The development
of improved willow clones for eastern North America 1
4, G.A. Tuskan 5
by R.F. Kopp 2, L.B. Smart 2, c.A. Maynard 3, J.G. Isebrands and L.P. Abrahamson 2,3
i ', [ Z • • ._ "_ "_ gl_
Effo,'_s aimed at genetic hnprovement ofSalix are increasing in Nerd'_ America. Most of these are directed towards de','eloping improved clo,-es for b/omass production, phytoremediation, nutrient filters, and stream bank stabilization in the Northeast and Nonh-central United States. Native species are of primary interest, but a small number of clones containing non-native germplasm are also being used m _e breeding program to provide valuable traits. Parent combinations for conu'olled crosses are being selected with the hope of maximizing the probability of producing clones exhibiting heterosis for traits of interest, such as rapid early growth, pest resistance, general adaptability, etc. The present strategy is to test as many parent clone combinations as possible, and then repeat the ruost protmstag crosses to produce large families from which the best clones will be selected for further testing. Molecular fingerprintiog technology will be applied to of accelerate the rate of improvement. National and international cooperation would facilitate regional clone and de;eloi_ment promotion willow as a bioenergy crop. Key. words: Salix, biomass production, breeding, heterosis, molecular fingerprinting
Lea efforts destin_.s 'a t'am_.lioration gdn,_tique du Salix croissent sans cesse en Am_rique du Nord. La majeu,'e pattie des efforts eat concentrSe sur le d_veloppcment de clones am_lior_.s pour la production de biomas_e, la phytorem4diation, le_ filtres d'_ldments nutritifs et la stabilisation des rives des cours d'eau dana te nord-est et le centre-nord des Etats-Unis. L'int&at porte avant toute chose sur lea es_ces indig_.nes, mais un petit hombre de clones contenant des cellules embryonnaires non indighnes sont 6galement utilises dana le programme de reproduction afin d'apporter des caract&istiques int6ressantes. Lea combinaisons parentales pot:r obtenir des descendants de proven,'mce contt'61,Sesont choisics dana le but de ma.rdrn.iserla probabilit_ de produire des clones dthnoulmnt une hdt&ogdndir6 dc_ caract_ristiqt,es int6ress-mtes, ton'mar la croiss,',.nce initiale rapide, Ia rdsistanee aux ravageurs, l'adaptabilit4 gdn4rale, etc. La slratdgie actuelle eat de tester autant de combinaisons parentales de clones que possible, et de reproduire par la suite lea descendants lea plus pronzetteurs pour produire des grandes families desquelles lea meilleurs clones seront choisis pour poursuivre tea tests. La technologic de I'empreinte digitale mol6culaire sera utilis,Se pour acc_l_rer le taux d'am6lioration. La cooNration nationale faciliterait le d4veloppement de clones rdgionaux et la promotion du saule en tant que ressource biodnerg4tique. Mots-clis : Salix. production de biomasse, reproduction, h6t&og4ndit6, empreinte digitale moldculaire et interaationale 1
m_ _ _
_ ,._
"_ ._
L
History of Willow Genetic Improvement
in the
United States
q-"ne dccumented history of Salix culture in North America starts during the period from 1840-1850 when German immigrants began producing willows for basketry" in New York State and Pennsylvania. Early basket makers used native species, but soon began importing and planting willows fromuniformiEurope, particularly Salix pt_rpurea L.. to increase product ty. The importance of selecting clones with desirable form and wood qualities that were adapted to local soils and pests was recognized in the earliest days of willow culture (Hubbard 1904). Early willow improvement efforts in the United States ineluded field trials of 70 European clones in the 1880s (Simpson 1898). The willow basket industry, in the U.S. reached during the 1870s and continued until World War 1I. a peak
Interest in growing and using poplars and willows for energy and to produce high-value chelnicals and other bio-ba..¢_,l products has increased in the United States during the past two decades, due to unstable petroleum prices, a desire to decrease dependency on imported fossil fuels, and concern about the environmental impacts of burning fossil fuel. Exceptionally high productivity rates have been achieved with hybrid poplars in the Pacific Northwest. Nit in l!:e Nortl_,:,',st and Northcentral United States Septoria canker severely limits growth of many hybrid poplar clones (Abrahamson et al. 1990. Ostry and McNabb 1990). However, Septoria is not a disease problem for willows. Because of disease problen'_s with hybrid poplars and reports of high biomass yields acNeved with willows grown under intensive culture systems in Europe (Stott 1984, Chrispt-imary gelaus tersson 1986), Salix became the of interest for short-rotation woody biomass production in the Northeast Urtited States during the late I980s. Despite the availability of improved clones from Europe, genetic improvementclones wilof that lows became necessary to obtain locally-adapted express irlcrease.d average production rates, improved growth
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tPreseated to tl_e 21st Session of the International Poplar Commission.
