Recent advancement in rust resistence in wheat,dayanand, 01986

WELCOME
to
SEMINAR SERIES
2020-21

Speaker
DAYANAND
M.Sc. (Agri.) 3rd Semester
Department of Genetics and Plant Breeding
Reg. No.:-04 AGRMA -01986 -2019
CPCA , SDAU , SK Nagar
MAJOR ADVISOR
Dr. S. D. Solanki
Associate Professor and Head
Department of Genetics and Plant Breeding,
C. P. College of Agriculture,
S. D. Agricultural University,
Sardarkrushinagar – 385 506
MINOR ADVISOR
Dr. J. M. PATEL
Associate Research Scientist,
Wheat Research station ,
SDAU ,Vijapur - 382 870
Dist. - Mehsana
Recent advancement and current strategies in rust resistance in
wheat

Content
 Introduction
 Types of Rust
 Characteristics of Rust Fungus
 Milestones
 Importance of Rust Fungi
 Rust Epidemic History
 Conventional Breeding Approch
 Molecular Breeding Approch
 New Breeding Techniques (NBT’s)
 Case Studies
 Achivements
 Conclusion
3

INTRODUCTION
Wheat
 Family - Poaceae (Gramineae)
 Genus - Triticum
 species of wheat
Chromosome No. Origin
1. Triticum aestivum (bread wheat) - 42 - Central asia
2. Triticum durum (macaroni wheat) - 28 - Abyssinia,
North Africa
3. Triticum dicoccum - 28 - Abyssinia
(Emmer or Khapli wheat)
4. Triticum monococcum - 14 - Asia minor
 Self-pollinating annual plant (Chasmogamy common). Infloroscence is Ear ‘or’ Head
and in botanicle term it is known as Spike.
 Flower is bisexual and zygomorphic. Fruit type is caryopsis.
 wheat provides nearly 55% of the carbohydrates and 20% of the food calories.
4

 Total production of wheat in India year 2019-20 is 107.59 million ton and in
world is 764.03 million ton. (DAC &FW, USDA)
 Total area under wheat in India is 29.32million hectare and in world is
216.94 million hectare.
 Productivity in India is 3.53 MT per hectare and in world is 3.52 MT per
hectare. (DAC &FW, USDA 2019-20)
 It is the largest cereal crop extensively grown as staple food sources in the
world .
 It is world’s most widely cultured crop occupying 22% cultivated areas.
 The World Bank has estimated that global wheat production would need to
increase by 60% to meet the food requirements of a world population of 9.6
billion by 2050.
 India alone will need more than 140 million tons of wheat by 2050 to feed an
estimated population of 1.73 billion.
5

Three types of rusts in wheat
Leaf rust
Stem rust
Stripe rust
Puccinia recondita
f. sp. tritici
Puccinia graminis
f. sp. tritici
Puccinia striformis f.
sp. tritici
Fig.1. Wheat Rust 6

Disease Pathogen Primary hosts Alternate
hosts
Symptoms
Leaf rust Puccinia triticina
f. sp. tritici
Bread and
durum wheats,
triticale
Thalictrum,
Anchusa,
Isopyrum,
Clematis
Isolated uredinia
on upper leaf
surface and
rarely on leaf
sheaths
Stem rust Puccinia
graminis f.
sp. tritici
Bread and
durum wheats,
barley, triticale
Berberis
vulgaris
Isolated uredinia
on upper and
lower leaf
surfaces, stem
and spikes
Stripe rust Puccinia
striiformis f.
sp. tritici
Bread and
durum wheats,
triticale, a few
barley cultivars
Unknown Systemic
uredinia on
leaves and
spikes and rarely
on leaf sheaths
Table 1
7
Source: Roelfs et al., 1992.

