marker-assisted selection in wheat

More documents

Recommendations

Info

Chapter 10 – Strategies, limitations and opportunities for marker-assisted selection in livestock 179individuals that carry one copy of the donorQTL allele but that are similar to the recipientbreed for the rest of the genome. The aim ofthe intercrossing phase is to fix the donorallele at the QTL. Marker information canenhance the effectiveness of the backcrossingphase of gene introgression strategies by: (i)identifying carriers of the target gene(s)(foreground selection); and (ii) enhancingrecovery of the recipient genetic background(background selection). The effectiveness ofthe intercrossing phase can also be enhancedthrough foreground selection on thetarget gene(s). If the target gene cannot begenotyped directly, carrier individuals canbe identified based on markers that flankthe QTL at
180Marker-assisted selection – Current status and future perspectives in crops, livestock, forestry and fishbetween lines or breeds. Thus, marker-QTLassociations identified in the F 2 generationcan be selected for several generations, untilthe QTL or markers are fixed or the disequilibriumdisappears. Zhang and Smith(1992) evaluated the use of markers in sucha situation with selection on BLUP EBV.Although both studies considered the idealsituation of a cross with inbred lines, therewill be opportunities to utilize a limitednumber of markers to select for favourableQTL regions that are detected incrosses between breeds, thereby enhancingthe development of superior synthetics.Pyasatian, Fernando and Dekkers (2006)investigated use of the whole genomeapproach of Meuwissen, Hayes andGoddard (2001) for MAS in a cross byincluding all markers as random effectsin the model for genetic evaluation. Theyshowed that this resulted in substantiallygreater responses to selection than selectionon identified QTL regions only. Due to themuch greater LD, whole genome selectionin a cross can be accomplished with a muchsmaller number of markers compared withthe number required for whole genomeselection in an outbred population.Within-breed selectionThe procedures described previously forincorporating markers in genetic evaluationresult in estimates of breeding values associatedfor QTL, together with estimates ofpolygenic breeding values. Alternatively, ifmolecular data are not incorporated intogenetic evaluations, as will be the casefor more ad hoc approaches and for genetests for Mendelian characteristics, separateselection criteria will be available thatcapture the molecular information. The followingthree selection strategies can then bedistinguished (Dekkers, 2004):• select on the QTL information alone;• tandem selection, with selection on QTLfollowed by selection on polygenic EBV;• selection on the sum of the QTL andpolygenic EBV.Selection on QTL or marker informationalone ignores information that isavailable on all other genes (polygenes)that affect the trait and is expected to resultin the lowest response to selection unlessall genes that affect the trait are includedin the QTL EBV. This strategy does not,however, require additional phenotypesother than those that are needed to estimatemarker effects, and can be attractivewhen phenotype is difficult or expensiveto record (e.g. disease traits, meat quality,etc.). Selection on the sum of the QTL andpolygenic EBV is expected to result in maximumresponse in the short term, but maybe suboptimal in the longer term becauseof losses in polygenic response (Gibson,1994). Indexes of QTL and polygenic EBVcan be derived that maximize longer-termresponse (Dekkers and van Arendonk,1998) or a combination of short- and longertermresponses (Dekkers and Chakraborty,2001). However, if selection is on multipleQTL and emphasis is on maximizingshorter-term response, selection on the sumof QTL and polygenic EBV is expected tobe close to optimal. Optimizing selectionon a number of EBVs, indexes and genotypes,while also considering inbreedingrate and other practical considerations isnot a trivial task. Kinghorn, Meszaros andVagg (2002) have proposed a mate selectionapproach that could be used to handlesuch problems, and it can be expected thatwith more widespread use of genotypicinformation for a larger number of regions,specific knowledge about individual QTLbecomes less interesting and will simplycontribute to prediction of whole EBV orwhole genotype.
