Cucumber is an economically important horticultural crop that is highly dependent on nitrogen fertilizer. Nitrate is the main nitrogen source for cucumber; however, the effects of nitrogen signaling on the early-stage growth of cucumber seedlings and the related regulatory mechanisms are still unclear. To compare seedling growth status at different nitrate levels, we performed a growth experiment using cucumber seedlings that had nearly exhausted their nitrogen reserves under nitrogen deficiency conditions (NO 3 − -N/NH4 + - N = 0 in MS medium). Using qPCR and in situ RNA hybridization localization of candidate CsNPF genes, we found that short-term nitrogen deficiency promoted changes in root vascular bundle morphology and xylem growth in cucumber seedlings, thereby enhancing their growth potential. Among the candidate genes, CsNPF7.2 , a gene located in the vascular cambium was found to be induced by short-term nitrogen deficiency. Considering the abundance of vasculature development marker genes, we speculated that the function of CsNPF7.2 might relate to the development of vascular bundles in plants suffering from nitrogen stress. The objective of our study was to investigate the growth changes in cucumber seedlings in response to different nitrogen levels, and to examine the mRNA accumulation and expression patterns of nitrate transporter CsNPF genes, so that critical genes can be identified to improve nitrogen use efficiency in cucumber cultivation. The results of this study provides a novel theoretical basis for optimizing cultivation, regulating rational fertilization levels, and improving nitrogen use efficiency in production. In addition, our study also provides new avenues for the further study of the function of CsNPF7.2 on regulating vasculature development in response to nitrogen stress.

中文翻译：

---

CsNPF7.2 具有调节早期缺氮胁迫下黄瓜幼苗生长的潜力

黄瓜是一种经济上重要的园艺作物，高度依赖氮肥。硝酸盐是黄瓜的主要氮源；然而，氮信号对黄瓜幼苗早期生长的影响及相关调控机制尚不清楚。为了比较不同硝酸盐水平下的幼苗生长状况，我们使用在缺氮条件下（NO 3 - -N/NH4 + - N = 0 在 MS 培养基中）几乎耗尽其氮储备的黄瓜幼苗进行了生长实验。使用qPCR和候选CsNPF基因的原位RNA杂交定位，我们发现短期氮缺乏促进了黄瓜幼苗根维管束形态和木质部生长的变化，从而增强了它们的生长潜力。在候选基因中，CsNPF7.2、发现位于血管形成层中的基因是由短期缺氮诱导的。考虑到丰富的脉管系统发育标记基因，我们推测 CsNPF7.2 的功能可能与遭受氮胁迫的植物中维管束的发育有关。我们研究的目的是研究黄瓜幼苗响应不同氮水平的生长变化，并检查硝酸盐转运蛋白 CsNPF 基因的 mRNA 积累和表达模式，以便确定关键基因以提高黄瓜氮的利用效率。栽培。本研究结果为优化栽培、调控合理施肥水平、提高生产中氮素利用效率提供了新的理论依据。此外，