Plant Spacing Effects on Stem Secondary Growth Dynamics in Tobacco (Nicotiana tabacum)

Plant spacing usually refers to distances between plants within and between rows in the field. Different spacing of crop planting would generally influence the size, plant architecture, economical productivity et al . Present research provided a time course monitoring on the tissue transmission in tobacco stem development from the plants with different spacing. The result showed cambium activity, vascular bundle thickness, lignin, cellulose, and hemicellulose content differed in the stem because of the varied plant spacing, as well as the macro nutrients deposition. Furthermore, the genes coding the homologous of key transcription factors HB8 and NST3 ( NtHB8s and NtNST3s ) which involved in plant secondary growth were clone in tobacco. In the time course, they also indicated diverse expression patterns among altered plant spacing treatment. Their transcriptomic activities were validated and the motifs which might bind transcription factor in their promoter regions were predicted. Promoters of NtHB8s and NtNST3s gene were rich in light response elements, as a result, light might be the main environmental factor for plant spacing to regulate stem secondary growth.