Abstract:

In our previous study, a cDNA library to poly(A) RNA isolated from mature pollen of Zea mays L. was constructed. One cDNA fragment, designated ZM401 (Z. mays), was obtained from maize mature pollen cDNA library by differential screening and cold-plaque screening method. It was specifically or preferentially expressed in mature pollen. According to the ZM401 cDNA fragment sequence, full length of ZM401 cDNA was generated by 5'' and 3'' RACE methods. ZM401 cDNA was 1 149 bp in length. Within the full-length cDNA sequence, a clear open reading frame (ORF) was undectable by OMEGA 2.0 and DNAMAN softwares. The longest potential ORF was 269 nucleotides (791–1 060), coding 89 AA, had a poor consensus sequence for translation initiation. But it had a poly(A) tail. All these results suggested that ZM401 was one of a growing number of non-coding mRNA-like RNA transcripts that exerted their cellular functions directly as RNA. RT-PCR and Northern blotting analyses showed the ZM401 was transcribed from tetrad stage of microspore development and increased in concentration up to mature pollen, which suggested that ZM401 belongs to late gene in pollen development. Two transcripts of the ZM401 gene were detected by Northern blotting analysis (1.2 kb, 2.0 kb). Southern hybridisation showed that the ZM401 in corn was present in one or a very few copes in the maize genome.

Key words: Zea mays, pollen, non-coding RNA, 5' RACE, 3' RACE, overlapping PCR, developmental expression pattern