conept of origin,diversity,microcentre etc

1. Sub.:- Fundamentals of Plant Breeding
Course No. :- APB- 5211
Credit hours:- 3(2+1)
Lec. Topic :- Centre of origin of Crop plants
Presentedby:-
Lt. Roshan Parihar, Asstt. Professor
Deptt.of Genetics&PlantBreeding
Indira Gandhi Krishi Vishwavidyalaya
Raipur, C.G.
BTC College of Agriculture & Research Station
,Sarkanda, Bilaspur,(CG)-495001
फसलों के उत्पत्ति कें द्र

2. Centre of Origin (1926)
• CENTRES OF ORIGIN: A centre of origin is a geographical area
where a group of organisms either domesticated or wild, first
develop its distinctive properties
• Plant domestication was not at random.
• Specific regions for start of domestication.
• Presence of wild relative is the basis for centre of origin.
• These are the reason where wild relatives of the plant
showed maximum adaptiveness.
• These conclusions were summarized in (The Origin,
Variation, Immunity and Breeding of Cultivated Plants), a
work that was translated into English in 1951.

3. •Renowned Swiss botanist, son of a famous botanist, Augustin-
Pyramus de Candolle (1778-1841), born in Paris took over his
father's botanic garden with a vast collection.
•De Candolle write a massive tome on plant geography that
assumed the derivation of each species from a specially created
individual.
•Alphonse de Candolle, in his 1882 book Origine de Plantes
Cultivées, was among the first to indicate regions where plant
domestication may have taken place: China, Southwest Asia
including Egypt, and Tropical Asia.
ALPHONSE DE CANDOLLE
NIKOLAI IVANOVIC VAVILOV (1887-1943)
• Renowned Russian botanist proposed theories of plant genetic diversity.
Vavilov developed a theory of the historical centers of origin of cultivated
plant and "The Law of Homologous Series in Variation,1922. Gave the
concept of origin, based on genetics, chromosome studies and anatomical
data. He told that most likely areas of origin were, where the plants
was cultivated and the wild ancestors grew. In 1926 he published
“Studies on the Origin of Cultivated Plants” which described his theory
Pioneer scientists

4. Vavilov’s Expeditions in search
of gene
• 1921-1934: 180 expeditions of the institute
• Around the world including 65 countries, he
himself visited 52 countries.
• Vavilov’s collected the plant resources
throughout the world with his original phyto-
geographic method.
• His know-how was the basis to determine
where to go.

5. Collection of germplasm
• Before the Second World War the collections of All-Union
Institute of Plant Industry numbered
• Over 36,000 accessions of wheat
• Over 10,000 of maize
• Over 23,000 of legumes
• Around 18,000 of vegetables
• Over 12,000 of fruit and small fruit crops
• Over 23,000 of forages.
• The total of accessions reached 2,50,000 in the times of N.I.
Vavilov.
• All this rich diversity was thoroughly studied at experiment
stations in different geographical zones of the country

6. Routes of the Vavilov’s main
expeditions 1916–1940

7. Primary Centre of Origin
• All the cultivated species of the world
have their origin in these primary
centre of origin and later they spread
to different places of cultivation.
• Main features are
• The number of wild species present
• Diversity of wild species
• Number of endemic species present
• Sources of dominant genes

8. Primary Centre of Diversity
• The place with maximum amount of variability
of a plant species without presence of wild
relatives represents its centre of diversity.
• It was also considered as Secondary Centre of
Origin.
• Crop diversity – the variation between and
within crops and between crops and wild
relatives.

10. Sources of Diversity
• According to Vavilov diversity was primarily a function
of spontaneous mutation.
• Over a long period of time it was accumulate
through:
• Selection.
• Strong selection pressure
• Isolation
• Inbreeding

14. Centre of Diversity = Centre of Origin
• Presence of both Wild relatives and Variability under the
control of dominant genes
Micro centre of origin
The exact centres were located in several
comparatively small geographic areas on the globe,
especially in the mountain areas of Asia, Africa,
along the Mediterranean coast and in South, Central
and North America.

15. MICRO CENTRES
• In some cases, small areas within the
centres of diversity exhibit tremendous
genetic diversity of some crop plants.
• These areas are refer to as micro centres.
• Micro centres are important sources for
collecting valuable plants from and also for
the study of evolution of cultivated
species.

