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The dispensable chromosome of Leptosphaeria maculans shelters an effector gene conferring avirulence towards Brassica rapa Marie Hélène Balesdent1*, Isabelle Fudal1, Bénédicte Ollivier1, Pascal Bally1, Jonathan Grandaubert1, Frédérique Eber2, Anne-Marie-Chèvre2, Martine Leflon3, Thierry Rouxel1 1 INRA, UR1290 BIOGER, Avenue Lucien Brétignières, BP 01, F-78850 Thiverval-Grignon, France 2 INRA, UMR1349 IGEPP, BP35327, F-35653 Le Rheu cedex, France 3 CETIOM, Avenue Lucien Brétignières, BP 01, F-78850 Thiverval-Grignon, France Supporting information Figs S1S3, Tables S1S6, Methods S1 Methods S1 Inoculation tests: modelling the loss of the dispensable chromosome in Leptosphaeria maculans populations Table S1 PCR primers used in this study Table S2 Analysis of the progeny of crosses between a resistant B. rapa plant (2n=20) and the susceptible B. napus (2n=38) variety Darmor Table S3 Analysis of the progeny of crosses between a resistant B. rapa plant (2n=20) and the susceptible B. napus (2n=38) variety Eurol Table S4 List and characteristics of SC22 predicted genes Table S5 List and characteristics of SC22 predicted proteins Table S6 Interaction phenotypes of wild-type or transformed Leptosphaeria maculans isolates on a Brassica differential set Fig. S1 Percentage of plants with different chromosome numbers assessed by flow cytometry in the progeny of B. rapa x B. napus (AAC) hybrids crossed to their recurrent parents Darmor or Eurol Fig. S2 Interaction phenotypes of wild type and transformed Leptosphaeria maculans isolates with AvrLm11 candidate genes Fig. S3 Evolution of the frequency of the dispensable chromosome in field populations of Leptosphaeria maculans under different fitness cost hypotheses Methods S1 Inoculation tests. Isolates were inoculated on cotyledons of 2 weeks-old seedlings. Each half cotyledon was punctured with a needle and a drop of 10µL of a 107 spores ml-1 was deposited on each hole. Plantlets were incubated in a growth chamber at 16 °C (night)-24 °C (day) with a 12 h photoperiod. Symptoms were scored 14 to 21 days after inoculation using the semiquantitative IMASCORE rating scale comprising 6 classes (IC) (Balesdent et al., 2001). IC1 is the typical hypersensitive response (HR), IC2 includes larger (1.5 to 3 mm) dark necrotic lesions, IC3 corresponds to lesion without any pycnidia, that may or may not show tissue collapse as in IC4 to IC6, but that is always sharply delimited by a dark necrotic margin that may extend within the lesion. IC4-IC6 are characterized by gray-green tissue collapse without a darkened margin, whose size increases with time, and showing no sporulation (IC4), a few pycnidia (IC5), or profuse sporulation (IC6). IC1 to IC3 are resistance responses, whereas IC4 to IC6 are susceptibility symptoms. At least 10 seedlings (10 replicates) were inoculated for each isolate-plant genotype combination. The result of the interaction was evaluated by calculating either the mean disease scoring, or the percentage of resistance (percentage of IC1-3) or susceptibility (percentage of