Genetics and Linkage Between Genes For Purple Coleoptile and Leaf With Brown Planthopper Resistance in Rice

Inheritance and interrelationship of genes governing brown planthopper (BPH) resistance with purple pigmentation in the coleoptile and leaf blade were studied in three crosses. Resistance n BPH was due to three dominant complementary genes, Bph5(t), Bph 6(t), Bph7(t), and coleoptile pigmentation due to two dominant complementary genes, Pc1, Pc2 in the cross RP 1748 (Leb Muey Nahng, BPH susceptible, coleoptile green) and ARC 6650 (BPH resistant and coleoptile purple). One of the genes for BPH resistance showed linkage with the gene for purple coleoptile (CO. value 3.0%). in the cross RP 1578, ARC 7328 (BPH susceptible, coleoptile purple) with CR 57 MR 1523 (BPH resistant, coleoptile green) resistance to BPH was due to two recessive complementary genes, bph 8(t) and bph 9(t) and pigmentation in the coleoptile was due to two complementary genes. The genes were independent of each other. in the cross RP 2205 involving ARC 5723 (BPH susceptible, leaf purple and coleoptile purple with ARC 6650 (green leaf) the F1 was BPH resistant with pigmented coleoptile and green leaf. Resistance to BPH was due to two dominant complementary genes. The gene for purple leaf showed interaction with I-Pl and a ratio 3 green: 13 purple leaf was observed in f2. The genes for coleoptile pigment are common to both parents. One of the genes for BPH resistance showed linkage with the inhibitor one for purple leaf 1-P1 with a C. O. value of 44.72% in the repulsion phase. The gene for purple leaf p1 was independent of the gene(s) for BPH resistance. From the results obtained it is inferred that the linkage sequence of genes for purple coleoptile Pc1/Pc2-BPH 5(t)/BPH 6(t)/Bph 7(D) -I-Pl belong to the II linkage group of Oryza saliva var. indica.