Detection of Barberry Plants (Berberis holstil) as an Alternate Host of Stem Rust (Puccinia graminis) of Wheat in Ethiopia

Abstract

Berberis is a genus o f many species of deciduous and evergreen shrubs. Two species
of Berberis are present in Africa, Berberis vulgaris in northwest Africa and B. holstii
in the mountains o f eastern and southern Africa. The presence of B. holstii in Ethiopia
is reported in a book o f Ethiopian and Eritrean flora; however, there is no information
indicating that the plant serves as an alternate host of wheat stem rust (Puccinia
graminis). Since 2009, Ambo Plant Protection Research Center has initiated studies
on distribution o f Barberry shrubs in the northern part o f the country and collection of
aeciospores from the shrub and inoculation of different small cereal crops to confirm
whether the aeciospores are function stem rust or not.To meet these objectives,
surveys were carried out in the northern part o f Ethiopia and identified 19 localities
where the shrub is grown. O f these, 12 were in north Shewa, three in Wello zones of
Amhara region and four in south Tigray zone. The shrub is habitat o f altitudes
ranging from 2500 to 3000 masl and grows on hilly and rocky land rich in black
organic soil. In north Shewa. the survey was carried out once in a month for the
whole year. Thus, aecial infections o f the plants were not observed from February to
June. In July, August and December, traces of aecia were noted, but from September
to November aecial infections were abundant. The aecial samples collected were
inoculated on seedlings of susceptible wheat, barley, rye and oat crops. Alter two
weeks of incubation o f aeciospores, stem rust (P. graminis) infections were recorded
on wheat, barley, rye and rarely on oat crops. P. graminis that infected wheat, barley
and rye have formae speciales tritici/secalis, while that of oat was formae speciale
avenae. Moreover, some of the stem rust pustules found on these seedlings were
inoculated on the sets of 20 wheat stem rust differential hosts and resulted in races
avirulent to all/majority of the Sr. genes. The study indicated that B. holstii is an
alternate host o f stem rust. This report is the first of its kind in Ethiopia and further
studies are recommended to determine the role of B. holstii in the epidemiology of
wheat rusts in Ethiopia.