Characterization of DWARF14 Genes in Populus.

Kaijie Zheng,Jin-Gui Chen,Meng Xie,Xiaoping Wang,Shucai Wang,Deborah A Weighill,Wellington Muchero,Hao-Bo Guo,Jun Yang,Daniel A Jacobson,Hong Guo,Yongil Yang,Gerald A Tuskan

doi:10.1038/srep21593

Abstract

Strigolactones are a new class of plant hormones regulating shoot branching and symbiotic interactions with arbuscular mycorrhizal fungi. Studies of branching mutants in herbaceous plants have identified several key genes involved in strigolactone biosynthesis or signaling. The strigolactone signal is perceived by a member of the α/β-fold hydrolase superfamily, known as DWARF14 (D14). However, little is known about D14 genes in the woody perennial plants. Here we report the identification of D14 homologs in the model woody plant Populus trichocarpa. We showed that there are two D14 homologs in P. trichocarpa, designated as PtD14a and PtD14b that are over 95% similar at the amino acid level. Expression analysis indicated that the transcript level of PtD14a is generally more abundant than that of PtD14b. However, only PtD14a was able to complement Arabidopsis d14 mutants, suggesting that PtD14a is the functional D14 ortholog. Amino acid alignment and structural modeling revealed substitutions of several highly conserved amino acids in the PtD14b protein including a phenylalanine near the catalytic triad of D14 proteins. This study lays a foundation for further characterization of strigolactone pathway and its functions in the woody perennial plants.

Highlights

Strigolactones (SLs) are a new class of plant hormones regulating shoot branching[1,2] and symbiotic interactions with arbuscular mycorrhizal fungi[3,4]
D14 has previously been shown to function as a receptor for SLs and the characterization of D14 and its orthologs has been reported in Arabidopsis, rice and petunia
PtD14a and PtD14b are highly similar at the amino acid level (i.e., 95.9% similarity and 91.7% identity), only PtD14a, but not PtD14b, was able to fully complement Arabidopsis d14 mutants when their expression was driven by the constitutive 35S promoter (Fig. 4)

Summary

Introduction

Strigolactones (SLs) are a new class of plant hormones regulating shoot branching[1,2] and symbiotic interactions with arbuscular mycorrhizal fungi[3,4]. Loss-of-function mutations in each of these genes resulted in increased number of branches. In Arabidopsis, the signaling of SLs is mainly regulated by MAX224, an F-box leucine-rich protein, and DWARF14 (D14), a member of the α /β -fold hydrolase superfamily[30,31,32,33]. Several lines of evidence support that D14 functions as a receptor for SLs. Genetic analysis indicated that loss-of-function mutations in D14 resulted in increased number of branches and that d14 mutants are insensitive to SLs30,31. Because shoot branching plays an important role determining photosynthetic light use efficiency and biomass yield, study on strigolactone pathways helps inform genetic improvement of woody plants to increase biomass production in the forestry, horticultural www.nature.com/scientificreports/. We investigate D14 orthologs in the model woody plant, Populus trichocarpa

Methods

Results

Conclusion