Alternative processing of the maize Ac transcript in Arabidopsis

Area of Science:

• Plant molecular biology
• Genetics
• Genomics

Background:

• The Ac/Ds system is a versatile maize transposable element used for genome mutagenesis in plants.
• Ac/Ds transposition frequency is notably lower in Arabidopsis thaliana compared to other dicots.
• Monocot gene transcripts can undergo alternative processing in dicot species.

Purpose of the Study:

• Investigate intron splicing and polyadenylation of maize Ac transposase pre-mRNA in Arabidopsis thaliana and other species.
• Determine the molecular basis for the low frequency of Ac/Ds transposition in Arabidopsis.
• Characterize Ac transposase transcript processing in heterologous plant systems.

Main Methods:

• Analysis of pre-mRNA splicing patterns in Arabidopsis, Nicotiana tabacum, Nicotiana plumbaginifolia, and Zea mays.
• Polyadenylation site analysis of Ac transposase transcripts.
• Northern blotting to quantify transposase transcript abundance.

Main Results:

• Alternative splicing of intron 4 in Arabidopsis generates heterogeneous full-length transposase transcripts.
• Multiple alternative polyadenylation sites (≥4) between introns 2 and 3 lead to truncated transposase transcripts in Arabidopsis.
• Truncated transposase transcripts are the most abundant message form in Arabidopsis.
• Alternative splicing and premature polyadenylation of Ac message were not observed in other examined species.

Conclusions:

• Alternative splicing and premature polyadenylation of Ac transposase pre-mRNA in Arabidopsis result in a low quantity of correctly processed transcript.
• This inefficient transcript processing is a likely contributor to the poor frequency of Ac/Ds transposition in Arabidopsis.
• Understanding heterologous transcript processing is crucial for optimizing transposable element applications in diverse plant species.