Developmental role of <i>MpTPL</i> in <i>M</i>. <i>polymorpha</i>.

<p><b>(A)</b> Mature dormant gemma of <sub><i>pro</i></sub><i>MpTPL</i>:<i>3xVENUSN7</i> with expression in two apical notches (asterisks). <b>(B)</b> 5-day-old gemmae of <sub><i>pro</i></sub><i>MpTPL</i>:<i>3xVENUSN7</i>. 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. <b>(C)</b> Mature 25-day-old <sub><i>pro</i></sub><i>MpTPL</i>:<i>3xVENUSN7</i> line showing expression in meristematic regions (asterisks). <b>(D)</b> Young gemmae cup (gc) primordia in mature <sub><i>pro</i></sub><i>MpTPL</i>:<i>3xVENUSN7</i> line. <b>(E)</b> Expression pattern of mature <sub><i>pro</i></sub><i>MpTPL</i>:<i>3xVENUSN7</i> thallus on mock and 10μM 2,4-D media. Plants were transferred to exogenous auxin after 16 days on B5 media. <b>(F)</b><sub><i>pro</i></sub><i>EF1</i>:<i>VENUS</i> indicating expression in apical notches (asterisk) and gemmae cups (gc). <b>(G)</b> Dorsal side of wild-type thallus covered with photosynthetic air chambers and two apical notches from which gemmae cups (gc) develop. <b>(H)</b><sub><i>pro</i></sub><i>EF1</i>:<i>MpTPL</i> plants show dorsiventrality but are affected in cup development (arrowhead). <b>(I)</b> Representative <sub><i>pro</i></sub><i>EF1</i>:<i>MpTPL</i><sup><i>N176H</i></sup> line with a compact and multi-bifurcated thalli, with at least 7 apical notches (asterisks) produced in a similar area compared to (G). <b>(J)</b><sub><i>pro</i></sub><i>EF1</i>:<i>MpTPL</i> 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. <b>(K)</b> Wild-type mature gemmae cup harboring dormant gemmae. <b>(L)</b><sub><i>pro</i></sub><i>EF1</i>:<i>MpTPL</i> plants have no gemmae cups, instead naked gemmae and gemmae primordia with filaments growing by transversal cell divisions can be seen. <b>(M)</b><sub><i>pro</i></sub><i>EF1</i>:<i>MpTPL</i><sup><i>N176H</i></sup> 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.</p>