1) ICRISAT developed mini core collections containing 1% of accessions from entire germplasm collections for crops like sorghum, pearl millet, chickpea etc. to enhance utilization of plant genetic resources in crop improvement. 2) Evaluation of mini core collections identified new sources of resistance to biotic and abiotic stresses and accessions with specific agronomic and nutritional traits. 3) Over 280 sets of mini core collections were provided to research institutions in 36 countries who utilized them to identify trait-specific germplasm for breeding programs.

1. Mini core collection – a means to enhance
utilization of germplasm
Hari D Upadhyaya, DVSSR Sastry, M Vetriventhan, SK Pattanashetti, KN Reddy and Sube Singh
About ICRISAT: www.icrisat.org
ICRISAT’s scientific information: http://EXPLOREit.icrisat.org
Introduction
Plant genetic resources (PGR) are the basic materials for progress in crop
improvement and an insurance against unforeseen threats to agricultural
production. Greater use of germplasm in crop improvement is needed for
sustainable conservation of genetic resources, to protect the natural ecosystems
and simultaneously enhance agricultural production for food security.
Crop improvement programs globally benefited from the genebank
collections
▪▪ ICRISAT’s RS Paroda Genebank distributed over 1.45 million seed samples to
researchers in 148 countries
▪▪ One hundred and nine accessions of germplasm have been released as 146
cultivars in 51 countries
▪▪ Over 800 cultivars were released in 79 countries utilizing germplasm and breeding
lines from ICRISAT.
Research approaches to enhance use of germplasm and its utilization
▪▪ A very small proportion (<1%) of the available germplasm has been used in crop
improvement
Table 1. Core and mini core collections established at ICRISAT genebank.
Number of accessions
Crop
Entire
collection
Used in core
development
Core
collection
Mini core
collection
Sorghum 37,943 22,473 2,247 242
Pearl millet 21,594 20,766 2,094 238
Chickpea 20,140 16,991 1,956 211
Pigeonpea 13,632 12,153 1,290 146
Groundnut 15,419 14,310 1,704 184
Finger millet 5,949 5,940 622 80
Foxtail millet 1,535 1,474 155 35
Mini core as a source of trait variation for use in crop improvement
Extensive multi-disciplinary evaluation of core/mini core collections at ICRISAT and
by national partners resulted in identifying new germplasm sources for use in
crop improvement.
Mini core
Accessions resistant to biotic stresses
▪▪ Chickpea: Wilt-67; dry root rot-6; Ascochyta blight-3; Botrytis grey mold-55;
multiple diseases-31; tolerant to Helicoverpa-5
▪▪ Pigeonpea: Sterility mosaic disease (SMD)-24, wilt-6, wilt + SMD-5, pod borer-10
▪▪ Groundnut: Aflatoxin-7, Early leaf spot-3, Late leaf spot (LLS) and rust-4, multiple
stresses-30
▪▪ Sorghum: Grain mold-50; Anthracnose-13; Downy mildew-6; Leaf blight-27
▪▪ Pearl millet: Blast-3 accessions for 4 pathotypes, Downy mildew-62 for at least 2
pathotypes
▪▪ Finger millet: 66 accessions to leaf, neck and finger blast
▪▪ Foxtail millet: 3 accessions to sheath, neck and head blast.
Accessions resistant to abiotic stresses
▪▪ Chickpea: Drought-18; salinity-31; high temperature-16; multiple resistance-40
▪▪ Pigeonpea: Salinity-16, water logging-23
▪▪ Groundnut: Drought-18; salinity-12; low temperature-20; multiple resistance-28
▪▪ Sorghum: Salinity-7; drought-7; seedling vigor under low temperature-6;
germinability under low temperature-5
▪▪ Finger millet: Salinity-21; High TE-11
▪▪ Foxtail millet: Salinity-1; High TE-2.
Germplasm with specific agronomic traits
▪▪ Chickpea: 24 accessions for multiple agronomic traits
▪▪ Groundnut: 18 accessions for multiple agronomic traits
▪▪ Pigeonpea: 54 accessions for high yield
▪▪ Sorghum: 20 for early maturity, 3 for grain yield
▪▪ Pearl millet: 4 for early maturity, 25 for high grain yield
▪▪ Finger millet: 7 for early maturity, 2 high yield
▪▪ Foxtail millet: 4 for grain yield, 6 for early maturity.