Characterstics of Rust Fungi
 Rusts are plant diseases caused by pathogenic fungi of the order
Pucciniales (previously also known as Uredinales).
 Rust diseases of wheat are among the oldest plant diseases known to
humans.
 Puccinia is an obligate parasite.
 Required two alternate host .
 It has macro cyclic life cycle.
 Rust is typically brownish-yellow to bright orange spots that form on
leaves. The spots are filled with a powdery substance.
 Plants that have rust growth will not directly die from this type of fungi, but
it can contribute the decline of the plant.
 Some of the common symptoms include defoliation, stunted growth or
branch dieback. Leaving plant exposed to rust will surely infect other plants
since rust is easily spread through the air.
 Both stem rust and stripe rust can cause 100% loss, whereas leaf rust can
result in 50% loss.
8

MILESTONES
 1767 - Italian scientist Fontana and Tozzetti independently provided first
detailed descriptions of stem rust fungus in wheat .
 1797 - Persoon named it Puccinia graminis.
 1854 - the Tulasne brothers recognized that some rust fungi could produce
as many as five spore stages.
1865 - Anton deBary first demonstrated the heteroecious life cycle of a rust
fungus with Puccinia graminis.
 Dr. K.C. Mehta of Agra College, Agra investigated the life cycle of cereal
rusts in India during the first half of 20th century.
Dr. R. Prasada trained by Dr K.C. Mehta continued the work on rusts .
A major scientific breakthrough of ICAR Scientists lead to the decoding
of genomes of 15 strains of wheat rust fungus Puccinia triticina.
9

Importance of Rust Fungi
 Wheat stem rust is the most devastating of the wheat rusts and can cause
almost total yield loss .
 The first stem rust epidemic record goes back to 1786 A.D. in central India
 The wheat production in India has faced serious problems during 1970 to
1980 because of rust epidemics.
 Widespread occurrence of leaf rust was observed during 1971-73 in
popular cultivar Kalyansona in northern plains during 1993-94 in HD2285
and HD2329 covering approximately 4 million hectares in NEPZ.
 Nayar et al. reported that both leaf rust and stripe rust occurred each year
from 1967 to 1974 but the losses were estimated only twice.
 Sporadic high incidences of stripe rust are recorded in some parts of Punjab
and recently in 2011 in north-western areas.
10

Rust Epidemics History
Sr Year Country Locations Yield Losses
1 1935 North America Dakota and
Minnesota
3.7 million
tons
2 1946-47 India Central India 20 % of total
wheat
production
3 1951 Latin America Chile 40 % of total
wheat
production
4 1993-94 Ethiopia Ethiopia 42-45 %
5 1999* Uganda Uganda 85-90 %
Author:-R.P. Singh (1992) Book:-Rust Disease Of Wheat
Table 2
11

Conventional Methods of Breeding for Rust
Resistence in Wheat
1. Pedigree breeding
 First outlined by Love in 1927. Selection made from F₂ onwards.
Pedigree record, Combination breeding.
Ex. – 7911 and 7911-5.
NP series wheat varieties.
2. Bulk Method of breeding
 First used by Nilson- Ehle in 1908.
Dissimilar to pedigree in handling of segregating population.
Bulking period from 6 – 30 generations.
12- 14 years to release a new variety.
Rust epidemic produces shrunken seeds (Knott, 1989). The shrunken seeds
are blown out before planting the next generation. This method also takes 10-
12 years for developing resistant high yielding cultivars.
12

3. Recurrent selection
This technique is based on reselection generation after generation with
interbreeding of the selections in order to gradually concentrate desirable
alleles in a population.
With the interbreeding of reselected plants, the breeder can access favorable
recombinations as well as improve traits within the gene pool. This method is
more useful for adult plant stem rust resistance that is controlled by several
genes, each of which has a small effect (polygenic resistance).
4. Backcrossing
Backcrossing is used to incorporate desired genes, either dominant or
recessive, into the highly productive, commercially successful variety that
lacks the rust resistant genes.
Backcross breeding is good approach for incorporating stem rust resistant
genes into adapted cultivars. The variety that receives the gene is the ‘recipient
parent’ and variety that is the source of the gene is called the ‘donor parent’.
Example – Malviya(Susceptible to stem rust) cross with sparrow (Resistant).
Linkage drag.
13

