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Ch. 12 Breeding methods for cross-pollinated crops

Ch. 12 Breeding methods for cross-pollinated crops. Mass selection F amily selection R ecurrent selection Convergent improvement of inbred lines by backcrossing. gene accumulation ( based on additive + epistasis gene action). 1. Mass selection (individual selection).

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Ch. 12 Breeding methods for cross-pollinated crops

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  1. Ch. 12 Breeding methods for cross-pollinated crops Mass selection Family selection Recurrent selection Convergent improvement of inbred lines by backcrossing gene accumulation (based on additive +epistasis gene action)

  2. 1. Mass selection (individual selection) 2. Family selection (Uni-parental selection) (seed parents selection) (1)Half-sib F. S. (Ear-to-row method) Evaluation of families (half-sib progenies) Application : perennial forage crops Open pollination within families

  3. (2)Full-sib family S. (crosses between selected plants) Application : maize Evaluation

  4. 3. Recurrent selection • To improve • • the performance of a population with a respect to one or more traits • • the combining abilities of inbred lines • Genetic basis : gene accumulation • Base population : open-pollinated populations, synthetic varieties 2 main common phases for each cycle i) Selected plants are selfed and evaluated (self-performance or performance of F1). ii) The selected parents are intermated to produce the population for the next cycle of selection 1 cycle: 2~3 years Concept of recurrent selection (Acquaah, 2012)

  5. (1) Recurrent selection for phenotype improvement : to improve the specific traits, (simple) * similar to mass selection, different points: selfing of selected plants 1st year - Selfing and individual selection 1st cycle ⓧ ⓧ ⓧ ⓧ ⓧ ⓧ • planting the selfed seeds by ear to row method • open pollination among plants 2nd year • harvest each line and bulk seeds 3rd year - Selfing and individual selection 2nd cycle ⓧ ⓧ ⓧ ⓧ ⓧ ⓧ • planting the selfed seeds by ear to row method • open pollination among plants 4th year • harvest each line and bulk seeds

  6. (2) Recurrent selection for general combining ability(일반조합능력개량 순환선발) : to improve the general combining ability of inbred lines through early testing of GCA --- 1cycle 3 years •GCA tester: tester inbred lines, open pollinated var. --- topcross for GCA test - Selfing of selected individuals, - Top-crossing of selected individuals to GCA testers 1st year ⓧ ⓧ ⓧ ⓧ ⓧ ⓧ C C C C C C 1st cycle • yield evaluation of F1s (GCA test of selected plants) • selection of high GCA plants 2nd year • cultivation by row of each selfed seeds harvested • 1st year from GCA-selected plants • open pollination among lines 3rd year • bulk seeds harvested from each line - Selfing of selected individuals, - Top-crossing of selected individuals to GCA testers 4th year ⓧ ⓧ ⓧ ⓧ ⓧ ⓧ C C C C C C 2nd cycle • yield evaluation of F1s (GCA test of selected plants) • selection of high GCA plants 5th year • cultivation by row of each selfed seeds harvested • 1st year from GCA-selected plants • open pollination among lines 6th year • bulk seeds harvested from each line Breeding Inbred lines of high GCA

  7. (3) Recurrent selection for specific combining ability(특정조합능력개량 순환선발) : to improve the general combining ability of inbred lines through early testing of SCA --- 1cycle 3 years * SCA tester: promising inbred lines which will be used for one of the parents ===>Same procedure as above (in case of GCA)

  8. (4) Reciprocal recurrent selection(상호순환선발법) : to improve the combining ability of inbred lines in 2 populations at the same time byreciprocal test of combining ability using the other population * combining ability tester : the other population to each other * Hybrid variety will be made by crossing between an inbred from population A and an inbred from population B. populationA populationB - Selfing of selected individuals, - Top-crossing of selected plants to some plants of the other pop. 1st year ⓧ ⓧ ⓧ ⓧ ⓧ ⓧ ⓧ ⓧ ⓧ ⓧ C C C C C C C C C C 1st cycle • yield evaluation of F1s • selection of high C.A. plants 2nd year • cultivation by row of each selfed seeds • harvested 1st year from C.A.-selected plants • open pollination among lines 3rd year • bulk seeds harvested from each line 4th year ⓧ ⓧ ⓧ ⓧ ⓧ ⓧ ⓧ ⓧ ⓧ ⓧ C C C C C C C C C C 2nd cycle • Same as above 5th year 6th year

  9. 4. Convergent improvement of inbred lines by backcrossing : to improve the performance of inbred lines by backcrossing to each of the parents  recovered line or derived line (재생 근교계) (1) Use of each parent as a donor Assumed genotypes Originalinbred lines A ⅹ B A=AABBCCddeeff B=aabbccDDEEFF F1 F1=AaBbCcDdEeFf Backcross AⅹF1 BⅹF1 Compare the performance of inbred lines and F1s. Which is better? BⅹBC1F1 AⅹBC1F1 A(B)=AABBCCDDeeff B(A)=aabbCCDDEEFF Derived inbred lines A(B) ⅹ B(A) (improved inbred line in terms of its performance) F1=AaBbCCDDEeFf F1

  10. (2) Use of another inbred line as a donor Assumed genotypes A=AABBCCddeeffgghh B=aabbccDDEEFFgghh Originalinbred lines A B F1=AaBbCcDdEeFfgghh Q P Donor lines P=aaBBccddeeffGGhh, Q=aabbccDDeeffggHH BⅹQ AⅹP First cross Backcross AⅹF1 BⅹF1 BⅹBC1F1 AⅹBC1F1 A(P’)=AABBCCDDeeffGGhh B(Q’)=aabbCCDDEEFFggHH Derived inbred lines A(P’) ⅹ B(Q’) F1 F1=AaBbCCDDEeFfGgHh

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