of plant genetic resources. Diversification of diet with new crop options may be desirable to ensure food security and address trends towards homogenization of diets globally. Plant genetic resources may also hold the key to sources of genetic variation that can contribute to supporting healthier human populations and provide essential options in adapting agriculture to climate change.

Global plant diversity

Plant diversity supports agriculture by providing the genetic resources from which agricultural crop and pasture species are derived. Plants are our primary source of foods, with most foods being directly derived from plants or from animals that in turn rely on plants for food. Plants are also essential for a wide range of non-food uses, being used for construction, clothing, energy and medicine. Increased productivity is required to keep pace with increased demand for agricultural products (Ray et al., 2013). This demand is driven by growth in human populations and changes in diet associated with factors such as economic development and increased awareness of food options. The amount and type of food being consumed is changing. Growing affluence results in greater consumption, and related changes in food preferences also increase pressure on food resources.

The diversity of plants can be considered at many levels. There are probably more than 300,000 species of flowering plants on earth. To utilize this diversity effectively in agriculture, we also need to understand diversity between and within species. Within species diversity is widely exploited in agriculture in the breeding of improved crop varieties. The diversity of plants at higher taxonomic levels is also important in defining the potential to use more diverse genetic resources in the development of agricultural genotypes. Close relatives of crop plants have long been used as resource for plant breeding. Technology advances enable more distant relatives of crop plants to become options for use in crop improvement.

Figure 1.1 Phylogenetic relationships between plants

Note: The flowering plants (angiosperms) are the main group of importance in agriculture. Some gymnosperms are also used in agriculture.

Source: Based on Henry (2005a).

Plants are a very diverse group of organisms. Figure 1.1 Phylogenetic relationships between plants shows the evolutionary relationships of the major groups of plants. Agriculture relies mainly on the seed plants. These can be divided into two groups: the gymnosperms and the angiosperms. The gymnosperms, such as conifers, are mainly exploited in forestry, with limited use in food production or agriculture (e.g. pine nuts). This group is unlikely to be monophyletic, that is, to all share a common ancestor (Hill, 2005). The angiosperms, or flowering plants, are the largest and most important group of plants for agriculture. Flowering plants are classified into several hundred families (Chase, 2005). Humans have found ways of using plants from many angiosperm plant families in agriculture, but we rely most heavily on species from a smaller number of families, with the most important for agriculture probably being the Poaceae, or grass family, that includes the major cereal food species and pasture grasses.

Plant species have been traditionally classified using morphological characteristics, but advances in molecular tools have provided new insights into plant diversity, allowing relationships between plants to be better understood. The relationships among the major groups of angiosperms are depicted in Figure 1.2 Phylogenetic relationships between flowering plants. Most agricultural species are monocots or eudicots. Dicotyledonous plants are not monophyletic with a basal dicotyledonous group of flowering plants and a large distinct dicotyledonous group, the eudicots. The two main groups within the eudicots, the rosids and the asterids, are important in agriculture. Examples of agricultural species from these plant groups are listed in Table 1.1 The uses of seed plants.

Figure 1.2 Phylogenetic relationships between flowering plants

Note: The relationships between the major groups of flowering plants continue to be refined by DNA analysis, providing a guide to the most appropriate resources for use in agricultural crop improvement. This ‘big picture’ perspective is importance in searching for diversity that might be used in crop improvement.

Source: Based on Furtado et al. (2014).

