Proteomic analysis reveals key proteins involved in ethylene-induced adventitious root development in cucumber (Cucumis sativus L.)

Abstract

The mechanisms involved in adventitious root formation reflect the adaptability of plants to the environment. Moreover, the rooting process is regulated by endogenous hormone signals. Ethylene, a signaling hormone molecule, has been shown to play an essential role in the process of root development. In the present study, in order to explore the relationship between the ethylene-induced adventitious rooting process and photosynthesis and energy metabolism, the iTRAQ technique and proteomic analysis were employed to ascertain the expression of different proteins that occur during adventitious rooting in cucumber (Cucumis sativus L.) seedlings. Out of the 5,014 differentially expressed proteins (DEPs), there were 115 identified DEPs, among which 24 were considered related to adventitious root development. Most of the identified proteins were related to carbon and energy metabolism, photosynthesis, transcription, translation and amino acid metabolism. Subsequently, we focused on S-adenosylmethionine synthase (SAMS) and ATP synthase subunit a (AtpA). Our findings suggest that the key enzyme, SAMS, upstream of ethylene synthesis, is directly involved in adventitious root development in cucumber. Meanwhile, AtpA may be positively correlated with photosynthetic capacity during adventitious root development. Moreover, endogenous ethylene synthesis, photosynthesis, carbon assimilation capacity, and energy material metabolism were enhanced by exogenous ethylene application during adventitious rooting. In conclusion, endogenous ethylene synthesis can be improved by exogenous ethylene additions to stimulate the induction and formation of adventitious roots. Moreover, photosynthesis and starch degradation were enhanced by ethylene treatment to provide more energy and carbon sources for the rooting process.

Identification of Key Genes during Ethylene-Induced Adventitious Root Development in Cucumber (Cucumis sativus L.)

“…As an important small gaseous molecule, ETH affects the growth and development of plants, and it is also a major regulator in response to diverse stresses. Many studies have shown that ETH can induce adventitious rooting in cucumber and marigold [ 1 , 15 , 16 ]. Using the iTRAQ technique and proteome analysis, Lyu et al [ 16 ] revealed that ETH treatment increased photosynthesis and starch degradation to provide energy for adventitious rooting in cucumber.…”

“…Many studies have shown that ETH can induce adventitious rooting in cucumber and marigold [ 1 , 15 , 16 ]. Using the iTRAQ technique and proteome analysis, Lyu et al [ 16 ] revealed that ETH treatment increased photosynthesis and starch degradation to provide energy for adventitious rooting in cucumber. However, some key genes involved in ETH-promoted adventitious root development in cucumber have not been identified.…”

“…Therefore, ETH-treated explants completed energy conversion by reducing the expression of CsBAM1 and CsBAM3 in the starch signaling pathway and the content of starch, which may be beneficial for adventitious rooting. According to Lyu et al [ 16 ], 48 h after treatment is the root elongation phase. At this stage, starch might be converted to glucose to provide energy for root growth.…”

“…Although ETH may influence many aspects of plant growth and development, the roles of ETH in adventitious root development are still unclear. Our previous studies have demonstrated that 10 μM ETH could significantly induce adventitious root development in cucumber and marigold ( Tagetes erecta L.) [ 1 , 15 , 16 ]. Moreover, ETH is associated with other signal molecules, such as nitric oxide (NO), auxin, and calcium ions (Ca 2+ ) in the promotion of adventitious rooting [ 1 , 8 , 17 , 18 ].…”

“…However, many studies have only elucidated its mechanism from the perspective of pharmacology, and the genes or proteins in ETH-induced adventitious rooting are still unknown. Proteomic analysis found that exogenous ETH could promote adventitious rooting in cucumber by regulating some important proteins [ 16 ]. However, the key genes of ETH-induced adventitious rooting are still unclear.…”