Identification And Analysis Of New Insertion Sites For BTA In Maize

Maize is an important food and feed crop in China,and is of great importance for our food security.Transposons are an important part of the maize genome,and their jump affects gene structure and expression.Transposons are involved in the regulation of flowering,seed development,disease resistance,and resistance to abiotic stresses,and are important for plant growth and development.Previously,in a study in our laboratory,a transposon insertion into the Zm SWEET4 c gene resulted in a mutant smk with smaller maize kernels,which was named BTA(B73 active TE hAT),and 120BTA-like transposons were identified on the B73v4 genome.in the present study,by transposon probe capture,a In this study,multiple BTA and BTA-like insertion sites were identified in the self-progeny of smk by transposon probe capture,and the characteristics of the insertion sites,and the reasons for the active BTA were analyzed.The main results were as follows:1、A total of 79 new insertion loci were identified in six samples of different generations of smk self-progeny,generated by BTA and five BTA-like transposons.Thirty-eight loci were randomly selected from the 79 loci for PCR validation,and 27 insertion loci were verified as true,with an accuracy rate of 71.05%.This indicates that the new insertion sites were identified with high confidence.2、The insertion sites were found to be distributed on 10 chromosomes of maize,with BTA and five BTA-like inclined insertion gene regions,with a preference for T and G for the second and eighth base of the target site repeat sequence(TSD),respectively.in several tissues of B73,including leaves,female ears,seeds,and roots,the insertion sites showed high levels of H3K27 ac and low levels of DNA methylation compared to the flanking regions.3 、 Analysis of the annotated hAT led to the identification of a possible autonomous transposase.The transposase locus was named hAT2908 at chr6:106,095,770-106,098,809.It has an 8 bp target site repeat sequence,its TIR is highly matched to that of BTA,and its internal sequence is highly similar to that of BTA.This autonomous transposon was found to be capable of expression and translation by RNA-seq and Ribo-seq analysis.Its gene structure and protein structure were predicted by RNA-seq,and its amino acid sequence was compared with that of classical hAT transposase(Hobo,Ac,Tam3),which has a conserved structural domain of hAT transposase and key amino acids essential for transposase activity.Analysis of genome-wide DNA methylation sequencing data revealed that CG and CHG methylation levels of hAT2908 in smk were reduced in the first exon.