The basis of MABC strategy is to transfer a specific
allele at the target locus from a donor line to a recipient
line while selecting against donor introgressions across the
rest of the genomes [11]. The use of molecular markers,
which permit the genetic dissection of the progeny at each
generation, increases the speed of the selection process,
thus increasing genetic gain per unit time [12]. The main
advantages of MABC are (1) efficient foreground selection
for the target locus, (2) efficient background selection for
the recurrent parent genome, (3) minimization of linkage
drag surrounding the locus being introgressed, and (4)
rapid breeding of new genotypes with favorable traits. The
effectiveness of MABC depends on the availability of closely
linked markers and/or franking markers for the target locus,
the size of the population, the number of backcrosses,
and the position and number of markers for background
selection [13]. MABC has previously been used in rice
breeding to incorporate the bacterial blight resistance gene
Xa21 [14, 15] and waxy gene [16] into elite cultivars. The
availability of the large-effectQTL Saltol for salinity tolerance
in rice, a theoretical framework for MABC, and the existence
of intolerant varieties that are widely accepted by farmers
provided an opportunity to develop cultivars that would
be suitable for larger areas of submergence-prone rice [17].
Molecular breeding technologies have been widely applied
in countries all over the world. It provides powerful tool for
development of stress tolerant varieties that can deal with the
adverse effects from climate change. However, application of
molecular breeding as MABC has just initiated sporadically
in Vietnam. Hence, the attempt of this study was to develop a
salinity-tolerant version of the widely grown BT7 by applying
the MABC method. The improved cultivar may be useful for
growing in the soil salinity of the coastal areas of Vietnamese
Deltas.