Developmental role of MpTPL in M. polymorpha.
(A) Mature dormant gemma of proMpTPL:3xVENUSN7 with expression in two apical notches (asterisks). (B) 5-day-old gemmae of proMpTPL:3xVENUSN7. Expression has expanded from apical notches (asterisk) to zones of newly formed air chambers (arrowheads). Inset illustrates background fluorescence in the wild type with identical settings. (C) Mature 25-day-old proMpTPL:3xVENUSN7 line showing expression in meristematic regions (asterisks). (D) Young gemmae cup (gc) primordia in mature proMpTPL:3xVENUSN7 line. (E) Expression pattern of mature proMpTPL:3xVENUSN7 thallus on mock and 10μM 2,4-D media. Plants were transferred to exogenous auxin after 16 days on B5 media. (F)proEF1:VENUS indicating expression in apical notches (asterisk) and gemmae cups (gc). (G) Dorsal side of wild-type thallus covered with photosynthetic air chambers and two apical notches from which gemmae cups (gc) develop. (H)proEF1:MpTPL plants show dorsiventrality but are affected in cup development (arrowhead). (I) Representative proEF1:MpTPLN176H line with a compact and multi-bifurcated thalli, with at least 7 apical notches (asterisks) produced in a similar area compared to (G). (J)proEF1:MpTPL plants have diminished area in low auxin concentrations compared to controls. Each plant is an independent primary transformant grown for a month on 2.5μM 2,4-D. (K) Wild-type mature gemmae cup harboring dormant gemmae. (L)proEF1:MpTPL plants have no gemmae cups, instead naked gemmae and gemmae primordia with filaments growing by transversal cell divisions can be seen. (M)proEF1:MpTPLN176H gemmae cups are elongated and narrow, similar to developmental effects produced by exogenous auxin application in the wild type. Scale bars in A and B = 0.5mm; C, D, E, F, H, M = 1mm; G and I = 1.5mm; J = 1 cm; K = 300μm; L = 75μm; M = 0.6mm.