Expression of light signals genes, nitrate and sugar transporter genes, and SAGs in maize
We wondered whether the improved performance of maize leaves under PS compared to the PF resulted from increased transcript abundance of maize-related SAGs. To address this question, the effect of different light treatments on expression levels of ZmPHYA1b ,ZmPHYB1c , ZmPIF4.1 , and ZmPIF5.1 using qRT-PCR analysis was tested. The results showed that the expression levels ofZmPHYA1b , ZmPIF4.1 , and ZmPIF5.1 were significantly up-regulated on day 10 to day 20 then started to decrease up to day 40 in PS leaves under PL (Fig. 6A), while significantly down-regulated in PF leaves in all process. There were no significant differences inZmPHYA1b , ZmPIF4. 1, and ZmPIF5.1 expression levels in NF and NS. Except for PIF4, similar results for PHYA and PIF5 protein expression were also observed. PF leaves significantly increased theZmPHYB1c expression level from day 1 up to day 20; after that, it started to decrease. Although ZmPHYB1c expression levels increased in NF and NS treatments, however, their expression levels were not significantly different. In contrast, PS treatment significantly down-regulated the ZmPHYB1c expression level (Fig. 6B).
Carbon and nitrogen balance in plant cells is important in measuring plant senescence activity. Expression analysis ofZmPaO , ZmSAG2, andZmSAG12.1 showed an up-regulated level of the transcript after ten days of PS treatment, indicating that senescence was induced in PS leaves. However, a significant decrease in transcripts was observed in the next 30 days in PS compared to NF and NS. In contrast, the maximum expression peaks for ZmNRT1.1a , ZmSUT1a, andZmSWEET11.1 were observed in PF and PS after ten days of partial shade treatment in leaves. Under PL treatment, the transcription levels of ZmNRT1.1a, ZmSUT1a, and ZmSWEET11.1 were found higher than in NL. No significant difference in transcript levels was observed in NF and NS leaves (Fig. 7).