关键词: 榅桲, 碱胁迫, 苯丙烷生物合成代谢通路, 碳酸酐酶, 转录组分析

Abstract: To investigate the molecular mechanisms of pear dwarf rootstock quince（Cydonia oblonga）responding to NaHCO3‑induced alkaline stress，hydroponically cultivated quince seedlings were subjected to mild alkaline stress（T1）with 5 mmol/L NaHCO₃ and moderate alkaline stress（T2）with 10 mmol/L NaHCO₃，without NaHCO₃ as a control（CK）. After six weeks of treatment，chlorophyll content，net photosynthetic rate in leaves，and K⁺/Na⁺ ratios in leaves and roots were measured. Additionally，transcriptome sequencing and analysis were performed on the roots. The results showed that both chlorophyll content and net photosynthetic rate in quince leaves gradually decreased with alkaline stress increasing. Compared to CK，the chlorophyll a+b content in T1 and T2 decreased significantly by 15.71% and 45.38%，respectively，while the net photosynthetic rate decreased by 15.90% and 55.42%，respectively. The K⁺/Na⁺ ratios in leaves and roots of T1 and T2 were significantly reduced by 45.40% and 96.69%，and 92.04% and 96.32%，respectively，compared to CK.Transcriptome sequencing revealed a total of 4 974 differentially expressed genes（DEGs）between T1，T2，and CK，with T2 showing a significantly higher number of DEGs than T1.Gene ontology（GO）and Kyoto encyclopedia of genes and genomes（KEGG）pathway enrichment analyses indicated that the biological processes（BP）in T1 and T2 were mainly enriched in terms such as hydrogen peroxide catabolic process and response to wounding，while KEGG pathways were primarily enriched in phenylpropanoid biosynthesis. Gene set enrichment analysis（GSEA）showed that the phenylpropanoid biosynthesis pathway was more active under T1 and T2 compared to CK.Weighted gene co‑expression network analysis（WGCNA）revealed that the hub gene cydonia_oblonga_newGene_11700，annotated as a lignin metabolism transcription factor，was significantly induced by alkaline stress in T1.In T2，the hub genes cydonia_oblonga_newGene_11460 and cydonia_oblonga_newGene_14681，both annotated as carbonic anhydrases，were identified.The expression patterns of five selected DEGs were validated by qRT‑PCR，and the results were consistent with the RNA‑Seq analysis.In summary，quince mobilizes more genes in response to moderate alkaline stress compared to mild stress，and the lignin biosynthesis pathway and carbonic anhydrases play important roles in quince’s response to NaHCO3‑induced alkaline stress.

Key words: Cydonia oblonga, Alkaline stress, Phenylpropanoid biosynthesis pathway, Carbonic anhydrase, Transcriptomic analysis