Overexpression of the ABA Synthesis Gene OsABA2 Enhances Seed Storability in Rice.

Abstract

Seed storability is critical for seed production and germplasm conservation. Numerous studies have linked seed storability to abscisic acid (ABA) metabolism; however, the use of biotechnological approaches to strategically and rapidly enhance seed storability in rice through manipulation of ABA biosynthesis genes remains unexplored. In the current study, we developed overexpression lines (OE) of OsABA2, which encodes a XANTHOXIN DEHYDROGENASE, a key enzyme in the ABA synthesis pathway. Our experimental results showed that the relative expression of OsABA2 was upregulated in response to artificial aging treatment. The germination rate of OsABA2-OE lines was significantly higher, while the electrical conductivity of the seed leachate was lower compared to the wild type (WT), indicating improved seed vigor. Following artificial aging treatments, OsABA2-OE lines exhibited less pronounced changes in storage substances such as sugars and total starch, relative to WT. Reduced diaminobenzidine (DAB) staining intensity in OsABA2-OE lines suggested lower levels of reactive oxygen species (ROS). Correspondingly, the contents of hydrogen peroxide and malondialdehyde were lower, whereas catalase activity and total antioxidant capacity were higher in OsABA2-OE lines after artificial aging treatments. Comparative transcriptome analysis further revealed that the overexpression of OsABA2 may enhance seed storability by modulating the expression of ROS scavenging genes. For practical application, Gang46B-a hybrid rice parental line with poor storability-significantly improved its post-aging germination rates. These findings demonstrate that the overexpression of OsABA2 enhances seed storability by regulating ABA biosynthesis pathway and associated oxidative response. Thus, OsABA2 represents a promising molecular target for precise improvement of seed storage traits. This approach could be utilized for the improvement of seed storability in rice and other crops, offering valuable implications for the seed industry.