Gene-flow in Beta (beet) complex and its consequences for growing of HT sugar beet

Transcription

1 Gene-flow in Beta (beet) complex and its consequences for growing of HT sugar beet Josef Soukup, Josef Holec and Kateřina Hamouzová Department of Agroecology and Biometeorology Faculty of Agrobiology, Food and Natural Resources Czech University of Life Sciences Prague, Czech Republic

2 Some liaisons can be dangerous.

3 Weed control in sugar beet one of the most difficult crops, very sensitive to herbicides limited number of herbicide active ingredients (PMP, DMP, EFM + some other) weeds must be controlled at very early growth stages usually 3-4 sprayings are necessary some weeds are hard-to-control (ABUTH, AETCY, perennials, OSR, weed beet,...)

4 Evolution of HT sugar beet Liberty Link a Roundup Ready varieties glufosinate and glyphosate tolerance (GM) Conviso Smart (Bayer + KWS) foramsulfuron + thiencarbazone-methyl (non- GM) KWS + Monsanto pipeline glyphosate + glufosinate + dicamba (GM)

5 Development of herbicide resistant weed beet?

6 crop wild weed complex Evolution of crops man disturbed habitats weeds ferals wild species crops natural habitats volunteers agroecosystems weeds

7 Ferality and volunteerism Volunteers first step to ferality and source of gene introgression? Endo-ferality consequence of mutations and genetic drift Exo-ferality back-crossing with wild relatives, wedy and feral forms

8 Taxonomic classification of genus Beta (Schmidt, 1998, Lange et al., 1999) Section Genome Species Chromosome No. (2n) B. vulgaris L ssp. vulgaris 18 ssp. maritima(l.) 18 Section I: Beta (syn. Primary Arcang ssp. adanensis Vulgares Ulbrich) (Pamuk.) Ford-Lloyd 18 &Will. B. patula Ait. 18 Section II: Corollinae (Ulbrich) Section III: Nanae (Ulbrich) Section IV: Procumbentes Ubrich (syn. Patellares Transhel) Secondary Tertiary B. macrocarpa Guss. 18, 36 B. corolliflora Boss. 36 B.macrorhiza Stev. 18 B. lomatogona F. et M. 18 B. trygina Walesy 54 B. intermedia Bunge 18 B. nana Boiss. et Heldr. 18 B. patellaris Moq. 18, 36 B. procumbens Chr. Smith 18 B. webbiana Moq. 18

9 Special features of Beta-complex Wild, crop, weed and feral forms occurr often in sympatry No hybridisation barriers all forms open-pollinators chromosome No. 18 in all forms overlapping of flowering time good pollen afinity viable offspring (sometimes better fitness than parents) Man assisted dispersion (crop seed, weedy forms, ferals,...)

10 Domesticated beet forms

11 Different ecological plant types within the Beta complex out of agroecosystems wild sea beets ruderal feral beets in agroecosystems Photo: Stevanato, Soukup weed beet beet crop

12 Gene-flow within the Beta-complex Seed production areas B.v.ssp.maritima sugarbeet (multiplication field) sowing plants vernalisation germ. plants reprod. seeds reprod. seeds seedbank harvest Wild habitats Sugarbeet production areas sugarbeet Agroecosystem B.v.ssp.maritima germ. plants vernalisation reprod. seeds sowing plants weed beet germin. weed plants vernalisation reprod. reprod. harvest seeds seeds seedbank seedbank Squire, Landova 2006

13 Role of bolting gene for annuality Bolting gene(s) initiate an elongation of stem and creation of reproductive organs Recessive forms require vernalisation for expression Dominant forms do not require vernalisation and cause bolting in F1 generation (bolt easily)

14 Consequences of gene flow within Beta - complex 1. Direction wild (weed, feral) crop (into agroecosystem) introgression of unwanted traits (annuality, morphological anomaly) dispersion of annuality and HT genes via bolting 2. Direction crop wild/feral (out of agroecosystem) introgression of specific crop genes into wild popul. changes of fitness, genetical pollution by cultural genes Direction crop weed (within agroecosystem) bolting crop may introduce the (resistance) genes into populations of weed beets introgressed traits (HT) can later spread among weed beet population and/or contaminate also the multiplication crop stands 14

15 Frequency of bolting gene in wild beet populations along the French coast technical sugarbeet Seed production area According to Van Dijk, 2004

16 seed distribution for sugar beet growing across the Europe seed multiplication areas Distribution of wild sea beet populations (Hanf, 1999)

