Comparative metabolomic analysis of seed metabolites associated with seed storability in rice (Oryza sativa L.) during natural aging.

Seed storability is an important trait for crop breeding, however, the mechanism underlying seed storability remains largely unknown. Here, a mass spectrometry-based comparative metabolomic study was performed for rice seeds before and after 24-month natural storage between two hybrid rice cultivars, IIYou 998 (IIY) with low storability and BoYou 998 (BY) with relative high storability. A total of 48 metabolites among 90 metabolite peaks detected were conclusively identified, and most of them are involved in the primary metabolism. During the 24-month storage, 19 metabolites with significant changes in abundance were found in the storage-sensitive IIY seeds, but only 8 in the BY seeds, most of which are free amino acids and soluble sugars. The observed changes of the metabolites in IIY seeds that are consistent with our protoemics results are likely to be involved in its sensitivity to storage. Levels of all identified 18 amino acid-related metabolites and most sugar-related metabolites were significantly higher in IIY seeds both before and after storage. However the level of raffinose was lower in IIY seeds before and after storage, and did not change significantly throughout the storage period in both two cultivars, suggesting its potential role in seed storability. Taken together, these results may help to improve our understanding of seed storability.