Abstract
Potato tuber yields depend on nitrogen (N) supply, which affects source–sink relations. Transcriptome sequencing of the foliar source using a single field trial identified gene expression responsive to 180 kg N ha−1. The expression of N-responsive genes was further analyzed in the next stage using a NanoString nCounter over an expanded number of foliar samples from seven field trials with varying N rates, sites, and cultivars. Least absolute shrinkage and selection operator (LASSO) regression models of gene expression predictive of yield, total plant N uptake, and tuber-specific gravity (proxy for dry matter) were built. Genes in the LASSO model for yield were associated with source–sink partitioning. A key gene regulating tuberization and senescence, StSP6A Flowering locus T, was found in the LASSO model predicting tuber yield, but not the other models. An aminotransferase involved in photorespiratory N assimilation and amino acid biosynthesis was found in all LASSO models. Other genes functioning in amino acid biosynthesis and integration of sulfur (S) and N metabolism were also found in the yield prediction model. The study provides insights on N responses in foliage of potato plants that affect source–sink partitioning. Additionally, N-responsive genes predictive of yield are candidate indicators of N status.
Highlights
Tubers are underground starch-storage extensions from the stem, which are used for vegetative propagation and are the major sink organ of the potato (Solanum tuberosum L.)
To better understand source responses to N that affect sink development, the current study examined gene expression in source tissue mid-season to find N-responsive biological processes associated with tuber yield
Leaves were sampled for gene expression between 42 and 50 days after planting (DAP) from the seven trials, which was coordinated with the timing of a second application of N in split N fertilization (Table 1) [6]
Summary
Tubers are underground starch-storage extensions from the stem, which are used for vegetative propagation and are the major sink organ of the potato (Solanum tuberosum L.). Agronomy 2020, 10, 1617 on radiation intercepted by leaves and is responsive to N fertilization [1]. Increasing N supply increases plant canopy development, which increases radiation reception leading to increases in photosynthates used for tuber production [2,3,4]. Sub-optimal N supply leads to growth retardation and low tuber yield and quality. Application of N in excess of the plant’s N requirement can contribute to environmental pollution, nitrate leaching to groundwater and emissions of nitrous oxide, a greenhouse gas [5]. High N rates can result in decreased tuber quality [6,7]
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