Progress of Research on Phytohormone Interaction in Germination of Direct-Seeded Rice under Submergence

Abstract

Due to rainfall, closed weeding of paddy fields and other reasons, submergence stress often occurs during the germination and emergence stages of direct-seeded rice (Oryza sativa L.), which leads to intensified anaerobic respiration, accelerated consumption of stored nutrients, difficulty in germination of rice seeds, uneven emergence of seedlings and varying yields. Recent advances in the understanding of phytohormone interaction and the regulation of signaling pathways in crops have increased the feasibility of modulating responses to phytohormones in crop plants to enhance adaptation to environmental changes. In this review, we summarize recent advances and progress in the understanding of the regulation of phytohormone signaling pathways and their interactions with diverse internal and external signaling cues under submergence. We also discuss how these physiological modulations of phytohormones and their abundant signaling crosstalk can be applied to enhance the submergence tolerance of direct-seeded rice during germination through the manipulation of seedling morphogenesis and the fine-tuning of stress responses. Finally, we discuss how complex phytohormone signaling pathways could regulate the metabolism of stored nutrients, anaerobic respiration and energy supply in submerged direct-seeded rice seeds, thereby improving their submergence tolerance. This review hopes to provide a basis for studies of the tolerance mechanisms of submerged direct-seeded rice and the promotion of the simplified direct-seeded rice cultivation model.