RT Journal Article
SR Electronic
T1 Developmental genetics of corolla tube formation: role of the tasiRNA-ARF pathway and a conceptual model
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 253112
DO 10.1101/253112
A1 Baoqing Ding
A1 Rui Xia
A1 Qiaoshan Lin
A1 Vandana Gurung
A1 Janelle M. Sagawa
A1 Lauren E. Stanley
A1 Matthew Strobel
A1 Pamela K. Diggle
A1 Blake C. Meyers
A1 Yao-Wu Yuan
YR 2018
UL http://biorxiv.org/content/early/2018/06/19/253112.abstract
AB More than 80,000 angiosperm species produce flowers with petals fused into a corolla tube. As an important element of the tremendous diversity of flower morphology, the corolla tube plays a critical role in many specialized interactions between plants and animal pollinators (e.g., beeflies, hawkmoths, hummingbirds, nectar bats), which in turn drives rapid plant speciation. Despite its clear significance in plant reproduction and evolution, the corolla tube remains one of the least understood plant structures from a developmental genetics perspective. Through mutant analyses and transgenic experiments, here we show that the tasiRNA-ARF pathway is required for corolla tube formation in the monkeyflower species Mimulus lewisii. Loss-of-function mutations in the M. lewisii orthologs of ARGONAUTE7 and SUPPRESSOR OF GENE SILENCING 3 cause a dramatic decrease in abundance of TAS3-derived small RNAs and a moderate up-regulation of AUXIN RESPONSE FACTOR 3 (ARF3) and ARF4, which lead to inhibition of lateral expansion of the bases of petal primordia and complete arrest of the upward growth of the inter-primordial regions, resulting in unfused corollas. By using an auxin reporter construct, we discovered that auxin distribution is continuous along the petal primordium base and the inter-primordial region during the critical stage of corolla tube formation in the wild-type, and that this auxin distribution is much weaker and more restricted in the mutant. Together, these results suggest a new conceptual model highlighting the central role of auxin directed synchronized growth of the petal primordium base and the inter-primordial region in corolla tube formation.