Table 1.1 The uses of seed plants

Plants	Uses
Gymnosperms	Food: pine nuts, bunya nuts
	Construction: pine
Angiosperms
Amborellaceae	Amborella (only New Caledonia)
Nymphaeaceae	Ornamental: water lilies
	Food: (seeds and rhizomes)
	Cosmopolitan: (fresh water)
Austrobaileyales	One genus, two species only in Australia, no known uses
Chloranthaceae	Ornament: (Chloranthus glaberi)
	Beverage: (Chloranthus officinalis)
	Medicine: (Hedyosmum brasiliense)
Magnoliales	Food: nutmeg (Myristica fragrans), custard apple (Annona)
	Ornament: Magnolia
	Construction
Laurales	Food: avocado (Persea americana) cinnamon, bay leaves
	Ornament
	Construction
	Other: perfume (Doryphora sassafras)
	Medicine
Canellales	Ornament
	Food: white cinnamon (Canella winterana)
	Medicine
Piperales	Food: pepper (Piper nigrum)
	Beverage: kava (Piper methysticum)
	Ornament
	Medicine
Alismatales	Ornament
	Food: Sagittaria sagittifolia (tubers)
Pandanales	Food: (starchy fruits)
	Ornament: Pandanus
	Other: perfume, baskets
Dioscoreales	Food
	Medicine
Liliales	Beverage: sarsaparilla
	Ornament: Lilium, Tulipa (tulip)
	Medicine
Asparagales	Food: onions, garlic, lee, vanilla, asparagus
	Ornament: Gladiolus, Iris, Freesia, Daffodils, Orchids
	Medicine
	Other: saffron (Crocus sativus)
Arecales	Food: coconuts, copra, dates, sago, palm oil
	Fibre: coir, raffia
	Ornament
Poales	Food: rice, wheat, maize, barley, sorghum, millet, sugarcane, bamboo, pineapple
	Animal Feed: pastures
	Ornament: lawns, water plants
	Other: baskets, brooms, thatching
Plants	Uses
Dasypogonaceae	Ornament: Xanthorrhoea
	Other: varnishes
Commelinales	Ornament: wandering Jew, water hyacinth
Zingiberales	Food: banana, ginger, cardamom, turmeric, arrowroot
	Fibre: manila, hemp
	Ornament: Strelitzia, Canna
	Other: perfume
Ceratophyllales	Other: protects fish in fresh water
Ranunculales	Food: fruits
	Ornament: Clematis, Ranunculus (buttercups)
	Medicine: opium (Papaver somniferum)
Sabieaceae	Ornament
Proteales	Food: Macadamia integrifolia
	Ornament: Banksia, Grevillea, Telopea, Protea, Leucadendron, planes
	Construction: timber
Buxaceae	Ornament
	Construction
Dilleniaceae	Ornament: Hibbertia, Dillenia
Caryophyllales	Food: Arraranthus
	Ornament: cockscombs (Celosia cristata), Ptilotus
Santalales	Medicine
Saxifragales	Food: grapes (Vitis vinifera), gooseberries, currants (Ribes)
	Ornament: Hydrangeas, Kalanchoe
	Construction: timber
	Other: perfume
Crossosomatales	Ornament
	Construction
	Medicine
Gereniales	Ornament: Geranium, Pelargonium
	Construction: timber
	Medicine
	Other: perfume
Myrtales	Food: cloves (Syzygium aromaticum), lilly pilly
	Ornament: bottlebrushes, Tibouchina, Fuchsias
	Construction: Eucalyptus
	Medicine
	Other: essential oils
Celastrales	Beverage: Arabia tea (Catha edulis)
	Medicine
	Other: essential oils
Malpighiales	Food: cassava (Manihot glaziovii), passionfruit (Passiflora)
	Ornament: Poinsettia (Euphorbia), violets
	Industry: castor oil (Ricinus communis)
	Other: rubber (Hevea brasiliensis)
Oxalidales	Ornament: flycatcher plant (Cephalotus follicularis)
	Construction: timber
Plants	Uses
Rosales	Food: fruits (apple, plum, pear, cherry, mulberries, fig, raspberries, strawberries)
	Fibre: hemp (Cannabis sativa)
	Ornament: roses
	Beverage: hops (Humulus lupulus)
	Construction: elms
Fabales	Food: peas, beans, groundnut (peanut), soybean
	Animal Feed: clover, lucerne
	Other: nitrogen fixing
	Construction: timber
	Ornament: Acacia
Fagales	Food: chestnut (Castanea sativa), walnut, pecan
	Construction: beeches, oaks, birches
Cucurbitales	Food: cucumber, pumpkin, melon
	Ornament: Begonia
Brassicales	Food: oilseed rape, mustard, vegetables, (cabbage, cauliflower), papaya (Carica papaya)
	Animal Feed: fodder
Sapindales	Food: orange, lemon, lime, mango, cashew, pistachio, lychee (Litchi chinensis), maple sugar
	Ornament: maples
	Medicine
	Construction: mahoganies
	Other: perfume, posion ivy
Malavales	Fibre: cotton (Gossypium)
	Ornament: Hibiscus
	Construction
	Other: chocolate
Cornales	Ornament: dogwoods
Ericales	Beverage: tea (Camellia sinensis)
	Ornament: Camellia
	Construction
Garryales	Medicine
Lamiales	Food: olives (Olea europaca)
Solanales	Food: potato, aubergine, tomato, pepper, sweet potato
	Ornament: morning glory (Ipomoea purpurea)
	Medicine
	Other: tobacco
Gentianales	Beverage: coffee (Coffea)
	Ornament: Gentian, oleandeas (Nerium), Gardenia
	Medicine: quinine (Cinchona)
Aquifoliales	Ornament: holly
	Construction
Apiales	Food: carrot, celery, parley, fennel, dill
	Medicine
	Other: perfume
Asterales	Food: sunflower, lettuce, chicory, Jerusalem artichoke
	Ornament: Dahlia, Gerbera
Dipsacales	Beverage: elderberry (wine)
	Ornament: honeysuckles (Lonicera)
	Medicine

Source: Adapted from Henry (2005b).

The relationships between plants may be assessed by analysis of their DNA. The nuclear and maternal (chloroplast and mitochondria) genomes may show different relationships. Reticulate evolution, found in many plant groups, including agriculturally important species, allows chloroplast transfer or ‘capture’ between species.

The importance of the diversity of micro-organisms in the environment of plants is increasingly being revealed as an important contributor to plant performance. This genetic resource is much less well known than the plants themselves but is also important for agriculture (see also Beed et al., Chapter 8 of this Handbook).

Diversity of species

Reliance on key species in agriculture

Despite the use of many different plants by humans, a relatively small number account for a large proportion of global agricultural production and food ...

Table of contents

• Cover
• Title
• Copyright
• Dedication
• CONTENTS
• Contributors
• Introduction: agricultural biodiversity, the key to sustainable food systems in the 21st century
• PART 1 Biological resources for agricultural biodiversity
• PART 2 The origins and history of agricultural biodiversity
• PART 3 The value of agricultural biodiversity
• PART 4 Agricultural biodiversity: human health and well-being
• PART 5 The drivers of agricultural biodiversity
• PART 6 Safeguarding agricultural biodiversity
• Index