Determining conserved xylem response to drought in woody plants for use in grapevine editing

Abstract

Grapevine is a relatively drought-tolerant crop that adopts a variety of strategies in response to water deficit [1]. Hydraulic traits linked to water transport efficiency and xylem embolism vulnerability are especially important and show a large degree of variation between cultivars [2]. How exactly these traits influence the performance of grapevine plants under drought stress conditions is difficult to decipher, as they are closely associated with other water-use related traits like stomatal conductance, and can also vary in effectiveness based on the length and intensity of the drought stress [3]. The variation in hydraulic traits is strongly influenced by xylem cell wall structure and composition, and trade-offs are made between xylem vessel roles as a hydraulic conduit and structural scaffold [4]. Genome editing can be used to study how the altering of xylem characteristics affects drought response, but identifying targets in grapevine is challenging, as tissue-specific gene expression data of grapevine xylem tissue under water deficit conditions is under-researched. To circumvent this limitation and identify potential targets, conserved responses between woody plants under water deficit conditions were investigated. Publicly available transcriptomic data from Citrus macrophylla [5], Eucalyptus grandis [6] and Populus trichocarpa [7] xylem tissue undergoing water stress trials were used. Conserved differentially expressed genes were identified, and gene ontology (GO) enrichment was performed to find over-represented GO terms that were conserved.

Additionally, a maximum relevance minimum redundancy network was constructed from the transcriptomic data of one of the Eucalyptus studies to assist in selecting potential targets. A list of targets was generated from these analyses that can be used for further validation with grapevine genome editing. Rapid plant genetic transformation systems such as hairy root transformation and protoplast editing can be used as models to assess alterations in xylem development, and cell wall and structure properties.

References

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