Rice stripe disease is one of the most serious viral disease in East
Asia, such as China, Japanese and Korea. The rice stripe virus (RSV) is
transmitted by small brown planthooper (SPBH), Laodelphax striatellus
Fall. It was indicated that most japonica varieties are susceptible,
while indica and upland varieties are highly resistant.
A mapping population of 98 BC1F9 lines (Backcross
inbred lines: BIL), derived from a backcross of Nipponbare (japonica)/Kasalath
(indica)//Nipponbare by the single-seed descent method, was used
for characterizing QTL resistant to rice stripe virus. About 35 seedlings
of each BIL and parent were used to evaluate the reactions to virus by
inoculating small brown planthopper containing rice stripe virus. The
rate of viruliferous SBPH was around 40% by dot-immunobinding assay. We
inoculated rice stripe virus to the population by individual inoculation
and field test.
By individual inoculation test, twenty-five to thirty seedlings of each
BIL were planted within 9cm × 9cm space in a plastic tray filled
with nutrient soil. When the rice plants reached 1.5-2.1 leaf stage, a
plastic cylinder 9 cm in diameter covered with gauze was put on each RIL.
Inoculation was practiced by releasing 2nd to 3rd
instar nymphs of vector insects into the plastic cylinder at the rate
of five insects per plant. During the inoculation, the insects were scattered
twice one day. After inoculation, the insects were removed and the inoculated
plants were taken normal care of. The symptom class of BIL population
and parents were evaluated according to Washio. O.s criteria. (Washio.
O. et.al 1968).
The field test was done in 2004 at Jianyan, Jiangsu province, P.R.C.,
where rice stripe disease was epidemic. The lines were planted in May,
which was the most susceptible period to the natural infection. Each test
line was represented by a row of 35 plants. The RSV incidence was symptomatically
evaluated at about 60 days after planting.
QTL of RSV-resistance was mapped with MAPMAKER/QTL1.1b. By individual
inoculation test, a total of two QTL controlling RSV resistance were detected
on chromosomes 7 and 11, respectively. Individual QTL accounted for 8.96
and 31.79% of the phenotypic variance. The Kasalath alleles increased
the resistance to RSV (Table 1, Fig. 1, Fig. 3). By field test, one QTL
only accounting for resistance to RSV was detected at the same location
as above on chromosome 11 (Table 2, Fig. 2, Fig. 4). The results indicated
that this QTL on chromo-
some 11 was important to control the resistance to RSV.
Hayano-Satio et al. (1998) detected Stv-bi,an
incompletely dominant gene resistant to RSV, coming from Modan, located
between XNpb220 and XNpb257 (XNpb254) on chromosome11.
Maeda H. et al. (1999) had detected one QTL controlling RSV resistance
located around XNpb257 in the middle of XNpb202 and C1172.
According to the markers locations and resources, we found that
the QTL on chromosome 11 in our study was located in the same location
as what Maeda H. and Hayano-Satio had detected. It was indicated that
the interval between C1172 and XNpb202 on chromosome 11 was closely associated
with genes resistant to RSV and a very conserved interval during evolution.
More studies about the interval will help us know the evolution of plant
Hayano-Saito, Y., T. Tsuji and K. Fuji, 1998. Localization of the rice
stripe disease resistance gene, Stv-bi, by graphical genotyping
and linkage analysis with molecular markers. Theor. Appl. Genet. 96(8):
Maeda, H., H. Nemoto, T. Yagi and Y. Fukuta, 1999. QTL analysis for rice
stripe disease resistance using recombinant inbred lines (RILs) derived
from crossing between Milyang and Akihikari. In: China Association of
Agricultural Science Societies, China National Rice Research Institute,
China National Hybrid Rice Research and Development Center, China Foundation
Society for Agricultural Science and Education (eds). Prospects of rice
genetics and breeding for the 21st century-Paper collection of international
rice genetics and breeding symposium. Beijing: China Agricultural Science
Technology Press. 53~57.
Washio, O., A. Ezuka, K. Toriyama and Y. Sakurai, 1968. Testing method
for genetic of and breeding for resistance to rice stripe disease. Bull.
Chugoku Natl. Agr. Exp. Stn. A16: 39~197.