16. • Vavilov felt that the maximum amount
of variability is present at the
periphery and the maximum
concentration of dominant gene in the
form of wild relatives is present at the
centre of the distribution.
• The concentration of the dominant
gene decreased towards the periphery
with the increase in concentration of
recessive gene mainly due to:
• Strong selection pressure
• Isolation
• Inbreeding

17. VAVILOVIAN CENTRES

18. Table.1- List of 8+3 (11) Vavilovian centres of origin
Old World Centres
I-The Chinese Center
II-The Indian centres (Hindustan centre)
IIa-The Indo-Malayan centres (subsidiary centre )
III-The Central Asiatic Center or Inner Asiatic centres
IV- Asia Minor or Persia or Near-Eastern Center
V – The Mediterranean Center
VI- The Abyssinian (now Ethiopian) center
New World Centres
VII - The South Mexican and Central American Centre:
VIII- South American Centre (Bolivia, Peru, Ecuador)
VIIIa-The Chilean centres (Subsidiary centre )
VIIIb-Brazilian-Paraguayan centres (Subsidiary centre )

19. Vavilovian Centres of origin
• I. The Chinese centres - in which he
recognizes 138 distinct species of which
probably the earlier and most important
were cereals, buckwheats and legumes.
• II. The Indian centres (including the
entire subcontinent) - based originally on
rice, millets and legumes, with a total of
117 species.

20. • IIa. The Indo-Malayan centres (including
Indonesia, Philippines, etc.) - with root crops
(Dioscorea spp., Tacca, etc.) preponderant,
also with fruit crops, sugarcane, spices, etc.,
some 55 species.
• III. The Inner Asiatic centres (Tadjikistan,
Uzbekistan, etc.) - with wheat, rye and many
herbaceous legumes, as well as seed-sown
root crops and fruits, some 42 species.

21. • IV. Asia Minor (including Transcaucasia, Iran
and Turkmenistan) - with more wheats, rye,
oats, seed and forage legumes, fruits, etc.,
some 83 species.
• V. The Mediterranean centres - of more
limited importance than the others to the
east, but including wheats, barleys, forage
plants, vegetables and fruits -especially also
spices and ethereal oil plants, some 84 species.

22. • VI. The Abyssinian (now Ethiopian) centres -
of lesser importance, mostly a refuge of crops
from other regions, especially wheats and
barleys, local grains, spices, etc., some 38
species.
• VII. The South Mexican and Central
American centres - important for maize,
Phaseolus and Cucurbitaceous species, with
spices, fruits and fibre plants, some 49
species.

23. • VIII. South America region (Bolivia, Peru, Ecuador) -
important for potatoes, other root crops, grain crops of
the Andes, vegetables, spices and fruits, as well as
drugs (cocaine, quinine, tobacco, etc.), some 45 species.
• VIIIa. The Chilean centres - only four species -
outside the main area of crop domestication, and one of
these (Solanum tuberosum) derived from the Andean
centres in any case. This could hardly be compared with
the eight main centres.
• VIIIb. Brazilian-Paraguayan centres - again outside
the main centres with only 13 species, though Manihot
(cassava) and Arachis (peanut) are of considerable
importance; others such as pineapple, Hevea rubber,
Theobroma cacao were probably domesticated much
later.

24. The Law of Homologous Series in hereditary Variation (1920)
• Characters found in one species may be found in another
depending on the relationship.
• Genomics, the science of gene mapping has provided the scientific
underpinning for Vavilov’s “Law of Homology.”
• Species and genera, genetically related to each other, possess
identical series of genetic variation with regularity, allowing
prediction of identical forms for other species and genera with
known forms for one species.
• Vavilov points out necessity of genetic analysis for those
characteristics, which show parallel variation for different species
and genera, and in 1935, when he gets enough facts, the scientist
concludes that closely related species and genera possess many
common genes together with some specific ones.

25. Triticum aestivum Triticum durum Hordeum vulgare
2n=42 2n=28 2n—14
The Law of Homologous Series in hereditary Variation
A B C D A B C
B: Short awned
D A
C: lnflatum
B C D
D:AwnlessA :Long awned

26. CONCLUSION
• Wide range of plant diversity in the tropical
and warm temperate regions of the world our
major food crops have come mainly from high
mountain valleys, isolated from each other to a
large extent and with a very habitat range.
• People made selections of wheat, barley, oats,
rye, potatoes, and maize which were eventually
cultivated.