Genome-wide identification and functional analysis of the polyamine metabolism-related genes in Foxtail millet...

Polyamines are small, aliphatic, nitrogenous bases that play vital roles in the growth and development of organisms. In certain cereal crops, polyamines regulate grain growth and development, and exogenous application can considerably enhance grain-filling efficiency and grain quality. However, the functions of genes associated with polyamine metabolism in foxtail millet (Setaria italica L.) remain poorly characterized. In this investigation, nine genes related to polyamine metabolism, belonging to five gene families, were identified in foxtail millet. These nine genes are distributed across three of the nine chromosomes. The cis-acting elements in these gene promoters are primarily related to plant growth and development, environmental stress, and hormone response. Transient expression experiments revealed that SiSPDS2 is located in the cytoplasm and nucleus. In Arabidopsis, SiSPDS2 overexpression increased seed spermidine content and significantly enhanced plant height, silique length, seed size, and 1000-seed weight, suggesting that SiSPDS2 can positively regulate seed growth and development. This study provides a theoretical basis for further research into the role of polyamines in the growth and development of foxtail millet.