IC4-6) symptoms. Modelling the loss of the dispensable chromosome in Leptosphaeria maculans populations. We used a simple model in which it is assumed that there is no migration in the local populations. The population of year i is composed of isolates issued from ascospores generated by random mating between individuals composing the population of year i-1. The frequencies of isolates with (MC+) and without (MC-) are fi and (1-fi) respectively. Probabilities of crosses between two MC+ isolates, two MC- isolates, or one MC+and one MCisolates therefore are fi2, 2fi(1-fi) and (1-fi)2, respectively. MC-x MC- crosses give rise to only MC- isolates (Leclair et al., 1996). It is hypothesized that MC+ x MC- crosses generate 50% MC+ and 50% MC- isolates while MC+ x MC+ crosses generate MC- isolates with a mutation rate, termed G, found as G=0.048 in our study. If considering that the loss of the MC has no fitness cost (i.e. the proportion of MC- isolates involved in mating at the end of the infectious cycle is identical to that present in the primary inoculum), the frequency of MC+ isolates in year i+1 will be: (1) which can be simplified as (1) fi+1=(1-G)fi2 + 0.5x2fi(1-fi) + 0x(1-fi)2 fi+1= fi(1-G fi) If considering that the loss of the MC has a fitness cost, this can be globally assimilated to a lowered proportion of MC- isolates involved in mating at the end of the infection cycle, whatever the biological parameter(s) responsible for this fitness cost. From the (1-fi) MCisolates constituting the primary inoculum in year i, only ρ(1-fi) will therefore contribute to sexual mating producing inoculum for year i+1, with 0 ρ1. Similarly MC+ isolates contributing to mating will be fi’= 1- ρ(1-fi). Under this hypothesis the proportion of MC+ isolates at the beginning of year i+1 will be calculated by replacing fi by fi’ in (1) as follows (2) fi+1= fi’(1-Gfi’) = (1- ρ(1-fi))(1-G(1- ρ(1-fi))) This equation was used to construct the curves of evolution with time of the frequency of the MC in natural populations starting with an initial frequency of 0.955 (estimated from the 2000-2001 sampling), G=0.048 and ρ values ranging from 0 (MC- isolates are unable to complete the life cycle) to 1 (no fitness cost linked to the loss of the MC). As shown in Fig. S3, only a strong fitness cost linked to the loss of the MC can explain the maintenance of the MC in such high proportions during a 10 years time interval. Supporting Table S1 PCR primers used in this study Primer name Sequence Location on L. maculans genomea Min22.0_Ub ATAGGTCTACCTTAAATATATAATAGC SC22_100123..100149 Min22.0_L CAAGACCTATAGATAGTATCCTTTTC SC22_100620..100645 (c) Min22.1_U ACAAAGGCGACGAAACAGG SC22_428258..428258 (c) Min22.1_L AGAAAGATTGGCTTCGTTGC SC22_427877.. 427896 Min22.4_U CAAGATGCGCAAGATGACAG SC22_661552.. 