title: Evolution of physiological responses to salt stress in hexaploid wheat.
abstract: Hexaploid bread wheat (Triticum aestivum L., genome BBAADD) is generally more salt tolerant than its tetraploid wheat progenitor (Triticum turgidum L.). However, little is known about the physiological basis of this trait or about the relative contributions of allohexaploidization and subsequent evolutionary genetic changes on the trait development. Here, we compared the salt tolerance of a synthetic allohexaploid wheat (neo-6x) with its tetraploid (T. turgidum; BBAA) and diploid (Aegilops tauschii; DD) parents, as well as a natural hexaploid bread wheat (nat-6x). We studied 92 morphophysiological traits and analyzed homeologous gene expression of a major salt-tolerance gene High-Affinity K(+) Transporter 1;5 (HKT1;5). We observed that under salt stress, neo-6x exhibited higher fitness than both of its parental genotypes due to inheritance of favorable traits like higher germination rate from the 4x parent and the stronger root Na(+) retention capacity from the 2x parent. Moreover, expression of the D-subgenome HKT1;5 homeolog, which is responsible for Na(+) removal from the xylem vessels, showed an immediate transcriptional reprogramming following allohexaploidization, i.e., from constitutive high basal expression in Ae. tauschii (2x) to salt-induced expression in neo-6x. This phenomenon was also witnessed in the nat-6x. An integrated analysis of 92 traits showed that, under salt-stress conditions, neo-6x resembled more closely the 2x than the 4x parent, suggesting that the salt stress induces enhanced expressivity of the D-subgenome homeologs in the synthetic hexaploid wheat. Collectively, the results suggest that condition-dependent functionalization of the subgenomes might have contributed to the wide-ranging adaptability of natural hexaploid wheat.
authors: Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun 130024, China;
authors: Chunwu
authors: C
authors: Yang
authors: Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun 130024, China;
authors: Long
authors: L
authors: Zhao
authors: Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun 130024, China;
authors: Huakun
authors: H
authors: Zhang
authors: Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun 130024, China;
authors: Zongze
authors: Z
authors: Yang
authors: Department of Agronomy, Jilin Agricultural University, Changchun 130118, China; and.
authors: Huan
authors: H
authors: Wang
authors: Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun 130024, China;Department of Crop and Soil Sciences.
authors: Shanshan
authors: S
authors: Wen
authors: Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun 130024, China;
authors: Chunyu
authors: C
authors: Zhang
authors: Department of Crop and Soil Sciences,School of Molecular Biosciences, andCenter for Reproductive Biology, Washington State University, Pullman, WA 99164 diter@wsu.edu baoliu@nenu.edu.cn rustgi@wsu.edu.
authors: Sachin
authors: S
authors: Rustgi
authors: Department of Crop and Soil Sciences,School of Molecular Biosciences, andCenter for Reproductive Biology, Washington State University, Pullman, WA 99164 diter@wsu.edu baoliu@nenu.edu.cn rustgi@wsu.edu.
authors: Diter
authors: D
authors: von Wettstein
authors: Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun 130024, China; diter@wsu.edu baoliu@nenu.edu.cn rustgi@wsu.edu.
authors: Bao
authors: B
authors: Liu
mesh_terms: D032461:Chromosomes, Plant / Q000235:genetics; D004171:Diploidy; D019143:Evolution, Molecular; D056084:Genetic Fitness; D018745:Genome, Plant; D009584:Nitrogen / Q000378:metabolism; D009997:Osmotic Pressure; D010788:Photosynthesis / Q000235:genetics; D011123:Polyploidy; D054712:Salinity; D055049:Salt Tolerance / Q000235:genetics* / Q000502:physiology*; D012964:Sodium / Q000378:metabolism; D057891:Tetraploidy; D014908:Triticum / Q000235:genetics* / Q000502:physiology*
chemical_list: D012964:Sodium; D009584:Nitrogen
keywords: Na+ homeostasis; salinity tolerance; transcriptional rewiring