phasing a vcf file for imputation through loimpute

Question

[analyst]

Dear scientists,

I have to perform imputation of my variants. I am following loimpute for imputation that requires input variants in mpileup format and reference phased vcf file through this command:

> loimpute -i file.mp.gz -h refpanel-phased.vcf.gz -o outputfile

To run above command I prepared mpileup files through samtools command:

> samtools mpileup file.bam | gzip -c > file.mp.gz

However I am not sure how to make this refpanel-phased vcf file for wheat.

Looking forward to your valuable suggestions.

Thanks