661571 Min22.4_L CTTGCCCAATCTGGGATTCT SC22_661713..661732 (c) Min22.6_U CGACTCGTCCATTCTTCCAT SC22_712428..712447 Min22.6_L GGAGGAAACCGAGCAGAGTA SC22_712589..712608 (c) Min16987_U GCTTACCTCTCTTGTAAGGGTA SC22_294720..294741(c) Min16987_L TGCAAATAGGGTAAATAGGTAAGC SC22_294545..294568 Min16163_U TTTGAAGCCTACTACCACTGAAGA SC22_553588..553611 (c) Min16163_L CTGCTGTTGGAGGCAAAGTC SC22_553538..553557 P119130_U CGTGAGGTCTCTGAAGAAGC SC22_436773..436792 (c) P119130_L GGACAGAGAAGCTCGACACG SC22_436574..436593 (c) P119250_U CAGGGGTAAAGTTGGTGGTG SC22_609109..609128 P119250_L GCCTTGGCTTTATCCTCCTC SC22_609410..609429 (c) P119260_U ATGCCCAACACTCAAACTCC SC22_624709..624728 P119260_L GCAGCATAGTCAGCGAATTG SC22_624994..625013 (c) P119270.1_U ACTATCACGGGCGATGATCT SC22_629390..629409 P119270.1_L CCCACTTCCATATATCTGTAATTCTA SC22_629671..629696 (c) MatU TGGCGAATTAAGGGATTGCTG SC20_556096..556116 (c) MatL1 CTCGATGCAATGTACTTGGAGC NA MatL2 CGGAGGTGAAGTTGAAGCCG SC20_555675..555694 AvrLm11-U2 (uP119060_U) TGCGTTTCTTGCTTCCTATATTT SC22_294427..294449 (c) AvrLm11-L (uP119060_L) CAAGTTGGATCTTTCTCATTCG SC22_294090..294111 AvrLm11-5UTRU GCGTTTCTTGCTTCCTATATTTTCTGC SC22_294422..294448 (c) AvrLm11-5UTRnestU GCAAACTGGAAGGGGCAGTAGGCTG SC22_294329..294353 (c) AvrLm11-3UTRU GCAAGTTGGATCTTTCTCATTCGC SC22_294089..294112 AvrLm11-3UTRnestU CGTGTGTACTCCTTCCGTTACGACC SC22_294234..294258 AvrLm11U1 GCCGCTTAGCTACACTTCGC SC22_294983..295002 (c) AvrLm11-XhoL GAGAGACTCGAGCCCTCTATATGCGTTCCTTAG SC22_293518..293538 a Location (in bp) along Super-Contig 22 (SC22) or 20 (SC20); (c) indicates a reverse orientation of the primer; NA, not applicable (the primer is located on the opposite Mating-Type idiomorph to that of the sequenced isolate). b Markers in bold are those used to check the complete deletion of SC22 in field isolates lacking AvrLm11. Supporting Table S2 Analysis of the progeny of crosses between a resistant B. rapa plant (2n=20) and the susceptible B. napus (2n=38) variety Darmor Cross analyseda Resistance segregationb R F1 BC1 BC2 BC3 a S χ² (p value) Meiotic stability in selected resistant plants Selected plant # 1g 0 49 69 3.39 1 (0.066) 2 3 51 23 10.59 1 (0.001) 2 3 4 5 6 19 9 3.57 1 (0.059) 2 3 4 5 6 7 8 2nc PMCd Average meiotic behavioure % Cells with 19IIf 38 38 38 38 38 38 38 38 39 38 38 38 38 38 38 38 39 14.3 0 25** 55 65** 25 25 25 66.7** 42.9 45 63** 43.5 54.5 55.6 - 21 22 20 20 20 20 20 20 20 21 21 20 20 23 22 9 6 1.90I+17.38II+0.38III+0.05IV 3.36I+16.54II+0.27III+0.18IV 1.75I+17.6II+0.15III+0.15IV 0.75I+18.4II+0.15III 0.6I+18.55II+0.1III 1.45I+18.2II+0.05III 1.35I+18.2II+0.15III 0.95I+17.5II+0.55III+0.1IV 2.3I+18.35II 0.76I+18.62II 0.8I+18.05II+0.24III+0.1IV 1.1I+18.35II+0.05IV 0.4I+18.5II+0.15IV 0.78I+18.26II+0.17IV 0.82I+18.46II+0.09III 0.89I+18.56II 1.17I+18.67II+0.17III F1 is the hybrid between one B. rapa resistant plant and the susceptible B. napus cv Darmor. BC1, BC2 and BC3 were obtained by crossing one resistant plant from the previous generation showing 2n=38 and the best meiotic behaviour with the susceptible recurrent B. napus cv. b R, number of resistant plants; S, number of susceptible plants toward L. maculans isolates with AvrLm11 following cotyledon inoculation tests. χ² and (p value) are given for the expected 50:50 R:S segregation. c Number of chromosomes of the selected plant as estimated by flux cytometry. d Number of Pollen Mother Cells (PMC) observed for each selected resistant plant. e