ZState University of New York College Forestry, Faculty Environment;d andWas_tington, Forest Environmental Science and Septea-ber of 2000.Vancouver, ofBiology. 1 ForestryDrive.Syra24-=8. t_'SA cuse. NY 13210 _ :_Stat¢University of New York College of Environmental Science and • I_ Forestry, Faculty of Forestry, 1 Forestry Drive, Syracuse. NY 13210 _ "_USDA Forest Setwice K, R.hinetaadcr. W15450t o_ato_y.5985 HighwayNotah Central Research Station, ForestrySciences Lab_OakRidge Nation,'dLaboratory, Environmental Scicr.cesDivision. P.O. Box 2008 Mail Stop 6422, Oak Ridge. TN 3783t
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ing the economic attractiveness of growing willows for bioenform, and improved levels of pest resistance, thereby irnprovergy and bio-based products. Willows are also being planted in North America for purposes other than bioenergy with increasing frequency. PIaytoremediation is an emerging technology being used for remediation of contaminated soils and filtration of water throughout North America (Isebrands 2000) and Europe
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(l'ctUu 1999).Phyt(w_nlcdiutioninvolves Ihedirect u._c planls t)f Ic_ decrease risks from contaminated soil. sludge, .,,cdiments, and ground water by contaminantremoval,degradatk_n, _'rconfil_emcnt(US EPA I1598). Willows (5olL_ spp.k_dc_lg with [x'.pku_ ([_OlmlU._ spp.), are tile most COllll'll()l'l[y usedtrec species I'¢w phytoremcdia[ion, due to their rapid growth zate, ease of prc,pagation, and denlonsuated cont,mlinant uptake c_pability. Willows are currently under study acrossNorth America for a v:uiely of i_hytt,remediation and rip_u'ianbuffer strip applications (Isebrands and Ka,nosky 2001_. WiIlo_,s are widely used in riparian management in North America. Dormant willows are planted as cuttings, D_sts, and brush rnattre.sses Ior stream bank stabirization fSchultz et el. 2(XY,.)). Willows :u'e also used to stabilize reservoir btmk.s.Re,arch on using willows for purification of waste-water and sludge ha.sbccrt in progress in Sweden since the 19S0s,and SaIL_climes have been shown to be effective for removing large quantities of nutrients from land-applied wastes in Europe (Perttu and Kowalik 1997) and even tl'te removal of caesium fronl radiocontaminated soils (Sennerby-Forsse et el. 1993). Nutrient illlet.,;COmlX_d ofgntsses have been succe._fully u.scd Ibr d,_x.'adcs in North America (Young et el. I980), but planting willows in filter strips is relatively new. Genetic improvement through selection and breeding may be _2cess_y to develop clonc.ssi:ccifically for planting in filter strips and clones tirol are more effeclive for stream and reservoir bank stabilization,
Tile Salix Gerl|lplasni
Resource in North AIII_'L'Jca North America contains a Salix germplasm resource floatis large, rich in genetic diversity, and virtually unexplored (Zsuffa 1988). About 70 willow species are native to Nu_th America (Fowells 1965). In addititm, willow species inu'c.nluccd from Europe, including S. elba and S. purpureo, have become naturalized in the Northeast and North-central United States and Southeast Canada (Voss 19_5i. Many native, naturalized and introduced species have desirable traits for biomass production, phytoremediation, nutrient filters, and stream bank stabilization, but few of them have been tested across a wide variety of geographic areas or site types (Table l). A genetically dive_.'sewillow breeding population is nece.sszuy to provide sufficient variation from which clones can be developed that are adapted to a wide variety of purposes and site conditions in eastern North America. A broad genetic base in tile breeding population will ensure flexibility in the b_'ceding program and the potential to adapt to changes in types of sites desired for planting and/or pest problems. Maintaining a genetically diverse germplasm collection is critical for tlie long-tern] success of willow breeding efforts (Eriksson et el. 198,1). From t 987 through 1999, researchers at the State University of New York College of E_vironmental Science and Forestry (SUNY-ESF) assembled a breeding population of willow containing more than 500 clones. Most of the clones caste from Ontario, Canada (developed by co-operators at the University of Toronto) and from wild stands across New York and Pennsylvania. and are of species native or naturalizcd in the Northeast. Ilowever, bccause many of the clones are closely related and several species are representcd by a small number of clones, the genetic diversity in this collection will be expanded in order to sustain a king-term breeding program.
