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ERA-PG / File repository / Call 2006 / / GENBLAST
| Title |
Deciphering the genetic basis of
field resistance to blast in European rice varieties to improve breeding
for durable resistance |
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| Acronym |
GENBLAST |
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| Duration |
1 October 2007
- 1 October 2010 |
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| Project leader |
Ramón Carreres, IVIA,
Spain |
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Other project
participants
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Didier Tharreau, CIRAD, France
Pere Arús, IRTA, Spain
José Maria
Osca Lluch, UPV, Spain
Manuel Aguilar Portero, CIFA-IFAPA, Spain
Carlos Baixauli
Soria*,
Fundación
RURALCAJA [Company], Spain
Luis Marqués Falcó, COPSEMAR [Company], Spain |
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| Funding |
National Institute for Agricultural
Research (INRA), France |
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Ministry for Education and Science (MICINN),
Spain |
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*participant with own funding |
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| Total granted budget |
€ 433,222 |
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| Abstract |
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Rice blast (caused
by Magnaporthe grisea) is the most damaging fungal disease of rice
(Oryza sativa L.), and it is the only pathogen of rice treated with
pesticides in Europe, where most of the rice growing areas are river
deltas and damps, with special environmental protection. The use of
resistant rice varieties is a cost effective method to control the
disease and can be incorporated as component of an integrated pest
management (IPM) strategy, avoiding fungicide applications in such
fragile areas. Determining the genetic and molecular basis of resistance
in European varieties and including this knowledge in breeding programs
is of primary importance to develop rice varieties durably resistant
to blast. This project aims at using the appropriate genomic tools
to identify the important genes for durable blast resistance and to
start creating resistant varieties adapted for European growing conditions,
through the combined efforts of different teams and using different
methods: evaluation of resistance to blast in the field and in controlled
conditions, study of expression patterns of genes involved in defense
mechanisms, characterization of allelic variability, and QTL analysis.
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| Progress |
 Work package 1: Evaluation of
resistance to blast in the field and in controlled conditions
From 2006 to 2008 we have obtained blast isolates from hundreds of samples
collected in the three main rice growing regions in Spain and characterized
their genetic diversity with microsatellite markers. The analyses show
that: 1) the population in the South, seems genetically different from
the populations in the Central and Northern regions of Spain, 2) most of
the isolates sampled belong to genetic groups already identified in Europe,
but 3) some Spanish isolates could define new genetic groups.
In these three main rice growing regions of Spain, 60 varieties and differential
lines were evaluated in 2007 and 2008 for blast resistance, in a specific
design that favors blast pressure. Leaf and neck blast damages were measured
for each variety or line. Susceptible varieties have been clearly identified.
A list of complete resistant genes not yet overcome has been obtained.
That will be useful in breeding for resistance.
Rice partial resistance to blast was measured in controlled conditions
on a set of 18 varieties and 3 susceptible and resistant checks. Several
blast strains representing European pathotypes and with broad virulence
spectrum were inoculated. The level of partial resistance to blast is relatively
high in most varieties tested. Some varieties show both complete and partial
resistance.
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 Work package 2: Expression
pattern of genes involved in defense mechanism
Plants have a natural basal resistance to pathogen attack. There are set of genes
highly expressed before infections that are probably contributing to this preformed
defense mechanism. The objective of this work package is to evaluate the interest
of these genes as resistance markers for European varieties. Transcriptomic data
were analyzed to identify potential candidate genes to measure preformed partial
resistance. Among thousands of genes, 20 have been identified as potentially
interesting to measure preformed partial resistance in rice. Further, these genes
were validated by Quantitatitve-Reverse Transcription PCR (QRT- PCR).
The expression before inoculation of these validated genes was measured on a
set of controls and 18 diverse rice cultivars with varying degrees of partial
resistance. But no close correlation between partial resistance and gene expression
level was found. This result was confirmed by repeating the entire assay with
a limited set of varieties and genes. This discrepancy with previous results
seems to show that preformed resistance is not the same in temperate japonica
than in tropical japonica rice varieties. |
Work package 3: Characterization
of allelic variability
This Work package has started at the end of year 2 and will be completed
during year 3. Forty-eight rice cultivars, mainly japonica type, have been
selected for discovery of polymorphisms, through Ecotilling, in a selection
of candidate genes related to defense mechanism against pathogens. Some
polymorphism has been already found. EcoTilling technique and sequencing
of selected DNA fragments is still in progress.
 Work package 4: QTL analysis
and obtaining of resistant breeding lines
Rice plants of two F2 populations, derived from crosses between
cultivars considered as potential donors of resistance and elite
Spanish varieties, have been genotyped with SSRs markers evenly
distributed along the rice genome, with higher density in chromosomal
regions where specific resistance genes and QTLs have been previously
found (markers generated from candidate genes in WP3 will also
be scored at the end of this year). Genetic maps have been constructed
for the 2 crosses but more markers are needed in some regions.
Both F2 populations have been evaluated for resistance to representative
blast isolates through inoculation in controlled conditions.
Also, partial resistance of the F3 lines of one cross has been
evaluated in the field in two sites (F3 lines of the 2nd cross
will be evaluated during 2009). Accordingly, QTL analysis have
been performed, and some QTLs of interest have been detected.
F4 lines of the first population have been selected after QTL
data and agronomic behaviour, and are been assayed in the three
growing areas, as well as tested throug inoculation under controlled
conditions. |
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| Project
website |
http://www.genblast.com
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| Output
from the project (publications, patents, data resources, etcetera) |
The project was presented in two international
meetings:
- First ERA-PG Grantholders meeting. Puerto de la Cruz (Tenerife). October
2nd, 2007. Abstracts of the Granted Projects of Sub Call B pp 56
- IVth International Rice Blast Conference.
Changsha (China). October 9-14, 2007. Genblast project: Deciphering
the genetic basis of field resistance
to blast in European rice varieties to improve breeding for durable
A flyer in Spanish describing the project
was produced and distributed to rice growers.
Click here to download the english version of the flyer.
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