5. Single seed descent (SSD)
 Modified bulk mehod.
Instead of bulking the entire seed lot of selected plants, a single seed is selected
randomly from each selected plant and advanced individually until reaching
homozygosity. In SSD, a large F₂ population with adequate recombination among
parental combination is generated.RIL development.
 Selection is usually practiced once desired level of inbreeding (homogygosity) is
attained. Rapid advancement of generation.
6. Mutation breeding
Mutation breeding would be an important tool when existing germplasm fails to
provide desired recombinants
Mutaion breeding can be used to produce stem rust resistant wheat cultivars. In an
experiment, a large number of mutagenised lines produced from wheat cultivar
“Guardian” by X-ray mutagenesis showed altered resistance to both yellow and
brown rust.
During screening mutants (Gurdian) showed either enhanced resistance or
enhanced susceptibility to yellow and brown rust (Boyd et al., 2002).
A limitation with mutation breeding is mutation drag.
14

7. Anticipatory/Pre-emptive breeding to control wheat rusts
Anticipatory resistance breeding is the process of predicting future pathotypes
and producing resistant germplasm in order to reduce the future losses by breeding
for resistance to these virulent pathotypes before they become prevalent in a
region (McIntosh et al., 1997).
Due to increased human travel, export and import of goods, there are more
chances that an exotic race or pathotype will reach another country or continent.
Anticipatory breeding is an important approach to be followed for overcoming
future pathotypes of stem rust as there is always a threat that new races of stem
rust will originate.
Knowledge of the pathogenicity phenotypes and host resistance genes in wheat
cutivars in respective growing areas are key aspects to be considered for
successful application of this approach.
15

Molecular Breeding Technologies for Rust Resistance in
Wheat
1. Marker Assisted selection
 MAS is the process by which selection of individual plants is based on
molecular markers. It is the breeding strategy in which selection is based on
molecular markers closely linked to the gene of interest rather than the gene itself.
Types of molecular markers.
(1) Hybridisation based – RFLP, SCAR.
(2) PCR based – RAPD,AFLP,SSR,SNP.
(3) Seqence variation – RFLP.
(4) Length variation – SSR.
1. Foreground selection.
2. Background selection.
3. Negative selection.
16

Genes For Rust Resistance Transferred Through Hybridisation From
Releted Wild Species into Wheat and Subseqent Tagged by Molecular
Markers
Disease Resistence
gene
Donar species Recipient
chromosome
Molecular marker
Leaf rust Lr9 Aegilopes umbellulata 6BL RAPD-STS,RFLP
Lr24 Lophopyrum elongatum 3DL RFLP
Lr32 Triticum tauschii 3DS RFLP
Stem
rust
Sr22 Triticum boeoiticum 7AS-L RFLP
Sr24 Lophopyrum elongatum 3DL RFLP
Sr39 Aegilopes speltoides - Microsatellites-
SCAR
Yellow
rust
Yr15 Triticum diccoides - RFLP-RAPD
17
Table 3
B. D. Singh(2016) Book - Objective plant breeding

1.1 Marker Assisted Backcrossing
This approach depends on the reliability of the marker that is tightly linked with
a stem rust resistance gene.
Both Forward and background selection is used in MAB.
 Linkage drag.
1.2 Marker Assisted Pyramiding of Genes
Combining exotic sources of resistance in a single genotype, Although
pyramiding of rust resistance genes is possible through conventional breeding it is
difficult to identify plants with more than one resistance gene.
Molecular markers help in the identification of plants that carry combinations of
resistance genes.
Molecular markers linked to pyramided genes facilitate the selection of different
combinations of resistance genes in the progeny plants from crossing a disease
susceptible variety and a donor line carrying the disease resistance genes.
Pathogens frequently overcome single gene host resistance due to the emergence
of new plant pathogen races.
18

