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Luo X.,China Agricultural University | Luo X.,Key Laboratory of Crop Heterosis and Utilization of Ministry of Education | Luo X.,Beijing Key Laboratory of Crop Genetic Improvement | Luo X.,Key Laboratory of Crop Genetic Improvement and Genome of Ministry of Agriculture | And 25 more authors.
Plant Science | Year: 2011

Many rice breeding programs have currently reached yield plateaus as a result of limited genetic variability in parental strains. Dongxiang common wild rice (Oryza rufipogon Griff.) is the progenitor of cultivated rice (Oryza sativa L.) and serves as an important gene pool for the genetic improvement of rice cultivars. In this study, heterotic loci (HLs) associated with six yield-related traits were identified in wild and cultivated rice and investigated using a set of 265 introgression lines (ILs) of O. rufipogon Griff. in the background of the Indica high-yielding cultivar Guichao 2 (O. sativa L.). Forty-two HLs were detected by a single point analysis of mid-parent heterosis values from test cross F1 offspring, and 30 (71.5%) of these HLs showed significantly positive effects, consistent with the superiority shown by the F1 test cross population in the six yield-related traits under study. Genetic mapping of hsp11, a locus responsible for the number of spikelets per panicle, confirmed the utility of these HLs. The results indicate that favorable HLs capable of improving agronomic traits are available. The identification of HLs between wild rice and cultivated rice could lead to a new strategy for the application of heterosis in rice breeding. © 2011.

Feng X.,China Agricultural University | Feng X.,Key Laboratory of Crop Genomics and Genetic Improvement | Feng X.,Key Laboratory of Crop Heterosis and Utilization of Ministry of Education | Feng X.,Beijing Key Laboratory of Crop Genetic Improvement | And 20 more authors.
Plant Cell, Tissue and Organ Culture | Year: 2011

Sorbitol promotes plantlet regeneration frequency (PRF) of rice calli. To better understand this phenomenon, calli of upland rice cv. HD65 were induced on medium containing 10 g sorbitol/L, and subcultured and regenerated on media containing 20 and 40 g sorbitol/L, respectively. Using complementary DNA (cDNA)-amplified fragment length polymorphism (AFLP) analysis, we investigated differential gene expression between sorbitol-supplemented (SC) and sorbitol-free calli (NC) during the regeneration stage. From >4,000 transcript-derived fragments (TDFs), we identified 118 differentially expressed TDFs between SC and NC. Of these, 37 were cloned and sequenced, and 12 were further confirmed by semiquantitative reverse-transcription polymerase chain reaction (RT-PCR) analysis. Database searches indicated that 10 TDFs showed no significant homology to genes with known or putative functions, although they were previously reported to be expressed in rice calli. These cDNAs might encode novel proteins related to plantlet regeneration. Of all the 27 well-known TDFs, 35. 1% were highly expressed in SC, and had roles in signal transduction (13. 5%), transcription and translation (13. 5%), and regulation (8. 1%). Four TDFs were related to plant growth and regeneration: TDF5, TDF17, TDF21, and TDF26, which showed homologies to a nucleoside diphosphate kinase (NDPK), a cyclin, a receptor-like protein kinase precursor, and TCP-1, respectively. Furthermore, 35. 1% were related to metabolism, 27. 0% to energy, and 8. 1% to defense. These results suggest that, in addition to its roles as a carbon source and an osmotic regulator, sorbitol may also act as a chemical signal to directly or indirectly alter gene expression. Sorbitol exerts its effects via complex transcriptional networks to enhance PRF of calli. © 2011 Springer Science+Business Media B.V.

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