Lee Bok-Rye, Zaman Rashed, La Van Hien, Park Sang-Hyun, Kim Tae-Hwan
Department of Animal Science, Institute of Agricultural Science and Technology, College of Agriculture & Life Science, Chonnam National University, Gwangju 61186, Korea.
Asian Pear Research Institute, Chonnam National University, Gwangju 61186, Korea.
Plants (Basel). 2021 Sep 23;10(10):1993. doi: 10.3390/plants10101993.
To investigate the regulatory role of ethylene in the source-sink relationship for nitrogen remobilization, short-term effects of treatment with different concentrations (0, 25, 50, and 75 ppm) of ethephon (2-chloroethylphosphonic acid, an ethylene inducing agent) for 10 days (EXP 1) and long-term effects at 20 days (Day 30) after treatment with 100 ppm for 10 days (EXP 2) on protein degradation and amino acid transport in foliar sprayed mature leaves of (cv. Mosa) were determined. In EXP 1, endogenous ethylene concentration gradually increased in response to the treated ethephon concentration, leading to the upregulation of expression and downregulation of expression. Further, the increase in ethylene concentration caused a reduction in protein, Rubisco, and amino acid contents in the mature leaves. However, the activity of protease and expression of amino acid transporter (), an amino acid transport gene, were not significantly affected or slightly suppressed between the treatments with 50 and 75 ppm. In EXP 2, the enhanced ethylene level reduced photosynthetic pigments, leading to an inhibition of flower development without any pod development. A significant increase in protease activity, confirmed using in-gel staining of protease, was also observed in the ethephon-treated mature leaves. Ethephon application enhanced the expression of four (, , , and ) and the phloem loading of amino acids. Significant correlations between ethylene level, induced by ethephon application, and the descriptive parameters of protein degradation and amino acid transport were revealed. These results indicated that an increase in ethylene upregulated nitrogen remobilization in the mature leaves (source), which was accompanied by an increase in proteolytic activity and amino acid transport, but had no benefit to pod (sink) development.
为了研究乙烯在氮素再转运源库关系中的调控作用，测定了用不同浓度（0、25、50和75 ppm）的乙烯利（2 - 氯乙基膦酸，一种乙烯诱导剂）处理10天（实验1）的短期效应，以及用100 ppm处理10天后在第20天（第30天）的长期效应（实验2）对喷施叶面的成熟叶片（品种Mosa）中蛋白质降解和氨基酸转运的影响。在实验1中，内源乙烯浓度随着处理的乙烯利浓度逐渐增加，导致 表达上调和 表达下调。此外，乙烯浓度的增加导致成熟叶片中蛋白质、核酮糖-1,5-二磷酸羧化酶/加氧酶（Rubisco）和氨基酸含量降低。然而，蛋白酶活性和氨基酸转运基因氨基酸转运体（ ）的表达在50和75 ppm处理之间没有受到显著影响或略有抑制。在实验2中，增强的乙烯水平降低了光合色素，导致花发育受到抑制且没有荚果发育。在用蛋白酶凝胶内染色证实的乙烯利处理的成熟叶片中也观察到蛋白酶活性显著增加。乙烯利处理增强了四个 （ 、 、 和 ）的表达以及氨基酸的韧皮部装载。揭示了乙烯利处理诱导的乙烯水平与蛋白质降解和氨基酸转运的描述参数之间的显著相关性。这些结果表明，乙烯增加上调了成熟叶片（源）中的氮素再转运，这伴随着蛋白水解活性和氨基酸转运的增加，但对荚果（库）发育没有益处。
