marker-assisted selection in wheat - ictsd

Chapter 14 – Marker-assisted selection in Eucalyptus 255extremely variable. A textbook case isthe Rio Claro hybrid swarm in Brazil(Campinhos and Ikemori, 1977; Brune andZobel, 1981), a eucalypt arboretum whereNavarro de Andrade, the “father of eucalypts”in Brazil first introduced and planteda collection of 144 different Eucalyptusspecies between 1904 and 1909. Several ofthese species hybridized once the naturalbarriers to introgression were removed inthe exotic habitat so that seeds collectedfrom these stands were largely interspecifichybrids. Large commercial plantationswere established in Brazil with seeds fromthis arboretum following fiscal incentivesfor reforestation granted by the governmentstarting in 1966. Although some of theresulting forests were on average economicallyinferior, in these very variable standssome outstanding trees for growth, formand disease resistance derived from chanceevents of recombination were found. Theadvent of operational cloning techniquesat the beginning of the 1980s allowed capturingthe superiority of such hybrids thatare still used today in some of the mostproductive eucalypt clonal plantations inthe world.The history of eucalypt breeding, whichis short when compared with crop species,was detailed by Eldridge et al. (1993) andmore recently reviewed and updated byPotts (2004). Some of the earliest breedingwas undertaken by French foresters inMorocco in 1954–55 (Eldridge et al., 1993).The advent of industrially-oriented eucalyptstands in the 1960s led to a more formalapproach to breeding with, for example, theestablishment of the Florida E. grandisbreeding programme in 1961 (Franklin,1986), E. globulus breeding in Portugal in1965–66 (Potts et al., 2004) and large provenancetests of E. camaldulensis in manycountries (Eldridge et al., 1993). However, amajor breakthrough in eucalypt plantationtechnology occurred in the 1970s with theestablishment of the first commercial standsof selected clones derived from hardwoodcuttings in the Democratic Republic of theCongo (Martin and Quillet, 1974) followedby Aracruz in Brazil (Campinhos andIkemori, 1977). At the same time, in manytropical countries such as Brazil and SouthAfrica, efforts were intensified to establishextensive provenance/progeny trialsof species such as E. urophylla, E. grandisand some others that belonged to the samesubgenus Symphyomyrtus (Eldridge et al.,1993). These trials were established fromopen pollinated seed lots collected fromselected trees in the wild and constitutedthe base populations for subsequent selectivebreeding in many countries. This initialeffort, which was carried out typically bygovernment forestry research institutions,was followed during the 1980s by moreintensive collections by private organizations,targeting elite provenances identifiedin earlier collections as being more adaptedfor species such as E. grandis, E. tereticornisand E. viminalis (Eldridge et al., 1993).Eucalyptus breeding and plantationforestryEucalyptus plantation forestry species arewell known for their fast growth, straightform, valuable wood properties, wideadaptability to soils and climates, andease of management through coppicing(Eldridge et al., 1993; Potts, 2004). Theyare now planted in more than 90 countrieswhere the various species are grownfor products as diverse as sawn timber,poles, firewood, pulp, charcoal, essentialoils, honey and tannin as well as for shadeand shelter (Doughty, 2000). They are animportant source of fuel and building materialin rural communities in countries such