Transcriptome analysis of Pará rubber tree (H. brasiliensis) seedlings under ethylene stimulation

Abstract

Background Natural rubber (cis-1,4-polyioprene, NR) is an indispensable industrial raw material obtained from the Pará rubber tree (H. brasiliensis). Natural rubber cannot be replaced by synthetic rubber compounds because of the superior resilience, elasticity, abrasion resistance, efficient heat dispersion, and impact resistance of NR. In NR production, latex is harvested by periodical tapping of the trunk bark. Ethylene enhances and prolongs latex flow and latex regeneration. Ethephon, which is an ethylene-releasing compound, applied to the trunk before tapping usually results in a 1.5- to 2-fold increase in latex yield. However, intense mechanical damage to bark tissues by excessive tapping and/or over-stimulation with ethephon induces severe oxidative stress in laticifer cells, which often causes tapping panel dryness (TPD) syndrome. To enhance NR production without causing TPD, an improved understanding of the molecular mechanism of the ethylene response in the Pará rubber tree is required. Therefore, we investigated gene expression in response to ethephon treatment using Pará rubber tree seedlings as a model system. Results After ethephon treatment, 3270 genes showed significant differences in expression compared with the mock treatment. Genes associated with carotenoids, flavonoids, and abscisic acid biosynthesis were significantly upregulated by ethephon treatment, which might contribute to an increase in latex flow. Genes associated with secondary cell wall formation were downregulated, which might be because of the reduced sugar supply. Given that sucrose is an important molecule for NR production, a trade-off may arise between NR production and cell wall formation for plant growth and for wound healing at the tapping panel. Conclusions Dynamic changes in gene expression occur specifically in response to ethephon treatment. Certain genes identified may potentially contribute to latex production or TPD suppression. These data provide valuable information to understand the mechanism of ethylene stimulation, and will contribute to improved management practices and/or molecular breeding to attain higher yields of latex from Pará rubber trees.

Cloning, Expression Characteristics of Farnesyl Pyrophosphate Synthase Gene from Platycodon grandiflorus and Functional Identification in Triterpenoid Synthesis

“…officinalis . Exogenous ethephon induction significantly increased the activities of HMGS , HMGR , FPS , CPT , DHAD, and ADF , upregulated the genes related to biosynthesis, such as carotenoids, flavonoids, and abscisic acid, and promoted the yield of latex and the accumulation of secondary metabolites in rubber tree. , After MeJA treatment, the expression of the PgFPS gene increased by 3.125 times in the roots of P. grandiflorus, which increased by 3.236 times in the stems after ethephon treatment.…”

Brassinosteroids Regulate the Water Deficit and Latex Yield of Rubber Trees

“…At the same time, the allocation and transport of phytohormones under specific physiological conditions can improve the adaptability of plants to the environment [ 27 ]. The application of several phytohormones to rubber trees has been frequently reported, such as ethylene, abscisic acid and jasmonic acid, which are related to the growth and resistance of rubber trees [ 28 , 29 , 30 ]. In this study, we determined the role of BR in regulating water deficit and latex yield in rubber trees.…”

Genome-Wide Identification, Evolution and Expression Analysis of the Glutathione S-Transferase Supergene Family in Euphorbiaceae

“…In Euphorbiaceae, RcGSTF1 and RcGSTU6 , RcGSTU12 , RcGSTU13 , RcGSTU16 , RcGSTU19 , RcGSTU20 , RcGSTU22 , and RcGSTU23 are also highly expressed in root tissue, even after abiotic stress, consistent with A. thaliana being involved in maintaining redox homeostasis in Euphorbiaceae root tissue. In a study of the response of H. brasiliensis to ethylene, Nakano et al (2021) found that expression of members of the GSTU subfamily was highly induced by ethephon treatment to cope with abiotic stress, and also reflected the conservation of the function of the GST supergene family in Euphorbiaceae plants. Glutathione, paraquat, copper and naphthylacetic acid (NAA) were demonstrated by Smith et al (2003) to induce expression of AtGSTF2 in the roots of A. thaliana seedlings independently of the ethylene sensing mechanism, and participate in auxin-related regulation and transport.…”