Mitochondrial Respiration and Redox Metabolism in Vegetative and Generative Organs of Winter and Spring Wheat at Booting and Anthesis

Wheat (Triticum aestivum L.) is one of the world’s key grain crops. In cereals such as wheat, energy metabolism drives growth, development, and stress resistance, and is therefore central to crop productivity. The relevance of this work is due to the critical role of respiratory metabolism in ensuring wheat productivity during the reproductive period and the lack of data on the adult plant respiration during this period. The present study aimed to compare mitochondrial respiration and the associated parameters of redox metabolism in the vegetative and generative organs of winter (‘Irkutskaya’) and spring (‘Novosibirskaya 29’) wheat at the booting and anthesis stages. The study was conducted using vegetative (flag and sub-flag leaves, FL and SFL) and generative (spikes, Sp) organs. At the booting stage and compared to Sp, FL and SFL of both wheat varieties exhibited higher H2O2 and MDA levels and greater antioxidant enzyme activity, but lower water-soluble carbohydrate contents and mitochondrial respiration rates. Mitochondria from inflorescences were found to have higher respiration rates, a predominant contribution of the cytochrome pathway, and a high degree of coupling between oxidation and phosphorylation processes. The high activity of alternative oxidase in leaves, together with the high abundance of alternative NAD(P)H dehydrogenase (NDs-II) proteins, indicates an important role of mitochondrial energy-dissipating systems in green leaves during inflorescence development and anthesis. In general, wheat inflorescences are characterized by higher mitochondrial activity then wheat vegetative organs, especially during the booting stage. During the transition to anthesis, respiratory and redox metabolism parameters in inflorescences converge with those of leaves, possible due to a slowdown in growth processes and preparation for grain formation and filling.