Expression of cold‐inducible genes and frost hardiness in the crown meristem of young barley (Hordeum vulgare L. cv. Igri) plants grown in different environments

The purpose of this work was to examine environmental control of expression, at the mRNA level, of cold‐inducible genes and to test the relationship of the expression of the genes to cold acclimation. Barley plants (Hordeum vulgare L. cv. Igri) at the three‐ to four‐leaf stage were (a) grown in different temperature environments between 20/15°C and +4/‐4°C or (b) transferred between 20/15°C and 6/2°C or (c) grown under drought or nutrient stress conditions. Frost hardiness (using a regrowth method) and mRNA levels for three cold‐induced genes, blt4‐9, blt14 and blt101, from meristematic crown tissue (vegetative shoot meristem plus subtending stem and associated root initials) were measured. Hardiness and levels of blt4‐9, blt14 and blt101 mRNAs increased with lower growth temperatures, below a maximum inductive temperature. Prior temperature environment and plant age affected the rate of change in mRNA levels of these genes in response to a change of temperature environment. Hardiness was strongly correlated with mRNA levels of these genes in plants grown in different temperature environments. This correlation did not extend to plants exposed to drought or nutrient stresses. Implications are drawn for plant responses to a warmer climate.