Reference "Genetic basis and mapping of the resistance to Rice yellow mottle virus. III. Analysis of QTL efficiency in introgressed progenies confirmed the hypothesis of complementary epistasis between two resistance QTLs"

Reference ID

7803

Title

Genetic basis and mapping of the resistance to Rice yellow mottle virus. III. Analysis of QTL efficiency in introgressed progenies confirmed the hypothesis of complementary epistasis between two resistance QTLs

Source

Theoretical and applied genetics, 2001, vol. 103(6-7), pp. 1084-1092

Authors (6)

Ahmadi-N	Albar-L
Pressoir-G	Pinel-A
Fargette-D	Ghesquiere-A

Abstract

Our previous studies have hypothesised that a complementary epistasis between a
QTL located on chromosome 12 and a QTL located on chromosome 7 was one of the
major genetic factors controlling partial resistance to Rice yellow mottle virus
(RYMV). We report research undertaken to verify this hypothesis and to
introgress the resistant allele of these two QTLs from an upland resistant
japonica variety, Azucena, into a lowland susceptible indica variety IR64. Three
cycles of molecular marker-assisted back cross breeding were performed using
RFLP and microsatellite markers. Resistance to RYMV was evaluated in F2 and F3
offspring of the BC1 and BC2 generations. Marker-assisted introgression (MAI)
was very efficient: in the selected BC3 progeny the proportion of the recipient
genome was close to 95% for the ten non-carrier chromosomes, and the length of
the donor chromosome segment surrounding the two QTLs was less than 20 cM. The
relevancy of the complementary epistasis genetic model proposed previously was
confirmed experimentally: in BC1 and BC2 generations only F3 lines having the
allele of the resistant parent on QTL12 and QTL7 show partial resistance to
RYMV. Comparison of our experimental process of MAI with the recommendations of
analytic and simulation studies pointed out the methodological flexibility of
MAI. Our results also confirmed the widely admitted, but rarely verified,
assumption that QTL-alleles detected in segregating populations could be treated
as units of Mendelian inheritance and that the incorporation of these alleles
into elite lines would result in an enhanced performance. The next step will be
the design of tools for the routine use of molecular markers in breeding for
partial resistance to RYMV and the development of material for the analysis of
resistance mechanisms and the structure of a virus resistance gene in rice.