Maize Genetics Cooperation Newsletter vol 84 2010

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of authors.

 

 

Ottawa, Ontario, Canada

Eastern Cereal and Oilseed Research Centre

 

Yaan, Sichuan, China

Sichuan Agricultural University

 

Heterotic Groups of Canadian Maize Inbred Lines Based on Pedigree and SSR Markers

Reid, L.M., X. Zhu, B. Bernard, K. Xiang, C. Voloaca, and T. Woldemariam

 

    Corn breeders of Agriculture and Agri-Food Canada (AAFC) have collected maize genotypes from around the world and adapted them to the different short growing season regions of Canada. In many cases, the heterotic backgrounds of these genotypes were unknown, while others had been developed from mix of two or more heterotic groups. In the early years of inbred development at AAFC, testers of known heterotic backgrounds were not available with maturities suitable to Canadian climates.  This sometimes resulted in the release of inbreds with little knowledge on their combining ability with the different heterotic patterns. Over the past few years, we have been evaluating the inbred lines released from AAFC during the last 20 years and classifying them into known heterotic groups based on pedigree and Simple Sequence Repeat (SSR) markers.

A total of 129 inbred lines were classified into nine groups based on pedigree (Table 1). Eighteen inbred lines with five major sources (BSSS, B73, B14, B37, and BSTE) were categorized into Group I (BSSS group); 19 inbred lines with three major sources (Inra 258, Pfister 44 and Lethbridge Gene Pool) were classified into Group II (European flint group); Group III (Lancaster group) included 15 inbred lines with the major sources of MO17, OH43, LH83, W153 and H99; Group IV (Minnesota #13 group) consisted of seven inbred lines with the major source of Minnesota #13 and Pride 5; Group V (Early Butler group) consisted of seven inbred lines; Group VI (Iodent group) consisted of four inbred lines; Group VII (Pioneer 3990 group) consisted of 11 inbred lines; Group VIII (Pioneer 3994 group) consisted of 13 inbred lines; and 35 inbred lines with no major sources were classed as Group IX.

    The 129 inbred lines analyzed with 105 SSR primers were distributed across the 10 maize chromosomes, with an average of 10.5 primes per chromosome. A total of 380 alleles were detected with 2 to 7 per locus, with an average of 3.62. The results indicated that such variation was significantly associated with the number of alleles detected. Cluster analysis was carried out based on the matrix of genetic similarities using the Unweighted Pair Group Method Using Arithmetic Average clustering algorithm using NTSYS-pc version 2.2 (Exeter Software New York, USA). All the inbred lines were classified into 13 groups (Table 1).

When comparing the pedigree groups with the SSR groups, the two groupings were basically identical for the majority of the inbred lines (Table 1). The results showed that there were two to six SSR groups per pedigree group, while group VII included two SSR groups and the group VIII included six groups.

Ordinations were conducted by using canonical discriminant analysis (Kshirsagar, Multivariate analysis. 1972) and classification probabilities by carrying out classificatory discriminant analyses (Fig. 1). The analyses were performed using SAS (SAS Institute, Inc 1989) version 9.1.3 (2007). Comparing the groups based on the discriminant analysis of SSR data with the pedigree groups, the inbred lines in the ninth pedigree group with unknown sources were classified into eight other groups (Table 1), some inbred lines in the same pedigree group were classified into different groups. According to the cross-validation results, this classification was 94.7% probability reliable.

     We are currently conducting further classification analysis based on combining ability data of these inbreds with testers of known heterotic patterns.


Table 1. Major pedigree and three types of classifications of 129 maize inbred lines released by AAFC (inbreds prefixed with CB, CL, CM or CO) and several check inbreds.

Inbred

 

