Genome-Wide Identification and Analysis of <i>SUS</i> and <i>AGPase</i> Family Members in Sweet Potato: Response to Excessive Nitrogen Stress during Storage Root Formation

Abstract

(1) The development of sweet potato storage roots is impacted by nitrogen (N) levels, with excessive nitrogen often impeding development. Starch synthesis enzymes such as sucrose synthase (SUS) and ADP-glucose pyrophosphorylase (AGPase) are pivotal in this context. Although the effects of excessive nitrogen on the formation of sweet potato storage roots are well documented, the specific responses of IbSUSs and IbAGPases have not been extensively reported on. (2) Pot experiments were conducted using the sweet potato cultivar “Pushu 32” at moderate (MN, 120 kg N ha−1) and excessive nitrogen levels (EN, 240 kg N ha−1). (3) Nine IbSUS and nine IbAGPase genes were categorized into three and two distinct subgroups based on phylogenetic analysis. Excessive nitrogen significantly (p IbAGPL1, IbAGPL2, IbAGPL4, IbAGPL5, IbAGPL6, IbAGPS1, and IbAGPS2 in fibrous roots and IbSUS2, IbSUS6, IbSUS7, IbSUS8, IbSUS9, IbAGPL2, and IbAGPL4 in storage roots, and then significantly (p p IbAGPL3, which was strongly negatively correlated with the number and weight of storage roots per plant. (4) IbAGPL3 may be a key gene in the response to excessive nitrogen stress and modifying starch synthesis in sweet potato.

Keywords

• excessive nitrogen stress
• sweet potato
• storage root
• starch synthesis
• <i>IbAGPL3</i>