Endosperm cell size reduction caused by osmotic adjustment during nighttime warming in rice

• Published in: Scientific reports 2021-02, Vol.11 (1), p.4447-4447, Article 4447
• Main Authors: Wada, Hiroshi, Chang, Fang-Yu, Hatakeyama, Yuto, Erra-Balsells, Rosa, Araki, Takuya, Nakano, Hiroshi, Nonami, Hiroshi
• Format: Article
• Language: English
• Subjects: 631/449/2661; 631/449/2661/2663; 639/638/11; Biosynthesis; Cell Size; Cell Wall - metabolism; Cell Wall - physiology; Cereal crops; Edible Grain - metabolism; Edible Grain - physiology; Endosperm; Endosperm - metabolism; Endosperm - physiology; Hot Temperature; Humanities and Social Sciences; Ionization; Mass spectrometry; Mass spectroscopy; Metabolites; Metabolomics; Metabolomics - methods; multidisciplinary; Oryza - metabolism; Oryza - physiology; Osmosis - physiology; Osmotic potential; Plant Shoots - metabolism; Plant Shoots - physiology; Rice; Ripening; Science; Science (multidisciplinary); Seeds - metabolism; Seeds - physiology; Starch; Starch - metabolism; Turgor; Water - metabolism; Water deficit
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-83870-1

High night temperature (HNT) often reduces yield in field crops. In rice, HNT during the ripening stage diminishes endosperm cell size, resulting in a considerable reduction in final kernel weight; however, little is known about the underlying mechanisms at cell level. In this study, we performed picolitre pressure-probe-electrospray-ionization mass spectrometry to directly determine metabolites in growing inner endosperm cells of intact seeds produced under HNT conditions, combining with 13 C feeding and water status measurements including in situ turgor assay. Microscopic observation in the inner zone suggested that approximately 24.2% of decrease in cell expansion rate occurred under HNT at early ripening stage, leading to a reduction in cell volume. It has been shown that HNT-treated plants were subjected to mild shoot water deficit at night and endosperm cell turgor was sustained by a decline in osmotic potential. Cell metabolomics also suggests that active solute accumulation was caused by a partial inhibition of wall and starch biosynthesis under HNT conditions. Because metabolites were detected in the single cells, it is concluded that a partial arrest of cell expansion observed in the inner endosperms was caused by osmotic adjustment at mild water deficit during HNT conditions.