Can we design an ideal energy crop? Plant breeding research bridging ecology, eco-physiology and genetics

Transcription

1 Department of Crop Production Ecology Martin Weih Can we design an ideal energy crop? Plant breeding research bridging ecology, eco-physiology and genetics => Plant breeding with focus energy crops => Case study Salix breeding project => What would be an ideal energy crop?

2 Bridging ecology, eco-physiology and genetics

3 Plant breeding Application of genetic principles to produce plants that are more useful to humans. This is accomplished by selecting plants found to be economically or aesthetically desirable, first by controlling the mating of selected individuals, and then by selecting certain individuals among the progeny. (Encyclopedia Britannica)

4 Plant breeding: Ideal crops Ideotype (cereal) Schematic representation of the ideal yielding plant producing a large amount of high quality grain with low fertilizer input. (Chardon et al J Exp Bot)

5 Plant breeding: Ideal crops DW SEEDS grain yield/plant DW VEG vegetative biomass DW (DR+SEEDS) tot. biomass HI harvest index NHI nitrogen harvest index UI utility index N% N conc. Four ideotypes summarizing the specifications of different groups using agronomic indicators (from Chardon et al J Exp Bot)

6 Energy crop A plant which is grown and exploited for its energy content Commercial energy crops are typically densely planted, high yielding crop species Annual and perennial crops Dedicated energy crops

7 Energy from crops in Sweden (2006) 2% Salix for combustion 2.17 PJ 53% Cereals for ethanol production 1.23 PJ 30% Hemp for combustion 0.08 PJ 2% Reed canary grass for combustion 0.09 PJ 2% Source: updated from Johnsson 2006 Cereals for combustion 0.36 PJ 9% Oilseed rape for RME production 0.14 PJ 4%

8 Salix and poplars are fast-growing trees (early successional species) 10 MAI (Mg ha -1 yr -1 ) Populus Picea Stand age (yr) Source: Weih (2004) Can. J. For. Res.

9 Willow SRF in Sweden Commercially bred hybrid willows (Salix spp.) Plantations on fertile agricultural or forest land Coppice systems, high plantation density Currently c. 10,000 ha managed by 1000 farmers Structures for commercial management in place Woody biomass chips used for energy

10 The Salix production system Planting Harvest From Weih (2013) in Biofuel Crops (Ed. B.P. Singh)

11 Energy content 1 t dry Salix wood chips 4-5 MWh energy 0.5 t oil Energy ratio (ouput/input) ca. 20

12 Major limiting factors for willow biomass production Mineral nutrients Water Standing biomass (t ha -1 ) (A) W 0 F 0 W 0 F+ W+F 0 W+F+ From Weih & Nordh (2005) Tree Physiol.

13 Genotype differences in growth Fertilisation response varies between genotypes (Variety x fertilisation interaction effect, ANCOVA P = 0.049) Possibilities for breeding? 0 Standing biomass (t ha -1 ) (B) F 0 F+ Jorr Gudrun Björn Tordis Tora Loden After first cutting cycle (3 years) From Weih & Nordh (2005) Tree Physiol.

14 Biomass yields energy crops (Numbers adjacent to bars indicate single published field trials) Source: Allwright & Taylor (2016) Trends Plant Sci 21:43-54

15 Factors affecting cropping security: Pests! Leaf beetle (Phratora vulgatissima) Moose Gall midge Melampsora rust

16 Dept. of Crop Production Ecology Martin Weih Salix molecular breeding actions: Integrating molecular genetics, eco-physiology and ecology From Weih (2013) in Biofuel Crops (Ed. B.P. Singh)

17 Approach: Speed up development of new varieties with a combination of phenotypic and marker-based selection (MAS) Development of genetic maps. Analysis of phenotype and inheritance of resistance, tolerance and growth traits as well as development of genetic markers for these traits. Test the markers in breeding populations

18 Genetic linkage maps Field, greenhouse and lab experiments (phenotyping!) Association phenotype-genotype (nat. populations), QTL (mapping populations) Candidate genes (Poplar genome), molecular markers, SNP, gene expression

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20 Field trials in Sweden and Italy with focus on water and nutrient economy Experimental design - 2 irrigation treatments genotypes (6 blocks)

21 Phenotyping in field experiments (Sweden and Italy) Assessments: - Biomass growth - Leaf N content - Water use efficiency (e.g. isotope methodology) - Phenology (bud burst, growth cessation, leaf senescence)

