To explore the molecular mechanism underlying the response of Camellia huana to low-phosphorus stress, transcriptome sequencing was carried out, and the genome-wide responses of plants under different durations (0 days, 15 days, and 30 days) of low-phosphorus stress were analyzed. The sequencing results were validated by qRT‒PCR and analyses of related physiological and biochemical parameters. Compared with those in the control group (CK, 0 days), 426/802 and 861/1678 genes were up- and downregulated in the 15 day (15D) and 30 day (30D) groups. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed sugar and energy metabolism, cytomembrane lipid metabolism and hormone metabolism pathways were enriched in most of these differentially expressed genes (DEGs). The expression levels of genes involved in sugar metabolism, except for AGP (ADP pyrophosphorylase) and GBSS (granule-bound starch synthase), generally increased, especially those of β-amylase and SP, indicating that the starch source of Camellia huana under low-phosphorus stress mainly depended on SP-catalyzed G-1-P. The expression of genes involved in the EMP pathway and photosynthesis was generally inhibited. Low-phosphorus-induced stress strongly affected cytomembrane lipid metabolism, resulting in the downregulation of genes involved in phospholipid metabolism and the upregulation of genes involved in sulfur lipid metabolism. Finally, stress induced the expression of genes involved in the ethylene (ETH) synthesis pathway and inhibited the expression of genes involved in auxin, abscisic acid (ABA) and methyl jasmonate (MeJA) synthesis. The qRT‒PCR results were consistent with the transcriptome sequencing results. Physiological and biochemical index analyses revealed that the levels of ATP and soluble sugars decreased gradually, while those of superoxide dismutase (SOD), glutathione S-transferase, catalase (CAT) and plant chlorophyll increased. The levels of ABA and ETH gradually increased, while those of indoleacetic acid (IAA) and MeJA decreased. The physiological and biochemical parameter analysis results were similar to those of RNA-seq and qRT‒PCR. This study investigated the molecular mechanism underlying the response of Camellia huana to low-phosphorus-induced stress and provided a theoretical basis for the subsequent widespread planting of Camellia huana in low-phosphorus soil.
Keywords Camellia huana; Low-phosphorous stress; Transcriptional sequencing; qRT‒PCR; Physiological and biochemical detection