Ethephon Increases Rubber Tree Latex Yield by Regulating Aquaporins and Alleviating the Tapping-Induced Local Increase in Latex Total Solid Content

Abstract

The concentration of phloem solute generally falls from leaves to roots. However, a local increase in latex total solid content (LILTSC) was identified near the tapping cut of rubber trees. To understand the mechanism of ethephon-stimulated latex yield, the formation and ethephon (an ethylene releaser) alleviation of the LILTSC near the tapping cut were examined. It was found that the LILTSC near the tapping cut of a tapped rubber tree was caused by the tapping-accelerated rubber biosynthesis which began following the first tapping and became significant after the fourth tapping. Ethephon stimulation markedly reduced the LILTSC. The latex yield change pattern upon ethephon stimulation was associated with the kinetic change of LILTSC and the decomposition dynamic of ethephon into ethylene. Once the LILTSC was reduced by ethylene release upon ethephon stimulation, the latex yield increased; however, when the ethylene release upon ethephon stimulation receded, the LILTSC was restored and the effect of ethephon stimulation dissipated. The reduction of LILTSC by ethephon stimulation could be ascribed to the translocation property of ethylene in plants and its regulation of aquaporins. Because maximum ethylene release upon tapping-cut-ethephon-application occured close to the tapping cut, the aquaporins were more upregulated in this region, leading to a reduction of the LILTSC and an increase in latex yield. All these results suggest that the LILTSC near the tapping cut was caused by tapping; the ethephon-induced aquaporin up-regulation and LILTSC reduction are involved in the mechanism of ethephon-promoted latex yield.

Ethrel® stimulant increases the activity of soluble invertase isoforms in rubber tree (Hevea brasiliensis) bark tissues

“…Production enhance of dry rubber in ES trees (Table 2) is consistent with results found in literature (Gorton, 1972;Zhu and Zhang, 2009;Tang et al, 2010;Dusotoit-Coucaud et al, 2010). It has been reported that bark treatment on rubber trees with Ethrel ® induced a decrease in latex solid total concentrations (Coupé and Chrestin, 1989), which corresponded to an inflow of water in latex vessels (An et al, 2016;Tungngoen et al, 2009). Once which, mature lactiferous cells are plasmodesmata devoid (De Fay et al, 1989), it has been suggested that aquaporin could be a physiological mechanism that induces latex production increase by ethylene stimulation, because aquaporin activity is regulated at post-translational level in response to hormonal treatments (An et al, 2016).…”

“…It has been reported that bark treatment on rubber trees with Ethrel ® induced a decrease in latex solid total concentrations (Coupé and Chrestin, 1989), which corresponded to an inflow of water in latex vessels (An et al, 2016;Tungngoen et al, 2009). Once which, mature lactiferous cells are plasmodesmata devoid (De Fay et al, 1989), it has been suggested that aquaporin could be a physiological mechanism that induces latex production increase by ethylene stimulation, because aquaporin activity is regulated at post-translational level in response to hormonal treatments (An et al, 2016). Work performed with PB217 clone confirmed the genes expression that regulate aquaporin transcription (HbPIP2;1 and HbTIP1;1) was clearly promoted by ethylene, which resulted in increased yield latex dilution after treatment with Ethrel ® (Tungngoen et al, 2009).…”

Estimulación de árboles de caucho bajo diferentes frecuencias de sangría en el Noroeste de Colombia

“…En el primer caso, las diferencias en los contenidos de CST están asociadas al aumento en la producción de látex (Tabla 1), y en el segundo, a lo repetitivo del proceso de sangrado, hecho que probablemente generó una mayor demanda de partículas de caucho durante cada sangría. Al respecto, An et al (2016) informan que la estimulación con etefón aumenta el rendimiento del látex tan pronto como se realiza su aplicación, el cual generalmente alcanza su máximo un tiempo después (7 días). Los estudios realizados por Attanayake et al ( 2018), donde se probaron diferentes concentraciones de etefón, señalan que los valores del CST en tratamientos estimulados disminuyeron significativamente, pasando de un 46 % sin estimulación a un 34 % cuando la concentración del estimulante fue del 5 %.…”

Improvement of Productivity of the Moderate Metabolism Clone GT 1 of Hevea Brasiliensis Muell. Arg. by Early Upward Tapping in Côte d'Ivoire

“…The dry rubber production data expressed in kgha -1 y -1 of early upward tapping are convincing, given the production gains that they made possible in the first four years of tapping (production gain ≥ 30% per year) compared to J, [3,16]. Production of rubber is strongly and positively influenced by the number of stimulation applications for a given clone and the latex harvesting technology [17][18][19][20][21] and also by the concentration of ethephon [21]. The practice of hormonal stimulation allows a substantial increase in production by increasing the flow time [22].…”