Accessions with specific nutritional traits
▪▪ Chickpea: Protein-5; anthocyanin-5
▪▪ Pigeonpea: Zinc-15; iron-15
▪▪ Groundnut: Oil-18; protein-18; O/L-18, iron-48; zinc-43; multiple-16
▪▪ Sorghum: Protein-10; iron-11; zinc-14; iron & zinc-9; stalk sugar-11
▪▪ Pearl millet: Iron-4; high zinc-6, protein-2
▪▪ Finger millet: Iron-3; protein-2; calcium-4
▪▪ Foxtail millet: Iron-4; zinc-5; protein-6; calcium-5.
NARS using mini core collections
Provided on request 280 sets of mini core collections to NARS partners in 36 countries
(Algeria, Argentina, Australia, Bangladesh, Burkina Faso, Canada, China, Egypt,
Ethiopia, France, Germany, Guyana, India, Iran, Japan, Kenya, Korea, Malawi, Mali,
Mexico, Niger, Nigeria, Pakistan, Senegal, Sweden, Syrian Arab Republic, Tanzania,
Thailand, Trinidad & Tobago, Turkey, Uganda, United Arab Emirates, United Kingdom,
United States, Vietnam, and Zimbabwe) (Fig 2).
Conclusions
▪▪ Our strategic research on mini core has helped in identification of trait or multiple
trait specific genetically diverse sources that have met the needs of breeders for
use in breeding to develop high yielding climate resilient crop cultivars with a
broad genetic base
▪▪ Molecular characterization of mini core and trait specific germplasm has
enhanced usefulness of germplasm to breeders in enhancing traits more
efficiently and in allele mining
▪▪ Mini core collection is an International Public Good (IPG) and serves as a
gateway to the utilization of germplasm in crop improvement
▪▪ NARS benefited greatly by use of mini core in identifying trait-specific genetically
diverse sources for their use in crop improvement
▪▪ Germplasm use increased after formation of mini core collection in breeding
programs at ICRISAT.
Genotypic variation for root mass (left) and salinity tolerance (right) in chickpea.
Figure 2. Usefulness of developing
mini core collections in identifying
promising sources.
Figure 1. Flow diagram to establish
core and mini core collections in a
crop species.
▪▪ Main reason for low use of germplasm is
lack of information on traits of economic
importance, large size of collections, and
breeders’ interest in their own working
collection
▪▪ To enhance use of germplasm core collections
(10% of entire collection) developed in
sorghum, pearl millet, chickpea, pigeonpea,
groundnut, finger millet, and five small millets
foxtail millet, proso millet kodo millet, little
millet and barnyard millet, but the number of
accessions is still large (Table 1)
▪▪ ICRISAT scientists (Upadhyaya and Ortiz.
2001) postulated the mini core (10% of core
collection or 1% of entire collection) concept,
to enhance utilization of germplasm (Figure 1)
▪▪ Mini core collections of sorghum, pearl millet,
chickpea, pigeonpea, groundnut, finger millet
and foxtail millet were developed (Table 1).
Mini core collection as an association mapping panel
Mini core collection has been used as an association mapping panel to identify
genomic regions associated with important traits e.g. for plant height, maturity, kernel
weight, tiller number, germinability under low temperature stress, and anthracnose,
leaf rust and grain mold resistance in sorghum.
NARS identified trait-specific germplasm from mini core collection
▪▪ Groundnut: Oil quality and content – China (11), Vietnam (10), India (13);
agronomic traits – China, Vietnam and Thailand (5 each), India (10 each in four
locations); disease resistance – China (Bacterial wilt-14), Thailand (LLS and rust-10)
and India (LLS, rust and aflatoxin-39); multiple traits – India (23); large seed size –
India (27); confectionary type – India (15)
▪▪ Chickpea – India: Large-seeded Kabuli-13, high yield-28, early maturity-23,
Ascochyta blight-6, Botrytis grey mold-2
▪▪ Pigeonpea – India: Early maturity-8, high seed yield-2, wilt: 39, SMD + wilt: 24
▪▪ Sorghum – USA: Anthracnose-123, Head smut-58, Downy mildew-31
▪▪ Pearl millet – India: Early maturity-4, large seed size-5, green fodder-19, grain
yield-9
▪▪ Small millets – India: Finger millet – seed yield and early maturity (15 accessions
in 4 locations)
▪▪ Foxtail millet - India- Seed yield and early maturity (15 accessions in 4 locations).
Variation for drought tolerance
(root length density) in chickpea mini core.
Variation for low temperature tolerance
(at germination) (left) and salinity tolerance
in groundnut (right).
Nov 2016