D. GENCHEV and I. KIRYAKOV
Dobroudja Agricultural Institute – General Toshevo, BG-9520 General Toshevo, Bulgaria
GENCHEV, D. and I. KIRYAKOV, 2001. Genetic control of the reaction to common bacterial blight Xanthomonas campestris pv. phaseoli (Smith) Dye in HR 45 and NAB 69 dry bean lines Ph. vulgaris L. Bulg. J. Agric. Sci., 7: 15-21
In the last few years at Dobroudja Agricultural Institute, General Toshevo, on the basis of transferred geneplasm from Phaseolus acutifolius into Ph. vulgaris, lines of comparatively high resistance to a large number of X.c. pv. phaseoli (Xcp) Bulgarian strains populations were created. The genetic control of leaf and pod reaction of the lines HR 45 and NAB 69 was determined in reciprocal crosses with the susceptible variety Abritus. The multiple needle method was used to inoculate leaves and a dissecting needle was used to inoculate the pods of these plants. Leaves and pods reaction was registered 14 days after inoculation according to a 9-degree scale. The response was considered resistant at grades 1-4 and susceptible at grades 5-9.
The resistance of both plant organs (leaves and pods) to four Xcp strains (XB-9622-1, XB 9612-1F, XB 972-2 and XB 9333-1F) was determined quantitatively. The genetic control of resistance in the leaves of line HR 45 depended on the Xcp strain and the direction of crossing. The resistance of leaf response in XB 9622-1 was determined by a single recessive gene.
In the cross Abritus x HR 45/XB 9612-1F the resistance leaf reaction was controlled by a single dominant gene. The same is control for pod resistance response both in Abritus x HR 45/XB 9622-1 and HR 45 x Abritus/XB9612-1F. The genetic control of the resistance reaction in the reciprocal crosses was performed by two dominant complementary genes. In our opinion, the second dominant gene, which is the complementary one, is located in the cytoplasmic organelles (plastids or mitochondria) of the resistant line HR 45. Since the distribution of these organelles is not strict after cell division as in the nuclear chromosomes, the problem with segregation will persist until the breeding of lines originating from a zygote containing only cytoplasmic organelles which carry this gene. In order to achieve this, much longer selection of individual plants may be needed.
Resistance in line NAB 69 is, on the whole, controlled by recessive genes. Genetic control of leaves in NAB 69 x Abritus/XB 9333-1F and Abritus x NAB 69/ XB 972 is carried out by a single recessive gene, in NAB 69 x Abritus/XB 972-2 – by two recessive polymeric genes, and in Abritus x NAB 69/XB 9333-1F – by two recessive complementary genes. In this line the resistance is less manifested than in line HR 45.
The values of the coefficients for both broad and narrow sense heritability varied from 0.103 to 0.866 and from 0.018 to 0.794, respectively, according to the source of resistance, the susceptible parental component, the direction of crossing, the strain and other factors. In line HR 45 the resistance was more strongly inherited than in line NAB 69.
Different genetic control of leaf and pod resistance response, regardless of the direction of crossing, was registered in the reciprocal cross Abritus x HR 45, inoculated with XB 9622-1. In the other cases the genetic control depended on the direction of crossing.