关键词: 野生大豆, 耐低磷, GsNAC1, 根系构型, RNA-seq

Abstract:

【Objective】The productivity of acid soil crops is severely impacted by the limited availability of phosphorus. Soybean (Glycine max) is an important grain and oil crop, known for its preference for phosphorus. Phosphorus deficiency significantly affect both the yield and quality of soybean. While the NAC (NAM, ATAF1/2, CUC2) transcription factor family has been recognized for its involvement in regulating plant responses to various biotic and abiotic stresses, its role in soybean under low phosphorus stress remains largely unexplored. In this study, we focused on the low-phosphorus-tolerant wild soybean variety BW69 as our material, with the objective of cloning and analyzing the expression patterns and functions of the low-phosphorus-tolerant gene GsNAC1. This investigation lays the foundation for a deeper understanding the mechanisms behind the regulation of GsNAC1 response to low phosphorus stress. 【Method】The full-length sequence of GsNAC1 was cloned from BW69, and the characteristics of its encoded amino acid sequence were explored by bioinformatics analysis. In addition, the tissue expression patterns of GsNAC1 were examined through quantitative real-time PCR (qRT-PCR). The subcellular localization of GsNAC1 was observed using laser confocal microscopy. Furthermore, soybean genetic transformation experiments were conducted for further phenotype analysis, and RNA-seq analysis was performed to identify differentially expressed genes (DEGs) related to low phosphorus stress. 【Result】The GsNAC1 gene was successfully cloned, with a full-length coding region of 876 bp. Phylogenetic analysis showed a 62.46% sequence similarity between GsNAC1 and AtATAF1, and no difference was observed with the GmNAC1 sequence from the Williams 82 reference genome. Subcellular localization experiments further revealed that GsNAC1 was localized in the nucleus. Using qRT-PCR, it was discovered that GsNAC1 is expressed in roots, stems, leaves, apes, flowers and pods, with the highest relative expression level found in the roots. Notably, GsNAC1 exhibited significant upregulation in response to low pH and low phosphorus conditions. To assess the phenotypic effects, we performed experiments using both hydroponic and soil cultivation methods under low phosphorus conditions. The transgenic lines showed notable increases in root/shoot ratio, total root length, root surface area, root volume, and phosphorus content compared to the wild type (WT). Transcriptome analysis revealed that GsNAC1 may enhance tolerance to low phosphorus stress by promoting the expression of genes such as GmALMT6, GmALMT27, GmPAP27, and GmWRKY21. 【Conclusion】The expression of GsNAC1 was up-regulated by low pH and low phosphorus, and overexpression of GsNAC1 significantly enhanced the tolerance to low phosphorus stress in soybean, playing a promoting role in the response to low phosphorus stress. Besides, GsNAC1 may enhance the tolerance to low phosphorus stress in soybean by regulating the expression of downstream genes.

Key words: Glycine soja, low phosphorus tolerance, GsNAC1, root system configuration, RNA-seq