Contents - Faperta

172 Biotechnological Approaches for Pest Management and Ecological Sustainability
Rice
The complete genetic linkage map of rice was published by the end of the twentieth
century (Kurata et al., 1994, 1997; Palevitz, 2000), can be used for identifi cation of
genomic regions associated with resistance to insects. Considerable progress has
been made in identifi cation of molecular markers/QTLs associated with resistance to
insect pests in rice. Several RAPD markers linked to yellow stem borer, S. incertulas
resistance have been identifi ed; the chromosome location of these genes is unknown
(Selvi et al., 2002).
Much progress has been made in tagging and mapping the genes conferring resistance
to rice gall midge, O. oryzae. Resistance to O. oryzae is linked with RG329 (1.3 cM) and
RG476 (3.4 cM) markers on chromosome 4 (Mohan et al., 1994). RAPD fragment F8 1700 is
associated with susceptibility and F10 600 with resistance to O. oryzae (Nair et al., 1995),
while RAPD fragment E20 570 is associated with resistance and E20 583 with susceptibility to
gall midge (Nair et al., 1996). Behura et al. (2000) reported an AFLP marker, which is amplifi
ed in biotypes 1, 2, and 5 of rice gall midge, but not in biotype 4. The former are avirulent
on hosts bearing the Gm2 resistance gene (e.g., Phalguna), while biotype 4 is avirulent to
hosts with Gm2 gene. Avirulence to Gm2 gene is sex-linked. An AFLP marker SA598 linked
to Gm7, conferring resistance to biotypes 1, 2, and 4, has also been identifi ed (Sardesai
et al., 2002). Gm7 is a dominant gene and is nonallelic to Gm2. A dominant resistance gene,
Gm1, has been tagged and mapped on chromosome 9 (Biradar et al., 2004). The SSR markers
RM316, RM444, and RM219 located on chromosome 9 are linked to Gm1 at genetic
distances of 8.0, 4.9, and 5.9 cM, respectively. Gm8 has been tagged and mapped on the rice
chromosome 8 ( Jain et al., 2004). Two fragments, AR257 and AS168, were linked to the
resistant and susceptible phenotypes, respectively. Another resistant phenotype-specifi c
marker, AP19(587) was also identifi ed using RAPDs. There is a tight linkage between the
markers and the Gm8 locus. Many of these markers can be used in MAS to develop rice
cultivars with resistance to gall midge.
For brown planthopper, N. lugens, genomic regions on chromosomes 3 and 4 contain
genes for resistance (Z. Huang et al., 2001). Two QTLs are associated with resistance to
N. lugens (Alam and Cohen, 1998), of which one QTL is linked to antixenosis and second to
tolerance. In another population, Xu et al. (2002) found that a main effect QTL for N. lugens
resistance maps to the vicinity of a major rice gene controlling leaf and stem pubescence,
suggesting that this QTL may explain antixenosis to N. lugens. The N. lugens resistance
genes bph11 and Bph13 map to chromosome 3 (Kawaguchi et al., 2001; Renganayaki et al.,
2002). The N. lugens resistance genes Bph1, bph2, bph9, and Bph10 have been mapped to a
25 cM block on rice chromosome 12 (Ishii et al., 1994; Hirabayashi and Ogawa, 1995; Murata
et al., 2000; P.N. Sharma et al., 2003), while bph4 and bph12 map to chromosomes 6 and 4,
respectively (Hirabayashi and Ogawa, 1999; Kawaguchi et al., 2001). A major resistance
gene, Bph18(t), has been identifi ed in the introgression lines IR 65482-7-216-1-2, which had
been derived from the wild rice, Oryza australiensis Domin. ( Jena et al., 2006). It is nonallelic
to Bph10 and is located on the long arm terminal region of chromosome 12, fl anked by SSR
marker RM463 and STS marker S15552.
QTLs linked to green rice leafhopper, Nephotettix cincticeps (Uhler) resistance genes in
rice have been identifi ed in progeny from doubled haploid populations involving indica
and japonica rice crosses. Oryza sativa L. O. offi cinalis Wall ex Watt. crosses have also been
used to identify QTLs for resistance to green leafhopper (N. Huang et al., 1997; Y. Fukuta
et al., 1998; Z. Huang et al., 2001). Chromosomal location of the gene linked to early panicle
initiation and resistance to green leafhopper resistance [Grh3(t)] have been used to identify