Comparison of genetic resistance to rice gall midge in landrace rice Muey Nawng 62M and cultivated rice RD22

Abstract

The Asian rice gall midge (Orseolia oryzae; GM) is a significant pest of rice crops across Asia, causing substantial reductions in rice yield. This study investigates the genetic resistance to the GM in the cultivated rice variety RD22, compared to the landrace variety Muey Nawng 62M (MN62M). The research evaluated the interactions of two F₂ rice populations with the GM. These populations were derived from crosses between PYO16-001-3-24B x MN62M, and PYO16-001-3-24B x RD22. The experiments were conducted in greenhouse conditions using a GM population from Phrae province. The segregation ratios for susceptibility and resistance traits in the progeny were analyzed using a chi-square test. The results showed a 9:7 ratio, indicating that both MN62M and RD22 possess two recessive genes that control resistance to the GM. This resistance pattern follows a duplicate recessive gene interaction. Genotyping with the SSR markers in the gm12 region revealed that the RM3340 marker is associated with GM resistance in MN62M. Further testing was performed on fifteen F₄ progeny lines that carry the gm12 region, including three lines obtained from MN62M and twelve lines obtained from RD22. These progenies were evaluated for their interactions with three GM populations from Chiangrai, Nan and Phrae provinces. Four lines exhibited resistance (R) or moderate resistance (MR) across all three GM populations, suggesting that RD22 carries the gm12 region, which likely originated from MN62M, an ancestor of RD22. These results demonstrate that RD22 can be utilized as a valuable genetic resource for developing other rice varieties resistant to the GM by inheriting the segment of gm12 through marker-assisted selection.