The overall goal of our will(_w breeding D)pulatiun devclopmcnl efl'_wl is lu us.,,cmblea large and diver.,,c germpln.,,m collection thai _,,ill permit continuous iu_l'WOVernentsver o many breeding generations. Specific goals include doubling II'te number (fl" S. erio_ cFlufla cIiilleS I'rom. approxinl_ltclv 100 to 200 and expanding the number of S. pttrpureo c{ones from 20 to 150.Ba._d oil genetic diversity estimates fL;r S.eri. _,cephala,approximately 150 clones collected fr_m a b,'oad get,graphic range should conlain most of the alleles present in the species (Aravanopoulos et aL 1999,_. Up to 75 ckm_zs (_t" both S. hwida and 5: nigra, and a small number of clones of other SatL_ species will be collected. Clones from non-native species will be obtained frm'n colleagues in Asia z_ndEurope to provide additional useful genes th_tt may be incorpt)rated into production clones through advanced-generation breeding. Efforts to expand our willow germplasm collcction began in July 20(X).We co[lcctcd If'A)willow chilies fio,n native stands across New York. Obits, Permsylvania, Connecticut. and Massachusetts and propagated them in a greenhouse for field-planting during spring 2(X) I. Trees were selected bused on vigour, forltl, itftd insect and disease resistance relative to " other trees of the same Sl.Vecics tile i,umcdiale vicinity, Mt_st in of the clones collected thus far were identified as S. eriocephala and S. puq_urea with smaller numbers of S, ha'ida and S. ni£ra also included. Colleclions will be ct)mplclcd in Michigan, Minnesota and Wisconsin during 2001. All of the new clones collected for this project wilt be planted in observation trials on two sites, one in New Yo_'kand the othcr in Wisconsin. The purposcx of these trials are: 1) tO assess the phenotypic variability in _ew clones collected from a wide geographic region. 2) to determine how the clones perform in locations distant fi'om Lh¢ir origin, and 3) to identify clones for future breeding vmfk v,ith desirable traits. The trials will also serve as clonul archives duplicated on _wo sites to minimize the chance of losing clones. Intra- anti inter-specific hybrid clones produced in our previous breeding efforts will be included in d_cse ui_ds to compare _,'ith clothes collected from native stands. Production clones cur,'ently being planted will also be included in ihese trials to serve as cuntrols ("cotnmerciai checks"). Cloncs will be selected for use in the first parental generatiou based on measurements and observations completed during the first and second growing seasons after the initial coppice. Selection criteria will vary, dependhlg on the desired end-use of the clones. Statistical analyses will be used tt_ determine if clonal differences exist in initial height growth, average stem diameter, sttx_l dry weight, number of stems per .stool, disease and/or insect resistance,-and ci'own form (Table 2) and if clone-by-site interaction is large. If large cloneby-sile interactions _u'eobserved, then sel_tion of superior clones ,.,.,ill e _':complished in a .__i!e-sl.',c.cifit'. b mariner. 1.2J'gev,'u'iabitity will be maintained in Ihe base breeding populatitm t_) allow selection tbr nun_erous end-uses. Background on Genetic Illil}rOVelllent of Willow ill North America A limited ,'mxountof willow breedittg and selection has been conducted in North America. Native species were bred in the 1980s by researchers at the University of Toronto to produce F t inu'a- and interspccific hybrids for biocnergy production (Mosseler 1985). Controlled breeding of S. eriocephala and
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Table 1, Clas.sil_cation Sectional Ctas.,_il3cat[o n 1 Subgenus Sah.x H:lmbotti,_n=e
otSalix
species testcd in biomass Species S. an,ygdaloides S. nigra Marsh S. alba L. S. fragilis L. S. marmrdona Koidz. S. hici(la Muhl. S. exig,,a Null.
production
trials in the Northeast Form
or North-central
United States.
