Identification and Functional Evaluation of Three Polyubiquitin Promoters from Hevea brasiliensis

Abstract

Hevea brasiliensis is an economically important tree species that provides the only commercial source of natural rubber. The replacement of the CaMV35S promoter by endogenous polyubiquitin promoters may be a viable way to improve the genetic transformation of this species. However, no endogenous polyubiquitin promoters in Hevea have been reported yet. Here, we identified three Hevea polyubiquitin genes HbUBI10.1, HbUBI10.2 and HbUBI10.3, which encode ubiquitin monomers having nearly identical amino acid sequences to that of AtUBQ10. The genomic fragments upstream of these HbUBI genes, including the signature leading introns, were amplified as putative HbUBI promoters. In silico analysis showed that a number of cis-acting elements which are conserved within strong constitutive polyubiquitin promoters were presented in these HbUBI promoters. Transcriptomic data revealed that HbUBI10.1 and HbUBI10.2 had a constitutive expression in Hevea plants. Semi-quantitative RT-PCR showed that these three HbUBI genes were expressed higher than the GUS gene driven by CaMV35S in transgenic Hevea leaves. All three HbUBI promoters exhibited the capability to direct GFP expression in both transient and stable transformation assays, although they produced lower protoplast transformation efficiencies than the CaMV35S promoter. These HbUBI promoters will expand the availability of promoters for driving the transgene expression in Hevea genetic engineering.

An optimized somatic embryo transformation system assisted homozygous edited rubber tree generation method mediated by CRISPR/Cas9

“…The promoter of Cas9 gene have a significant impact not only on editing efficiency, but also have an impact on the editing type, many other promoters produce higher editing efficiency and a higher proportion of homozygous or biallelic mutations than the CaMV35S promoter (Feng et al ., 2018; Wang, et al ., 2022). The Cas9 gene sequence in present study is optimized based on the rice codon, driven by 2 × 35S promoter, next we will replace the 2×35S promoter of Cas9 with the endogenous constitutive strong promoter pHbUbiquitin of H. brasiliensis (Xin, et al ., 2022), and optimize Cas9 gene according to the codon bias of H. brasiliensis .…”

Tree Genetics: Molecular and Functional Characterization of Genes

“…Chosenia arbutifolia [10] is used as a raw material for technological aims and for landscape planting in China. Studies on two economically relevant species, a woody perennial shrub, Camelia sinensis [11], and a tree, Hevea brasiliensis [12], are also covered in this issue. Finally, [5] involves the Japanese larch, Larix kaempferi.…”

“…The results showed the differential accumulation of RNA belonging to 14 genes related to another development and meiosis, providing a theoretical basis for future research. The study of [12] reports the identification of three polyubiquitin genes for H. brasilensis, as the replacement of the CaMV35S promoter by endogenous polyubiquitin promoters might improve the genetic transformation efficiency of this species. Since no endogenous polyubiquitin promoters in rubber tree were reported, those identified in [12] will expand the availability of molecular tools for driving the transgene expression in genetic engineering.…”