Disease Resistance Rice

PRESENTED BY: Pawan NagarReg. no.: 04-2690-2015M.Sc.(Fruit Science)

RICE ( Oryza Sativa )Rice is the world’s most important food crop

grown in than hundred Countries of the world.

Origin: South East Asia

Distribution: It is grown in humid tropical and subtropical climate and 90 percent of the rice is produced and consumed in S. E. Asia. Rice producing countries are India, Japan, china others countries.

Rice is one of the oldest cultivated crop.

The two cultivated species of rice are

•Oryza sativa : Asian rice•Oryza glaberrima :African rice

Disease Resistance

Disease: Disease is an abnormal condition produced by an organism .E .g fungi ,bacteria ,nematodes and insects.

Resistance :The ability of the host to prevent the pathogen form producing Disease.

Types of Genetic Resistance• Qualitative Resistance

• Distinct classes of resistance and susceptible plants

• Controlled by one or a few genes• Also called “Vertical” resistance• Highly efficiency in specific race.

• Quantitative Resistance• Continuous variation among genotypes• Many loci• Also called “Horizontal” resistance• Efficiency variable against all race .

Method of Breeding for Disease Resistance1.Introduction2.Selection3.Mutation4.Hybridization5.Budding & Grafting6.Biotechnological Method

1.Introduction : Resistant Varieties may be introduced for cultivation in new area.

2.Selection : selection of resistance plant form commercial varieties is easiest method.

3.Hybridization : Transferring disease resistance from one varieties species to other.

Back cross method used to transfer resistance gene agronomic highly desirable varieties.

4.Budding & Grafting :The disease resistance in vegetativly propagated material is transferred by adopting either by budding & grafting. By grafting & budding the resistance material the resistance can be transferred.

5 .Mutation breeding :When adequate resistance is not available in the germplasm ;mutation is breeding resorted to induced resistance. This is also used to break the linkage between the desirable resistance gene and other desirable gene.

What is Marker-assisted selection (MAS)?

Marker assisted selection (MAS) refers to the use of

DNA markers that are tightly linked to target loci as

a substitute for or to assist phenotypic screening.

Pyramiding multiple resistance genes in a single cultivar

Usefulness of MAS – Pyramiding multiple R genes

Bacterial leaf blight (BLB) resistance genes - Xa21, xa13, xa5 (IARI)

Rice Gall midge resistance genes (TNAU)

Blast resistance genes - Pi1, Pi2 ( CRRI )

Multiple resistance gen9s – Blast, BLB and Gall midge ( IARI)

Indian Success stories in Rice

Sources of Disease Resistance1.A Known Variety2. Germplasm Collection3. Related Species4. Mutation5. Somaclonal Variation6. Unrelated Organisms

TESTING FOR DISEASE RESISTANCE

Disease resistance tests may be carried out in the field or in a glass –house.

Glass –house tests are more reliable since the favourable environment for disease development can be provided more readily in a glass-house than in field.

Soil –Borne Diseases: Diseases ,Such as Wilt, root rot etc.E.g.Stem rot Rice.

Air –Borne Diseases: Diseases ,Such as rusts , leaf spots ,blights. E.g. Bacterial blight of Rice.

Seed- Borne Diseases : Some diseases are seed-borne ,E.g. Smuts, Wheat bunt etc. E.g. False Smut of Rice , Brown spot of Rice.

Insect –Transmitted Diseases :Most of the Viral diseases are transmitted by insects. Such insect are known as Vectors. Insect Vectors include aphids, leaf hoppers etc.

Major Disease in RiceFungal Disease: 1.Blast 2.Brown spot 3.Sheath blight 4.False smut Bacterial blight Rice Tungro Virus

Bacterial blight syndromeCausal organism : Xanthomonas oryzae pv.oryzae

‘Pale yellow’ leaf

‘Kresek’ or wilting ‘Leaf blight’ phase

Brown spot of Paddy

Symptoms:In severe infection these spots may coalesce and spread all over the leaves.

The grains of infected panicles become shriveled and discolored. If grain forms test bitter.

Causal organism : Cochliobolus miyabeanus

False smut or green smut of Paddy

Causal organism : Ustilaginoides virens (Claviceps oryzae)

Symptoms

The disease symptoms observed only on the ears.

A few grains in ear head are covered with powdery masses and disseminated by air and cause infection of healthy flowers

Diseases Resistance Varieties Rice

Blast IR22, Guj 1IR28,Gurjari,GR 101,Kamini

Bacterial leaf blight

IR 28,Ratna,Sathi,IR 24,Ambika

Rice Tungro Virus IR 28,Pusa 33Brown leaf spot Navagam -19, orissa T

141

Advantage of Disease ResistanceForm Farmer’s Point of view It is the best,

cheapest and easiest method of disease control.Generally non-toxic to man, live-stock and

wildlife.Do not pollute the environment.Resistant Varieties reduce pest damage at all

levels of infestation.It is only the method available to control some

highly specialized disease like wilt, root rot, rusts, smuts and nematodes.

Limitation of Disease ResistanceSelf sterility in the host plant.

Strictly local aspects of requirement.

Linkage of resistance gene with gene of inferior quality.

occurrences of physiological races varying capacities.

Achievements of Disease resistanceIn India the resistance strains to most of

disease have been produced in every crop under cultivation.

Breeding resistance strains for other disease is investigation and it is expected that sooner or later resistance strain to every disease will be produced and available to compact their menace.

THANKS