Characterization of DELLA protein family members in Populus alba × Populus glandulosa and their functional analysis in wood formation

Linxi Yang, Quanzi Li, Yingli Liu

Journal of Nanjing Forestry University (Natural Sciences Edition） ›› 0

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南京林业大学学报（自然科学版）
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Journal of Nanjing Forestry University (Natural Sciences Edition） ›› 0 DOI: 10.12302/j.issn.1000-2006.202604016

Characterization of DELLA protein family members in Populus alba × Populus glandulosa and their functional analysis in wood formation

  • Linxi Yang1, Quanzi Li2, Yingli Liu1,*
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Abstract

【Objective】The present study focuses on the systematic identification of DELLA protein family members in Populus alba × Populus glandulosa, with the purpose of exploring their roles in wood formation and clarifying the molecular pathways through which these proteins regulate secondary growth.【Method】To identify DELLA family genes across the whole genome of Populus alba × P. glandulosa, we employed HMM and Blastp tools in combination with conserved domain analysis. Phylogenetic analysis and sequence alignment were carried out to determine the classification and nomenclature of these DELLA family members. Based on the tissue-specific expression patterns of DELLA genes, key members were selected for further study. Subsequently, RNA interference (RNAi) transgenic plants targeting PagRGA and PagRGL were constructed, using either the CaMV-35S promoter or the xylem-specific PtrGT8D1 promoter for gene expression regulation. The effects of DELLA gene silencing on plant growth, cambial activity, secondary cell wall thickening, and wood composition were investigated using phenotypic observation, vibratome sectioning, scanning electron microscopy, cell wall composition analysis, and transcriptome profiling.【Result】(1) A total of nine DELLA members were identified in P. alba × P. glandulosa, which were classified into four groups: PagRGA1, PagRGA2, PagRGL1, and PagRGL2. All members contained the conserved DELLA and GRAS domains. (2) RNAi silencing of PagRGA1/2 and PagRGL1/2 significantly decreased cambial cell layers by 1-3, reduced xylem width, lowered lignin content, and RT-qPCR verification confirmed downregulated expression of lignin biosynthetic enzyme related genes. Among them, the phenotypic differences of PagRGA RNAi plants are more significant. (3) Transcriptome analysis revealed that differentially expressed genes were enriched in meristem- and cell division-related GO terms following DELLA genesilencing. Auxin-related pathways were predominantly enriched in plants driven by the CaMV-35S promoter.【Conclusion】DELLA proteins represent a critical signaling module regulating secondary growth in P. alba × P. glandulosa, and functional redundancy exists among different members. DELLA proteins coordinately regulate cambial cell division and secondary cell wall deposition by modulating the expression of relevant genes and integrating multiple hormone signals.

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P. alba × P. glandulosa / gibberellin / DELLA protein / cambium / secondary cell wall

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Linxi Yang, Quanzi Li, Yingli Liu. Characterization of DELLA protein family members in Populus alba × Populus glandulosa and their functional analysis in wood formation[J]. Journal of Nanjing Forestry University (Natural Sciences Edition）. 0 https://doi.org/10.12302/j.issn.1000-2006.202604016

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