Marker-aided introgression of bacterial leaf blight (BLB) resistance genes to CMS line (IR58025A) and PSB Rc72H
2005
Ordoñez, S.H., Jr. | Baliuag, N.N.A. | Garcia, F.D. | Casimero, V.V. | De Leon, J.C. | Redoña, E.D.
Of the 13 segregating populations (BC3F4) in the DS [dry season], six showed high phenotypic similarity to the original IR58025B. In these six populations, 372 individual possible donor plants were selected and individually tagged. Of the 372 individual plants, 131 successful paired crosses and 45 successful backcrosses were generated. In addition, 13 new populations (BC3F2) from IRRI [International Rice Research Institute], Los Banos, Laguna, Philippines] were evaluated. In the evaluation of last season's crosses, the A x B (resistant) was found highly fertile, indicating that the maintaining ability of the B line had been altered as a result of the previous introgression work. Since the genetic background of the donor of the BLB resistance genes is IR24, a known restorer line, the authors expect the change in the ability of the B line to maintain sterility. Genotypic selection should focus on the restorer genes present. Selection of true-to-type IR58025B (BLB resistant) was done in the field before harvesting to constitute the parents of next season's crosses. During the WS [wet season], significant results were gathered from the molecular analysis done at IRRI to confirm the presence of Xa genes in the progenies of A x B and B x B crosses done last season. However, in the phenotyping evaluation of fertility/sterility, majority were fertile, indicating that the parents might still have Rf genes. This result, however, needs further evaluation under controlled condition as the seed set observed may be caused by cross pollination.
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