Plant Molecular Biology 48: 667–681, 2002.
© 2002 Kluwer Academic Publishers. Printed in the Netherlands.
Molecular genetics of heat tolerance and heat shock proteins in cereals
, Natalya Klueva
, Carla Perrotta
, Mariolina Gulli
, Henry T. Nguyen
Division of Genetics and Environmental Biotechnology, Dept. of Environmental Sciences, University of Parma,
43100 Parma, Italy (
author for correspondence; e-mail firstname.lastname@example.org);
Plant Molecular Genetics
Laboratory, Dept. of Plant and Soil Science and Center for Biotechnology and Genomics, Texas Tech University,
Lubbock, TX 79409, USA;
these authors contributed equally to this paper
Received 21 August 2001; accepted in revised form 18 September 2001
Key words: abiotic stress, gene cloning, gene mapping, heat shock proteins, heat tolerance
Heat stress is common in most cereal-growing areas of the world. In this paper, we summarize the current
knowledge on the molecular and genetic basis of thermotolerance in vegetative and reproductive tissues of cereals.
Signiﬁcance of heat stress response and expression of heat shock proteins (HSPs) in thermotolerance of cereal
yield and quality is discussed. Major avenues for increasing thermotolerance in cereals via conventional breeding
or genetic modiﬁcation are outlined.
Most of the world crops are exposed to heat stress
during some stages of their life cycle (Stone, 2001).
Exposure to higher than optimal temperatures, or heat
stress, reduces yield and decreases quality of cereals.
Furthermore, as the world population grows exponen-
tially, there is a need to both increase agricultural pro-
ductivity and to expand productive areas of the world
into warmer climates. Both of these goals require sig-
niﬁcant breeding efforts to improve high-temperature
tolerance of cereal yield and quality. Meanwhile, ce-
real breeding to date had utilized a limited number of
progenitor germplasms and emphasized a high yield
potential under favourable environmental conditions
narrowing down genetic diversity of stress resistance
traits, including heat stress tolerance (Holden et al.,
1993). Hence, there is a strong need to elucidate mole-
cular and genetic basis of heat tolerance in cereals,
to identify beneﬁcial genes and alleles, and to utilize
them in the molecular breeding programmes targeted
to produce superior cereal cultivars in the future.
Heat stress-induced decrease of the duration of de-
velopmental phases leading to fewer organs, smaller
organs, reduced light perception over the shortened
life cycle, and perturbation of the processes related
to carbon assimilation (transpiration, photosynthesis
and respiration) are most signiﬁcant for losses in
cereal yields (Stone, 2001). In this review, we sum-
marize the current knowledge of genetic basis and
molecular mechanisms of heat tolerance in cereals.
Cereals hereby include cultivated species belonging
to the genera oats (Avena), barley (Hordeum), mil-
let (Pennisetum), rice (Oryza), rye (Secale), sorghum
(Sorghum), wheat (Triticum)andmaize(Zea). Where
relevant, data obtained on other species are discussed.
Furthermore, we outline major avenues for improve-
ment of high-temperature tolerance in cereals, in terms
of both yield and quality, by conventional breeding or
molecular genetic modiﬁcation.
Genetics of thermotolerance
Heat tolerance is not controlled by a single ‘ther-
motolerant’ gene in cereals. Different components of
tolerance determined by different sets of genes are
critical for heat tolerance at different stages of the
life cycle and in various tissues. Quantitative trait loci
analysis, correlation and co-segregation approaches,