1. W.D.S.Mihirani
PGIA (Plant Protection)
MSc. Molecular & Applied Microbiology
DURABLE RESISTANCE AGAINST FUNGAL PLANT
PATHOGENS
INTRODUCTION
Both the developing and developed world has paid attention towards continuing
major threat of Fungal diseases of plant; highlighting the needs for effective,
durable sources and uses of plant defensive ability against a broad spectrum of
pathogens. The research & programs were building up around the concept of
most profitable and environmental friendly strategies for farmers to control
fungal pathogen.
Durable resistance which may be partial or complete can be controlled by several
genes. It can be conferred by single genes, by a few genes or many genes
(Johnson 1983,Porlevliet 1983). Also durable resistance seems to be associated
with mutagenic system ( Simmonds 1988)
A thorough understanding of these mechanisms can be only comes with a
complete detail analysis of the interaction between particular host and pathogens
at population level. Also there is no single model that can universally applicable
and believe not only one strategy will give adequate control against pathogen
evolution.
Most devastating Fungal pathogens in Wheat are Leaf rust, Strip rust and
Powdery mildew are controlled by supporting gene Lr34 and now it is being using
by Wheat cultivars around the world for more than 50 Years.
This review will bring the strategies using now and then in the world for Durable
Resistance against Fungal pathogens.

2. W.D.S.Mihirani
PGIA (Plant Protection)
MSc. Molecular & Applied Microbiology
THE REASONS BEHIND THE DURABILITY
There can be several reasons for Durable resistance against pathogen (Th.Jacobs
& JE Parlevliet ,1993)
I. The farming system
II. Pathogens differs in their versalitity ;especially biotroph and hemi
biotrophic air borne Fungi adapt easily to introduced resistance
III. Non-durable ,race specific genes may last longer if certain strategies are
applied
IV. Resistance genes themselves are durable
STRATEGIES BEHIND THE PLANT FUNGUS DURABLE RESISTANCE
PYRAMIDING
Gene Pyramids has played effective role in durable resistance for longer period
(more than 50 years). But now it was discovered some failure of Wheat stem rust
race Ug99 in Uganda, the late 1990s. Even though the Gene Pyramids still fits for
the definition of durability.
The mechanism(s) not completely understood that which pyramid increase the
durability. Pathogen which does not reproduced sexually is mutating to virulence
against all resistance genes in the pyramid.
Dyck & Kerber recognized that rate of mutation to virulence and size of the rust
population influence the duration of effectiveness of genetically complex
resistance.
The estimate calculation of population size, mutation rate and relative fitness
showed that single and double mutant pathogenic genotype would like to
maintain asexual or sexual pathogen population (J.F.Schafer & A.P.Roelfs, 1985)
The rate of mutation to virulence at loci in P.graminis f. sp tritici believed to be
indicative of a population in which the fungal locus was heterozygous for
dominant avirulance.

3. W.D.S.Mihirani
PGIA (Plant Protection)
MSc. Molecular & Applied Microbiology
“Hypothesis began to form that durability of pyramids can be increased by
choosing combination of resistance genes such that avirulance mutants occur
infrequently against at least one resistance in each clonal leakages” ( Zeigler et al ;
1994 & 1995; - Christopher C.mundt,2014)
MIXTURE
Race specific gene for disease control concern about pathogen population in the
host mixer environment having possibility to develop high aggressive virulence
race there by occurring of mutants also.
PARTIAL RESISTANCE
The resistance provides,reduced infectivity and longer latency periods. So that
number of lesions developing in the partially resistance line would delay or
reduced relatives to those occurring more susceptible control.
DURABLE RESISTANCE AGAINST FUNGI
Plant fungal gene resistance host genes interaction and corresponding avirulance
genes including obligatory Fungi parasite like powdery mildews, dowry mildew,
rust and biotrophic fungus C.fulvum & perthotrophic fungus phynchosporium are
assumed to be gene for gene resistance.
Wheat gene Lr34 associated resistance to two rust diseases of leaf rust caused by
Puccinia triticum and strip rust by P. striiformis and powdery mildew caused by
Blumeria graminis. This method differs from the gene to gene provide resistance
Lr34 protein resembles the ABC ( Adenosine triphosphate Binding Cassette)
transposons which having high mutation frequency responsible for conferring the
durable Lr34 disease resistance.(Figure 1)
The mutants are more susceptible for the plant strip rust, powdery mildew & leaf
rust but didn’t show any leaf tip necrosis. ABC transporter gene has shown slow
rusting during early infection process of leaf rust in seedling of mutants.

4. W.D.S.Mihirani
PGIA (Plant Protection)
MSc. Molecular & Applied Microbiology
(Simon G. Krattinger . et al ,2009)
Single resistance genes with large effect in larger geographical area “Boom” are
widely adapted. In gene to gene interaction mechanism pathogens produced
elicitor molecules that are recognized by specific receptor of the plant cells. When
an acknowledgement of elicitor by the the plant cell defense response is
activated. (Figure 2)
Figure 2.

5. W.D.S.Mihirani
PGIA (Plant Protection)
MSc. Molecular & Applied Microbiology
CONCLUSION
Durable resistance is highly variable phenomenon , where the Biotechnology
increase the economic importance of breeding for resistance. To get better
knowledge of durable resistance; analysis of host and pathogen interaction and
improvements of durability need to know. It is involved more than one strategies
to durability against Fungal plant pathogens and geographical and pathogen
population also impact to resistance.
REFERENCE
(1) Bruce A. McDonaldand Celeste Linde Institute of Plant Sciences, Plant Pathology
Group, Federal Institute of Technology, ETH-Zentrum, LFW, CH-8092 Z¨urich,
(2) A Putative ABC Transporter Confers Durable Resistance to Multiple Fungal Pathogens
in Wheat http://www.researchgate.net/publication/24026894
(3) Durability of Disease - TH.JACOBS and J.E. PARLEVLIET Agricultural University,
Wageningen, The Netherlands
(4) Successful search for a resistance gene in tomato targeted against a virulence factor of
a fungal pathogen RICHARD LAUGE , MATTHIEU H. A. J. JOOSTEN, JAIR P. W.
HAANSTRA,PAUL H. GOODWIN,PIM LINDHOUT, AND PIERRE J. G. M. DE WIT