3.5.3. Secondary Metabolism

The genes responsible for the biosynthesis of phenylpropanoid, sesquiterpenoid, diterpenoid, flavonoid, anthocyanin, and other secondary metabolites showed altered expression under N starvation in both genotypes, including members of the cytochrome P450 family (*LOC107844024*, *LOC107860971*, *LOC107849698*, *LOC107871074*, *LOC107867086*, *LOC107845094*, *LOC107877698*, *LOC107856388*, and *LOC107874613*) and anthocyanin biosynthesis (*LOC107845761* and *LOC107866550*) (Figure 7D). The flavonoid biosynthesis process consists of the largest number of DEGs followed by the phenylpropannoid biosynthesis process. All the unique DEGs in the leaves of 750-1 were repressed, while most of the unique DEGs in the roots of ZCFB were up-regulated.

## 3.5.4. Cell Wall Synthesis and Structure

In the leaves, all of the unique DEGs in this category were repressed in both of the genotypes, including *xyloglucan 6-xylosyltransferase 2* (*LOC107842350*), which is responsible for cell wall synthesis in ZCFB, as well as *Glucan edo-1,3-beta-glucosidase* (*LOC107879143*) and *beta-D-xylosidase* (*LOC107854300*), which functions in cell wall degradation in 750-1 (Figure 7E). Most of these genes in the roots of the two genotypes were up-regulated, including *probable pectate lyase 5* (*LOC107848186* and *LOC107848183*) in 750-1 and *putative pectinesterase 11* (*LOC107869412*) and *polygalacturonase-like* (*LOC107856362* and *LOC107869773*) in ZCFB.