Native Range .N.C. USA Eastern USA Central Europe Central Europe Northern China Eas:ern N. America North America
Aridel ss.
tree tree u¢e tree tree shrub shrub
Salix
Subalbae Salicaster Longifoti_e Subgenus V_.:r_ Vettix
S. bebbiana Sur_. S. discolor" .Muhl. S. petiolaris Smith S. dasychtdos Wimm. S. pcllita Anderss. S. sachalhrensis Schmidt. S. vimmalis L. S. eriocephala Muhl.
shrub shl'ub shrub tl'ee shrub shrub shrub .shrub shrub shrub
transcontineata/ NorLh America North America C. Europe to E. S:beria E. Can_,da Japan C. Europe to E. Siberia North America E. Siberia, China Europe
Vimcn
Cordatae Helix _Secdonal classification according
S. n,iyabeana Seeman S. purpt_rea L. to Dora ( 1976_.
S. sericea by researchers at Vassar College in Poughkeepsie, NY yielded intra- and interspecific hybrids, which were used in studies on herbivore preference and gene introgression (Roche arid Fritz 1997, Hardig et al. 2000). Our group initiared a progr,'u'n of controlled willow breeding in I998 to produce wilIows for bioenergy or conversion to high-value chemicals. Native and introduced species were used to produce F 1intra- and interspccific progeny in 1998, and some of these clones were crossed in 2(X30 to produce F 2 progeny (Kopp et al. 2000). Thus, very few multiple-generation, structured Salix pedigrees exist today that could be useful in gene expression studies. lnterspecific hybridization of willows may yield superior clones through the combination of desirable traits, hcterosis. and greater phenotypic stability it1varied environments (Stettier et al. 1996). Many examples of successful interspecific hybridization with willows have been reported (Argus 1974, Hathaway 1977. Zsuffa er al. 1984, Larsson 1998). However, interspccific hybridization of willow species native to North America generally resulted in F I hybrid progeny, which often had decreased vigour and poor survival, though some individuals exceeded the growth of either parent (Mosseler 1990). S. eriocephala females failed to yield viable seed in any interspeciflc hybridization attempts in studies cornpleted by Mosseler (1990) or Kopp (2000), S. eriocephala is known to be difficult to hybridize when it is the pistillate parent because of inhibition of pollen tube growth (Mosseler 1989). These findings suggest that S. et_ocephaIa males should be used in interspecific hybridization efforts with this species. Vigorous growth by S. vhrlinalis in northern Europe is well documented (Gullberg 1993, R/Snnberg.W_istljung and Gullberg 1996, Larsson 1998), but various insect pests, par-
ticularly potato leaf'hoppers (Empoascafabae Harris), cause substantial damage and associated poor growth of this species in the Northeast and North-central United States (Kopp2000). Preliminary information from an unreplicated field u'ial suggests that progeny of crosses between S. vimina/is and S. miyabeana, an Asian species, may be less susceptible to potato leafhopper attack. If substantiated, S. viminalis germplasm may contribute to the production of high-yielding hybrid clones for use in North America once genes for resistance to potato leafhopper can be introduced. Role of Biotechnology in Willow Tree
Improvement
