Degree
Doctor of Philosophy (PhD)
Department
School of Plant, Environmental, and Soil Sciences
Document Type
Dissertation
Abstract
Nitrogen (N) and phosphorus (P) are essential macronutrients required by plants for normal growth and development. In sweetpotato [Ipomoea batatas (L.) Lam.], these nutrients are the most limiting factors affecting both yield quality and quantity. While most research focuses on agronomic responses and genomic analyses, limited research has examined transcriptomic responses to nutrient stress in sweetpotato. Here, we employed next-generation sequencing to investigate the molecular mechanisms underlying N and P deficiency responses in cultivar 'Bayou Belle' (BB). We utilized root tip tissue and investigated responses during the critical stage of root development and storage root formation at 5, 10, and 15 days after planting (DAP). To the best of our knowledge, this represents the first transcriptome-wide study on N deficiency responses in sweetpotato. Our results show that BB exhibits distinct early (5 DAP) and sustained late (10–15 DAP) gene expression patterns. BB prioritizes nitrogen remobilization through early NRT2.7 activation while demonstrating preferential ammonium-based metabolism, with ammonium transporters and assimilation enzyme, upregulated at all timepoints. In contrast, nitrate assimilation enzymes were suppressed across timepoints. Notably, copper amine oxidases were upregulated, providing ROS-mediated stress tolerance and internal ammonium sources. Enhanced alanine, aspartate, and glutamate metabolism at 10–15 DAP was also observed. Under low P conditions, BB demonstrates time-specific regulation of P transport with initial sensing and recognition occurring at 5 DAP and upregulation of transporters at 10-15 DAP. Root architectural attributes remained comparable to P-sufficient plants despite significant height reduction. BB also employed phosphate-scavenging strategies through purple acid phosphatases and aluminum-activated malate transporter at 10–15 DAP. Further analysis of phosphate starvation-responsive genes among sweetpotato cultivars reveals cultivar-specific gene expression changes, highlighting differences in Pi response. Collectively, these results demonstrate that sweetpotato employs coordinated, stage- and cultivar-specific transcriptional responses to manage N and P deficiencies. Understanding these molecular strategies provides a foundation for developing nutrient-efficient cultivars and optimizing fertilizer recommendations, while achieving economic yields.
Date
10-29-2025
Recommended Citation
Arce, Lisa I., "Transcriptome and Gene Expression Profiling of Sweetpotato Responses to Nitrogen and Phosphorus Deficiency During Storage Root Formation" (2025). LSU Doctoral Dissertations. 6914.
https://repository.lsu.edu/gradschool_dissertations/6914
Committee Chair
La Bonte, Don
Included in
Agricultural Science Commons, Bioinformatics Commons, Molecular Genetics Commons, Plant Breeding and Genetics Commons