A CA.40-KDA MAIZE (ZEA-MAYS L.) EMBRYO DEHYDRIN IS ENCODED BY THE DHN2 LOCUS ON CHROMOSOME-9

Dehydrins (LEA D11 proteins) are the products of multigene families in a number of higher plants [5]. To date, however, only one dehydrin lo cus, dhn1 (a major embryo and drought-induced protein of ca. 18 kDa) h as been placed on chromosome 6L of the genetic linkage map of maize. T he presence of a larger, ca. 40 kDa embryo protein that is also specif ically detected by anti-dehydrin antibodies had been observed in some maize inbreds, including B73, suggesting that other dhn loci may exist . The ca. 22 kDa and ca. 40 kDa immunopositive proteins were purified from B73 and their amino acid compositions determined. The two protein s' amino acid compositions are typical of dehydrins, yet they differ f rom each other, indicating that they are distinct dhn gene products. D ifferent size alleles for both proteins, or presence/absence in the ca se of the ca. 40 kDa protein, were evident from comparisons of embryo proteins of various maize inbreds. Analysis of segregating Fz progeny derived from self-pollination of Fl hybrids from four crosses (B73 x O H43, Mo17 x A632, AHO x A632, Latente x A632) revealed that alleles of the two genes assort independently. Map positions of the two dhn loci were then determined using two maize recombinant inbred line (Rn) map ping populations. The predicted map position of the gene controlling p roduction of the ca. 22 kDa protein confirmed that this protein is the product of the dhn1 gene. The gene encoding the ca. 40 kDa dehydrin-l ike protein maps to a new locus on chromosome 9S near wx1, which we ha ve named dhn2.