Abstract
The vigor of tea plants (Camellia sinensis) and tea quality are strongly influenced by the abundance and forms of nitrogen, principally NO3−, NH4+, and amino acids. Mechanisms to access different nitrogen sources and the regulatory cues remain largely elusive in tea plants. A transcriptome analysis was performed to categorize differentially expressed genes (DEGs) in roots and young leaves during the early response to four nitrogen treatments. Relative to the continuously nitrogen-replete control, the three nitrogen-deprived and resupplied treatments shared 237 DEGs in the shoots and 21 DEGs in the root. Gene-ontology characterization revealed that transcripts encoding genes predicted to participate in nitrogen uptake, assimilation, and translocation were among the most differentially expressed after exposure to the different nitrogen regimes. Because of its high transcript level regardless of nitrogen condition, a putative amino acid transporter, TEA020444/CsCAT9.1, was further characterized in Arabidopsis and found to mediate the acquisition of a broad spectrum of amino acids, suggesting a role in amino acid uptake, transport, and deposition in sinks as an internal reservoir. Our results enhance our understanding of nitrogen-regulated transcript level patterns in tea plants and pinpoint candidate genes that function in nitrogen transport and metabolism, allowing tea plants to adjust to variable nitrogen environments.
Highlights
Increasing agricultural production has been achieved mainly by the application of a dramatic increase of nitrogen (N)-containing fertilizers, as well as by the breeding of high-yielding crops along with improved agronomic practices [1,2,3]
Transcriptome Analysis Overview Based on PacBio RSII and next-generation sequencing-based RNA-Seq (NGS)
To identify transcripts for PacBio RSII, an equal amount of high-quality RNA was pooled from sixteen individual samples of two organ types, bud with two young leaves and newly developed white roots, from the four different N treatments
Summary
Increasing agricultural production has been achieved mainly by the application of a dramatic increase of nitrogen (N)-containing fertilizers, as well as by the breeding of high-yielding crops along with improved agronomic practices [1,2,3]. Plants 2020, 9, 1218 serious concerns of environmental damage to the soil and to water pollution [6]. The necessity of lowering fertilizer requirement and better N use efficiency (NUE) breeding has been recognized and strengthened as long-standing goals within the plant production sector [7,8,9]. While inorganic-N forms are predominant in most agricultural soils, organic-N forms dominate in specific habitats such as forest, meadows, and organic agricultural ecosystems [12]. It was previously shown that amino acid-N is vital to plants even with nitrate and ammonium supply [13]
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