Open AccessGenomewide analysis of the lateral organ boundaries domain gene family in Eucalyptus grandis reveals members that differentially impact secondary growth
Author(s) -
Lu Qiang,
Shao Fenjuan,
Macmillan Colleen,
Wilson Iain W.,
Merwe Karen,
Hussey Steven G.,
Myburg Alexander A.,
Dong Xiaomei,
Qiu Deyou
Publication year - 2018
Publication title -
plant biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.525
H-Index - 115
eISSN - 1467-7652
pISSN - 1467-7644
DOI - 10.1111/pbi.12754
Subject(s) - biology , xylem , phloem , gene , gibberellin , auxin , secondary growth , gibberellic acid , gene expression , microbiology and biotechnology , transcription factor , botany , genetics , germination
Summary Lateral Organ Boundaries Domain ( LBD ) proteins are plant‐specific transcription factors playing crucial roles in growth and development. However, the function of LBD proteins in Eucalyptus grandis remains largely unexplored. In this study, LBD genes in E. grandis were identified and characterized using bioinformatics approaches. Gene expression patterns in various tissues and the transcriptional responses of Eg LBD s to exogenous hormones were determined by qRT ‐ PCR . Functions of the selected Eg LBD s were studied by ectopically overexpressing in a hybrid poplar ( Populus alba × Populus glandulosa ). Expression levels of genes in the transgenic plants were investigated by RNA ‐seq. Our results showed that there were forty‐six Eg LBD members in the E. grandis genome and three Eg LBD s displayed xylem‐ ( Eg LBD 29 ) or phloem‐preferential expression ( Eg LBD 22 and Eg LBD 37 ). Confocal microscopy indicated that Eg LBD 22, Eg LBD 2 9 and Eg LBD 37 were localized to the nucleus. Furthermore, we found that Eg LBD 22 , Eg LBD 29 and Eg LBD 37 were responsive to the treatments of indol‐3‐acetic acid and gibberellic acid. More importantly, we demonstrated Eg LBD s exerted different influences on secondary growth. Namely, 35S::Eg LBD 37 led to significantly increased secondary xylem, 35S::Eg LBD 29 led to greatly increased phloem fibre production, and 35S::Eg LBD 22 showed no obvious effects. We revealed that key genes related to gibberellin, ethylene and auxin signalling pathway as well as cell expansion were significantly up‐ or down‐regulated in transgenic plants. Our new findings suggest that LBD genes in E. grandis play important roles in secondary growth. This provides new mechanisms to increase wood or fibre production.