Agriculture Reference
In-Depth Information
high-quality, high-throughput phenotyping, without which gene map-
ping cannot be optimal (Cobb et al. 2013).
Most of the materials in our collection will be resequenced, using GBS
to fully exploit our phenotypic databases of evaluations across environ-
ments and time. Through haplotype analysis, we will be able to gain
evidence of important genomic regions that have been selected by
breeders through time.
Clearly, digital information is going to have an important role in next-
generation breeding. As the rice community is making constant progress
in gene function and allelic/haplotypic identi
cation, in the near future
we expect to rely more and more on digital information provided by
allelic sequencing for local breeding.
V. BREEDING FOR RESISTANCE TO RICE PATHOGENS
The rice-growing environments in LAC are highly conducive to rice
disease epidemics. The main disease problems are rice blast (caused by
Pyricularia oryzae
), sheath blight (caused by
Rhizoctonia solani
),
sheath spot (caused by
Rhizoctonia oryzae
and
Rhizoctonia oryzae-
sativae
), leaf scald (caused by
Gerlachia oryzae
), brown spot (caused
by
Bipolaris oryzae
), sheath rot (caused by
Sarocladium oryzae
), stem
rot (caused by
Sclerotium oryzae
), RHBV transmitted by the insect
vector
Tagosodes oryzicolus
, rice stripe necrosis virus (RSNV) trans-
mitted by
Polymyxa graminis
, the emergent economically important
bacterial panicle blight caused by
Burkholderia glumae
, and a number
of other stem and grain discoloration diseases. The degree of incidence
and severity of these diseases differ according to the production
systems, but together they account for up to 12% of yield losses
(Pantoja et al. 1997). This relatively low loss due to diseases is largely
attributed to management practices, which in general include the
application of fungicides.
Rice breeders and pathologists in LAC have concentrated efforts on
the development of germplasm resistant mainly to blast, sheath blight
and sheath spot, and RHBV. In general, fairly reliable
field evaluation
methods for selection for high resistance/tolerance have been developed
for these diseases by several national rice research programs in the
region. The Rice Program at CIAT has had the responsibility to build and
support the capability of LAC national rice research programs to apply
tools to solve the problems affecting rice production and to conduct
collaborative research that would result in rice cultivars with improved
resistance to diseases. The main problems in developing resistance to
