Download Pearl millet, food for the future in the Sahel

Scientific bulletin 325 - July 2009
Pearl millet, food for the future in the Sahel
Pearl millet is the staple
food for 50 million people
living in the Sahel. It is
extremely resistant to
drought and well adapted
to poor soils and remains
the only crop that truly
corresponds to the
environmental conditions
and traditional diet.
However, harvests vary
considerably depending
on rainfall and soil
fertility. Environmental
conditions vary
greatly, with drought
intensifying from year
to year, climate change
and desertification: to
confront these harsh
situations in the region
and ensure sufficient
yields, Sahel farmers
need the possibility to
choose suitable varieties.
Since pearl millet
domestication more than
3 500 years ago, humans
have thus selected some
important agronomic
characters and developed
a great diversity of
varieties, adapted to
different climates.
Researchers from the IRD
and Abdou Moumouni
University in Niamey,
Niger, recently identified
a gene responsible for
this adaptation, called
PHYC. This is one of the
genes which play a role
in light perception in
plants. In the context of
current climate change,
the discovery of this key
genetic factor allows
the development of
appropriate varieties.
Left: Nigerian woman showing different varieties of millet she grows (© IRD /Cédric Mariac).
Right: Millet field in Niger (© IRD /Claire Costis).
Pearl millet, the staple source of energy for millions of people, is the bedrock of food security in the Sahel.
It is one of the most important food
crops in the region, along with two
other cereals, sorghum and rice. In
Niger, a major producer in Africa second only to Nigeria, pearl millet crops
cover for example more than 65% of
the cultivated surface area and make
up three-quarters of the country’s cereal production. It is the crop plant best
adapted to arid and semi-arid zones.
Pearl millet has been grown for over
3 500 years all over the Sahel and the
tropical countries of West Africa. The
plant and its cultivation originated in
Niger and Mali, diffused over equatorial Africa then towards India, thanks
notably to a genetic adaptation to different climates, one of the key factors
in the domestication and diffusion of
cultivated millet.
A gene, an adaptation
What genes have humans selected
over the millennia in order to cultivate
millet under different climates? Researchers from the IRD and University
Abdou Moumouni in Niamey, Niger,
determined one of those responsible
for this adaptation: the PHYC gene
which plays a predominant role in the
plant’s light perception. The scientists
discovered a significant association
between the genetic variations, from
one species to another, the PHYC gene
and those governing flowering time,
and also certain morphological traits
such as spike length and stem diameter. Flowering time was strongly linked
to climatic conditions: a long flowering
time was better adapted to more humid climates, a shorter one suitable for
drier conditions. For example, the species cultivated in coastal tropical Africa
flower in 160 days, whereas flowering
in Sahelian varieties can be observed
from 45 days. The genetic factors underlying the differences between these
varieties were hitherto unknown.
An innovative method
Identification of the PHYC gene was
achieved by using a novel method
which takes into account the evolutionary history of millet populations. The
research team first selected 90 inbred
Institut de recherche pour le développement - 44, boulevard de Dunkerque, CS 90009
F-13572 Marseille Cedex 02 - France - www.ird.fr
You can find the IRD photos concerning this bulletin, copyright free for the press, on www.ird.fr/indigo
lines already genotyped and ran 3 field
trials in Niger between 2005 and 2006
to characterize them. Flowering date,
CONTACT :
ramification, plant height, spike length
and diameter: all the parameters were
Yves VIGOUROUX,
thoroughly investigated. Sequencing1
researcher at IRD
was performed on eight flowering paUMR Diversité et adaptation
des plantes cultivées (Dia-PC) thway genes of the lines studied. A
statistical association analysis of these
(IRD, AGRO_M, INRA,
different genes was applied, taking
Université Montpellier 2)
account of the population structure
and phylogenetic relationships in the
Address :
samples studied. Using these crosCentre IRD de Montpellier
sings, which have taken place over
BP 64501
thousands of years, the scientists iso34394 Montpellier cedex 5
lated highly precisely a gene highly imTel : 33 (0)4 67 41 62 45
portant for pearl millet’s adaptation to
[email protected]
climate.
Up to now, the search for such genetic
REFERENCES :
factors consisted in making crosses in
order to obtain hybrids and analyse the
Dangles O., Carpio C.,
lineages thus obtained. Such genetic
Saïdou A.-A., Mariac
C., Luong V., Pham J.crossing made it possible to analyse
L., Bezançon G. and
only a small number of generations
Vigouroux Y. Association
of individuals and isolate only large
Studies Identify Natural
blocks of chromosomes. The identifiVariation at PHYC Linked
cation of genes subsequently necessito FloweringTime and
tates many years of supplementary reMorphological Variation in
search. The new approach used in this
study provides a way of considerably
accelerating identification of agriculturally significant genes.
Predictions of future climates in the
Sahel region zone remain riddled with
uncertainties. However, arid and semi-arid areas are subject to abrupt
changes of climate. Thus, for 40 years,
the Sahel has been experiencing a
trend of rainfall decrease. Identification of pearl millet’s gene for adaptation to different climates offers a
way to select and develop the varieties most appropriate for such a
context of environment and climate
change.
Millet could therefore become
spearhead in the combat against
drought in the Sahel.
Redaction DIC - Gaëlle Courcoux
Translation - Nicholas Flay
1. Sequencing consists in determining the
order of DNA nucleotides that make up
genes.
Pearl Millet. Genetics, 182,
p. 899-910, 2009
DOI: 10.1534/
genetics.109.102756
KEY WORDS :
Millet, Sahel, climate,
adaptation
PRESS OFFICE :
© IRD / Marie-Noëlle favier
© IRD / Marie-Noëlle favier
Scientific bulletin 325 - July 2009
For futher information
Vincent Coronini
+33 (0)4 91 99 94 87
[email protected]
INDIGO,
IRD PHOTO LIBRARY :
Daina Rechner
+33 (0)4 91 99 94 81
[email protected]
www.ird.fr/indigo
Malian women grinding millet. Millet is still the
only crop adapted to environmental conditions
and people’s diet.
Board illustrating the variety of mils cultivated
in Niger.
Did you know?
The Sahel is the cradle of the domestication of pearl millet. The oldest
pottery bearing representations of wild and cultivated millet were found in
Mauritania 3 500 years ago.
Gaëlle Courcoux, coordinator
Délégation à l’information et à la communication
Tél. : +33 (0)4 91 99 94 90 - fax : +33 (0)4 91 99 92 28 - [email protected]