Identification and inheritance of new sources of resistance to bacterial blight in two synthetic cotton lines
2005
Suliman, A.M., University of Gedarif, Gedarif (Sudan) , Faculty of Agricultural and Environmental Sciences | Ali, A.M., Agricultural Research Corporation, Wad Medani (Sudan) | Ibrahim, A.S., University of Gezira, Wad Medani (Sudan) , Faculty of Agricultural Sciences
Resistance to bacterial blight was identified in two synthetic lines (Synl and Syn2) of cotton containing mixed genomes of Gossypium species (G.barbadense, G. arboreum, G. turneri and G. hirsutum). Inheritance of bacterial blight resistance was investigated in F land F2 between these synthetic lines and the susceptible commercial cultivars, Barakat-90 (P1) and Barac (67) B (P2), at the Gezira Research Station for two seasons (2002/03 and 2003/04) and an off season. The plants were inoculated by the bacterium (Post-Barakat race) using the pressure inoculation method and disease severity was graded on 0-5 scale. The results revealed that the F1 plants were nearly as susceptible as the two commercial cultivars. The continuous distribution in the F2, S suggests that resistance in Synl and Syn2 is partially dominant. The segregation of P1Syni and P2Syni F2 plants did not deviate from a single-locus model and fit closely the 1:3 ratios suggesting that resistance in Synl is controlled by one recessive gene. On the other hand, segregation in the F2 of P2Syn2 fit a two- locus model (7: 9) indicating duplicate recessive epistasis and suggesting that two genes are controlling resistance in Syn2. PISyn2 F2 segregation gave a ratio that did not fit any of the known genetic ratios. Crosses with Barac (67) B showed better resistance than those with Barakat-90. These synthetic lines provide a new source of heritable resistance and can be used for improving resistance in commercial cultivars
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