A novel topical spray was developed to increase resistance to both cold damage and cold mortality in plant foliage, flowers, and fruits. In environmental chamber experiments, application of the spray to monocot and dicot foliage lowered the environmental temperatures associated with the first onset of cold injury and with cold mortality from 2.2 to 9.4 °F, compared with controls sprayed with tap water, over an effective temperature range (depending on species) of ≈0 to 32 °F. The threshold temperature for flower mortality was lowered from 2.2 to 3.2 °F depending on species. Mature fruit suffered significantly less freeze damage when pretreated with the spray formulation. The spray is composed of ingredients that are non-toxic to plants, humans, and other animals. The patent-pending formulation has been commercialized under the trade name FreezePruf.

A detailed characterization of the lysine biosynthetic pathway in plants is yet to be completed. It is, however, assumed that the diaminopimelic acid pathway exists in the plant kingdom, as commonly described forEscherichia coli.Modification and refinement of lytic complementation, a technique previously utilized in bacterial systems, facilitated the isolation of a functional Diaminopimelate Dehydrogenase gene from aGlycine max nuclear gene library. The isolated gene codes for the enzyme meso-diaminopimelate dehydrogenase. The coding capacity for the enzyme was originally contained on a 6.6kb fragment in a Charon 4a soybean gene bank. Subcloning of the 6.6kb fragment resulted in the recombinant plasmid pMW75. Subsequent subcloning resulted in a 4.05 kb fragment contained in pLW14. One region of homology was observed upon hybridization to EcoR1 digested soybean DNA. Homologous sequences were also observed in Triticum DNA.Meso-diaminopimelate dehydrogenase activity was demonstrated inGlycine max embryos. Maximum enzymatic activity of the cloned enzyme was observed at a pH of 8.0. The enzyme encoded by the soybean gene has an apparent molecular weight of 67 000.

An ultrastructural study of pollen-derived plants and normal microspore development indicates that chloroplasts and mitochondria are physically altered during microsporogenesis. These changes appear to debilitate the organelle so that only chloroplasts and mitochondria of the female parent are contributed to the offspring.

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