Marker-Assisted Selection for pyramiding the stem rust resistance gene Sr24,
Sr26, and SrR in Westonia background .
Rohit et al. (2010)
PCR Markers
1)Sr24:-Sr24#12
2)Sr26:-Sr26#43
3)SrR:-IB-159
Fig. 2
19
Australia

1.3 Marker assisted recurrent selection (MARS)
In recurrent selection, evaluation and selection of the best individuals from a
population is followed by recombining these selected individuals in the next
cycle of selection and repeating the entire process.
It increase the frequency of desirable alleles .
MARS is based on identification of markers associated with the trait of
interest that are used to select desirable genotypes.
The main advantage of MARS is that it reduces the amount of breeding time
per cycle.
1.4 Marker assisted shuttle breeding (MASB)
Shuttle breeding was the innovation of Dr. Norman Borlaug who had the
initial objective of speeding the process of breeding and selection by growing
two successive plantings per year (Borlaug, 2007).
In the shuttle breeding system, the crop is grown at one location in summer
season where growing conditions are favorable and then moving the plants to
another location during winter season where winter conditions are favorable for
planting.
20

This process is very useful for selecting plants for disease resistance as this
approach allows immediate evaluation of the progeny of a plant selected for disease
resistance in a different location.
Through MASB, plants that are resistant to stem rust are selected using markers
and these plants are then shuttled to other regions to verify their resistance to stem.
This strategy was successfully used for leaf rust in wheat.
In developed countries such as the U.S., Australia, Canada etc., MASB is not used
because greenhouse facilities are good and plants are evaluated under artificial
conditions using disease inoculum or selected using molecular markers.
2. Genomic selection for rust resistance breeding
Genomic selection (GS) was proposed in 2001 by Meuwissen et al.(2001).
Genomic selection is a powerful molecular breeding method in which plants are
selected on the basis of a large number of markers covering the whole genome
compared to the few specific markers used in traditional MAS.
The advantage of genetic markers covering the whole genome is that all QTL are
in linkage disequilibrium (LD), at least with one or more markers.
Breeding population (BP), Training population (TP).
21
Cont.

It not only accelerates the selection cycles, but also increases the selection gains
per unit of time because selections are based only on markers, with reduced field
testing.
This way, the worth of breeding lines can be known without field testing.
3. Transgenic technology for rust resistance breeding
Transgenic technology has been regarded as a powerful and rapid method of
plant breeding to improve resistence against rust in wheat.
In the past two decades, many transgenic strategies have been attempted for
engineering immunity into wheat against different rust diseases.
Initial transgenic strategies for enhanced resistance involved overexpression of
genes encoding different defence proteins such as receptor (R) proteins,
pathogenesis-related (PR) proteins, antifungal metabolites, antimicrobial peptides,
growth inhibitors, virulence protein inhibitors in susceptible plants.
Transgenic wheat overexpressing Lr10 displayed resistance against leaf rust.
22
Cont.

Transgenic wheat lines expressing an APR gene Lr34 displayed enhanced
resistance against the leaf rust pathogen both at seedling and adult stage, and
this gene also conferred cold tolerance in one genetic background.
Transgenic expression of Sr33, a gene introgressed from A. tauschii into
wheat, in a susceptible wheat variety conferred resistance to the Ug99 race of
stem rust, which has the potential to cause up to 100% crop losses as it is
virulent against many of the resistance genes in wheat (Periyannan et al.,
2013).
Host Plant Genetic
Engineering
Strategy
Target Gene Gene
Function
Effects
Wheat Over
expression
Barley Chi26 Fungal cell
wall-degrading
enzyme
Resistance to
rusts
Wheat Over
expression
Medicago
MtDEF4.2
Antimicrobial
peptide
Durable
resistance
against leaf
rust
Table 4 23

