Gene expression pattern in response to wounding, methyl jasmonate and ethylene in the bark of Hevea brasiliensis

Abstract

Natural rubber production in Hevea brasiliensis is determined by both tapping and ethephon frequencies. It is affected by a complex physiological disorder called tapping panel dryness. This syndrome is likely to be induced by environmental and latex harvesting stresses. Defence responses, including rubber biosynthesis, are dramatically mediated by wounding, jasmonate and ethylene (ET), among other factors. Using real-time RT-PCR, the effects of wounding, methyl jasmonate (MeJA) and ET on the relative transcript abundance of a set of 25 genes involved in their signalling and metabolic pathways were studied in the bark of 3-month-old epicormic shoots. Temporal regulation was found for 9 out of 25 genes. Wounding treatment regulated the transcript abundance of 10 genes. Wounding-specific regulation was noted for the HbMAPK, HbBTF3b, HbCAS1, HbLTPP and HbPLD genes. MeJA treatment regulated the transcript abundance of nine genes. Of these, the HbMYB, HbCAS2, HbCIPK and HbChi genes were shown to be specifically MeJA inducible. ET response was accompanied by regulation of the transcript abundance of eight genes, and six genes, HbETR2, HbEIN2, HbEIN3, HbCaM, HbPIP1 and HbQM, were specifically regulated by ET treatment. Additionally, the transcript level of the HbGP and HbACR genes was enhanced by all three treatments simultaneously. Overall, a large number of genes were found to be regulated 4 h after the treatments were applied. This study nevertheless revealed some jasmonic acid-independent wound signalling pathways in H. brasiliensis, provided a general characterization of signalling pathways and will serve as a new base from which to launch advanced studies of the network of pathways operating in H. brasiliensis.

Validation of reference genes for quantitative real-time PCR during latex regeneration in rubber tree

“…In previous research, 18S and ACTIN genes have been the most widely used reference genes for expression normalization in rubber tree (Dusotoit-Coucaud et al, 2009;Duan et al, 2010;Li et al, 2010;Tang et al, 2010). However, extensive analysis is not conducted to validate their suitability as reference genes in those studies.…”

MYC genes with differential responses to tapping, mechanical wounding, ethrel and methyl jasmonate in laticifers of rubber tree (Hevea brasiliensis Muell. Arg.)

“…We have ever characterized HbCOI1 and HbJAZ1 in laticifer cells, which are related to COI1 and AtJAZ1/AtJAZ2 from Arabidopsis, respectively (Peng et al, 2009;Tian et al, 2010). The expression of HbCOI1 is up-regulated in latex of laticifers (Peng et al, 2009) while down-regulated in bark tissues by methyl jasmonate (Duan et al, 2010), suggesting that JA-responsiveness is diverse between different tissues of rubber trees. However, ethrel has little effect on the expression of HbCOI1 both in latex and in bark tissues (Peng et al, 2009;Duan et al, 2010).…”

“…The expression of HbCOI1 is up-regulated in latex of laticifers (Peng et al, 2009) while down-regulated in bark tissues by methyl jasmonate (Duan et al, 2010), suggesting that JA-responsiveness is diverse between different tissues of rubber trees. However, ethrel has little effect on the expression of HbCOI1 both in latex and in bark tissues (Peng et al, 2009;Duan et al, 2010). Transcription pattern analysis also reveals that HbJAZ1 is strongly up-regulated by tapping and mechanical wounding in latex, but not by ethrel application (Tian et al, 2010).…”

The Hevea brasiliensis AP2/ERF superfamily: from ethylene signalling to latex harvesting and physiological disease response

“…This early induction HbETR2 was suppressed by an ethylene inhibitor, 1-MCP. In this work, Duan et al (2010) have shown the effect of ethylene and wounding treatments on the downstream-response genes of ethylene signalling pathway. Thus, it opened the perspective of crosstalk signalling between phytohormones in Hevea brasiliensis.…”

“…The molecular actors involved in ethylene perception and signalling were also studied in Hevea brasiliensis (Duan et al, 2010). Two genes of ethylene perception, Hevea brasiliensis Ethylene Receptor 2 (HbETR2) and Hevea brasiliensis Ethylene-insensitive 2 (HbEIN2), and a gene of ethylene signalling (HbEIN3) were differentially regulated by ethylene treatment.…”