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).