3.4.40
GENETIC CONTROL OF TRITICALE RESISTANCE TO SEPTORIA DISEASE

G. LUPASHKU

Institute of Genetics, Academy of Sciences, Padurilor str. 20, Chisinau 2002 MD, Republic of Moldova

Background and objectives
According to several reports [1, 2] epiphytotics of Septoria disease in cereal crops have widely developed in some regions. In the Republic of Moldova Septoria disease first appeared on triticale in 1997. The collected forms differed in their reaction to Septoria tritici. The goal of our study was to identify the potential damage caused by Septoria disease and the genetic control of resistance in triticale.

Results and conclusions
It has been established that uninfected plants are never observed in the susceptible types of triticale. The grouping of these samples into weakly and strongly infected plants showed that in the second group, the productivity parameters such as kernel weight per spike and weight of 1000 kernels are lower by 24-30 and 20-25%, respectively, than in the first group. The evaluation of infectivity in 12 genetic populations, each of which included P1, P2, F1, F2, BC1 and BC2 showed that in 7 of them resistance to the pathogen predominated in F1, and in 5, susceptibility. Two types of reaction were discovered in the F1 involving participation of the same resistant parent, which proves that the genes encoding resistance might fall into the influence of the modifier gene for dominance. Backcrossings revealed the effects (separate or combined) decreasing the infectivity level: additive (90%), dominant (46%), homozygote-homozygous (27%), homozygote-heterozygous (53%), and heterozygote-heterozygous (46%).

The minimum number of genes determined using several formulae, by which the genotypes contrasting in resistance differ was between 4 and 12. The discovery of inheritable resistance to Septoria should encourage further breeding programmes.

References
1. Karjalaien R, Karjalaien S, 1990. J. Agr. Sci. Fini. 62, N3, 255-263.
2. Mieike H, Meien-Vogeler F, 1992. Mitt. Biol. Bundesanst. Landund Forstwirt. Berlin-Dahlem 283, 60.