Development of Oryza sativa L. by Oryza punctata Kotschy ex Steud. monosomic addition lines with high value traits by interspecific hybridization

Oryza punctata\ua0is a distantly related wild\ua0Oryza\ua0species having BB genome with untapped genetic resources for rice improvement. Low crossability between the cultivated\ua0O. sativa\ua0and\ua0O. punctata\ua0restricts the success of transferring many desirable traits into cultivated rice. Artificially induced autotetraploids of an elite breeding line, IR31917-45-3-2, were produced and crossed with\ua0O. punctata. Allotriploid F1\ua0plants were backcrossed to IR31917-45-3-2 and generated progenies with extra chromosomes from\ua0O. punctata. Twenty BC1F1\ua0and 59 BC2F1\ua0plants were produced with chromosome numbers ranging from 24 (2n) to 29 (2n\ua0+\ua05) and 2n\ua0(24) to 26 (2n\ua0+\ua02), respectively. Eleven monosomic alien addition lines (MAALs) were characterized morphologically and cytologically and designated as MAAL 1–12. MAALs were genotyped using\ua0O. punctata\ua0genome-specific molecular markers and detected chromosome segments inherited from\ua0O. punctata.\ua0O. punctata\ua0introgressions across all the chromosomes of\ua0O. sativa\ua0were identified except for chromosome 8. The most frequent introgressions were observed in chromosomes 4, 6, 10, and 11, which could be the recombination hotspots between A and B genomes. Some of the qualitative traits such as black hull, purple coleoptile base, purple stigma, long awn, and short grain size from\ua0O. punctata\ua0were inherited in some disomic introgression lines (DILs). Several DILs inherited genes from\ua0O. punctata\ua0conferring resistance to brown planthopper, green leafhopper, and diseases such as bacterial blight and blast. This is the first report on successful gene transfer from\ua0O. punctata\ua0into\ua0O. sativa

Development of an intergeneric hybrid between Oryza sativa L. and Leersia perrieri (A. Camus) Launert

An intergeneric hybrid was successfully developed between\ua0Oryza sativa\ua0L. (IRRI 154) and\ua0Leersia perrieri\ua0(A. Camus) Launert using embryo rescue technique in this study. A low crossability value (0.07%) implied that there was high incompatibility between the two species of the hybrid. The F1\ua0hybrid showed intermediate phenotypic characteristics between the parents but the plant height was very short. The erect plant type resembled the female parent IRRI 154 but the leaves were similar to\ua0L. perrieri. Cytological analysis revealed highly non-homology between chromosomes of the two species as the F1\ua0plants showed 24 univalents without any chromosome pairing. The F1\ua0hybrid plant was further confirmed by PCR analysis using the newly designed 11 indel markers showing polymorphism between\ua0O. sativa\ua0and\ua0L. perrieri. This intergeneric hybrid will open up opportunities to transfer novel valuable traits from\ua0L. perrieri\ua0into cultivated rice