Polyploidization affects the allelic variation of jasmonate-regulated protein Ta-JA1 belonging to the monocot chimeric jacalin (MCJ) family in wild emmer wheat.

The jasmonate-regulated protein Ta-JA1 belongs to the monocot chimeric jacalin (MCJ) family and plays a vital role in stress resistance in wheat. However, the impact of wheat polyploidization on Ta-JA1 remains unclear. In this study, 149 members of the MCJ family were identified among members of Triticeae using a genome-wide approach. The genes were resolved into three clades; MCJ genes in each clade were derived from different donor genes during evolution. Segmental duplication may have been the primary driver, compared with tandem duplication, of expansion in the MCJ family of wheat. Gene loss and acquisition occurred during tetraploidization, and the core expansion of the family occurred after tetraploidization. Sequencing data for 2104 accessions of T. aestivum and 99 accessions of T. dicoccoides showed that Ta-JA1-2A and Ta-JA1 were highly conserved in common wheat, and four alleles (TdJA1-Ax2, TdJA1-Ay2, TdJA1-Ax3, and TdJA1-Ay3) were detected in T. dicoccoides. Using gene-specific markers, one AsJA1-B allele was detected in 11 Ae. speltoides accessions and one TuJA1-Ax1 allele was detected in 70 T. urartu accessions. Six alleles were detected on chromosome 2A: TdJA1-Ax1 (13 accessions), TdJA1-Ay1 (57 accessions), TdJA1-Ax2 (23 accessions), TdJA1-Ay2 (42 accessions), TdJA1-Ax3 (29 accessions), and TdJA1-Ay3 (251 accessions). Only one allele (TdJA1-B) on chromosome 2B was detected in 415 T. dicoccoides accessions. A geographical distribution analysis revealed that Israel hosted higher allelic variation than other regions. Quantitative reverse transcription PCR analysis indicated that divergence in expression has occurred among Ta-JA1 alleles and, notably, TdJA1-Ax1 and TdJA1-Ay1 showed significantly higher expression levels than the other four allelic types in T. dicoccoides. The present results contribute to an improved understanding of the effects of polyploidization on the MCJ gene family and the functions of Ta-JA1, and may be useful to enrich common wheat germplasm resources.