LAUSR

Significance Wheat grain avenin-like proteins (ALPs) have functions for dough quality and antifungal activities. A genome-wide characterization of ALP encoding genes in bread wheat is conducted. Results showed that most ALPs are transcriptionally active in developing grains and are up-regulated upon Bgt infection. The allelic diversity of ALPs in 21 natural populations of wild emmer wheat (WEW) in Israel were studied. Many ALP allelic variations in WEW were associated with regional environmental adaption. Our findings demonstrate that the diversifying natural selection through climatic and edaphic factors was a major driving force for the allelic diversity of ALP genes. The results indicate that WEW harbors a high genetic diversity of ALPs utilizable for wheat improvement. Fifteen full-length wheat grain avenin-like protein coding genes (TaALP) were identified on chromosome arms 7AS, 4AL, and 7DS of bread wheat with each containing five genes. Besides the a- and b-type ALPs, a c type was identified in the current paper. Both a and b types have two subunits, named x and y types. The five genes on each of the three chromosome arms consisted of two x-type genes, two y-type genes, and one c-type gene. The a-type genes were typically of 520 bp in length, whereas the b types were of 850 bp in length, and the c type was of 470 bp in length. The ALP gene transcript levels were significantly up-regulated in Blumeria graminis f. sp. tritici (Bgt)-infected wheat grain caryopsis at early grain filling. Wild emmer wheat [(WEW), Triticum dicoccoides] populations were focused on in our paper to identify allelic variations of ALP genes and to study the influence of natural selection on certain alleles. Consequently, 25 alleles were identified for TdALP-bx-7AS, 13 alleles were identified for TdALP-ax-7AS, 7 alleles were identified for TdALP-ay-7AS, and 4 alleles were identified for TdALP-ax-4AL. Correlation studies on TdALP gene diversity and ecological stresses suggested that environmental factors contribute to the ALP polymorphism formation in WEW. Many allelic variants of ALPs in the endosperm of WEW are not present in bread wheat and therefore could be utilized in breeding bread wheat varieties for better quality and elite plant defense characteristics.