Major pedigree

Pedigree

group

Discriminant analysis group

SSR cluster

group

B73

BSSS/B73

I

I

I

CM105

B14

I

I

II

CM174

B14

I

I

II

CO269

BSSS

I

I

XII

CO360

B37/B14/Minnesota#13

I

I

II

CO362

B14

I

I

II

CO363

B14

I

I

II

CO364

B14

I

I

XII

CO370

BSTE

I

I

VI

CO388

B73/BSTE/Early Butler

I

I

XII

CO389

B73/BSTE/Early Butler

I

I

IX

CO408

B37/Pfister44

I

I

XII

CO434

B14

I

I

II

CO435

B14

I

I

XII

CO439

BSSS

I

I

II

LH300

B14

I

I

II

MBS1236

B14/Pioneer 3978

I

I

VI

TR4033

B14

I

I

II

CL30

European flint

II

II

V

CO251

Pfister44/Early Butler

II

II

XII

CO255

Inra 258

II

II

XIII

CO343

MO17/Inra 258

II

III

XII

CO344

MO17/Inra 258

II

II

XII

CO345

Pfister44/Inra 258/OH43

II

II

XIII

CO349

Inra 258/B14

II

II

XII

CO365

Pfister44/BSSS

II

II

XII

CO382

Inra 258/MO17

II

II

XIII

CO383

Inra 258/MO17

II

II

XII

CO384

Inra 258/B14

II

II

XII

CO409

Inra 258/Pioneer 3977

II

II

XIII

CO412

Inra 258/OH43/B14

II

II

XII

CO414

Inra 258/B14

II

II

XII

CO416

Pfister 44/B14

II

II

II

CO418

European hybrids

II

II

VI

CO422

Inra 258/OH43/B14

II

II

XII

CO437

European hybrids

II

II

VII

LH290

Pioneer 3978/F2

II

II

XIII

CO359

W153R/LH82

III

III

VI

CO367

W153R/LH82

III

III

VI

CO368

W153R/LH82

III

III

VI

CO369

W153R/LH82

III

III

VI

CO386

MO17/MAG

III

I

IV

CO390

H99/OH43

III

III

XIII

CO393

Pioneer 3990/MO17

III

III

IV

CO394

Pioneer 3990/MO17

III

III

IV

CO395

Pioneer 3990/MO17

III

III

IV

CO427

OH43/H99

III

III

IV

CO428

OH43/H99

III

V

XII

CO429

W153R/LH82

III

III

VI

LH176

LH82/Pioneer 3704

III

III

XIII

Mo17

MO17

III

III

IV

OH43

OH43

III

III

XIII

CB21

Pfister 44/Minnesota #13

IV

IV

III

CO106

Minnesota #13

IV

IV

X

CO303

Pride 5/BSSS

IV

IV

XII

CO328

Pride 5/BSSS

IV

IV

XII

CO350

Pride 5/Pioneer 3977

IV

IV

III

CO415

Pride 5/Pioneer 3968

IV

IV

III

CO440

Pride 5/BSSS

IV

IV

III

CO220

Early Butler

V

V

IX

CO325

Early Butler/BSSS

V

V

V

CO346

Early Butler

V

V

XI

CO361

BSSS/BSTE/Early Butler

V

VII

XII

CO387

Pioneer 3990/BSTE/ Early Butler

V

V

IV

CO424

BSSS/ Early Butler

V

V

XII

CO443

BSSS/ Early Butler

V

V

IX

CO421

Iodent/F2

VI

VI

III

CO442

Iodent

VI

VI

III

LH162

Iodent/MO176

VI

VI

IV

TR1957

Iodent

VI

VI

VI

CO266

Pioneer 3990

VII

VII

IV

CO289

Pioneer 3990

VII

VII

IV

CO377

Pioneer 3990

VII

VII

XII

CO378

Pioneer 3990

VII

VII

IV

CO380

Pioneer 3990

VII

VII

IV

CO381

Pioneer 3990

VII

VII

XII

CO396

Pioneer 3990/Inra 258/BSSS

VII

VII

XII

CO397

Pioneer 3990/Inra 258/BSSS

VII

VII

IV

CO398

Pioneer 3990/Inra 258/BSSS

VII

VII

IV

CO406

Pioneer 3990

VII

VII

XII

CO407

Pioneer 3990

VII

VII

IV

CB12

Pioneer 3994

VIII

VIII

III

CO341

BSSS/Pioneer 3994

VIII

VIII

V

CO366

Pioneer 3994/Minnesota #13

VIII

VIII

III

CO375

Pioneer 3994/Minnesota #13

VIII

VIII

XII

CO376

Pioneer 3994/Minnesota #13

VIII

VIII

III

CO403

Pioneer 3994/Minnesota #13

VIII

VIII

XII

CO404

Pioneer 3994/Minnesota #13

VIII

VIII

XIII

CO405

Pioneer 3994/Minnesota #13

VIII

VIII

XIII

CO410

BSSS/Pioneer 3994

VIII

VIII

VI

CO417

Pioneer 3994/Minnesota #13

VIII

VIII

IV

CO425

BSSS/ Pioneer 3994

VIII

VIII

VI

CO436

Pioneer 3994/Minnesota #13

VIII

VIII

III

CO438

Pioneer 3994/Unknown

VIII

VIII

III

CO253

Unknown

IX

II

V

CO342

Unknown/Ottawa flint/Minnesota#13

IX

III

VII

CO347

Unknown

IX

III

VIII

CO348

Unknown

IX

VI

VI

CO351        

Unknown/Ottawa flint/Minnesota#13

IX

V

VII

CO352

Asgrow RX777

IX

I

I

CO353

Asgrow RX777

IX

I

XII

CO354

Asgrow RX777

IX

I

I

CO355

Pioneer 3389

IX

III

I

CO356

Pioneer 3389

IX

V

I

CO357

Pioneer 3389

IX

III

IV

CO358

Pioneer 3389

IX

V

XII

CO371

Unknown

IX

IV

VIII

CO372

Unknown

IX

II

XIII

CO373

Unknown

IX

IV

XIII

CO374

Unknown

IX

II

VIII

CO379

Unknown

IX

V

III

CO385

Unknown

IX

II

VI

CO391

Asgrow RX777

IX

I

I

CO392

Ottawa flint/Minnesota#13/OH43/B14

IX

II

XII

CO399

Pioneer 3925

IX

IV

VI

CO400

Pioneer 3925

IX

IV

VI

CO401

Unknown

IX

VIII

V

CO402

Unknown

IX

VIII

VII

CO411

Pioneer 3995

IX

II

III

CO413

Pioneer 6124/Pioneer 3968

IX

VII

V

CO419

Unknown

IX

IV

V

CO420

Unknown

IX

VI

V

CO423

Unknown

IX

V

III

CO426

Unknown

IX

III

VI

CO430

Unknown

IX

VII

IV

CO431

Unknown

IX

VI

IV

CO432

Unknown

IX

IV

VI

CO433

Pride K127

IX

IV

VI

CO441

Unknown

IX

III

VI

Groups based on the pedigree.

Groups based on the discriminant analysis of SSR data.

Groups based on the genetic similarities using the Unweighted Pair Group Method Using Arithmetic Average clustering algorithm.

Fig. 1 Canonical discriminant analyses of the SSR markers. 1 = BSSS group; 2 = European flint group; 3 = Lancaster group; 4 = Minnesota #13 group; 5 = Early Butler group; 6= Iodent group; 7= Pioneer3990 group; 8= Pioneer 3994 group.