Abstract
BackgroundThe brown planthopper (BPH) has become the most destructive and a serious threat to the rice production in Asia. Breeding the resistant varieties with improved host resistance is the most effective and ecosystem-friendly strategy of BPH biological management. As host resistance was always broken down by the presence of the upgrading BPH biotype, the more resistant varieties with novel resistance genes or pyramiding known identified BPH resistance genes would be needed urgently for higher resistant level and more durability of resistance.ResultsHere, we developed near isogenic lines of Bph9 (NIL-Bph9) by backcrossing elite cultivar 93–11 with Pokkali (harboring Bph9) using marker-assisted selection (MAS). Subsequently, we pyramided Bph6 and Bph9 in 93–11 genetic background through MAS. The resulting Bph6 and Bph9 pyramided line LuoYang69 had stronger antixenotic and antibiosis effects on BPH and exhibited significantly enhanced resistance to BPH than near isogenic lines NIL-Bph6 and NIL-Bph9. LuoYang69 derived hybrids, harboring heterozygous Bph6 and Bph9 genes, also conferred high level of resistance to BPH. Furthermore, LuoYang69 did not affect the elite agronomic traits and rice grain quality of 93–11. The current study also developed functional markers for Bph9. Using functional dominant marker, we screened and evaluated worldwide accessions of rice germplasm. Of the 673 varieties tested, 8 cultivars were identified to harbor functional Bph9 gene.ConclusionThe development of Bph6 and Bph9 pyramided line LuoYang69 provides valuable resource to develop hybrid rice with highly and durable BPH resistance. The development of functional markers will promote MAS of Bph9. The identified Bph9 containing cultivars can be used as new sources for BPH resistance breeding programs.
Highlights
The brown planthopper (BPH) has become the most destructive and a serious threat to the rice production in Asia
To improve BPH resistance of 93–11, 93–11 was used as the recurrent parent to backcross with Pokkali (IRGC 108921, harboring BPH resistance gene Bph9) for seven generations and self-crossed to produce the population of BC7F2 (Additional file 1: Figure S1) Two flanking markers InD2 and RM28466 tightly linked to Bph9 locus were used to select the positive progenies for continuous backcrossing
A total of 119 polymorphic molecular markers evenly distributed on 12 chromosomes were used to examine the recovery rate of genetic background (RRGB) of candidate Near isogenic line (NIL)
Summary
The brown planthopper (BPH) has become the most destructive and a serious threat to the rice production in Asia. Breeding the resistant varieties with improved host resistance is the most effective and ecosystem-friendly strategy of BPH biological management. As host resistance was always broken down by the presence of the upgrading BPH biotype, the more resistant varieties with novel resistance genes or pyramiding known identified BPH resistance genes would be needed urgently for higher resistant level and more durability of resistance. Of more than 20 kinds of serious paddy pests known at present, brown planthopper (BPH, Nilaparvata lugens Stål), a migratory and monophagous rice insect, has proved to be the most destructive, especially in the Asia For preventing the damage caused by BPH, several approaches have been implemented including chemical and biological controlling (Normile, 2008). Comparing with the conventional chemical controlling, developing the host resistance by
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