Univalents (I), bivalents (II), trivalents (III) and quadrivalents (IV) observed at metaphase 1. f ** The plants with the highest percentage of 19 bivalents (II) were selected for the next BC generation. g for this interspecific cross, very few seeds were obtained and only one plant germinated and could be phenotyped for resistance. Supporting Table S3 Analysis of the progeny of crosses between a resistant B. rapa plant (2n=20) and the susceptible B. napus (2n=38) variety Eurol Cross analyseda Resistance segregationb R F1 BC1 BC2 BC3 a S χ² (p value) 10 2 48 73 5.16 (0.023) Meiotic stability in selected resistant plants Selected plant # 1 2 3 19 62 22.83 1 -6 (2 10 ) 2 3 4 5 6 7 8 8 25 8.76 1 (0.0031) 2 3 4 2nc PMCd Average meiotic behavioure % Cells with 19IIf 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 0 20** 0 50 55 45 50 65 40 61.9** 47.6 60 50** 65** 55.6 20 20 20 22 20 20 20 20 20 21 21 20 20 20 18 3.80I + 16.60II + 0.25IV 1.15I+17.80II+0.35III+0.05IV 1.00I+16.65II+0.3III+0.70IV 0.64I+18.23II+0.18III+0.09IV 0.8I+18.45II+0.1III 0.55I+18II+0.35III+0.1IV 0.85I+18.4II+0.05III+0.05IV 0.2I+18.4II+0.25IV 1I+17.85II+0.3III+0.1IV 0.71I+18.43II+0.14III 0.9I+18.34II+0.14III 0.5I+18.45II+0.15IV 0.2I+18.4II+0.25IV 0.6I+18.3II+0.2IV 1.11+18.45II F1 is the hybrid between one B. rapa resistant plant and the susceptible B. napus cv Eurol. BC1, BC2 and BC3 were obtained by crossing one resistant plant from the previous generation showing 2n=38 and the best meiotic behaviour with the susceptible recurrent B. napus cv. b R, number of resistant plants; S, number of susceptible plants toward L. maculans isolates with AvrLm11 following cotyledon inoculation tests. χ² and (p value) are given for the expected 50:50 R:S segregation. c Number of chromosomes of the selected plant as estimated by flux cytometry. d Number of Pollen Mother Cells (PMC) observed for each selected resistant plant. e Univalents (I), bivalents (II), trivalents (III) and quadrivalents (IV) observed at metaphase 1. f ** The plants with the highest percentage of 19 bivalents (II) were selected for the next BC generation. . Supporting Table S4 List and characteristics of SC22 predicted genes Location on SC22a Isochore locationb Feature lenght (bp) TpA/ApTc lmctg_1587_v2_egn4_Lema_T119030.1 101169..104023 GC1 2855 0.81 1.02 2220 55.45 56.35 lmctg_1587_v2_egn4_Lema_uT119040.1 104915..105094 (c) GC1 180 1.76 1.00 102 44.12 52.94 lmctg_1587_v2_egn4_Lema_T119050.1 105263..106588 (c) GC1 1326 1.19 0.96 1326 56.33 61.31 lmctg_1587_v2_egn4_Lema_uT119060.1 294086..294450 (c) AT2 365 1.61 0.99 288 48.26 54.17 427173..427364 GC2 192 0.81 1.52 192 21.88 54.69 lmctg_1589_v2_egn4_Lema_T119070.1 427482..429663 (c) GC2 2182 1.31 0.91 2001 54.57 57.72 lmctg_1589_v2_egn4_Lema_uT119080.1 429788..429979 (c) GC2 192 0.32 1.28 192 63.54 68.75 lmctg_1589_v2_egn4_Lema_T119090.1 430119..431945 GC2 1827 0.63 1.01 1827 63.27 67.00 lmctg_1589_v2_egn4_Lema_T119100.1 432453..433069 GC2 617 0.72 1.00 510 53.14 53.53 lmctg_1590_v2_egn4_Lema_T119110.1 433905..434534 GC2 630 1.26 0.94 357 48.18 44.54 lmctg_1590_v2_egn4_Lema_T119120.1 