Evolution of Angiosperm Pollen. 6. The Celastrales, Oxalidales, and Malpighiales (Com) Clade and Zygophyllales

Anatomy and RNA-Seq reveal important gene pathways regulating sex differentiation in a functionally Androdioecious tree, Tapiscia sinensis

“…The breeding system and other traits mapped on the phylogenetic tree of Fraxinus L. (Oleaceae) show that dioecy has three separate origins; in one instance, dioecy evolved from hermaphroditism via androdioecy following the transition from insect to wind pollination [45, 86]. Dioecy may also evolve in conjunction with the evolution of wind pollination in some previously insect-pollinated species [87, 88]. T. sinensis is a wind-pollinated and insect-pollinated species [52, 53], and this mixed pollination pattern may be a possible evolutionary pathway from hermaphroditism to dioecy [55].…”

Dissecting molecular evolutionary relationship of Krameriaceae inferred from phylotranscriptomic analysis

“…The equality of evolutionary rate between sequences of T. eichlerianus and K. lanceolata, with sequence of Tetrastigma obtectum used as an outgroup in Tajima's relative rate test (Tajima, 1993) performed using MEGA X (Kumar et al, 2018) revealed 23009 identical sites in all three sequences, 1948 divergent sites in all three sequences, 2098 unique differences in T. eichlerianus (Zygophyllaceae), 2005 unique differences in K. lanceolata (Krameriaceae) and 3056 unique differences in T. obtectum. The order Zygophyllales is distinct by the presence of harman alkaloids (Kubitzki, 2007), diversity of lignans and neolignans (Sheahan, 2006;Simpson et al, 2006), and lack of mycorrhizae; however, arbuscular mycorrhizae have been reported from roots of L. tridentata in the Mojave desert (Apple et al, 2005); deep cortical or pericyclic (superficial) cork cambium; vessel elements with simple perforation plates; rays (predominantly) uniseriate; transverse stomatal orientation (Carlquist, 2005); pollen colpate (Tao et al, 2018); micropyle endostomal; seeds more or less exotestal; and lack of endosperm (APG IV, 2016).…”

“…The systematic relationships of the Zygophyllaceae and Krameriaceae have often been debatable (APG IV, 2016). The Krameriaceae was considered as a subfamily of Fabaceae, or near to Polygalaceae (Simpson, 1989;Simpson et al, 2004); however, aligned as sister to Zygophyllaceae based on evidences from the anatomical (Gregory, 1994;Carlquist, 2005), DNA (Savolainen et al, 2000;Wang et al, 2009) and pollen data (Tao et al, 2018). While the wood anatomy (Carlquist, 2005) and plastosome analysis (Ali et al, 2019) revealed the separation of Krameriaceae from the Zygophyllaceae, Granot and Grafi (2014) emphasized the phylogenetic significance of the epigenetic information with reference to Zygophyllaceae, and argued that the placement of Krameriaceae under the Zygophyllales needs to be re-examined.…”

Morphological differences between anemophilous and entomophilous pollen

“…The subtle differences in their exine morphology and ultrastructures reflect their relationship to the respective pollination syndrome. Tao et al (2018) studied the morphological characteristics of pollen grains of orders Celastrales, Oxalidales, Malpighiales, and Zygophyllales and found that thinner exine is positively related to anemophilous pollination. In this study, we compared the pollen exine thickness of anemophilous plants and entomophilous plants and found that the pollen exine of anemophilous plants is significantly thinner than that of entomophilous plants ( p < 0.05 ) (Table 2).…”