17 Primary type of weed beets annual bolters in sugar beet crop

18 patches of weed beet seedlings rows of emerging sugar beet

19 Secondary type of weed beets populations emerging from soil seed bank

20 Frequency of annuality in local weed beet populations % of bolting plants Trněné Pole Svrkyně Čáslav Okoř Ostrovačice Zvoleněves Loucká Šatov Tursko Libochovičky Suchdol u Čáslavi

21 Weed beet in oil-seed crops in oil seed rape (spring) in oil seed rape in sunflower

22 Anthocyan coloration of hypocotyl (root, shoot)

23 Root branching and coloration

24 Habitus orthotrophic habitus pleiotrophic habitus

25 Seed production - multigermicity avg seed clusters / plant 2 3 seeds / seed cluster

26 Primary dormancy (% germination after harvest in weeks) germination [%] Tursko 2002 Tursko 2003 Tursko weeks after harvest

27 Life cycle, reproduction ability, seedbank persistence of weed beet No. of glomerules germination (%) soil temperature ( C) f=2342 ± 1101 No. of matured plants XII.04 I.05 II.05 III.05 IV.05 V.05 VI.05 VII.05 VIII.05 IX.05 X.05 XI.05 p =0,07-0,22 s p =0,17-0,42 z No. of emerged plants p =0,27-0,46 g 70 germination (%) y = 63,709e -0,5229x R 2 = 0,9816 Soil seed bank P =0,73-0,95 m 10 0 X. 02 IV. 03 X. 03 IV. 04 X. 04 IV. 05 X. 05 Many publications: Sester et al, ( ) 27

28 Factors influencing the spatial dispersion of genes Distance of pollen transport influenced mainly by abiotic factors Probability of outcrossing Pollen of weed beet (avg. size 25 µm) Pollen source and quality Pollen vectors Landscape properties Pollen affinity by maternal plants Offspring viability 28

29 Outcrossing experiment between sugar beet and red beet Beginning of June Nearly 50% of all germinated glomerules showed anthocyan coloration in 100 m distance in prevailing wind direction

30 Mathematical model of pollen transport (Artificial Compressibility Method) Wind velocity 11 ms -1 Wind velocity 1.7 ms -1 Rapid decline to 100 m From 200 m only low pollen amount 30 (Modelling: J. Brechler)

31 How to avoid the spread of weed beets? Sugar beet in seed production areas: by common seed production practices (selection of fields without weed beet, isolation distances at the same level as conventional, cropping intervals 5? years in crop rotation) by breeders methods (CMS, ploidy level, tr incorporation of HT in parents, etc. see e.g. Desplanque et al., 2002) 31

32 Current requirements on sugar beet seed purity Current threshold for admixture in conventional sugar beet seed is 0.2 % in Europe So far, isolation distances more than 600 m must be usually kept between conventional beets and sexual compatible taxa in seed multiplication Differences between the pollen transport of conventional and HT varieties are not expected 32

33 Is an absolute crop isolation from wild/weed/feral populations possible? probably not, unknown pollen sources Change of seed production areas? Are there in Europe other suitable places for multiplication? Are those without weedy/feral beets up to now? 33

34 Sugar beet in root production areas: Gene-flow between neighbouring fields is not expected (vegetative stage) Stewardship rules regulating inputs: seed purity (to exclude bolting admixture) isolation in space and time: (avoid gene-flow) control of bolters: (hand weeding, Rotowiper) control of weed beets (different modes of action, hand weeding, Rotowiper) 34

35 Prevention a testing of seed lots

36 Results of seed testing on contamination by weed beets in CZ Lots tested Without contami nation Less than 0.05 % w.b. More than 0.05 % w.b Data: UKZUZ

37 Summary of the testing: Contaminated lots are introduced every year The limit is usually kept but: ha of sugar beet = seeds at an average admixture of 0,015 % of weed beets in a seed lot = weed beet plants introduced yearly! 1 weed beet plant produces seeds...

38 Control of bolters / weed beets 38

39 Current populations of weed beets can be easily controlled by herbicides in ALS tolerant beet varieties (Conviso Smart)

40 Conclusions Impurities arising as seed inputs are the main issue of sustainable introduction of HT sugar beet The attention must be paid before all to the seed multiplication areas Ensuring that seed comes from high quality producers is the most important factors for introduction of HT sugar beet Efficient control of bolters and weed beets in sugar beet fields is crucial for future of s.b. growing 40