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Cytokinin (CTK) has an important regulatory effect on plant morphology, physiology, and yield, and is one of the main factors regulating nitrogen absorption, transport, and metabolism. This paper reviews the research progress in nitrogen absorption, transport and metabolism, cytokinin synthesis, transport and signal transduction, etc., focusing on the physiological mechanisms by which CTK and nitrogen collaborate to regulate the root–shoot relationship and its impact on agronomic traits of crops. The synthesis of trans‐zeatin (tZ) and trans‐zeatin riboside (tZR) is generally regulated by root nitrogen, which is transported them to the sprouts, regulates nitrogen allocation and metabolism, and affects photosynthetic characteristics and yield. In young shoots, nitrogen upregulates the synthesis of isopentenyl, adenine (iP), and iP‐nucleoside (iPR) and transports to roots through the phloem, reducing nitrogen uptake and transport, affecting root morphology. Based on this, the role of, CTK in coordinating relationships between source repositories and enhancing injection. We conducted an analysis on how various cultivation methods impact CTK metabolism and its relationship with plant growth. Additionally, we discussed the challenges associated with applying CTK functions to paddy field production and suggested future research directions. [ABSTRACT FROM AUTHOR]

Because cotton is the most important fiber crop, the differentiation and development mechanism of cotton fiber cells has been a hot topic in cotton research. NAC (for NAM, ATAF, and CUC2) is a class of plant‐specific transcription factor families that regulate multiple aspects of plant growth and development. Previously, we identified 33 differentially expressed NAC genes in upland cotton based on fiber‐related transcriptome profiling. In this study, we conducted chromosome localization, systematic evolution, and gene structural analysis of 242 NAC genes genome‐wide based on a high‐quality reference genome of upland cotton. In addition, the expression pattern analysis of 16 differentially expressed GhNACs was carried out by RT–PCR using ovules at early fiber initiation stages of n2 recessive naked seed mutant (n2NSM) and Xuzhou142 fuzzless–lintless mutant (Xu142fl). The results showed that GhNAC230 and GhNAC115 were most closely related to AtSND1 and downregulated in ovules of Xu142fl compared with n2NSM. Quantitative RT–PCR (qRT–PCR) analysis of GhNAC230 demonstrated its gradual accumulation from −1 days postanthesis (DPA) to 1 DPA in n2NSM and further confirmed its downregulated expression in 1 DPA ovules of Xu142fl compared to n2NSM. The current study predicted a pair of NAC genes that might be key candidate genes that are crucial for lint fiber development. [ABSTRACT FROM AUTHOR]