Here we present a detailed protocol for efficiently making homo- and heterografts between watermelon and bottle gourd, in addition to methods of tissue sampling, data generation, and data analysis, for the investigation of cold-responsive microRNAs.
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Method Article
Generating Homo- and Heterografts Between Watermelon and Bottle Gourd for the Study of Cold-responsive MicroRNAs
* These authors contributed equally
In This Article
Summary
Abstract
MicroRNAs (miRNAs) are endogenous small non-coding RNAs of about 20 - 24 nt, known to play important roles in plant development and adaptation. There is an accumulating evidence showing that the expressions of certain miRNAs are altered when grafting, an agricultural practice commonly used by farmers to improve crop tolerance to biotic and abiotic stresses. Bottle gourd is an inherently climate-resilient crop compared to many other major cucurbits, including watermelon, rendering it one of the most widely used rootstocks for the latter. The recent advancement of high-throughput sequencing technologies has provided great opportunities to investigate cold-responsive miRNAs and their contributions to heterograft advantages; yet, adequate experimental procedures are a prerequisite for this purpose. Here, we present a detailed protocol for efficiently generating homo- and heterografts between the cold-susceptible watermelon and the cold-tolerant bottle gourd, in addition to methods of tissue sampling, data generation, and data analysis. The presented methods are also useful for other plant-grafting systems, to interrogate miRNA regulations under various environmental stresses, such as heat, drought, and salinity.
Introduction
Grafting has long been employed as an agricultural technique to improve crop production and tolerance to biotic and abiotic stresses1,2,3. In heterografting systems, elite rootstocks can enhance water and nutrients uptake of plants, strengthen resistance to soil pathogens, and limit the negative effects of metal toxicity4,5, which may confer the grafts an enhanced growth vigor and increased tolerance to environmental stresses. In many cases, heterografting can also impact fruit qualities in horticultural plants, leadi....
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Protocol
1. Seed Sterilization and Germination
- For surface sterilization, soak the bottle gourd seeds in a 500-mL beaker filled with water at 58 °C with occasional stirring, until the water temperature drops to 40 °C.
- Meanwhile, put 3 kg of peat soil into a nylon bag and, to sterilize it, autoclave it at 120 °C/0.5 MPa for 20 min.
- Keep soaking the bottle gourd seeds for 4 - 5 h more with no stirring.
- Once the water reaches room temperature, rinse the seeds 2x - 3x with distilled water.
- Drain the excess water and allow the seeds to sprout in a gauze bag at 28 °C in a growth chamber in the dark.
- After germination,....
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Results
Figure 2: Phenotypes of various grafts at room temperature and cold-stressed conditions. (a) This panel shows homo- and heterografted seedlings at room temperature as the control. (b) This panel shows homo- and heterogra.......
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Discussion
In this protocol, we described in detail a highly efficient and reproducible method to make homo- and heterografts between watermelon and bottle gourd. This method, requiring no specific equipment, is very easy to operate and typically has a very high survival rate of grafting. The method can also be used to make grafts for other cucurbits, such as between watermelon, cucumber, and pumpkin.
It is worth noting that the relative size (age) of the rootstock and scion is critical to making a succe.......
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Disclosures
The authors have nothing to disclose. The small RNA sequencing data is deposited in the GenBank under the accession number SRP136842.
Acknowledgements
This work was supported by the National Natural Science Foundation of China (31772291), the Research Project for Public Interest in Zhejiang Province (2017C32027), the Key Science Project of Plant Breeding in Zhejiang (2016C02051), and the National Program for the Support of Top-notch Young Professionals (to P.X.).
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| TRIzol Reagent | Invitrogen | 15596026 | |
| RNA-free DNase I | Takara | D2270A | |
| Truseq Small RNA sample prep Kit | Illumina | RS-200-0012 | |
| 2100 Bionalyser | Agilent | 5067 | |
| DNA Polymerase | Thermo Fisher Scientific | F530S | |
| UEA sRNA workbench 2.4-plant version (software) | NA | NA | http://srna-workbench.cmp.uea.ac.uk/ |
| Rfam 11.0 database (website) | NA | NA | http://rfam.janelia.org |
| miRBase 22.0 (website) | NA | NA | http://www.mirbase.org/ |
| MIREAP(software) | NA | NA | https://sourceforge.net/projects/mireap/ |
| TargetFinder (software) | NA | NA | http://targetfinder.org/ |
References
- Schwarz, D., Rouphael, Y., Colla, G., Venema, J. H. Grafting as a tool to improve tolerance of vegetables to abiotic stresses: Thermal stress, water stress and organic pollutants. Scientia Horticulturae. 127, 162-171 (2010).
- Li, Y., et al. Mechanisms of tolerance differences in cucumber seedlings grafted on rootstocks with different tolerance to low temperature and weak light stresses. Turkish Journal of Botany. 39 (4), 606-614 (2015).<....
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