Application of biotechnology to willow tree improvement may accelerate the rate of genetic gain. Recently developed molecular techniques may enable willow breeders to narrow the pool of candidate breeding trees, so that effort is not wasted on crosses that have low probability ofproducing dcsirable progeny. Molecular markers can help to characterize populations, estimate genetic variability within and among wild or generated populations, and identify individuals at a young agethatwillexpmssau'aitatmatudty (Dinus andTuskm_ 19971. Molecular fingerprinting can be used to produce genetic maps for traits ofit_terest. A genetic map including restriction fragment length polymorphism (RFLP), sequence-tagged sites (STSs), and RAPD markers was produced for a hybrid poplar family dcrved from all inbred F2 family (Bradshaw et aL 1994).This m,apwas used to identify quantitative trait leci (QTLs) with large effects on growth, form, and phenology (Bradshaw arid Stettler 1995). Similar techniques may be applied to willow breeding. We have generated populations of Fj and F,2_rogep
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"l'2dflc.'l','aits il,{crt',_t witl,w I_immL_._ 2 ,,r r.r produdiou. Mcnsurational Traits Biomass rtKlu,:tion" p Ste.m hci_hl" Stem diamctur _ Number f_tcm_ u "_ Stoo[ _ form .SurvivaP ',V_md densit) _
l'h.,,sic,l,_gical TraiLs
_rraits that will bc IJlr_;IglJl'¢d I.,{l Ii'_'C$ lit illl _11_ '¢.. bTrait_ _ill be measuredastime a,_drundtn_permit. 'hm
Syl!elxic _lr,ou Imxluc_ic,v" In_ect u._¢el_libihly:' _ Patho_ca m_cg_tinili W' i"a[]lilycombiJmtio(',s (approxitrv.ltely wilt r'e comple:edwhen 50) Mammal bro',,,s: Rt,._¢el;tibility flowers and juvenile growth atld [_cst resistance data are _ t[e."bicide _ tolerance available ti0mclonesollected c orprc.KIuced from1.993o2(Y]I. t Foliage chemistry t' Parentclone combinations will be selected to ma;-2tL_O. 2t '_Session of the Intcntational Poplar Comll_ission. Portland, Oregon, Septembcr 24-30. 20()0. 13 p. [sebrm_ds, J.G. mid D.F. Karnosky. 2001. Environmemal benefits of t_l:[at culture. In D.[. Dicknmnn et al. reds.). Poplar Cnl{ure in N't_rth Amen'ion. N'RC Rc._earch Press, Ottawa, Ontario. Canada (in press). Kopp, R.F. 2000. Genetic improvement of SalL_ Using Traditiona[ Breeding and AFLP Fingerprinting. Ph.D. Disserlation. State U_fivers[ty of New York College of Environmental Science and Forestry, Syracuse, NY. [75 p. Kopp, R.F., I,.B. Smarl, L.P. Abrahamson, C.A. Maynard and J.G. lsebramls. 2000. Gc_]ctit: iHtprtwemcm olSalLt" tbr the NL_rtheast and North-Central United States. bt J.G. Isebrands and J, Richardson (compi.lers). USDA Forest Service North Central Research Station General Technical Report NC-215.21 s_Session of the International Poplar Commission (IPC 2000) Poplar and Willow Culture: Meeting the Needs _f Society and the Environment. l,ars.',ou, S. 1998. Genetic improvemem of wiltow for short-rotation coppice. Biomass and Biocnergy 15: 2.'g.-26. Mosseler, A. 1985. An overview of Salix breeding in Otltario. Procecdings of the 2IY Meeting of fl_eCanadiaq TreeImprovement As._t' ciation. August I9-22, 1995, Quebec City. QC. pp. 142-150. Mosseler, A. 1989, lnterspccific pollen-pistil inco_gruity in Salix. Canadian ]ournal of Forest Research 19:1161-I 168. .Mo&_eler, A. 1990. Hybrid performance and species crossability relatmnships in willows (Salix). Canadian Journal of B(_tany 68: 2329--2338. Ostry, _,I.E. and II.S. MeNabb. 1990. Minimizing disease i_Liury to hybrid poplars. Jonrnal of Environme_tal tlotticulture 8: 96--9S. Pertlu. K.L. 1999. Environmental and hygienic aspects of v.illow coppice in Sweden. Biomass and Biocnergy 16: 29t-297. l'cr1,tn, K. and P.J. Kowalik. 1997. Sali,c vegetation filters for purification of waters and soils. Biomass and Bioenergy 12: 9-19. Roche, B.M. and R.S. Fritz. 1997. Geuetics of resistance of SalL,: sericea to a diverse community of herbivores. Evolution 51: 1490--149S.