Although transgenic technology is a versatile technology with unlimited scope
for application in plant breeding, it has faced increasing opposition from the public
especially against its use in food crops. (In recent time Bioceres company of
argentina made a transgenic wheat HB 4 and it is also approved by argentinian
government , but biggest importer of argentinian wheat is brazil and they are not
agree to import this GM wheat.
HB4 technology provides seeds that are more tolerant to drought, minimizing
production losses, and giving greater predictability to yields. HB4 seed varieties
increased wheat yields by 20%, on average, during growing seasons impacted by
droughts.
Another hindrance to the commercialization of a transgenic crop variety is that it
has to undergo rigorous risk assessments, which are time-consuming and cost-
intensive.
Due to the random nature of integration, there is a possibility of pleiotropic
effects, potential silencing and varied gene expression in modified plants and
therefore, it is necessary to generate a large number of events to get the desired
traits.
New Breeding Techniques (NBT’s)
24

Furthermore, the retention of genetic material such as selection marker genes,
which have no role in conferring the desired traits, is considered undesirable.
To overcome the disadvantages associated with traditional and modern plant
breeding techniques including transgenesis.
A set of novel tools have been developed referred to as New Breeding
Techniques (NBTs). NBTs facilitate modification of plants in a faster, more
precise and predictable manner compared to conventional breeding and
biotechnology techniques. In contrast to transgenesis where genes and DNA
sequences can be moved between any species.
NBT uses genetic material from the same species or from closely related
species capable of sexual hybridization.
The gene pool exploited in NBTs is similar to the gene pool available for
traditional breeding.
NBT techniques are very useful to develop rust resistence in wheat.
25
Cont.

1. Synthetic Genomics
R gene-mediated resistance based on recognition of a single elicitor or effector
is often not durable and can easily be broken down by rapidly evolving
pathogens, necessitating the discovery of novel R genes for breeding resistant
crop plants.
Resistance breeding is hampered by the low occurrence of useful R genes.
Therefore, synthetic R genes, possessing domains governing resistance against
different pathogens, could provide broad and durable resistance in crop plants.
Cloning and characterization of R genes and other resistance related genes in
wheat.
Gene shuffling and site-directed mutation could be used for construction of a
library of recombinants, and the recombinant libraries could be screened for
potential synthetic R genes. These synthetic R genes can be screened for their
effectiveness in protecting crop plants using pathogen effectors.
Design of synthetic gene configurations with minimal targeted modifications in
the specific domains could provide newer specificities and more durable types of
resistance from the available major R genes and also reduce any pleiotropic
effects associated with resistance mechanisms.
26

2. Agroinfiltration
Agroinfiltration is the local infiltration or inoculation of plant tissues (usually
leaves) with Agrobacterium cells to deliver a gene cassette.
The response of the plant to the expression of the introduced proteins or
silencing factors (RNAi) is monitored to select plants for further breeding.
The technique is mainly applied as a diagnostic tool for disease resistance
testing in some crops.
As the Agrobacterium cells are applied locally to vegetative tissues, the T-DNA
is not stably integrated into the germline and is, therefore not transmitted to the
progeny (Shenoy & Sharma, 2012).
Wheat germplasm could be screened with effector proteins of different
pathogens to identify genotypes with specific disease resistance.
Agroinfiltration is a transient expression assay technique, it speeds up the
screening of generated and naturally existing plant material for specific traits and,
furthermore, it is very useful for functional characterization of genes and
regulatory elements.
 Agroinfiltration has been used for disease resistance screening in wheat and
many other crops.
27

Agroinfiltration technique has great application in pathogenomics and resistance
breeding and has use in almost all the NBTs as well as in conventional transgenic
studies.
3 Cisgenesis and Intragenesis
Cultivation of conventional transgenic crops has been successful in increasing
yield levels, Public apprehensions and stringent and unscientific regulatory
measures have not allowed realization of the full potential of genetic modification
in crop improvement.
To overcome these problems, genetic modifications of plants by exploitation of
the genetic pool of the species or from closely related species capable of sexual
hybridization have been explored and are referred to as cisgenesis and intragenesis,
respectively (Holme et al., 2013).
In cisgenesis, gene cassettes carry endogenous genes with a native promoter and
thus, relatively fewer modifications in the plant genomes.
28
Cont.

