Differential Expression of Durum Wheat Gluten Proteome under Water Stress during Grain Filling.

Environmental stress during grain filling may affect wheat protein composition, thus influencing its final quality. A proteomic approach was used to evaluate changes in storage protein composition under water stress of two Italian durum wheat (Triticum turgidum ssp. durum) cultivars, Ciccio and Svevo. The high-molecular-weight glutenin region increased progressively in both cultivars and under two water regimens. The L48-35 region, corresponding to low-molecular-weight (LMW) glutenin subunits, increased slightly during grain development and decreased under water stress in both cultivars. In particular, an s-type LMW related to superior technological quality was down-expressed in the early-mid period in Svevo and in the mid-late period in Ciccio. Finally, the L<35 region, corresponding to gliadin-like proteins, decreased slightly during grain development and increased under stress in both cultivars. Several α-gliadins, associated with immunological potential, increased their expression under water stress, especially in Svevo in the early-mid stage of grain filling.

Comparative analysis of gluten proteins in three durum wheat cultivars by a proteomic approach.

The gluten protein composition and expression level influence dough properties and are cultivar and environment dependent. To broaden the knowledge of the durum wheat gluten proteome, three cultivars were compared in two different growing seasons by a proteomic approach. Cultivar-specific and differentially expressed spots in the two years were identified by mass spectrometry. Significant differences were observed among the cultivars: Ofanto showed the lowest protein spot volumes in the high molecular weight (HMW) and low molecular weight (LMW) <35,000 regions and the highest in the LMW 48,000-35,000 region, Latino the lowest in the LMW 48,000-35,000 region, and Simeto an intermediate expression level in both LMW regions. In the warmer year the up-regulation of HMW glutenins, α-gliadins, and a globulin 3 protein and the down-expression of LMW glutenins and γ-gliadins were observed. Among the cultivars, Simeto showed the highest stability across the environments.

Seawater stress applied at germination affects mitochondrial function in durum wheat (Triticum durum) early seedlings.

Seawater stress effects on mitochondrial ATP synthesis and membrane potential (ΔΨ) were investigated in germinating durum wheat seedlings under moderate (22% seawater osmolarity, -0.62 MPa) and severe (37% seawater osmolarity, -1.04 MPa) stress. To estimate the osmotic component of salt stress, mannitol solutions (0.25 and 0.42 m) iso-osmotic with the saline ones were used. Moderate stress intensity only delayed mean germination time (MGT), whereas higher seawater osmolarity reduced germination percentage as well. In contrast, Na+ and Cl- accumulation showed a sharp increase under moderate stress and only a small further increase under severe stress, which was more pronounced for Cl-. Only severe stress significantly damaged succinate-dependent oxidative phosphorylation, which may be related to the stress-induced alteration in inner mitochondrial membrane permeability, as indicated by changes in ΔΨ profiles. Proline-dependent oxidative phosphorylation, however, was inhibited under moderate stress. This suggests the occurrence of an adaptation mechanism leading to proline accumulation as an osmoprotectant. Moreover, both the osmotic and the toxic components of seawater stress were detrimental to oxidative phosphorylation. Damage to germination and MGT, in contrast, were mainly caused by osmotic stress. Therefore, mitochondrial function appears to be a more sensitive target of toxic stress than growth. In conclusion, the effects of seawater stress on mitochondrial ATP synthesis vary in relation to the substrate oxidised and stress level, inducing both adaptive responses and damage.