Histological analyses in 155 plants demonstrate that 1) CZ of 10-day-old seedlings in 155 was almost flat, which was not as vaulted as C24. 2) At day 21, the CZ was vaulted, but the PZ (peripheral zone) lost its original uphill hogback.

• 突变体茎顶端分生组织(shoot apical meristem,SAM)的石蜡切片观察表明:1)10d苗龄155的SAM扁平,不像野生型形成拱形; 2)21d时,155的SAM和C24一样呈拱形,但是SAM的两侧PZ(peripheral zone)较野生型平坦。