Transcriptome and Physiological Analysis of Rootstock Types and Silicon Affecting Cold Tolerance of Cucumber Seedlings.

Heng Luan,Yan Li,Chenxu Niu,Min Wei,Xinmiao Nie

doi:10.3390/plants11030445

Abstract

Cucumbers grafted on rootstocks with different de-blooming capacity show varying levels of cold tolerance. The content of fruit bloom correlates with its silicon-metabolizing capacity, and rootstock grafting can alter not only the cold tolerance but also the silicon-metabolizing capacity of the scion. The molecular mechanisms responsible for resistance due to rootstocks and silicon and the pathway that affects cold tolerance, however, remain poorly understood. Therefore, we performed physiological and transcriptome analysis to clarify how rootstock types and silicon affect cold tolerance in cucumber seedlings. Then, we randomly selected eight differentially expressed genes (DEGs) for quantitative real time PCR (qRT-PCR) analysis to proof the reliability of the transcriptome data. The results showed that silicon can enhance the cold tolerance of cucumbers by boosting the phenylpropanoid metabolism, and rootstock grafting can boost the active oxygen scavenging ability and synthesis level of hormones in cucumbers and maintain the stability of the membrane structure to enhance cold tolerance. The difference in cold tolerance between the two rootstocks is because the cold-tolerant one has stronger metabolic and sharp signal transduction ability and can maintain the stability of photosynthesis, thereby contributing to the stability of the cellular system and enhancing tolerance to cold.

Highlights

Cucumber (Cucumis sativus L.) is a major vegetable crop cultivated in solar greenhouses in China and is sensitive to cold [1]
These results indicate that grafting and silicon addition apparently enhance the cold tolerance of cucumbers
By comparing with the GO Consortium, we found that the silicon-inwere similar to the rootstock-grafting-induced differentially expressed genes (DEGs) in terms of functional classification, duced DEGs were similar to the rootstock-grafting-induced DEGs in terms of functional mostly in the metabolic process, catalytic activity, membrane part, binding, and cellular classification, mostly in the metabolic process, catalytic activity, membrane part, binding, process categories (Figure 3)

Summary

Introduction

Cucumber (Cucumis sativus L.) is a major vegetable crop cultivated in solar greenhouses in China and is sensitive to cold [1]. Grafting is an essential agronomic technique to enhance the cold tolerance of cucumbers [2], especially for cucumber production in greenhouses in northern China. Black-seeded pumpkins were mainly used as a rootstock for cucumber grafting, as they exhibit strong resistance, high yield, and other advantages [3]. The commercial value of black-seeded-pumpkin-grafted cucumber has decreased due to fruit bloom [4]. Cucumbers with less fruit bloom and brighter surface have become more popular in the market [5]. To reduce the fruit bloom and increase the commercial value, the proportion of cucumber varieties grafted on white-seed rootstock with strong de-blooming ability has been increasing in production

Methods

Results

Discussion

Conclusion