22 Traits assoc. with increased biomass prod.: Phenology

23 Traits assoc. with increased biomass prod.: Shoot biomass (g) A Leafy period duration (days) B Bud burst date (day of year) 1000 C D Phenology Shoot biomass (g) Growth cessation (day of year) Completion of leaf absc. (day of year) 220 E F Shoot d.w. increase (g) From Weih (2009) Tree Physiol Leaf N concentration (%) Completion of leaf absc. (day of year)

24 Linkage map construction (A. Rönnberg-Wästljung, S. Berlin) Mapping populations: - S. viminalis x S. schwerinii (470 indiv.) - S. viminalis x S. viminalis (282 indiv.) Molecular markers (SNP, microsat., AFLP) One linkage group in willow aligned to the poplar homolog Poplar LG III III-1 0,6 III-3_sa 1,1 III_21_sa 2,2 III-15 2,5 III-2_sa 2,8 III-4_sa 3,5 III_26_sa_pI 3,9 III_8om_sa 7,2 III_23_sa_pI III_23_sa_pIII 8,9 III-3c 9,8 III_24_sa 11,0 III-12_sa 11,4 III-13_sa 12,4 SB ,3 III-14_sa 13,5 III-15_sa 14,7 III-17_sa 16,9 III-18_sa 17,6 R_4_sa 17,7 III-19_sa 18,8 Willow LG III => Identification of markers/genes for important traits! 0,0 3,4 7,8 12,4 14,8 14,9 17,0 17,3 19,1 19,8 27,2 33,7 46,2 57,1 60,2 73,1 82,2 87,1 94,5 101,1 106,7 121,9 122,1 124,7 128,3 130,1 131,0 132,9 135,8 L13y.336 L31gr.242 III-1 L2gr.155 III-2_sa III-3_sa III_21_sa III-15 III_26_sa_pI III-4_sa III_8om_sa L14gr.157 III-3c III_24_sa III-12_sa III-13_sa SB1048 III-14_sa L12gr.180f III-15_sa L31gr.177 III-18_sa R_4_sa A32.gr.1 L30b.256 III-17_sa I-3_sa L29b.159 III-19_sa

25 Denser linkage map genes for growth cessation (Berlin et al. 2011)

26 QTL for bud burst, growth cessation & leaf senescence (Ghelardini et al. 2014)

27 QTL for bud burst, growth cessation & leaf senescence Substantial variation in all traits All traits associated with many QTL that all explained < 10% each In total 80 QTL of which some are clustered in hotspots Some QTL co-localize with those found in poplar QTL must be verified in other backgrounds Important step towards candidate genes for phenology traits that could be used for marker-assisted selection (MAS) to enhance biomass growth in willow

28 Leaf beetle control (C. Björkman) Aim: to analyze the heritability of and identify genetic/chemical markers for resistance against beetles. Parts of the resistance may operate directly (i.e. leaf chemistry) and indirectly through natural enemies (bent dashed arrow). A reliable bio-assay protocol for estimating resistance against leaf beetles has been developed. Enemy egg Enemy (Bark removed to lay bare an egg) Illustrations: Christer Björkman

29 Improved resistance to leaf rust (J. Stenlid, B. Samils) Rust on susceptible material can cause great production losses (up to 40 %). Rust assessments in the field and, by using a leaf disc bioassay, in the laboratory. Photo: Berit Samils Leaf rust caused by the fungi Melampsora larici-epitea Great variation in rust resistance components was found between individuals in two mapping populations. The S. viminalis x S. schwerinii population showed the highest degree of variation and many individuals had a high level of resistance. A number of rust resistance loci (QTL) were located on the linkage maps for the two populations. Leaf disc bioassay to assess leaf rust resistance in Salix.

30 Testing and application of markers in practical breeding - to test various markers in different breeding material; - to test the efficiency of selection with available markers in new breeding populations; - to apply markers for selection among seedlings as soon as markers become available; - Collaboration with breeding company Lantmännen

31 Ideal energy crop? We have today the methodology to select for desirable energy crops and crop characteristics through traditional and modern plant breeding. What crops and crop characteristics should we try to develop? Are there any trade-offs?

32 Ideal energy crop? 1) What key criteria would cause a species to be an ideal energy crop candidate? Which requirements would you have on such an ideal energy crop? 2) What are ideal agronomic attributes? 3) What are ideal quality (biochemical/processing) attributes? 4) What are ideal attributes for improvement by biotechnological methods? 5) What are ideal ecological/environmental attributes?