ENO2 Affects the Seed Size and Weight by Adjusting Cytokinin Content and Forming ENO2-bZIP75 Complex in Arabidopsis thaliana

Abstract

<i>Arabidopsis thaliana ENO2</i> (<i>AtENO2</i>) encodes two proteins AtENO2 (enolase) and AtMBP-1 (c-Myc binding protein 1-like). The loss of <i>AtENO2</i> function causes the constitutive developmental defects which are correlated with reduced enolase activity, but not AtMBP-1 transcript abundance. However, the regulation mechanism of <i>AtENO2</i> on the seed properties is still not clear. In this study, we found that the mutation of <i>AtENO2</i> reduced the seed size and weight. The level of glucose in seed was significantly elevated but that of starch was decreased in <i>AtENO2</i> mutants compared to WT plants. We also found that <i>AtENO2</i> mutation reduced the content of cytokinin which resulted in smaller cotyledons. The RNA-seq data showed that there were 1892 differentially expressed genes and secondary metabolic pathways were significantly enriched. Instead of AtMBP-1, AtENO2 protein interacted with AtbZIP75 which may mediate the secondary metabolism. Therefore, <i>ENO2</i> alters the size and weight of seeds which is not only regulated by the content of cytokinin and secondary metabolism, but may be affected by the interaction of ENO2 and bZIP57. These results are helpful to understand the novel function of <i>AtENO2</i> which provide a foundation for further exploration of the key candidate genes for crop breeding.