434982..435968 GC2 987 1.38 0.95 624 50.32 52.40 lmctg_1590_v2_egn4_Lema_T119130.1 436526..436999 (c) GC2 474 0.97 1.03 321 58.57 52.34 lmctg_1590_v2_egn4_Lema_T119140.1 437248..438727 (c) GC2 1480 1.13 0.93 1362 53.52 61.01 lmctg_1590_v2_egn4_Lema_T119150.1 439271..440148 (c) GC2 878 1.30 0.89 807 57.37 66.17 lmctg_1590_v2_egn4_Lema_T119160.1 440524..441130 GC2 607 0.74 1.10 555 50.99 55.68 lmctg_1590_v2_egn4_Lema_T119170.1 441180..441398 GC2 219 1.12 1.17 219 46.58 53.42 lmctg_1590_v2_egn4_Lema_T119180.1 441826..443256 GC2 1431 0.89 1.14 1431 53.67 60.59 lmctg_1590_v2_egn4_Lema_T119190.1 443437..443912 GC2 476 1.54 1.04 345 48.99 55.65 lmctg_1590_v2_egn4_Lema_T119200.1 549658..551406 (c) GC3 1749 0.95 1.15 1749 50.66 51.97 lmctg_1590_v2_egn4_Lema_T119210.1 552584..553177 GC3 594 0.56 1.32 594 58.42 54.04 lmctg_1590_v2_egn4_Lema_T119220.1 555624..558041 GC3 2418 0.78 1.23 2367 50.61 50.57 lmctg_1590_v2_egn4_Lema_uT119230.1 559439..560239 (c) GC3 801 1.09 0.96 270 53.33 62.22 lmctg_1590_v2_egn4_Lema_uT119240.1 560674..560970 GC3 297 0.98 0.99 297 52.86 44.44 lmctg_1590_v2_egn4_Lema_T119250.1 606564..610438 (c) GC4 3875 1.10 1.07 2880 57.05 63.13 lmctg_1590_v2_egn4_Lema_T119260.1 624144..625048 (c) GC5 905 2.26 0.71 360 55.83 56.67 Gene ID AT02_SuperContig_22_10_320860_321051 CDS CpA+TpG Lenght %GC %GC3d /ApC+GpT (bp) lmctg_1590_v2_egn4_Lema_T119270.1 629387..629707 GC6 321 1.76 1.06 321 50.16 47.66 lmctg_1590_v2_egn4_Lema_uT119280.1 629911..630127 GC6 217 0.89 1.24 129 41.86 39.53 lmctg_1590_v2_egn4_Lema_T119290.1 632100..632856 (c) GC6 757 1.35 0.84 585 51.45 64.62 lmctg_1591_v2_egn4_Lema_T119300.1 633273..634431 (c) GC6 1159 0.81 1.10 1098 66.76 78.69 lmctg_1591_v2_egn4_Lema_T119310.1 660397..662577 GC7 2181 1.00 1.05 2055 56.40 60.88 lmctg_1592_v2_egn4_Lema_T119320.1 703529..704293 (c) GC8 765 1.09 0.99 765 52.81 53.33 lmctg_1592_v2_egn4_Lema_T119330.1 704474..705397 GC8 924 0.85 1.17 924 54.44 61.04 lmctg_1592_v2_egn4_Lema_T119340.1 705880..706644 (c) GC8 765 0.82 0.95 765 53.59 48.24 lmctg_1592_v2_egn4_Lema_T119350.1 706950..708772 GC8 1823 1.05 1.06 1755 56.58 60.51 lmctg_1592_v2_egn4_Lema_T119360.1 709203..712628 (c) GC8 3426 0.87 1.18 3243 59.08 61.15 lmctg_1592_v2_egn4_Lema_T119370.1 713190..713936 GC8 747 1.13 0.94 747 55.56 61.04 a Location (in bp) along SC22 ; (c) indicates a reverse orientation of the gene. ATi and GCi refers to the AT-rich or GC-equilibrated isochores, as represented in Fig. 1. c TpA/ApT and (CpA+TpG)/(ApC+GpT) are two indices used to detect signatures of RIP (Repeat Induced Point) mutations. d Percentages of codons with a G or C at the third base position. b Supporting Table S5 List and characteristics of SC22 predicted proteins Expression in specific condition:d Protein lenght (AA) Predicted localization /targetinga BLASTb lmctg_1587_v2_egn4_Lema_P119030.1 739 - - Yes + + + + lmctg_1587_v2_egn4_Lema_uP119040.1 33 - - Yes - + - - lmctg_1587_v2_egn4_Lema_P119050.1 441 M Yes Yes + + + + lmctg_1587_v2_egn4_Lema_uP119060.1 95 S - Yes - +/- + +/- AT02_SuperContig_22_10_320860_321051 63 S - Yes + - - + lmctg_1589_v2_egn4_Lema_P119070.1 666 - Yes