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 proteinTa-JA1belongs to the monocot chimeric jacalin (MCJ) family and plays a vital role in stress resistance in wheat. However, the impact of wheat polyploidization onTa-JA1remains 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 ofT. aestivumand 99 accessions ofT. dicoccoidesshowed thatTa-JA1-2AandTa-JA1were highly conserved in common wheat, and four alleles (TdJA1-Ax2,TdJA1-Ay2,TdJA1-Ax3, andTdJA1-Ay3) were detected inT. dicoccoides. Using gene-specific markers, oneAsJA1-Ballele was detected in 11Ae. speltoidesaccessions and oneTuJA1-Ax1allele was detected in 70T. urartuaccessions. 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), andTdJA1-Ay3(251 accessions). Only one allele (TdJA1-B) on chromosome 2B was detected in 415T. dicoccoidesaccessions. 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 amongTa-JA1alleles and, notably,TdJA1-Ax1andTdJA1-Ay1showed significantly higher expression levels than the other four allelic types inT. dicoccoides. The present results contribute to an improved understanding of the effects of polyploidization on the MCJ gene family and the functions ofTa-JA1, and may be useful to enrich common wheat germplasm resources.