Characterization and Expression of Genes Involved in the Ethylene Biosynthesis and Signal Transduction during Ripening of Mulberry Fruit

Abstract

Although ethylene is well known as an essential regulator of fruit development, little work has examined the role ethylene plays in the development and maturation of mulberry (Morus L.) fruit. To study the mechanism of ethylene action during fruit development in this species, we measured the ethylene production, fruit firmness, and soluble solids content (SSC) during fruit development and harvest. By comparing the results with those from other climacteric fruit, we concluded that Morus fruit are probably climacteric. Genes associated with the ethylene signal transduction pathway of Morus were characterized from M. notabilis Genome Database, including four ethylene receptor genes, a EIN2-like gene, a CTR1-like gene, four EIN3-like genes, and a RTE1-like gene. The expression patterns of these genes were analyzed in the fruit of M. atropurpurea cv. Jialing No.40. During fruit development, transcript levels of MaETR2, MaERS, MaEIN4, MaRTE, and MaCTR1 were lower at the early stages and higher after 26 days after full bloom (DAF), while MaETR1, MaEIL1, MaEIL2, and MaEIL3 remained constant. In ripening fruit, the transcripts of MaACO1 and MaACS3 increased, while MaACS1 and MaACO2 decreased after harvest. The transcripts of MaACO1, MaACO2, and MaACS3 were inhibited by ethylene, and 1-MCP (1–methylcyclopropene) upregulated MaACS3. The transcripts of the MaETR-like genes, MaRTE, and MaCTR1 were inhibited by ethylene and 1-MCP, suggesting that ethylene may accelerate the decline of MaETRs transcripts. No significant changes in the expression of MaEIN2, MaEIL1, and MaEIL3 were observed during ripening or in response to ethylene, while the expressions of MaEIL2 and MaEIL4 increased rapidly after 24 h after harvest (HAH) and were upregulated by ethylene. The present study provides insights into ethylene biosynthesis and signal transduction in Morus plants and lays a foundation for the further understanding of the mechanisms underlying Morus fruit development and ripening.

Postcosecha de frutos: maduración y cambios bioquímicos

“…Two key enzymes are involved in the biosynthetic pathway, ACC synthase (ACS), which converts SAM into ACC, and ACC oxidase (ACO) which converts ACC into ethylene (Kende, 1993) and identified and characterized genes which encode them (Sato and Theologis, 1989;Hamilton et al, 1990Hamilton et al, , 1991. The expression profiles and regulatory mechanisms of ACS and ACO genes in fruits have been investigated in plants (Liu et al, 2015). han identificado y caracterizado los genes correspondientes que las codifican (Sato y Theologis, 1989;Hamilton et al, 1990Hamilton et al, , 1991.…”

“…han identificado y caracterizado los genes correspondientes que las codifican (Sato y Theologis, 1989;Hamilton et al, 1990Hamilton et al, , 1991. Los perfiles de expresión y mecanismos de regulación de los genes de ACS y ACO en frutos han sido investigados en plantas (Liu et al, 2015).…”

“…cantalupensis; Ayub et al, 1996), manzana (Wang et al, 2009) y en frutos de mora (Morus atropurpurea cv. Jialing; Liu et al, 2015).…”

Postcosecha de frutos: maduración, ablandamiento y control transcripcional

“…Los principales pasos en la biosíntesis de etileno (Figura 1) involucran la conversión de S-adenosilmetionina (SAM) a ácido 1-aminociclopropano-1-carboxílico (ACC) por la ACC sintasa (ACS) y luego por la ACC oxidasa (ACO) a etileno (Alexander y Grierson, 2002). En el tejido de frutos climatéricos, la biosíntesis de etileno inicia a un nivel bajo durante el desarrollo (sistema 1), pero al inicio de la maduración se vuelve autoctalítico (sistema 2) (Karlova et al, 2014), debido a que la presencia de etileno activa la acción del gen que codifica a la enzimaACO que convierte el ACC a etileno (Liu et al, 2015).…”

“…The major steps in ethylene biosynthesis (Figure 1) involve the conversion of S-adenosylmethionine (SAM) to 1-aminocyclopropane-1-carboxylic acid (ACC) by ACC synthase (ACS) and then by ACC oxidase (ACO) to ethylene (Alexander and Grierson, 2002). In the climacteric fruit tissue, ethylene biosynthesis begins at a low level during development (system 1), but at the beginning of maturation it becomes autoclaved (system 2) (Karlova et al, 2014), because presence of ethylene activates the action of the gene encoding the ACO enzyme that converts ACC to ethylene (Liu et al, 2015). En este sentido, una tendencia en las investigaciones ha sido el uso de técnicas de biología molecular dirigidas al aislamiento, reconocimiento y expresión de los genes de las principales enzimas que actúan durante el ablandamiento ocurrido en la maduración de los frutos (Brummell y Harpster, 2001).…”