8th INTERNATIONAL WHEAT CONFERENCE

BReedINg, PhySIoLogICAL ANd moLeCuLAR ASPeCTS
of exPReSSIoN of fReezINg ToLeRANCe IN WheAT
Mahfoozi S 1 , Sasani S. 1 Sarhadi E 2 . and Hosseini, G. 2
1 Department of Cereals Research, Seed and Plant Improvement Institute, P.O. Box 31585-
4119, Karaj, Iran
2 Agricultural Biotechnology Research Institute of Iran (ABRII), Karaj, Iran
E-mail Address of presenting author: siroosmahfoozi@yahoo.com,
Research has shown that freezing resistance (FR) in wheat is dependent upon integrated
adaptive mechanisms that include regulatory, structural and developmental genes. An
understanding of how adaptive mechanisms such as developmental, structural and regulatory
genes operate in cold hardy wheat cultivars will be useful in the design of plant
breeding and production systems for cold regions of the word. This paper reports on
the developmental regulation of FR, low-temperature –induced genes at the molecular
and plant levels, mode of gene action and the interrelationship between plant development
and accumulation pattern of carbohydrates and selection criteria for FR in wheat
(Triticum aestivum L ) cultivars grown in both field and controlled conditions. Commercially
grown most hardy, semi-hardy and non-hardy wheat cultivars along with near
isogenic lines (NILs) of wheat with different vernalization requirement and vegetative/
reproductive transition stages were planted. FR tolerance, as measured by LT50, and stage
of phenological development, as estimated from final leaf number and shoot apex developmental
morphology, were determined in controlled and in the field conditions during
the autumn and winter seasons in 2002-09. Also, a proteomic approach was applied to
study the molecular responses of hardy and semi hardy cultivars to freezing stress. Using
MALDI TOF-TOF mass spectrometry, the expression pattern of cold responsive proteins
was studied. In this paper changes in abundance and the appearance of novel cold-induced
proteins and the expression pattern of cold responsive proteins are discussed during
the vegetative/reproductive transition in very hardy and semi-hardy cultivars. Morphological,
biochemical, and physiological characters useful in the selection for FR and
the influence of developmental traits on expression of FR and accumulation of sugars and
water content are reported. The results present the evidence of close links between the
up-regulation of FR genes and developmental traits in wheat. Based on the observations,
breeding strategies are suggested for improvement of FR in wheat developed for regions
with both long mild winters, like the cold areas of Iran, and a high level of freezing stress,
like many parts of the northern hemisphere.
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