Altered sucrose metabolism and gene regulation in wheat (Triticum aestivum) K-type cytoplasmic male sterility

Abstract

K-Type cytoplasmic male sterility (K-CMS) plays an important role in breeding hybrid wheat. This study was designed to investigate the association of sucrose metabolism with K-CMS in wheat (Triticum aestivum L.) anthers at the binucleate stage. Levels of sucrose in the anthers of the K-CMS line remained higher than in the fertile line, but glucose and fructose contents in the anthers of the K-CMS line were dramatically lower than in the fertile line. Compared with the fertile line, the activities of cell-wall-bound invertase (CWIN), neutral invertase and vacuolar invertase (VIN) were significantly reduced. Quantitative real-time polymerase chain reaction analyses showed that the expression levels of one CWIN gene (IVR1), one VIN gene (IVR5) and a sucrose transporter gene (TaSUT1) were significantly downregulated in K-CMS anthers. Furthermore, western blot confirmed that the protein expression level of IVR1 was higher in sterile anthers than in male fertile anthers. Thus, it appears that the accumulation of sucrose in K-CMS anthers might involve a decrease in activity and a reduction in content of invertase. In conclusion, the results suggest that an inability to metabolise incoming sucrose to hexoses may be involved in the K-CMS pollen-developmental lesion.