Modification of disease resistance through both intragenic and cisgenic
approaches has been attempted in different plant species including wheat by
altering expression of existing resistance genes within a crop species or through
transfer of resistance genes from wild and related species.
Many wild species in wheat possess R genes conferring resistance to rust
diseases. Transfer of R genes from wild species by classical breeding is time-
consuming (often more than 10 years). crosses between wild species and wheat
can be complicated due to differences in ploidy level.
The native R genes, including their native promoters and terminators, could be
used for transformation of commercially cultivated varieties.
In recent times there has been an increased number of reports on cisgenics
development in different crop plants suggesting that this is considered a powerful
method for smarter use of genetic resources in crop breeding and is free from
controversies associated with transgenic crops.
29
Cont.

The plasmid pBarley/chi/bar harboring the full-length barley chi26 and bar
genes was used to transform immature embryos of bread wheat (Triticum
aestivum L.) cv. Hi-Line.
1 Developing transgenic wheat to encounter rusts
and powdery mildew by over expressing barley chi26
gene for fungal resistance.
Egypt Eissa et al.,(2017)
30
Restriction map of the plant expression vector pBarley/chi/bar. H, HindIII; B, BamHI;
E, EcoRI; N, NcoI. Sites of probe and genomic DNA digestions are indicated by red
solid and/or dotted lines.
Fig. 3

PCR products of chi26 (800 bp) (a) and bar (400 bp) (b) genes from the 14
independent T0 transgenic lines (CHI 1, CHI 3, CHI 6, CHI 7, CHI 9, CHI 10, CHI
14, CHI 16, CHI 20, CHI 22, CHI 30, CHI 47, CHI 50, and CHI 71, lanes 1–14,
respectively).
Fig. 4
31

Hi-Line 80S NA 80S 80S 80-S 80S 80-S 80S 80-S 80S
Eissa et al.,(2017)
Egypt
Table 5
32
Evaluation of field data for T4, T5, T6, T8, and T9 transgenic wheat families as well as their
parental non-transgenic cv. Hi-Line, for resistance against wheat rusts.

Fig. 5
33

Seven gene-linked markers (SSR) were used to identify the
presence of stripe rust resistant genes in 22 accessions of
synthetic hexaploid of wheat which were found to be resistant at
seedling plant stage.
2 Identification of stripe rust resistant genes in resistant
synthetic hexaploid wheat accessions using linked
markers.
Pakistan Farrakh et al.,(2015)
34
Markers ( SSR)
Xbarc08
Xbarc124
Xbarc167
Xcfa2149
Xwmc477
Xpsp3000
Xuhw89 Table 6

Presence or absence of stripe rust resistant genes in wheat
accessions.
Table 7
35

 Molecular identification of YrTP1 gene. Wheat accessions were resistant at
the seedling stage.
Fig. 5
36

 A population of 69 selfed progeny (M4) lines produced by X-ray
mutagenesis in the wheat cultivar Guardian.
 A ‘Guardian’ seed stock, obtained following two generations of controlled
self-pollination followed by multiplication from a single plant to minimise any
residual heterogeneity within the ‘Guardian’ population, was exposed as dry
seed to 200 Gy of X rays.
Plants regenerated from X-ray-treated seed formed the M1 generation, while
the selfed progeny of these plants formed the M2 generation. Subsequent
selfing gave rise to the M3 and M4 generations with no prior selection.
3
Mutations in wheat showing altered field resistance to
yellow and brown rust.
United Kingdom Boyd et al.,(2002)
37

