Transcriptome and physiological analyses provide insights into the leaf epicuticular wax accumulation mechanism in yellowhorn

Abstract

Plantations and production of yellowhorn, one of the most important woody oil and urban greening trees widely cultivated in northern China, have gradually become limited by drought stress. The epicuticular wax layer plays a key role in the protection of yellowhorn trees from drought and other stresses. However, there is no research on the mechanism of wax loading in yellowhorn trees. In this study, we investigated the anatomical and physiological characteristics of leaves from different germplasm resources and different parts of the same tree and compared their cuticle properties. In addition, the different expression patterns of genes involved in wax accumulation were analyzed, and a coexpression network was built based on transcriptome sequencing data. Morphological and physiological comparisons found that the sun leaves from the outer part of the crown had thicker epicuticular wax, which altered the permeability and improved the drought resistance of leaves, than did shade leaves. Based on transcriptome data, a total of 3008 and 1324 differentially expressed genes (DEGs) were identified between the sun leaves and shade leaves in glossy- and non-glossy-type germplasm resources, respectively. We identified 138 DEGs involved in wax biosynthesis and transport, including structural genes (such as LACS8, ECH1, and ns-LTP) and transcription factors (such as MYB, WRKY, and bHLH transcription factor family proteins). The coexpression network showed a strong correlation between these DEGs. The differences in gene expression patterns between G- and NG-type germplasm resources under different light conditions were very clear. These results not only provide a theoretical basis for screening and developing drought-resistant yellowhorn germplasm resources but also provide a data platform to reveal the wax accumulation process of yellowhorn leaves.

Transcriptome and Physiological Analyses of a Navel Orange Mutant with Improved Drought Tolerance and Water Use Efficiency Caused by Increases of Cuticular Wax Accumulation and ROS Scavenging Capacity

“…As expected, MT plants were much more tolerant to drought stress than WT plants, as indicated by their fewer wilting leaves under drought stress ( Figure 4 A–D). This result supported previous reports, which suggested that high cuticular wax deposition could improve plant tolerance to drought stress [ 5 , 28 , 34 , 35 ]. Proline and soluble sugar acted as compatible osmolytes involved in plant response to drought stress [ 36 , 37 ].…”

Genome-Wide Identification and Expression Analysis of the KCS Gene Family in Yellow Horn Reveal Their Putative Function on Abiotic Stress Responses and Wax Accumulation

“…The epidermal wax layer plays an important role in plant resistance to stress, especially drought stress. One KCS gene was differently expressed in yellow horn with different leaf wax thickness and showed a coexpression correlation with some transcription factors (e.g., MYB3) [16]. In this study, in order to further explore the role of KCS genes in the resistance response of yellow horn, bioinformatics methods were used to identify the members of the KCS gene family of yellow horn and the tissue expression patterns and expression level under abiotic stress were analyzed.…”

Population Genetics and Development of a Core Collection from Elite Germplasms of Xanthoceras sorbifolium Based on Genome-Wide SNPs

“…It is widely adaptable to various growth conditions, such as drought, low temperature, salt, alkali, and other conditions [2,3]. It is one of the most important species of woody oil [4]. The oil content of its seed kernel can be as high as 67%, of which 85-93% is unsaturated fatty acids, including 37.1-46.2% linoleic acid and 28.6-37.1% oleic acid, which are essential dietary fatty acids [5].…”