Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2002
Publication Date: 5/8/2003
Interpretive Summary: Agronomically useful genes were introduced from a wild relative of rice, O. rufipogon, into the cultivated gene pool, O. sativa (cv. IR64) and identified using an advanced backcross QTL (quantitative trait loci) strategy. Two hundred eighty five BC2F2 families derived from an interspecific cross between IR64 and O. rufipogon (IRGC 105491) were evaluated for twelve agronomic traits in two field environments in Indonesia and one hundred sixty five molecular markers were used to construct a genetic linkage map. Forty two QTL were identified, of which a third of the QTL alleles from O. rufipogon were observed to have a positive effect on yield and yield components in the genetic background of IR64. Results of this study are discussed in relation to previous studies using the same accession of O. rufipogon and different O. sativa varieties. Several QTL for plant height, grain weight, and flowering time detected in this study correspond to homeologous regions in maize.
Technical Abstract: A BC2F2 population developed from an interspecific cross between IR64 (Oryza sativa) and O. rufipogon (IRGC 105491) was used in an advanced backcross QTL analysis to identify and introduce agronomically useful genes from this wild relative into the cultivated gene pool. Two hundred eighty five families were evaluated in two field environments in Indonesia, with two replications each, for 12 agronomic traits. A total of 165 markers consisting of 131 SSRs and 34 RFLPs were used to construct the genetic linkage map. The objectives of this study were to:identify putative yield and yield component QTL that can be useful to improve the elite cultivar IR64, compare the QTL within this study with previously reported QTL in rice as the basis for identifying QTL that are stable across different environment and genetic backgrounds, and compare the identified QTL with previously reported QTL from maize to examine the degree of conservation across the grasses. By employing interval and composite interval mapping, 42 QTL were identified. Despite its inferior performance, 33% of the QTL alleles from O. rufipogon had a beneficial effect for yield and yield components in the IR64 background. Twenty-two QTL were located in similar regions as previously reported rice QTL, suggesting the existence of stable QTL across genetic backgrounds and environments. Twenty QTL were exclusively detected in this study, uncovering potentially novel alleles from the wild, some of which might improve the performance of the indica variety IR64. Additionally, several QTL for plant height, grain weight, and flowering time detected in this study corresponded to homeologous regions in maize containing previously detected maize QTL for these traits.