+umesh babu b s

HOST PLANT RESISTANCE FOR FOLIAR DISEASES OF

SORGHUM

sorghum is the world’s fourth most important cereal crop after wheat, rice, and maize.

It is grown on 42 million ha in 98 countries in Africa, Asia, Oceania.

It is a major source of food, feed, fiber, and fuel across a range of environments and production systems.

Sorghum is an annual crop that is drought tolerant, making it an excellent choice for dry areas.

sorghum is a major crop for the sustenance of human and livestock populations in hot and dry areas of the world

Sorghum (Sorghum bicolor (L.)

Anthracnose

leaf blight

Foliar diseases in sorghum

Rust

Downy mildew

The inherent ability of an organism (i.e., the crop plant) to resist or withstand the pathogen is called resistance.

The term host plant resistance is used When a pathogen species can be pathogenic on the host species but certain strains of that plant species resist certain strains of the pathogen species

-Terry (2001)

Host plant resistance is the ability of a plant variety to restrict the growth and development of a specified pathogen or the damage they cause when compared to susceptible plant varieties under similar environmental conditions and pathogen pressure.

HOST PLANT RESISTANCE

Ecological Resistance or Pseudo resistance

a. Host evasionb. Induced Resistancec. EscapeGenetic ResistanceA. Based on number of genes Monogenic resistance: Oligogenic resistance: Polygenic resistance:

Types of Resistance

B. Based on biotype reaction- Vertical resistance: specific resistance of a host to a particular race of a

pathogen.- Horizontal resistance: resistance of a host to all the race of pathogen . C. Based on population/Line concept- Pureline resistance: Exhibited by liens which are phenotypically and genetically

similar- Multiline resistance: Exhibited by lines which are phenotypically similar but

genotypically dissimilar Non host resistance - A plant may find it easy to defend itself ie to stay resistance (immune) when it is

brought in contact with pathogenic biotic agent to which the plant is not a host .this is known as non host resistance and it is the most common form of resistance in nature

- Example apple plants are not attacked by pathogens of tomato

The host with vertical resistance controls only one race. It is conditioned by one or a few genes, it is called major gene

or monogenic of oligogenic resistance.

Horizontal resistance(HR) Resistance to more than one race of the pathogen or to many or

all races of the pathogen is called Horizontal Resistance. It is non-specific resistance governed by polygenes.

Vertical resistance (VR) seedling resistance, race specific resistance or qualitative resistance

Functional structural Protoplasmic

Functional nature of resistance is determined by

Opening of the stomata ex in wheat

The basis of resistance

Structural characters include:

Corky layers

Tylosis formation

Protoplasmic factors controlling resistance:

Tannins

Anthocyanin

Anthracnose, leaf blight, and rust are important biotic constraints to grain and forage sorghum production worldwide and are best managed through host plant resistance.

ICRISAT, Hyderabad, India

Sharma et al.

Resistance to foliar diseases in a Mini-core Collection of Sorghum Germplasm

Resistance to foliar diseases in a Mini-core Collection of Sorghum Germplasm A sorghum mini-core collection, consisting of 242 germplasm

accessions developed from a core collection of 2,246 landrace accessions, originating from 58 countries, was evaluated to identify sources of resistance to foliar diseases.

The mini-core accessions were evaluated in anthracnose and leaf blight screening nurseries under artificial inoculation in the rainy and late rainy seasons, respectively, during 2009 and 2010.

For rust resistance, screening was done under artificial inoculation in the greenhouse as well as in the field under natural infection.

Thirteen accessions were found resistant (score ≤3.0 on a 1-9 scale) to anthracnose and 27 to leaf blight in both 2009 and 2010. Six accessions exhibited resistance to rust, both in the greenhouse and in the field.

Three mini-core accessions (IS 473, IS 23684, and IS 23521) exhibited resistance to all three diseases

Origin, race type, disease scores of selected accessions from the sorghum mini-core collection

MATERIALS AND METHODS The mini-core encompasses all five basic

races bicolor (20) caudatum (39) durra (30) guinea (29) kafir (21)]

Resistance to foliar diseases in a Mini-core Collection of Sorghum Germplasm

Sharma ICRISAT,

1. R = resistant; score 1-3 for anthracnose and leaf blight and ≤10% rust severity.

2. MR = moderately resistant; score 3.1-5.0 for anthracnose and leaf blight and 11-20% rust severity.

3. S = susceptible; score 5.1-7.0 for anthracnose and leaf blight and 21-50% rust severity.

4. HS = highly susceptible; score 7.1-9.0 for anthracnose and leaf blight and >50% rust severity

Field reaction of sorghum germplasm to foliar diseases

Seventy eight accessions in the local germplasm colletion of sorghum were field tested against 11 foliar diseases .

Differential diseases reaction w, 14 of as recorded; 10 accession were found free of leaf blight,14 of sooty stripe, 26 of zonate leaf spot, 7 of rough leaf spot, 6 of grey leaf spot, 2 of antharacnose, & 23 of bacterial streak.

Germplasm collected from the northern regions of punjab showed resistance to mould. As many as 48 accession were found resistance to smut and 28 to mould .

Most of the lines were moderately resistance through moderately susceptible to diseas. M. sarwar et all

0-1 = resistant, no or small chlorotic/necrotic lesions developed

2= moderately resistant, few scattered lesions, length covering uo to 5% leaf area.

3= moderately susceptible, lesion easily noticable and scattered over many leaves covering 6-20% leaf area.

4= susceptible, symptoms severe with 21-40% of total leaf area.

5= highly susceptible, lesions covering more than 40% leaf area

Screening sorghum varieties for resistance to anthracnose and other foliar diseases

THANKYOU