Identification and expression analysis of cytokinin metabolic genes , and in the biofuel plant .

The seed oil of is considered a potential bioenergy source that could replace fossil fuels. However, the seed yield of is low and has yet to be improved. We previously reported that exogenous cytokinin treatment increased the seed yield of . Cytokinin levels are directly regulated by isopentenyl transferase (IPT), cytochrome P450 monooxygenase, family 735, subfamily A (CYP735A), and cytokinin oxidase/dehydrogenase (CKX). In this study, we cloned six genes, one gene, and seven genes. The expression patterns of these 14 genes in various organs were determined using real-time quantitative PCR. was primarily expressed in roots and seeds, was expressed in roots, apical meristems, and mature leaves, was expressed in stems and mature leaves, was expressed in roots and mature leaves, was expressed in seeds at 10 days after pollination, and was expressed in mature leaves. was mainly expressed in roots, flower buds, and seeds. The seven genes also showed different expression patterns in different organs of . In addition, CK levels were detected in flower buds and seeds at different stages of development. The concentration of N-(Δ-isopentenyl)-adenine (iP), iP-riboside, and -zeatin (tZ) increased with flower development, and the concentration of iP decreased with seed development, while that of tZ increased. We further analyzed the function of using the CRISPR-Cas9 system, and found that the concentrations of tZ and tZ-riboside decreased significantly in the mutants, which showed severely retarded growth. These findings will be helpful for further studies of the functions of cytokinin metabolic genes and understanding the roles of cytokinins in growth and development.