Identification and expression characteristics of NLP (NIN-like protein) gene family in pepper (Capsicum annuum L.)

Background Pepper (Capsicum annum L.) is the main crop in the vegetable industry. The growth and development of peppers are regulated by nitrate, but there is limited research on the molecular mechanisms of nitrate absorption and assimilation in peppers. A plant specific transcription factor NLP plays an important role in nitrate signal transduction. Methods and results In this study, a total of 7 NLP members were identified based on pepper genome data. Two nitrogen transport elements (GCN4) were found in the CaNLP5 promoter. In the phylogenetic tree, CaNLP members are divided into three branches, with pepper NLP and tomato NLP having the closest genetic relationship. The expression levels of CaNLP1, CaNLP3, and CaNLP4 are relatively high in the roots, stems, and leaves. The expression level of CaNLP7 gene is relatively high during the 5-7 days of pepper fruit color transformation. After various non-Biotic stress and hormone treatments, the expression of CaNLP1 was at a high level. The expression of CaNLP3 and CaNLP4 was down regulated in leaves, but up regulated in roots. Under conditions of nitrogen deficiency and sufficient nitrate, the expression patterns of NLP genes in pepper leaves and roots were determined. Conclusion These results provide important insights into the multiple functions of CaNLPs in regulating nitrate absorption and transport.

Automated summary

In this study, seven CaNLP members were identified in peppers based on genome data, and two nitrogen transport elements were found in the CaNLP5 promoter. Phylogenetic analysis showed that pepper NLP and tomato NLP have the closest genetic relationship. The expression levels of CaNLP1, CaNLP3, and CaNLP4 were high in roots, stems, and leaves, while CaNLP7 expression was high during the color transformation of pepper fruit. These findings provide valuable insights into the roles of CaNLPs in regulating nitrate absorption and transport.