Yes + + + + lmctg_1589_v2_egn4_Lema_uP119080.1 63 M - Yes + - + + lmctg_1589_v2_egn4_Lema_P119090.1 608 M Weak Yes + + + + lmctg_1589_v2_egn4_Lema_P119100.1 169 - - Yes + + + + lmctg_1590_v2_egn4_Lema_P119110.1 118 - - Yes + - - - lmctg_1590_v2_egn4_Lema_P119120.1 207 - - Yes +/- - - + lmctg_1590_v2_egn4_Lema_P119130.1 106 S - Yes + + + + lmctg_1590_v2_egn4_Lema_P119140.1 453 TM Weak Yes + + + + lmctg_1590_v2_egn4_Lema_P119150.1 268 TM - Yes + + + + lmctg_1590_v2_egn4_Lema_P119160.1 184 - - Yes + + + + lmctg_1590_v2_egn4_Lema_P119170.1 72 - - Yes + + + + lmctg_1590_v2_egn4_Lema_P119180.1 476 - Yes Yes + + + + lmctg_1590_v2_egn4_Lema_P119190.1 114 - - No - - - - lmctg_1590_v2_egn4_Lema_P119200.1 582 - - Yes + + + + lmctg_1590_v2_egn4_Lema_P119210.1 197 - - Yes - - + - lmctg_1590_v2_egn4_Lema_P119220.1 788 - Weak Yes + + + + lmctg_1590_v2_egn4_Lema_uP119230.1 89 S - No - - - - lmctg_1590_v2_egn4_Lema_uP119240.1 98 - - No - +/- - - Protein ID Micro-array supportc in vitro 3dpi 7dpi 14dpi lmctg_1590_v2_egn4_Lema_P119250.1 959 S Yes Yes + + + + lmctg_1590_v2_egn4_Lema_P119260.1 119 M - No - - - - lmctg_1590_v2_egn4_Lema_P119270.1 106 - - No - - - - lmctg_1590_v2_egn4_Lema_uP119280.1 42 - - No - - - - lmctg_1590_v2_egn4_Lema_P119290.1 194 - - Yes + + + + lmctg_1591_v2_egn4_Lema_P119300.1 365 - Yes Yes - + + - lmctg_1591_v2_egn4_Lema_P119310.1 684 S - Yes + + + + lmctg_1592_v2_egn4_Lema_P119320.1 254 - - Yes + + + + lmctg_1592_v2_egn4_Lema_P119330.1 307 - - Yes + + + + lmctg_1592_v2_egn4_Lema_P119340.1 254 - - Yes + - - + lmctg_1592_v2_egn4_Lema_P119350.1 584 M Yes Yes + + + +/- lmctg_1592_v2_egn4_Lema_P119360.1 1080 - - Yes + + + + lmctg_1592_v2_egn4_Lema_P119370.1 248 - - Yes + + + + a Predictions of subcellular localisation of the protein; S, secretory pathway; M, mitochondrion; TM, trans-membrane domains; -, no specific localisation predicted. b BLAST hits of the proteins against non-redundant data bases (September 2012); Yes, BLAST hit with a p value < e-10; Weak, BLAST hit with a p value >e-5, -, no BLAST hit. c Micro-array data from Rouxel et al., 2011; Yes, gene models with expression levels higher than three times the median of random probe intensities in at least two of three biological replicates; No, gene models with expression levels not significantly different from random probe intensities. d Micro-array data from Rouxel et al., 2011; +, the gene is expressed in the two technical repeats for the corresponding condition; +/-, the gene is expressed for only one of two technical repeats; -, the gene is not expressed whatever the technical repeat; in vitro, RNA was extracted from L. maculans mycelium grown in Fries liquid medium; 3, 7 and 14 dpi, RNA was extracted from oilseed rape cotyledons inoculated with L. maculans 3, 7 and 14 days post inoculation, respectively. Supporting Table S6 Interaction phenotypes of wild-type or transformed Leptosphaeria maculans isolates on a Brassica differential set Isolateb B. napus or B. rapa linea v23.1.2 (Av5-6-7-8-11) v23.1.3 (Av1-4-5-6-7-8-11) Westarc Bristol (Rlm2, Rlm9) Columbus (Rlm1, Rlm3) Darmor (Rlm9) Pixel (Rlm4) 