Characterization of a novel Wx-A1b′ null allele and PCR markers for allele identification at three Wx loci

Wu, Lijuan and Yang, Zaijun and Wang, Junqiang and Shen, Shian and Yan, Zehong and Hu, Xinkun (2023) Characterization of a novel Wx-A1b′ null allele and PCR markers for allele identification at three Wx loci. CEREAL RESEARCH COMMUNICATIONS, 51 (4). pp. 859-866. ISSN 0133-3720 (print), 1788-9170 (online)

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Abstract

Amylose synthesis needs the important enzyme granule-bound starch synthase I (Wx protein), and mutants with a complete or partial lack of the Wx protein result in waxy or partial waxy wheat. In this study, a novel Wx-A1b′ null allele was identified from a waxy wheat variety Miannuomai 829. The 19 bp InDel of Wx-A1b was also detected at the junction of the first exon and the first intron of Wx-A1b′, and a non-synonymous substitution from G to T at position 2,041 bp of the eighth exon was identified between Wx-A1b′ and Wx-A1b, which resulted in Glu being replaced by a stop codon. By amplifying the flanking sequence, the Wx-B1 of Miannuomai 829 was confirmed to be completely deleted, and the Wx-D1 of Miannuomai 829 was Wx-D1b based on pedigree analysis. Phylogenetic analysis suggested that the Wx-A1b′ allele was more closely related to Wx-A1a′ and Wx-A1d of tetraploid wheat and evolved independently from Wx-A1a and Wx-A1c of non-waxy hexaploid wheat. A multiplex PCR-based marker simultaneously valid for null and normal alleles of Wx-A1 and Wx-D1 and a codominant marker for discriminating the null and normal alleles of Wx-B1 were developed. These two markers were verified in 22 F2:3 family lines from the Miannuomai 829/Chuanmai 68 cross. The results showed that these two markers can be used in breeding for waxy characteristics in wheat.

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