Riinnt}er_.Wfislljtmg. A.C. nnd Lt, Gullbcrg. 1996. Genetrc relafion.shil'_s .xztweengrowth chmaclcr'_ in 5ttlix riminalis grown in Swe} den. Theoretical and Applicd Genetics q3: 15-21. Schultz, R.C.. J.P. Collelli0 T.M. lsenhar[, C.O. M'arqttez, W.W. Simpkins and C.J. Ball. 2000. Ripari,'ut forest buffer praclice,_./,1 W.J. Rictveld. R.F. Fisher a'_d II.E. Garrcll (re.Is.). North America_t Agrofi_rcstry: An Integrated ScieJwe and Practice. pp. 1S9-2,_2. American Society of Agroltomy. Madison, W[. Seunerhy-Forsse, L., D..Melln and K. Rosen. 1993, Uptake and distributi_m of radiocesium in fast-growing S_llix t'imhutli_. Journ._i of Sustainable Forestry I: 93-103. Shnpson, J.M. 1898. Osicr_.'ulture. Unitc_.lStatcs Ekzp:.utmcmof Agdculture Bulletin No. [9.27 p. Slcttler, R.F., R.C. Fenn, P.F.. Hcihnart and B.J. S/anion. 1988. P_Tmlus trich_pcarpa x Popuhts deltoides hybrids f_r short ro_ati_m culture: variation patterns and 4-year field pcrl't_rmancc Canadian Journal of Forest Research 18: 745-753. SteHler, R.F., L. Zsuffa at_.d R. Wu. 1996. The rule _)fhybridiz-tcon in the genetic manipulation oi"Popuhh_. h_ R.F. Stcttler. I'I.D. Brudshaw Jr., P.E. tleih-nan and T.M. 1linckley (eds.). Biology of P¢q_uhts and Its Implications for Management and Conse_waltoa. P:_'t 1, Chapter 4. pp. 87-I 12. NRC Re._,'u'ch P_css, National Rose,arch Counoil of Canada. Ottawa, ON. SI.oll, K.G. 1984. Improving the. bioma_ lX_lcntkdof willow by scleetion and breeding. In K. Perttu (ed.). Ecology and Management of F, rcst Biomass Production Systems. Report 15. pp. 233--260 Swedish University of Agricultural Science, Uppsala. S,.,.'cdc,L Slrau,_s, S.I I., K. Raffa and P. LLst.21)00. Edfics and trans,,onto p[anrations. Journal of Forestry 98: 47-48. Tuskan, G.A. 1997. Clonal forestry, heterosis and advancedgeneration breeding. Proceedings of the 24th Bi.ennial Southern Forest Tree huprovemcnt Conference. ()tlando. FI.,, June t}'-I 2. 1997. pp. 390.--392. U.S. Environntenlal Proleeliou Agency !EPA). 1998, A ¢itiz_'n's guide to phytoremediation. EPA 542-F-98-t}11. Tech_ology Fact Sheet. Office of Solid Waste and Emergency Response 15102G). 6 p. Vahala, T., P. Slabel and 'r. Eriksson. 1989. Genetic transforlnation or willows (Salix spp.)by,'lgr_bacterium tumtfacicns. Pbnt Cell Reports 8: 55-58. Vuss, E.G. 1985. Michigat_ Fk_ra: A _uide to the tdemil"tc:!tit_t _t_O occurrence of the native and naturalized sccd-plant_ oi"[he St:_te. Part II. Dicots (Saururaceae-Cornaceac). Cranbr_a_k Institute of Science. Ann Arbor, M[. 724 p. Xing, Z. 1995. Genetic _ransl'ormation and regeneration of willows (SalLr spp). Ph.D. Dissetlation, SUNY College of Envixtnament."d Science and Forestry. Syracuse, NY. 13(I p. Young, R.A., 3_'. hmtrods and W. Anderson. 1981,).Effcctivencs_ I of vegetated buffer strips in cumrulling pollution from feedlo: runoff. Journal of Environmental Quality 9: 483-4,",17. Zsuffa, I, 1988. A review of progress in _lecling and breeding Noah American Salb: species for energy plantations at the Faculty uf Forestry, University of Toronto. Canada. h_ternation.',l Energy Agency Proceedings from Willow Breeding Symposium August 31-September 1, 1987. Research Notes 41: pp. 41-51. Swedish Uuiversity of Agricultural Sciet_ces, Uppsala, Sweden. Z.sufra, L., A. Musseler and Y. Ruj. 1984. F'rosl"x'cts for int_r:-q',eeific hybridization in willow for biornass productiou, h_ K. Pcrttu {cd.). Ecology and Management of Forest Bit_naass Pt'cductio_ Systems. Report 15. pp. 261-281. Swedish University of Agricultur_d Sciences, Uppsala. Sweden.
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