Abstract:
The Brown Plant Hopper (BPH), Nilaparvata lugens is one of the most serious rice
pests in Sri Lanka. About 5-10% of cultivated rice lands are affected due to BPH
damage. Due to several drawbacks associated with chemical control, host plant
resistance is the most effective way of BPH management. Some of the wild relatives of
rice have provided new sources of resistance to pests like BPH. Two accessions of Sri
Lankan O. nivara and some O. eichinigeri derived lines were identified as BPH
resistant. But up to now no experiments were conducted to evaluate resistance of above
lines. Therefore, this study was carried out to identify the nature of the resistance by
bioassay and molecular techniques for the use of rice improvement programs in Sri
Lanka.
Bioassay was conducted at RRDI, Bathalagoda. Five different BPH populations
maintained for three months period in screen house were used to screen selected rice
lines and varieties. Then the reaction of BPH & plant resistance was measured by using
standard honey dew test. During bioassay, resistant accessions were screened at
. molecular level to get some evidences to support the results obtained from the standard
honey dew test. Availability of 3 BPH resistant genes (BphlO, bph2, Bphl3) was
checked by using Gene specific 3 STS primers RG 457, KAM 4 and AJ 096
respectively at PGRC.
Molecular screening results revealed that all the tested O.nivara accessions and O.
eichinigeri derived lines haven’t Bph 10 gene in their genome while O.nivara (WRAC
04) accession may have bph 2 and Bph 13 genes and no any checked gene was found in
O.nivara (9864) accession. O. eichinigeri derived lines (TC 01 and TC 02) may have
Bph 13 gene in their genome. The honey dew screening results showed that Virulence
of PTB 33, Bg 379/2 and Kegalle populations was not significantly different from each
other. But virulence of Bg 379/2 and Kegalle populations was significantly different
from populations reared in IR 54751-2-34-10-6-2 line and Bg 380. Among selected rice
lines and varieties Bg 380 is the most susceptible. PTB 33, O.nivara accessions
(WRAC 04, 9864) and O. eichinigeri derived lines (TC 01 and TC 02) are not
significantly different from each other considering resistance to BPH and also
comparatively resistant to all the populations. Therefore, these lines can be used to
avoid genetic uniformity of cultivated rice in future.
