High photosynthetic capability observed in the wheat germplasm with rye chromosomes

Improving photosynthetic capability is one of the most important factors for increasing wheat yield potential. The photosynthetic capability of wheat germplasm with different alien chromosomes was investigated and compared with bread wheat cultivars (BC) in this study, including wheat addition lines (CA), hexaploid triticale (HT), octoploid triticale (OT), and synthetic hexaploid wheat lines (SHW). Results indicated that HT, OT, and SHW produced significantly higher biomass plant-1(BMPP), with HT displaying the highest grain yield plant-1 (GYPP). Distinct superiority of net photosynthetic rate (Pn) and carboxylation activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) was observed in HT and OT. Meanwhile, OT showed the highest expression of the Rubisco large subunit gene (rbcL) in the flag leaves at heading and grain-filling stages, though the coding region of rbcL was highly conserved in all investigated materials. Further analysis indicated that OT and Chinese Spring-rye disomic addition lines displayed higher expression of Rubisco small subunit gene (rbcS). Correlation analysis revealed significant and positive correlations between Pn and the expressions of rbcL (at both heading and grain-filling stages), the expression of rbcS (at heading stage), and the carboxylation activity of Rubisco (at grain-filling stage). Anatomical structure analysis of the chloroplasts showed SHW with longer chloroplasts and more chloroplast grana and grana lamella. In the present study, HT, OT, and Chinese Spring-rye disomic addition lines with rye chromosomes displayed greater photosynthetic capability than BC and SHW, and could be applied in breeding programs to improve the photosynthetic efficiency of wheat.