Inheritance of resistance to (NGR1) pathogen isolates of Pyricularia grisea in GULU-E finger millet last resistant variety of Uganda

  • J.C. Aru
  • N Wanyera
  • P Okori
Keywords: Broad sense heritability, durable resistance, modified backcrossing, virulence

Abstract

Finger millet is basis for food security which directly supports the livelihoods of rural majority living in marginal areas in East Africa. Gene action and heritability of blast resistance in GULUE finger millet was determined from crosses between GULU-E as female parent mated to four susceptible genotypes, using the North Carolina 1 crossing design, to determine nature of resistance. Inoculation of finger millet with a fungus, Pyricularia grisea, which causes blast, was done using one potentially most virulent local pathogen isolate (NGR1) identified from Ngora district, in Odwarat parish, which is one of the pathogen hotspots of eastern Uganda . It was identified following isolate screening trial for virulence in Makerere University, during 2012b. F1, F2 and backcrosses were evaluated under controlled conditions. Disease reaction indicated that resistance was partially dominant and additive, based on mid parent values from crosses. Segregating ratios and Chi-square tests of F2 populations fitted 13R:3S genetic model, indicating presence of duplicate dominant epistasis at a probability level of 0.05. Broad-sense heritability estimated by the variance components method was high (88.8%) on entry mean basis. Selection for resistant progeny derived from crosses between GULU-E and DR21 finger millet would be most effective in early generations, followed by modified backcrossing at F3 to the adapted recurrent resistant parent, leading to diversification of a population and derivation of materials for selection for disease resistance. From the study it is possible to accumulate genes for race specific resistance in host cultivars that might reduce development of disease epidemics in some areas. The genetic control of components of resistance and mechanisms of resistance in the host which affect the rate of development of disease epidemic, need to be determined, since they are important variables for durable resistance.

Keywords: Broad sense heritability, durable resistance, modified backcrossing, virulence

Published
2016-08-10
Section
Articles

Journal Identifiers


eISSN: 2410-6909
print ISSN: 1026-0919