Glutamate promotes sweet potato storage root swelling by enhancing starch accumulation

摘要

Storage root (SR) development is a crucial factor for producing high yields of sweet potato. To elucidate the mechanisms of SR development, we examined different glutamate (Glu) contents using pot experiments. The Glu acts as an efficient indicator of plant root size and provides a measurable and controllable factor for exploring plant root growth. The present study aimed to evaluate the effects of 0.5, 1.0, 3.0 and 5.0 mM Glu on sweet potato swelling and starch metabolic pathways in the Sushu-16 variety. Then, morphological observations were conducted and physiological characterizations, including starch, sucrose and hormone contents were measured under the different Glu concentrations. RNA-seq was used for gene expression studies in SRs and validated using RT-qPCR. The latter confirmed that starch metabolism was up-regulated and that Glu applications increased the starch content in SR, which enhanced SR swelling. Glu, especially 3 mM Glu, enhanced SR production and starch biosynthesis in sweet potato. These results increased the understanding of the molecular physiology of SR formation in sweet potato and highlighted the future prospects for SR swelling through Glu applications.