Histone deacetylase genes in lotus seed maturation: Identification and expression pattern analysis

Abstract Histone deacetylase (HDAC) plays an essential role in plant growth, development, and maturation. Although the biological function of HDAC in model plants (such as Arabidopsis and rice) has been studied relatively thoroughly, the research on HDACs in lotus seed has not been reported yet. In this study, 14 HDACs were determined in lotus seed, including eight in the RPD3/HDA1 subfamily, one in the SIR2 subfamily, and five in the HD2 subfamily. Bioinformatics analysis showed that NnHDA3 has a high similarity with MaHDA6. Similarly, NnHDA8 and MaHDA1, NnSRT1 and AtSRT2, NnHDA8 and AtHDA15, NnHDA2 and OsHDA706, and OsHDA710 and NnHDA3 have a conservative domain structure. The mRNA expression of NnHDA6, NnHDA8, and NnHDT5 in pulp positively correlated with maturity and starch content. On the contrary, the expression of NnHDA6 and NnHDT5 negatively correlated with chlorophyll content. During prolonged storage, NnHDA3 and NnHDT4 increased first and then decreased in pulp positively related to starch content. However, the expression of NnSRT1 in peel decreased first and then increased, and it is higher in peel than in pulp. Based on the above results, we speculate that NnHDA3 may be involved in the maturation and senescence of lotus seeds. NnHDA2 and NnSRT1 are involved in the metabolism of chlorophyll and starch during lotus seed ripening. Our results provide the first insight into the histone deacetylase in lotus seed ripening.