Figure 5. Association of FLP and MYB88 with PIN gene expression in lateral roots.

(a) FLP::GUS is widely expressed in emerging lateral roots at Stage I and this expression is reduced as lateral roots elongate, but remains high in Stage II columella cells. Then, FLP::GUS expression is gradually reduced from Stages III to IV. (b) MYB88::GUS expression was barely detected in initiating lateral roots (Stage l), but signal was found in columella cells in Stage II lateral roots. During Stage III, the GUS expression domain expanded into more columella cells. The signal then became more intense in columella cells in the apex during stages III and IV. (c) PIN3::PIN3-GFP is expressed in emerging wild-type lateral roots and then declines from Stage III onwards. PIN3-GFP fluorescence is weak in flp-1 lateral roots at all the same developmental stages. By contrast, the PIN3-GFP expression pattern appears to be unaffected in myb88 lateral roots. (d) PIN7::PIN7-GFP expression partially overlaps with that of PIN3::PIN3-GFP in lateral roots at Stage II, but later becomes enhanced. PIN7-GFP fluorescence intensity is reduced in flp-1 and myb88 lateral roots. Scale bar, 50 μm.