Brown planthopper (BPH), Nilaparvata lugens Stal, is a serious
insect pest of rice throughout Asia. Two Indica varieties, ADR52 (from
India) and Podiwi A8 (from Sri-Lanka), which previously identified to
be resistant to whitebacked planthopper, were also highly resistant to
BPH. QTL analysis was conducted to understand the genetic bases of BPH
resistance in ADR 52 and Podiwi A8. These varieties were crossed to Taichung
65 (T65), a Japonica variety susceptible to BPH. T65 was used as a female
parent whereas the resistant varieties were used as male parents. The
F1 and 81 F2 of the crosses and the parents were
evaluated for antibiosis to BPH by means of nymph mortality. At tillering
stage, 5 leaf sheaths of F2 individuals were infested with
10 second-instar BPH nymphs. The BPH population was collected in Chikugo,
Fukuoka Prefecture, Japan in 1989 and was maintained by continuously rearing.
Nymph mortality was scored at five days after infestation.
The two resistant parents showed high nymph mortality above 90%. The F1
of T65/ADR52 was moderately resistant and the frequency distribution in
the F2 was deviated to high nymph mortality. The F1
of T65/Podiwi A8 was highly resistant with the nymph mortality above 80%.
The nymph mortality of the F2 exhibited a continuous frequency
distribution and did not show any discrete segregation.
We constructed two framework maps with 155 and 142 simple sequence repeat
(SSR) markers (McCouch et al. 2002) based on the F2
populations of T65/ADR52 and T65/Podiwi A8, respectively. QTL analyses
for antibiosis to BPH were conducted by single factor analysis (SFA) using
QGene v3.06 (Nelson 1997) and simple interval mapping (SIM) using QTL
Cartographer v1.16 (Basten et al. 2002), with threshold of LOD>=2.0.
The same QTLs were detected by using both of the statistical analyses.
Therefore, only the results by SIM were shown in Table 1 and Figure 1.
In the F2 population of T65/ADR52, three QTLs affecting antibiosis
to BPH were detected on chromosomes 5, 6 and 12. Positive alleles affecting
antibiosis to BPH came from ADR52 on chromosomes 6 and 12, and from T65
on chromosome 5. As for Podiwi A8, three QTLs affecting antibiosis to
BPH were detected on chromosomes 3, 7 and 12. Alleles from Podiwi A8 contributed
to antibiosis to BPH at all the three QTLs.
Three genes for resistance to BPH, Bph1, bph2 and Bph9,
are closely linked on chromosome 12 (Hirabayashi and Ogawa 1995, Murata
et al. 1998, 2000). Among the two QTLs detected on chromosome 12,
the QTL detected in T65/ADR52 was located near Bph1. The
genetic effect showed almost complete dominance, which seemed to be similar
to that of Bph1. Another QTL detected in T65/Podiwi A8 was located
near bph2 and/or Bph9. The genetic effect of the QTL was
additive. Therefore, it is sure that these two QTLs on chromosome 12 are
not identical. In the present study, the remaining four QTLs for resistance
to BPH were newly detected based on the two F2 populations
compared to the QTLs previously reported (Alam and Cohen 1998, Su et
al. 2002). QTLs on chromosomes 6 and 12 controlled BPH antibiosis
of ADR52. In the case of Podiwi A8, which seems to be much more resistant
than ADR52, the accumulation of three QTLs might affect to antibiosis
to BPH. Development of isogenic lines for respective QTLs is necessary
to precisely map and characterize the genes for antibiosis to BPH.
References
Alam, S. N. and M. B. Cohen, 1998. Detection and analysis of QTLs for
resistance to the brown planthopper, Nilaparvata lugens, in a doubled-haploid
rice population. Theor. Appl. Genet. 97: 1370-1379.
Basten, C. J., B. S. Weir and Z. B. Zeng, 2002. QTL Cartographer version
1.16: a reference manual and tutorial for QTL mapping. World Wide Web
URL: http://statgen.ncsu.edu/qtlcart/.
Hirabayashi, H. and T. Ogawa, 1995. RFLP mapping of Bph-1 (Brown
planthopper resistance gene) in rice. Breed. Sci. 45: 369-371.
McCouch, S. R., L. Teytelman, Y. Xu, K. B. Lobos, K. Clare, M. Walton,
B. Fu, R. Maghirang, Z. Li, Y. Xing, Q. Zhang, I. Kono, M. Yano, R. Fjellstrom,
G. DeClerck, D. Schneider, S. Cartinhour, D. Ware and L. Stein, 2002.
Development and mapping of 2240 new SSR markers for rice (Oryza sativa
L.). DNA research 9: 199-207.
Murata, K., M. Fujiwara, C. Kaneda, S. Takumi, N. Mori and C. Nakamura,
1998. RFLP mapping of a brown planthopper (Nilaparvata lugens Stal)
resistance gene bph2 of indica rice introgressed into a
japonica breeding line 'Norin-PL4'. Genes Genet. Syst. 73:
359-364.
Murata, K., M. Fujiwara, H. Murai, S. Takumi, N. Mori and C. Nakamura,
2000. Bph9, a dominant brown planthopper resistance gene, is located
on the long arm of rice chromosome 12. RGN 17: 84-86.
Nelson, J. C. 1997. QGENE: Software for marker-based genomic analysis
and breeding. Mol. Breed. 3: 239-245.
Su, C. C., H. Q. Zhai, X. N. Cheng and J. M. Wan, 2002. Detection and
analysis of QTLs for resistance to brown planthopper, Nilaparvata lugens
(Stal), in rice (Oryza sativa L.), using backcross inbred lines.
RGN 19: 88-90.
|