Abstract
Trihelix genes play important roles in plant growth and development and responses to biotic and abiotic stresses. Here, we identified 56 full-length trihelix genes in Populus trichocarpa and classified them into five groups. Most genes within a given group had similar gene structures and conserved motifs. The trihelix genes were unequally distributed across 19 different linkage groups. Fifteen paralogous pairs were identified, 14 of which have undergone segmental duplication events. Promoter cis-element analysis indicated that most trihelix genes contain stress- or phytohormone-related cis-elements. The expression profiles of the trihelix genes suggest that they are primarily expressed in leaves and roots. Quantitative real-time reverse transcription polymerase chain reaction analysis indicated that members of the trihelix gene family are significantly induced in response to osmotic, abscisic acid, salicylic acid, methyl jasmonate and pathogen infection. PtrGT10 was identified as a target gene of miR172d, which is involved in the osmotic response. Repression of PtrGT10 could increase reactive oxygen species scavenging ability and decrease cell death. This study provides novel insights into the phylogenetic relationships and functions of the P. trichocarpa trihelix genes, which will aid future functional studies investigating the divergent roles of trihelix genes belonging to other species.
Highlights
Trihelix genes play important roles in plant growth and development and responses to biotic and abiotic stresses
By removing repetitive and redundant genes, we identified 56 putative trihelix genes in P. trichocarpa
Of the 56 trihelix genes, 39 had only one gene product, while the remaining 17 genes (30%) had multiple gene products, which could be attributed to alternative splicing according to the Phytozome V10.3 database
Summary
Trihelix genes play important roles in plant growth and development and responses to biotic and abiotic stresses. Trihelix transcription factors play important roles in the regulation of developmental processes involving flowers[4], trichomes, stomata, seed abscission layers and late embryogenesis and in responses to biotic and abiotic stresses[5,6,7] or to treatments with phytohormones such as abscisic acid (ABA) or salicylic acid (SA)[8]. Only one trihelix gene has been studied functionally in poplars, and the results suggest that trihelix genes may play important roles in the drought response[15]. Our preliminary results provide novel insights into the roles of trihelix genes in the poplar’s responses to biotic and abiotic stresses and phytohormone treatments that will aid future studies
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