JIA-2018-09

2012 CHEN Ke-qin et al. Journal of Integrative Agriculture 2018, 17(9): 2007–2014 3.4. The expression model of TFs involved in second- ary wall formation in CpSND1 overexpression lines SND1, as one of the first key transcription factor switches in secondary wall formation, not only could induce the secondary wall biosynthesis genes directly but also could activate the secondary key MYB transcription factor switches. Therefore, we detected the expression of downstream MYB46 , MYB83 , MYB58 and MYB63 in transgenic Arabidopsis , and the results showed that the transcription levels of all of the four MYB genes greatly increased (Fig. 4-A). We also analysed the expression levels of the Arabidopsis NAC genes involved in the secondary wall formation in transgenic Arabidopsis , and the c a ab b 0 100 200 300 400 500 600 700 800 WT L1 L4 L5 Relative expression CpSND1 b c b c d c d c a a a a a a a a a a a a b a b a a b a b c b c b 0 20 40 60 80 100 120 AtIRX7 AtIRX8 AtIRX9 AtCESA4 AtCESA7 AtCESA8 At4CL1 AtCCoAOMT Relative expression WT L1 L4 L5 WT B A D E C OE-CpSND1 WT OE-CpSND1 WT OE-CpSND1 50 μm 50 μm xy xy Fig. 3 Overexpression of CpSND1 in Arabidopsis . A, expression levels of CpSND1 in 3 transgenic lines, with wild type (WT) as the control. SND1, secondary wall-associated NAC domain protein1. B, the phenotype of CpSND1 overexpression lines. C, the dysplasia of flower organs in CpSND1 overexpression lines. D, the biosynthesis genes of lignin, cellulose and xylan were detected in CpSND1 -transgenic Arabidopsis by RT-PCR. AtIRX7 , At2G28110; AtIRX8 , At5g54690; AtIRX9 , At2g37090; AtCESA4 , At5g44030; AtCESA7 , At5g17420; AtCESA8 , At4g18780; At4CL , At1g51680; AtCCoAOMT , At4g34050. Different letters mean significant differences at the 0.05 probability level. The error bars mean SD. E, the observation of transverse sections, which were taken from the basal stems of wild-type and overexpression plants by scanning electron microscopy. The red arrow indicates the thickened secondary cell wall, and the green arrow indicates the lignin deposition in the xylem (xy) stained by sarranine in transgenic plants.