03.22.3.1 (Rlm3) 02.23.3.1 (Rlm7) 02-159-4-1 (Rlm11) 5.0 ± 0d a 5.0 ± 0 IBCN14 + AvrLm11 (Av5-6-11) 5.0 ± 0 IBCN14 (Av5-6) 4.9 ± 0.4 5.0 ± 0 4.9 ± 0.3 4.7 ± 0.5 4.4 ± 0.9 5.0 ± 0 5.0 ± 0 5.0 ± 0 5.0 ± 0 1.0 ± 0 1.0 ± 0 1.8 ± 0.4 5.00 ± 0 1.00 ± 0 5.0 ± 0 1.2 ± 0.4 1.3 ± 0.5 5.00 ± 0 5.00 ± 0 4.9 ± 0.45 5.0 ± 0 5.0 ± 0 1.3 ± 0.7 3.9 ± 1.6 4.6 ± 0.5 4.8 ± 0.4 4.6 ± 0.7 4.9 ± 0.2 3.4 ± 1.0 The resistance gene content is given in brackets. The avirulence allele composition is given in brackets. c Only resistance genes in plant genotypes that were susceptible to IBCN14 were assessed. d Mean phenotypic score17 days post inoculation for 10 (v23.1.2 and v23.1.3) to 20 (IBCN14, IBCN14+AvrLm11) plants, on a 1 (resistance) to 6 (susceptibility) scale. Scores > 3 correspond to compatible interactions (green); scores 3 correspond to incompatible interactions (pink). Values are mean ± 1SD. b 25 eurol darmor 20 15 Plants (%) 10 5 0 29 30 31 32 33 34 35 36 37 38 2n Supporting Fig. S1 Percentage of plants with different chromosome numbers assessed by flow cytometry in the progeny of B. rapa x B. napus (AAC) hybrids crossed to their recurrent parents Darmor or Eurol. 120 % of inoculation 100 sites leading to a 80 compatible interaction 60 phenotype 40 a 20 0 120 100 bIBCN14 v23.1.3 IBCN14 + uP119060 IBCN14 + P119130 IBCN14 v23.1.3 IBCN14 + uP119060 IBCN14 + P119130 IBCN14 v23.1.3 80 60 40 20 0 120 100 c 80 60 40 20 0 IBCN14 + uP119060 IBCN14 + P119130 Supporting Fig. S2 Interaction phenotypes of wild type and transformed Leptosphaeria maculans isolates with AvrLm11 candidate genes ▲, virulent isolate BCN14; ■, the v23.1.3 avirulent sequenced isolate; Green, 18 isolates transformed with the candidate AvrLm11 gene Lema_uP11060; blue, 14 isolates transformed with another predicted gene of SC22, Lema_P119130.1. Values are percentage of inoculation points corresponding to a susceptibility symptom (Infection classes 4-6) 15 days after inoculation on a, the susceptible control Westar, b, the Rlm7 line 02.23.3.1 and c, the resistant B. rapa line 02-159-4-1. Only comlementation of IBCN14 with uP119060.1 restores the avirulent phenotype of v23.1.3 on the B. rapa line. ρ= 1.0 Série12 0 Série3 0.2 Série4 0.3 0.9 Série6 0.4 Frequency of the dispensable chromosome in 0.8 populations Série7 0.5 Série8 0.6 Série9 0.7 Série10 0.8 Série11 0.9 1 0.7 Série1 Série5 0.6 0.5 0 1 2 3 4 5 6 7 8 9 10 11 12 Time (Years) Supporting Fig. S3 Evolution of the frequency of the dispensable chromosome in field populations of Leptosphaeria maculans under different fitness cost hypotheses. Each curve corresponds to the theoretical frequency over time under the random mating hypothesis, an initial frequency as estimated by field samplings, a frequency of loss at meiosis of 0.048 as observed under controlled condition, and different fitness cost (1-ρ) ranging from ρ=1 (no fitness cost) to ρ=0 (isolates that have lost the dispensable chromosome do not contribute to the next sexual cycle). ▲, observed frequencies of the dispensable chromosome in field populations collected in France from 2000 (year 0) to 2010 (year 10).