Page 2 and 3:
MARKER-ASSISTED SELECTIONCurrent st
Page 4 and 5:
iiiContentsAcknowledgementsForeword
Page 6 and 7:
Section v - marker-assisted selecti
Page 9 and 10:
viiithe specific gene or chromosome
Page 11 and 12:
CIATCIMMYTCIPCIRADcMCMDCMVCORPOICAC
Page 13 and 14:
xiiISNARISSRITPGRFAJGIKARILDLDLLD-M
Page 16 and 17:
xvContributorsAmalia BaroneProfesso
Page 18 and 19:
xviiElcio Perpétuo GuimarãesSenio
Page 20:
xixAndrea SonninoSenior Agricultura
Page 24 and 25:
Chapter 1Marker-assisted selection
Page 26 and 27:
Chapter 1 - An overview of the issu
Page 28 and 29:
Page 30 and 31:
Page 32 and 33:
Page 34:
Page 37 and 38:
16Marker-assisted selection - Curre
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 50 and 51:
Chapter 3Molecular markers for use
Page 52 and 53:
Chapter 3 - Molecular markers for u
Page 54 and 55:
Page 56 and 57:
Page 58 and 59:
Page 60 and 61:
Page 62 and 63:
Page 64 and 65:
Page 66 and 67:
Page 68 and 69:
Page 70:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 88 and 89:
Chapter 6Targeted introgression of
Page 90 and 91:
Chapter 6 - Targeted introgression
Page 92 and 93:
Page 94 and 95:
Page 96 and 97:
Page 98 and 99:
Page 100 and 101:
Page 102 and 103:
Page 104 and 105:
Chapter 7 - Marker-assisted selecti
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Page 124 and 125:
Page 126 and 127:
Page 128 and 129:
Page 130 and 131:
Page 132 and 133:
Page 134 and 135:
Page 136:
Page 139 and 140:
118Marker-assisted selection - Curr
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150: 128Marker-assisted selection - Curr
Page 188 and 189: Chapter 10Strategies, limitations a
Page 190 and 191: Chapter 10 - Strategies, limitation
Page 206 and 207: Chapter 11Marker-assisted selection
Page 208 and 209: Chapter 11 - Marker-assisted select
Page 220 and 221: Chapter 12Marker-assisted selection
Page 250 and 251:
Page 252 and 253:
Chapter 13 - Marker-assisted select
Page 254 and 255:
Page 256 and 257:
Page 258 and 259:
Page 260 and 261:
Page 262 and 263:
Page 264 and 265:
Page 266 and 267:
Page 268:
Page 272 and 273:
Page 274 and 275:
Page 276 and 277:
Page 278 and 279:
Page 280 and 281:
Page 282 and 283:
Page 284 and 285:
Page 286 and 287:
Page 288 and 289:
Page 290 and 291:
Page 292 and 293:
Page 294 and 295:
Page 296 and 297:
Page 298 and 299:
Page 300 and 301:
Page 302:
Page 305 and 306:
Page 307 and 308:
Page 309 and 310:
Page 311 and 312:
Page 313 and 314:
Page 315 and 316:
Page 317 and 318:
Page 319 and 320:
Page 321 and 322:
Page 323 and 324:
Page 325 and 326:
Page 328:
Section VMarker-assisted selectioni
Page 331 and 332:
Page 333 and 334:
Page 335 and 336:
Page 337 and 338:
Page 339 and 340:
Page 341 and 342:
Page 343 and 344:
Page 345 and 346:
Page 347 and 348:
Page 349 and 350:
Page 351 and 352:
Page 353 and 354:
Page 355 and 356:
Page 357 and 358:
Page 359 and 360:
Page 361 and 362:
Page 363 and 364:
Page 365 and 366:
Page 367 and 368:
Page 369 and 370:
Page 371 and 372:
Page 373 and 374:
Page 375 and 376:
Page 377 and 378:
Page 379 and 380:
Page 381 and 382:
Page 383 and 384:
Page 386 and 387:
Page 388 and 389:
Page 390 and 391:
Page 392 and 393:
Page 394 and 395:
Page 396 and 397:
Page 398 and 399:
Page 400 and 401:
Page 402 and 403:
Chapter 19Technical, economic and p
Page 404 and 405:
Chapter 19 - Technical, economic an
Page 406 and 407:
Page 408 and 409:
Page 410 and 411:
Page 412 and 413:
Page 414 and 415:
Page 416 and 417:
Page 418 and 419:
Page 420 and 421:
Page 422 and 423:
Page 424 and 425:
Page 426 and 427:
Chapter 20Impacts of intellectual p
Page 428 and 429:
Chapter 20 - Impacts of intellectua
Page 430 and 431:
Page 432 and 433:
Page 434 and 435:
Page 436 and 437:
Page 438 and 439:
Page 440 and 441:
Page 442 and 443:
Page 444 and 445:
Page 446:
Page 449 and 450:
Page 451 and 452:
Page 453 and 454:
Page 455 and 456:
Page 457 and 458:
Page 459 and 460:
Page 461 and 462:
Page 463 and 464:
Page 465 and 466:
Page 467 and 468:
Page 469 and 470:
Page 471 and 472:
Page 473 and 474:
Page 475 and 476:
Page 477 and 478:
Page 479 and 480:
Page 481 and 482:
Page 483 and 484:
Page 485 and 486:
Page 487 and 488:
Page 489 and 490:
Page 491 and 492:
Page 494:
This book provides a comprehensive
show all

marker-assisted selection in wheat

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?