Mahatma Phule Agricultural University, Rahuri
The results of the cross, G.I. 3794 X Fortuna, reported by Jodon in 1944 have been reanalysed. The results of revised genic interpretation of four characters and new linkages is presented in this paper.
(1) “Violet” type of fragrance was due to three aroma genes, FrV19 FrV2, FrV3 and an inhibitor, FrV-I. The inhibitor is hypostatic to FrV1 but epistatic to FrV2 and FrV3 either singly or together. The interaction of the four genes results in a ratio of 207 fragrant to 49 non-fragrant.
(2) Jodon correctly found that pubescence of lemma and palea was mono-dominant to the glabrous condition. The gene pair is designated as HPu-Hpu.
(3) The mature colour of lemma and palea was due to duplicate genes, HSt1 and HSt2 and an inhibitor, HSt-I. The inhibitor supresses straw colour in one of the duplicate genes. The ratio thus becomes 51 straw to 13 gold lemma and palea.
(4) C.I. 3794 is resistant to physiological form 4 of Cercospora. The improved strain, ‘Fortuna, is susceptible. Resistance was dominant in F1 and in F2 a ratio of 243 resistant to 13 susceptible plants was obtained. The ratio results due to four genes, of which any two together can produce resistant reaction to the pathogen. The genes are named Cea Ceb, Cec, and Ced.
(5) The genes for purple lemma and palea are symbolised as HPa, HPb and HPC
(6) The mid-season or lateness, of ‘Fortuna’ was dominant to the earliness of ‘C.I. 3794’, the ratio of the two types being 189 midseason to 67 early.
A basic gene, F1 has three complementary genes, Fla, Flb, and Flc and with each of these it produces lateness. The basic gene alone and any of the complementary genes either alone or together, without the basic gene, produce early types.
(7) Four linkage groups were found:
