One of the major protective adaptations of plants in response to drought is their ability to renew proteins during drought and to repair themselves rapidly after drought, i.e. after exposure to a combination of increased temperature plus dehydration. Corn plants subjected to presowing hardening were used as a model of plants with increased drought resistance. Such plants have a more drought resistant ultrastructure and form more high-energy substances, which promote synthetic processes in them. In hardened plants,15N incorporation into proteins during and after drought proceeds at a faster rate than in control plants. Also, their ribonuclease is less active with respect to messenger RNA (ribonucleic acid), and polysome degradation into ribosomes and subunits occurs more slowly during drought. Polysomes revert to normal after drought faster in hardened than in non-hardened plants. All this explains the greater resistance of plants exposed to presowing hardening.
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