L. Charbonnel-campaa et al., Isolation of a type 2 metallothionein-like gene preferentially expressed in the tapetum in Zea mays, GENE, 254(1-2), 2000, pp. 199-208
A Zea mays cDNA, MZm3-4, was isolated by differential screening of a cDNA l
ibrary obtained from meiotic stage anthers against a cDNA of 3-week-old see
dlings. Northern blot analysis of RNA from different maize tissues and from
male reproductive organs at various developmental stages demonstrated expr
ession of a single transcript in anthers, from the pollen mother cell stage
through the uninucleated microspore stage. In situ hybridization to anther
sections resulted in a distinct signal only in the tapetum. The MZm3-4 cDN
A is 743 nucleotides in length and has an open reading frame encoding a pro
tein of 75 amino acids. Sequence comparisons with various databases reveale
d that MZm3-4 exhibits high similarities with type 2 plant metallothioneins
at both the nucleotide and the amino-acid level. Primer extension analysis
indicated that MZm3-4 cDNA is deleted of 13 bp at the 5' end. Southern blo
t analysis showed that the MZm3-4 gene may be present in one or two copies
in a Z. mays inbred line genome. This is the first report of the isolation
of a type 2 metallothionein-like protein in maize. Moreover, the expression
of this type 2 metallothionein-like gene is high in the male reproductive
organs engaged in microsporogenesis. (C) 2000 Elsevier Science B.V. All rig
hts reserved.