Moso Bamboo’s Survival Strategy Against Chilling Stress in Signaling Dynamics

Phyllostachys edulis, an economically and ecologically significant bamboo species, has substantial research value in applications as a bamboo substitute for plastic and in forest carbon sequestration. However, frequent seasonal low-temperature events due to global climate change affect the growth, development, and productivity of P. edulis. Calcium signaling, serving as a versatile second messenger, is involved in various stress responses and nitrogen metabolism. In this study, we analyzed the calcium signaling dynamics and regulatory strategies in P. edulis under chilling stress. Differentially expressed genes (DEGs) from the CBF families, AMT families, NRT families, and Ca2+ sensor families, including CaM, CDPK, and CBL, were identified using transcriptomics. Additionally, we explored the law of Ca2+ flux and distribution in the roots of P. edulis under chilling stress and validated these findings by assessing the content or activity of Ca2+ sensor proteins and nitrogen transport proteins in the roots. The results indicated that the Ca2+ sensor families of CaM, CDPK, and CBL in P. edulis exhibited significant transcriptional changes under chilling stress. Notably, PH02Gene03957, PH02Gene42787, and PH02Gene19300 were significantly upregulated, while the expressions of PH02Gene08456, PH02Gene01209, and PH02Gene37879 were suppressed. In particular, the expression levels of the CBF family gene PH02Gene14168, a downstream target gene of the calcium channels, increased significantly. P. edulis exhibited an influx of Ca2+ at the root, accompanied by oscillating negative peaks under chilling stress. Spatially, the cytosolic calcium concentration ([Ca2+]cyt) within the root cells increased. The CIPK family genes, interacting with Ca2+-CBL in downstream signaling pathways, showed significant differential expressions. In addition, the expressions of the NRT and AMT family genes changed correspondingly. Our study demonstrates that Ca2+ signaling is involved in the regulatory network of P. edulis under chilling stress. [Ca2+]cyt fluctuations in the roots of P. edulis are induced by chilling stress, reflecting an influx of extracellular Ca2+. Upon binding to Ca2+, downstream target genes from the CBF family are activated. Within the Ca2+–CBL–CIPK signaling network, the CIPK family plays a crucial role in nitrogen metabolism pathways.