Current Progress in Understanding and Recovering the Wheat Genes Lost in Evolution and Domestication

Abstract

The modern cultivated wheat has passed a long evolution involving origin of wild emmer (WEM), development of cultivated emmer, formation of spelt wheat and finally establishment of modern bread wheat and durum wheat. During this evolutionary process, rapid alterations and sporadic changes in wheat genome took place, due to hybridization, polyploidization, domestication, and mutation. This has resulted in some modifications and a high level of gene loss. As a result, the modern cultivated wheat does not contain all genes of their progenitors. These lost genes are novel for modern wheat improvement. Exploring wild progenitor for genetic variation of important traits is directly beneficial for wheat breeding. WEM wheat (Triticum dicoccoides) is a great genetic resource with huge diversity for traits. Few genes and quantitative trait loci (QTL) for agronomic, quantitative, biotic and abiotic stress-related traits have already been mapped from WEM. This resource can be utilized for modern wheat improvement by integrating identified genes or QTLs through breeding.

Identification and Characterization of PLATZ Transcription Factors in Wheat

“…This suggests that homologous genes on the B genome may be absent or become pseudogenes in the lineage leading to wheat [ 31 ]. During the evolutionary process of wheat, rapid alterations and sporadic changes in wheat genome took place due to hybridization, polyploidization, domestication, and mutation, resulting in some modifications and a high level of gene loss [ 32 ]. Previous reports have stated that the preferential retention of dosage-sensitive genes (e.g., regulatory genes such as transcription factors) and gene loss following WGDs played a significant role in the evolution of eukaryotes [ 33 ].…”

Potential of Wild Relatives of Wheat: Ideal Genetic Resources for Future Breeding Programs

“…Evolution in the genus Triticum and the origin of cultivated wheat [9] Genome symbols and plasma types in the wheat group [10] Cytogenetics of wheat and its close wild relatives-Triticum and Aegilops [11] Genome symbols in the Triticeae (Poaceae) [12] Phylogenetic relationships of Triticum and Aegilops and evidence for the origin of the A, B, and D genomes of common wheat (Triticum aestivum) [13] Evolution of domesticated bread wheat [14] Wheat domestication: Lessons for the future [15] Distinguishing wild and domestic wheat and barley spikelets from early Holocene sites in the Near East [16] Emergence of agriculture in the foothills of the Zagros mountains of Iran [17] On the Identification of domesticated Emmer wheat, Triticum turgidum subsp. dicoccum (Poaceae), in the Aceramic Neolithic of the Fertile Crescent [18] DArTseq-based analysis of genomic relationships among species of tribe Triticeae [19] Domestication and crop evolution of wheat and barley: Genes, genomics, and future directions [20] Bread wheat: a role model for plant domestication and breeding [21] Roadmap for accelerated domestication of an emerging perennial grain crop [22] Current progress in understanding and recovering the wheat genes lost in evolution and domestication [23] Although phylogenetic relationships among wild relatives of wheat have been extensively reviewed by many researchers e.g., [24], we report here an information flow diagram for the trend of wheat domestication (Figure 2). This diagram shows wheat's evolution process and a general viewpoint of relationships among the close relatives of common wheat, which descended from a 3 million-year-old common ancestor and gave rise to the Aegilops and Triticum taxa [25].…”

Improvement and Re-Evolution of Tetraploid Wheat for Global Environmental Challenge and Diversity Consumption Demand

“…Tetraploid wheat is constituted by two groups: Timopheevi group wheat (Triticum timopheevi Zhuk., 2n = 4x = 28, A u A u B sp B sp /A u A u GG) and Turgidum group wheat (Triticum turgidum L., 2n = 4x = 28, A u A u BB) (Table 1), according to the Biosystematics of Triticeae updated by Yen and Yang [17]. The origin of allotetraploid wheat can be traced back to presumably 0.3-0.5 million years before present (BP) in or near the oak-pistachio woodland belt, also called Near Eastern Fertile Crescent (Figure 1) [29][30][31]. Wild emmer wheat (T. turgidum var.…”

“…The donor of the A-genome for all tetraploid and hexaploid wheat was proposed to be another wild einkorn wheat Triticum boeoticum (Triticum monococcum ssp. aegilopoides, 2n = 2x = 14, A b A b ), the ancestor of cultivated einkorn Triticum monococcum (2n = 2x = 14, A m A m ), according to the early cytogenetic investigation, whereas it was proved to be the T. urartu later [31][32][33][35][36][37][38][39]. Although the origin of the B genome is still uncertain, immense geographical, morphological, cytological, genetic, biochemical, and molecular evidence has been accumulated, suggesting Aegilops speltoides (SS) as the contributor of the B genome [17,34,[40][41][42][43][44].…”