It is a comprehensive account for a part of Core Course VI : Economic Botany Paper: Centers of Origin and Vavilov's work

1. Core Course VI :
Economic Botany(DSC PAPER 6)
Unit 1: Origin of cultivated Plants
Lecture 1: Vavilov’s Centers of origin;
Domestication
Ref : Plant Breeding B.D. Singh
Plant Breeding P.Satya
Dr Rita Som Paul
Associate Professor
Botany Department Siliguri College

2. Important points
• Crop plants – the useful plants that were
domesticated, bred and cultivated
extensively by humans
• Not all the plants were/are directly useful
• Wild plant diversity (Hot spots) vs crop
diversity ( Centers of origin)
• Crop domestication vs loss of biodiversity

3. #Concept of centers of Origin
• Alphonse de Candolle (1890), a Swiss Botanist,
disscussed about the techniques for tracing the
origin of crop plants in his book “Origin of
Cultivated Plants”:
• historical evidences
• distribution of wild relatives
• pattern of variation of traits
• ethnic knowledge
• Archaeological work

4. Concept of Centers of origin
• Nikolai Ivanovich Vavilov (1887-1943) was
basically a geneticist and plant breeder,
approaching the problems of cultivated plant
species in terms of the diversity within and
between them that might be put to practical
ends. For this reason Vavilov was not
particularly interested in diversity as such,
but only in the diversity that could be put to
practical advantage.

5. #Vavilov’s work
• Vavilov was a follower of de Candolle
• He travelled over hundred locations around the world
for germplasm collection and study crop variability
• In 1920 he proposed the law of homologous series of
variation, which states that the related species share
certain common characters. Therefore, a character
found in one species is expected to be obseved in
related species in a particular geographical area. Eg
absence of ligule in wheat and rye in Northern part of
central Asia, while present in other regions

6. • The concept of centers of origin was
developed by Vavilov in 1926. Vavilov
elaborated on the work of Engelbrecht (1916)
and considered the regions showing the
greatest diversity with presence of wild
relatives as the centers of origin of the a crop
plant.Logic :The plant that was domesticated
in a place will thrive in and around in hrmony
with environment and thus show greater
variation.

7. • Vavilov noted that the centers of
origin of cultivated plants occurred
mostly in mountainous regions
between the Tropic of Capricorn
(23°28') south of the equator and
about 45°N of the equator in the Old
World. In the New World crop
domestication occurred between the
two tropics (Cancer and Capricorn)
approximately. In all cases
agricultural origins and primitive
diversity occurred in high and
complex mountain regions. Why only
these?

8. • Vavilov was able to pinpoint the exact areas where
crop plant diversity showed us the centers of origin of
world crops.
• Vavilov considered that “as a rule the primary foci of
crop origins were in mountainous regions,
characterized by the presence of dominant alleles.” In
his work entitled The Phytogeographical Basis for
Plant Breeding (Vavilov 1935) he summarizes and
pulls together all his previous work on centers of
origin and diversity. In this he recognizes eight
primary centers, as follows.These centers are still
recognized in spite of several arguments against
them.Combining the concepts of centers of origin and
centers of diversity, Zhukovsky (1965) proposed 12
regions of crop diversity or megacenters with some
microgene centers

9. #Centers of origin (Vavilov)
• Primary Center, where the crop has been
actually domesticated- expected to be
centers of diversity (8 primary centers)
• Secondary Center, where it has been
introduced from primary center and adapted
to show high variation – often showing
higher diversity of a particular crop than in its
primary center ( 3 secondary centers)

10. I. The Chinese Center - in which he recognizes 138 distinct species of which probably the earliest and most important
were rice, soyabean, cucumber, onion,millets, radish, litchi, peach, etc
II A . The Hindustan ( Indian) Center (including the entire subcontinent) - based originally on rice, millets and
legumes,brinjal, jute, bamboo etc with a total of 117 species.
IIB. The Indo-Malayan Center (including Indonesia, Philippines, etc.) - with root crops (Dioscorea spp., Tacca, etc.)
preponderant, also with fruit crops(banana) sugarcane, spices(nutmeg, cloves,pepper), cocconut etc., some 55
species.
III. The Inner Asiatic Center ie Central Asia (Tadjikistan, Uzbekistan, etc.) - with wheats(breadwheat), rye and many
herbaceous legumes(pea, chickpea,mungbean), as well as seed-sown root crops (carrot), cotton, sesame,
flax,some 42 species.
IV.Near East or Asia Minor (including Transcaucasia, Iran and Turkmenistan) - with more wheats (Eincorn whaet,
emmer wheat), rye, oats, barley, fruits (date, melon,pomegranate,fig, apple,pear), etc., some 83 species.
V. The Mediterranean Center - of more limited importance than the others to the east, but including wheats (durum
wheat, emmer wheat), barleys, forage plants (Egyptian clover), vegetables (olive, cabbage) and fruits -especially
also spices (black mustard) and ethereal oil plants (pppermint), some 84 species.
VI. The Abyssinian (now Ethiopian) Center - of lesser importance, mostly a refuge of crops from other regions,
especially wheats(durum, emmer) and barleys, local grains(pearl millet, sorghum, African millet), spices, etc.,
some 38 species.
VII. The South Mexican and Central American Center - important for maize, Phaseolus and Cucurbitaceous species
(pumpkin), sweet potato, arrowroot, tobacco, Upland Cotton, cashew, guava etc some 49 species.
VIIIA. South America Andes region (Bolivia, Peru, Ecuador) - important for potatoes,tomato other root crops, grain
crops of the Andes, vegetables, spices and fruits, as well as drugs (cocaine, quinine, tobacco, etc.), some 45
species.
VIIIB. The Chilean Center - only four species - outside the main area of crop domestication, and one of these
(Solarium tuberosum) derived from the Andean center in any case. This could hardly be compared with the
eight main centers.
VIIIC. Brazilian-Paraguayan Center - again outside the main centers 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.

14. Domestication
• How did plants become domesticated despite their evolutionary
processes to protect them from being eaten by the development
of various defensive mechanisms such as poisons, bitter
substances, etc.? One strategy of survival adopted by many plants
is to produce so many seeds that even if most of them are eaten
enough will remain to provide for the next generation. And the
plants that do this superbly well are grasses. To a lesser extent
those that do this quite well are herbaceous legumes. This, then,
may be the solution to the problem of how humans began the
process of domestication. Hunter-gatherers took and ate the
natural surplus and left enough seeds (probably by chance) to
provide for the next generation. Later, when non-shattering
mutants occurred by chance, these were adopted automatically
by the primitive farmers. From this point evolution under
domestication began to take place.

15. Effect on genetic diversity
• Loss of genetic diversity – bottleneck theory
of domestication- loss of divergent alleles
• Increased dependence of domesticated plant
types on humans – narrow genetic base due
to continuous selection process
• Loss of reproductive fitness