A gene that underwent adaptive evolution, LAC2 (LACCASE), in Populus euphratica improves drought tolerance by improving water transport capacity

Abstract

Drought severely limits plant development and growth; accordingly, plants have evolved strategies to prevent water loss and adapt to water deficit conditions. However, experimental cases that corroborate these evolutionary processes are limited. The LACCASEs (LACs) family is involved in various plant development and growth processes. Here, we performed an evolutionary analysis of LACs from Populus euphratica and characterized the functions of LACs in Arabidopsis and poplar. The results showed that in PeuLACs, multiple gene duplications led to apparent functional redundancy as the result of various selective pressures. Among them, PeuLAC2 underwent strong positive selection. Heterologous expression analyses showed that the overexpression of PeuLAC2 alters the xylem structure of plants, including thickening the secondary cell wall (SCW) and increasing the fiber cell length and stem tensile strength. Altogether, these changes improve the water transport capacity of plants. The analysis of the physiological experimental results showed that PeuLAC2-OE lines exhibited a stronger antioxidant response and greater drought tolerance than WT. Three genes screened by transcriptome analysis, NAC025, BG1, and UGT, that are associated with SCW synthesis and drought stress were all upregulated in the PeuLAC2-OE lines, implying that the overexpression of PeuLAC2 thickened the SCW, improved the water transport capacity of the plant, and further enhanced its drought tolerance. Our study highlights that genes that have undergone adaptive evolution may participate in the development of adaptive traits in P. euphratica and that PeuLAC2 could be a candidate gene for molecular genetic breeding in trees.

Lignin Synthesis, Affected by Sucrose in Lotus (Nelumbo nucifera) Seedlings, Was Involved in Regulation of Root Formation in the Arabidopsis thanliana

“…Recently, LACs have been found to be involved in various abiotic stress responses in plants [49]. The overexpression of LAC2P can improve water transport, which leads to enhanced plant drought adaptation [59]. H 2 O 2 (hydrogen peroxide) is reported to be an important signaling molecule.…”

A Cotton Lignin Biosynthesis Gene, GhLAC4, Fine-Tuned by ghr-miR397 Modulates Plant Resistance Against Verticillium dahliae

“…GhLAC4 knockdown plants showed lower lignin content and decreased G-lignin biosynthesis according to lignin content measurement, chemical staining, and GC/MS analysis. Although there are many LACs in plants, only a few of them participate in monolignol polymerisation into lignin ( Niu et al, 2021 ). For example, of 17 laccase genes in Arabidopsis , only LAC4 , LAC11 , LAC15 , and LAC17 were verified to act in lignin biosynthesis according to genetic analysis ( Liang et al, 2006 ; Berthet et al, 2011 ; Turlapati et al, 2011 ; Zhao et al, 2013 ).…”

“…Plant laccases (LAC, EC. 1.10.3.2), which belong to the blue copper oxidase/ρ-diphenol:dioxygen oxidoreductase family, are widely distributed in higher plants, including gymnosperms, monocots, and eudicots ( McCaig et al, 2005 ; Turlapati et al, 2011 ; Wang et al, 2014 ; Niu et al, 2021 ). In Arabidopsis , there are 17 known members of the laccase family, which are classified into six groups ( McCaig et al, 2005 ; Hoegger et al, 2006 ; Turlapati et al, 2011 ), of which eight are expressed in stems ( Berthet et al, 2011 ; Zhao et al, 2013 ).…”

The Laccase Gene Family Mediate Multi-Perspective Trade-Offs during Tea Plant (Camellia sinensis) Development and Defense Processes

“…Furthermore, AtLAC14 and AtLAC15 were phylogenetically related to GhLAC1 and Gh-LAC15 in upland cotton, which have been demonstrated to be involved in positively regulating defense-induced lignification in the cell wall to enhance the broad-spectrum biotic stress response [12,13]. A recent study demonstrated that the overexpression of poplar PeuLAC2, which phylogenetically clustered with AtLAC14 and AtLAC15 of Arabidopsis, altered the xylem structure of plants, including thickening the secondary cell wall (SCW) and increasing the fiber cell length and stem tensile strength, and thereby mediated stronger antioxidant response and greater drought tolerance [44]. In our study, most CsLACs in subclade IV were remarkably upregulated in E. obliqua simulated feeding leaves.…”