Monogenic race specific blast resistance genes are
useful to incorporate in susceptible commercial rice cultivars
well adapted to local conditions. Identification of specific
genes for resistance to specific races is necessary to incorporate
resistance in upland rice cultivars. Sequential release of blast
resistant cultivars is a traditional recommended strategy in
Brazil (Prabhu and Guimarães, 1990). The novel Pi-ar gene
against the race IB-45, in the somaclone SC09 derived from
the susceptible upland rice cultivar 'Araguaia', may be of great
value for introgression in parental cultivar or in recurrent
selection programs. The progenies from crosses of 'Araguaia'
and 'IAC 201' with three resistant somaclones SC09, SC10
and SC23 exhibited resistance to race IB-45 of P. grisea. The
dominant nature of resistance in the somaclones was
determined in previous studies on inheritance (Araújo et al.,
1999). The durability of these genes has been widely tested
in the blast nurseries located in different parts of the country
(Araújo et al., 2000). The conventional backcross method
for the incorporation of this gene in the susceptible 'Araguaia'