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

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.