Blast resistance and grain quality are major problems in hybrid rice production in China.  In this study, two resistance (R) genes, Pi46 and Pita, along with the gene Wx^b, which mainly affects rice endosperm amylose content (AC), were introgressed into an elite indica restoring line, R8166, which has little blast resistance and poor grain quality through marker-assisted selection (MAS).  Eight improved lines were found to have recurrent genome recovery ratios ranging from 88.68 to 96.23%.  Two improved lines, R163 and R167, were selected for subsequent studies.  R167, which has the highest recovery ratio (96.23%), showed no significant differences in multiple agronomic traits.  In contrast, R163 with the lowest recovery ratio (88.68%) exhibited significant differences in heading date and yield per plant compared with the recurrent parent.  At two developmental stages, R163 and R167 had greatly enhanced resistance to blast over the recurrent parent.  Similar trends were also observed for agronomic traits and blast resistance in R163- and R167-derived hybrids when compared with the counterparts from R8166.  In addition, R163, R167, and their derived hybrids significantly improved the grain quality traits, including amylose content (AC), gel consistency (GC), chalky grain rate (CGR), and degree of endosperm chalkiness (DEC).  It confirmed the success of efficiently developing elite restoring lines using MAS in this study.

A substantial fraction of miRNA* species are conserved in animals and can repress activities of target genes. This study aims to investigate the miRNA* species in duck skin by using Solexa sequencing. We obtained a total of 96 miRNA* species in two skin small RNA libraries and identified 56 miRNA/miRNA* (miR/miR*) pairs. Nucleotide bias of miRNA* indicated that the priority was C>A>U>G for the first nucleotide and U>C>A>G for the last nucleotide. Comparison analyses showed that 3´-U accounted for a higher proportion in the 56 miR/miR* pairs. Among the top 20 expressed miRNA* species, 17 were shared by two libraries and most of the miRNA* species were highly conservative, especially in the “seed region”. miR-199a* were expressed highly in our samples, which was also previously shown abundant in mouse hair follicle. Furthermore, four miRNA* species were predicted to target their genes in signal pathways of feather follicle development and feather morphogenesis despite very low levels.