Flow chart showing the sequence of selection and field and
greenhouse testing at each generation.
Fig. 6
38

Comparison of the mean yellow rust infection scores from the 1996–1997 (M4 generation)
and 1997–1998 (M5 generation) field tests. The M4 and M5 generation yellow rust scores
were combined for analysis showing significant differences at F < 0.001. Those mutant lines
differing significantly from ‘Guardian’ are indicated by their line number. Mutant lines
showing a significant difference at LSD = 1% are in bold type, the remaining lines differing
at LSD = 5%.
Fig. 7
39

Mean percent whole-plant yellow rust infection on
adult plants.
Table 8
40

SSR Analysis
To eliminate the possibility that the mutant rust phenotypes were due to
genetic variation having been introduced by chance outcrossing, ‘Guardian’
and the seven selected mutant lines were screened for uniformity using SSR
markers.
Forty-four SSR markers, with at least one SSR marker on each arm of the 21
chromosome pairs of hexaploid wheat were tested. For each SSR marker
tested, identical banding patterns were obtained for ‘Guardian’ and the seven
mutants.
Confirming that each mutant was derived directly from ‘Guardian’ and that
no outcrossing occurred at any time during selection and seed collection.
41

Simple sequence repeat (SSR) markers tested on ‘Guardian’ and seven mutant
lines derived from ‘Guardian’. Controls. (A) SSR marker Xpsp2999 (chromosome
1AS); (B) SSR marker Xpsp3000 (chromosome 1BS).
Boyd et al.,(2002)
United Kingdom
Fig. 8
42

Field based assessment for adult plant resistance in promising fifty entries
against predominant pathotype 40-A of black rust.
0.2, 0.4, 0.6, 0.8, 1 for R, MR, X, MS and S respectively. ( 0 = Immune)
Inoculum suspension was prepared by diluting urediospores of predominant
pathotype 40-A.
Injections of inoculum suspension to each entry at boot leaf stage were
practiced with the help of hypodermal syringe.
43
4 Adult Plant Resistance of Wheat Entries to Black Rust
Race 40-A.
India Devi and Patel,(2018)

45
India Devi and Patel.(2018)

Rust resistant varieties released in Gujrat ( Achivements)
46
Sr. No. Variety Year Institute Special Feature
1. GW 322 2007 Wheat research
station ,SDAU,
Vijapur
High degree
resistence to
black and
brown rust.
2. GW 273 2002 Wheat research
station ,SDAU,
Vijapur
Field resistence
to black and
brown rust.
3. GW 366 2007 JAU, Junagarh Resistence to
Brown and
black rust.
ICAR-IIWBR

Conclusion
Plant breeding tools have evolved from simple selections at the beginning of
agriculture to the powerful molecular tools based on precision breeding.
Conventional breeding has led to varieties with resistance to certain degrees.
However, the resistance developed in crops was usually not very durable or broad-
spectrum.
Modern biotechnological tools provide a wide range of novel strategies for
developing broad-spectrum and durable resistance in crops.
The most powerful biotechnological tool, transgenic technology has suffered
opposition in countries following a process-based regulatory system.
As an alternative to transgenic technology, a new set of tools are gaining
popularity that allow precise modification, increased specificity and efficiency of
breeding, decreased development time and cost and increased genetic diversity for
breeding programmes.
47

NBTs are expected to need less stringent regulatory measures than transgenic
technology.
NBTs could be used to harness the great potential of next-generation genome
modification tools in plant breeding for enhancement of yield levels and plant
health.
This is essential for meeting the food needs of the growing population under
changing climatic conditions, increasing input costs and limited resources.
Genetic resistance is the most efficient, economical and environmental
friendly approach against rust diseases of wheat.
48
Cont.

THANKS
“Rust Never Sleeps” – Norman E. Borlaug

Recent advancement in rust resistence in wheat,dayanand, 01986

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