| Summary: | Tungro is one of the major viral diseases of rice plant, caused by two
types of viruses, namely Rice tungro bacilliform virus (RTBV) and Rice tungro
spherical virus (RTSV) and transmitted by the green leafhopper Nephotettix
virescens Distant. Planting of resistant varieties proved to be a effective
strategy in preventing the occurrence of tungro disease, but the tungro virus
resistant varieties are still limited. To determine the best breeding strategy,
the genetics of resistance to tungro virus, in particular gene action and
number of genes that controling resistance and heritability, needs to be
studied. In this study, TN1 variety was crossed with OBSTG02-28 and
OBSTG02-124 to produce F1, F1R, BC1.1, BC1.2, and F2. All derived population
were inoculated with tungro virus and the disease intensity was observed by
scoring and ELISA test. The results confirmed the resistance of the two lines.
No reciprocal effect was observed. The resistant gene of OBSTG02-28 was
controlled by two complementary dominant genes with a ratio of 9:7, while
the resistant gene of OBSTG02-124 was controlled by two complementary
recessive genes with a ratio of 7:9. Additive-dominant model was sufficient to
explain fitted with the transmission of resistance in the two crosses with a
significantly different additive gene action. The narrow sense heritability was
considered high in TN1 with OBSTG02-28 cross, indicating that selection for
resistance against tungro disease can be performed in early generations.
However, it was considered moderate in TN1 with OBSTG02-124 cross.
Therefore, the selection for resistance against tungro disease should be
performed in advanced generations
|
|---|