Abstract:
Asian Rice Gall Midge (Orseolia oryzae) (RGM) is a major insect pest, that
affects at tillering stage of rice and causes about 30%-40% of yield loss.
Cultivation of resistant rice varieties is the most successful approach to
controlling the pest and therefore development of RGM-resistant rice varieties
is a solution for prevention of an outbreak. So far 12 gall midge-resistant genes
have been identified. Those resistant genes can be used for RGM resistance
development. Molecular screening was done using SSR markers RM 23956,
LLR_del and gm3del3 to identify RGM-resistant genes Gm1, Gm4 and gm3
respectively. Molecular screening results revealed that out of the 24 tested
varieties, 20 varieties carried at least one resistant gene. Among those 20
varieties, the variety ‘Heen sulai’ carried Gm1, Gm4 and gm3 genes. ‘Gires’
and ‘Ptb 21’ varieties harbored gm3 and Gm4 genes. ‘Duru wee’, ‘Bg 406’,
‘IRBB 65’, ‘Bg 305’, ‘Bg 360’ and ‘Bg 380’ carried Gm1 and gm3 genes. The
variety ‘IR 36’ carried Gm1 and Gm4 genes. ‘Bg 359’, ‘Bw 78’ and ‘Bg1492’
varieties had only the Gm1 gene. Seven varieties/lines, ‘Bg 366’, ‘Bw 367’,
‘IRGC 9091-1’, ‘IRGC 9070-1’, ‘Zenith’, ‘Local 2.5’and ‘Bg 304’ carried
only the gm3 gene. These results confirmed that most varieties contained at
least one resistant gene. Therefore, these RGM-resistant rice varieties can be
effectively applied as donor parents for gene pyramiding to develop a rice
variety with durable RGM-resistance.
