*2.6. Expression Analysis of LiNAC Genes in Regulating the Weeping Trait*

To identify which *LiNAC* genes were involved in regulating the weeping trait of *L. indica*, we used real-time PCR to analyze the expression patterns of *LiNAC* genes in branches of 'Shaoguifei' and 'Xiariwuniang' during the early growth stage, the growth stage, and the end of the growth stage. The expression pattern analysis is shown in Figure 7. The relative expression levels of *LiNAC3* and *LiNAC20* showed the same trend in the early growth stage (S1), growth stage (S2), and the end of the growth stage (S3) for 'Shaoguifei' and 'Xiariwuniang', which showed an increase first and then a decrease, and the expression level was higher in S2. The relative expression levels of five genes, *LiNAC7*, *LiNAC8*, *LiNAC14*, *LiNAC19*, and *LiNAC11*, in 'Shaoguifei' gradually increased from the S1 stage and reached the highest in S3. We found that, except for *LiNAC8* and *LiNAC11*, the relative expression of *LiNAC7*, *LiNAC14*, and *LiNAC19* showed a trend of increasing and then decreasing in 'Xiariwuniang', with the highest expression in the S2. Interestingly, the expression trend of *LiNAC8* in 'Xiariwuniang' is consistent with that in 'Shaoguifei', while the relative expression level of 'Shaoguifei' is slightly higher than that of 'Xiariwuniang' in three stages and the relative expression level is about twice that of 'Xiariwuniang'. We noticed that the relative expression of nine genes (*LiNAC1*, *LiNAC9*, *LiNAC10*, *LiNAC16*, *LiNAC4*, *LiNAC5*, *LiNAC9*, *LiNAC21*, and *LiNAC15*) decreased significantly from S1 to S2 in 'Shaoguifei' and increased gradually in S3. Except for four genes, *LiNAC1*, *LiNAC10*, *LiNAC16*, and *LiNAC15*, whose relative expression decreased from S1 to S3 in 'Xiariwuniang', all the other five genes showed an increasing and then decreasing trend and their relative expression peaked at S2. The relative expression levels of *LiNAC2*, *LiNAC6*, *LiNAC12*, *LiNAC18*, and *LiNAC13* in 'Shaoguifei' showed a trend of gradual decline and the lowest expression level in S3 (except *LiNAC13*), especially *LiNAC12*, in S3 period, the expression level of *LiNAC12* was 0.1-times that of 'Shaoguifei'. Interestingly, *LiNAC2*, *LiNAC18*, and *LiNAC13* also showed the same expression trend as that of 'Shaoguifei' in 'Xiariwuniang'. Notably, the relative expression of *LiNAC2* in 'Xiariwuniang' was always higher than that of 'Shaoguifei', especially in the S1–S2 stages. Further, the expression of *LiNAC13* was always higher than that of 'Xiariwuniang' in all stages; the relative expression was 9.7-times higher than that of 'Xiariwuniang' in S3.

**Figure 7.** *Cont*.

**Figure 7.** The qRT-PCR analysis of 21 *LiNAC* genes in Upright and Weeping *L. indica* at different growth stages. S1, S2, and S3 indicate the early growth stage, the growth stage, and the end of the growth stage; significant differences are identified by SPSS with Duncan's test (*p* < 0.05) and are represented by different letters above the error bars.
