Two Nucleoporin 98 homologous genes jointly participate in the regulation of starch degradation to enhance growth in Arabidopsis

Abstract

Background: Starch is synthesized during the day for temporary storage in leaves and then degraded during the subsequent night to support plant growth and development. Impairment of starch degradation leads to stunted growth, even senescence and death. The nuclear pore complex is involved in many cellular processes, but its relationship with starch degradation is unclear until now. We previously identified two Nucleoporin98 ( Nup98 ) genes ( Nup98a and Nup98b ) redundantly regulated flowering through CONSTANS ( CO ) independent pathway. in Arabidopsis thaliana. The nup98a nup98b double mutant also showed severe senescence phenotypes. Results: We found that Nucleoporin 98 ( Nup98 ) participated in the regulation of sugar metabolism in leaves and in turn is involved in senescence regulation in Arabidopsis . We show that Nup98a and Nup98b redundantly function in the different steps of starch degradation, the nup98a nup98b double mutant accumulates more starch than wild type and has a severe early senescence phenotype compared to wild type. The expression of marker genes related to starch degradation was impaired in the nup98a nup98b double mutant, and indicator genes of carbon starvation and senescence expressed earlier in the nup98a nup98b double mutant than that in wild type plants, suggesting abnormality of energy metabolism was the cause of senescence of the nup98a nup98b double mutant. Addition of sucrose to the growth medium can rescue early senescence phenotype of the nup98a nup98b mutant. Conclusions: Our results provided a line of evidence on a novel role of the nuclear pore complex in energy metabolism related to growth and development, whereas Nup98 functioned in starch degradation conferring growth regulation in Arabidopsis .