Comparative transcriptome profiling provides insights into endocarp lignification of walnut (Juglans Regia L.)

Wu, Xiaoting; Zhang, Zechao; Sun, Mintao; An, Xiu-Hong; Qi, Yingbin; Zhao, Shugang; Zhang, Zhihua; Wang, Hongxia

doi:10.1016/j.scienta.2021.110030

Cited by 7 publications

(6 citation statements)

References 58 publications

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“…The endocarp of walnut collected at 20 DAF (unlignified stage) and 45 DAF (lignification stage) was selected for transcriptome sequencing, and three replicates were used in the analysis. The sequence data were deposited in GSA ( https://bigd.big.ac.cn/gsa/browse/CRA005050 ) [ 60 ]. Using RNA-Seq, we explored the gene expression patterns of the JrLAC gene family in the endocarp at the unlignified and lignification stages.…”

Section: Methodsmentioning

confidence: 99%

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The role of JrLACs in the lignification of walnut endocarp

Wang

Liu

et al. 2021

BMC Plant Biol

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Background The walnut shell, which is composed of a large number of sclereids originating from the lignified parenchyma of the endocarp, plays an important role in fruit development and during harvesting and storage. The physical and chemical properties of walnut shells are closely related to the lignin content. Laccase is the key enzyme responsible for lignin biosynthesis by the polymerization of monolignols and plays crucial roles in secondary cell wall formation in plants. In this study, we screened and identified laccase family genes from the walnut genome and investigated the expression of laccase during endocarp lignification in walnut. Results A total of 37 laccase genes were screened from the walnut genome and distributed on nine chromosomes and classified into 6 subfamilies, among which subfamily IV showed distinct expansion. We observed that endocarp lignification started 44 days after flowering (DAF), and at later periods, the lignin content increased rapidly, with growth peaks at 44–50 DAF and 100–115 DAF. The lignification of the endocarp proceeded from the outside to the inside, as demonstrated by section staining in combination with endocarp staining. Furthermore, the changes in the expression of laccase family genes in the endocarp at different developmental stages were studied, and JrLACs showed different expression trends. The expression of nine genes showed significant increase after 44 DAF, and among these, JrLAC12–1, JrLAC12–2 and JrLAC16 showed a significant change in expression at the lignification stage. A study of the expression of JrLACs in different tissues and at various endocarp developmental stages revealed, that most JrLACs were expressed at low levels in mature tissues and at high levels in young tissues, in particular, JrLAC12–1 showed high expression in the young stems. A significant positive correlation was found between the expression of JrLAC12–1 and the variation in the lignin content in the endocarp. Conclusion Laccase genes play an important role in the lignification of the walnut endocarp, and JrLACs play different roles during fruit development. This study shows that JrLAC12–1 may play a key role in the lignification of endocarp.

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Section: Methodsmentioning

confidence: 99%

“…ac. cn/ gsa/ browse/ CRA00 5050) [60]. Using RNA-Seq, we explored the gene expression patterns of the JrLAC gene family in the endocarp at the unlignified and lignification stages.…”

Section: Analysis and Validation Of Rna-seq Datamentioning

confidence: 99%

The role of JrLACs in the lignification of walnut endocarp

Wang

Liu

et al. 2021

BMC Plant Biol

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“…The differentially expressed genes involved in the phenylpropanoid pathway and flavonoid pathway include COMT, C3′H, HCT, CAD, POD, C4H, CCoAOMT, CCR, and CHS . These have a potential role in the endocarp development and lignification of walnut [ 36 ]. Similarly, the CCoAOMT gene plays a key role in regulating the rapid endocarp lignification process in Davidia involucrata Baill.…”

Section: Molecular Mechanisms Of Endocarp Lignificationmentioning

confidence: 99%

Mechanism of Stone (Hardened Endocarp) Formation in Fruits: An Attempt toward Pitless Fruits, and Its Advantages and Disadvantages

Khan

Noor

Jia

et al. 2022

Genes

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Stone (hardened endocarp) has a very important role in the continuity of plant life. Nature has gifted plants with various seed protection and dispersal strategies. Stone-fruit-bearing species have evolved a unique adaptation in which the seed is encased in an extremely hard wood-like shell called the stone. The lignification of the fruit endocarp layer produces the stone, a feature that separates drupes from other plants. Stone cells emerge from parenchyma cells after programmed cell death and the deposition of cellulose and lignin in the secondary cell wall. Generally, the deposition of lignin in primary cell walls is followed by secondary thickening of cell walls to form stone cells. This review article describes the molecular mechanisms and factors that influence the production of stone in the fruit. This is the first review article that describes the molecular mechanisms regulating stone (harden endocarp) formation in fruits. This article will help breeders understand the molecular and genetic basis for the stone formation in fruit, and this could lead to new and innovative directions to breed stoneless fruit cultivars in the future.

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“…It ranges from 20 to 48% in eudicot nut shells (Landucci et al 2020 ; Li et al 2018 ) and in J. regia from 30 to 50%, depending on cultivar (Zhao et al 2019 ). During the main lignification period of walnut shells (15 days), Wu et al ( 2021 ) revealed an upregulation of genes responsible for the transduction of plant hormone signal, the biosynthesis of phenylpropanoids and the metabolism of starch and sucrose. This suggests that the enormous increase in secondary cell wall formation and lignin biosynthesis needs to be supported by metabolites from active cells to be accomplished in this rather short time period.…”

Section: Introductionmentioning

confidence: 99%

The walnut shell network: 3D visualisation of symplastic and apoplastic transport routes in sclerenchyma tissue

Antreich

Huss

Xiao

et al. 2022

Planta

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Main conclusion High symplastic connectivity via pits was linked to the lignification of the developing walnut shell. With maturation, this network lessened, whereas apoplastic intercellular space remained and became relevant for shell drying. Abstract The shell of the walnut (Juglans regia) sclerifies within several weeks. This fast secondary cell wall thickening and lignification of the shell tissue might need metabolites from the supporting husk tissue. To reveal the transport capacity of the walnut shell tissue and its connection to the husk, we visualised the symplastic and apoplastic transport routes during shell development by serial block face-SEM and 3D reconstruction. We found an extensive network of pit channels connecting the cells within the shell tissue, but even more towards the husk tissue. Each pit channel ended in a pit field, which was occupied by multiple plasmodesmata passing through the middle lamella. During shell development, secondary cell wall formation progressed towards the interior of the cell, leaving active pit channels open. In contrast, pit channels, which had no plasmodesmata connection to a neighbouring cell, got filled by cellulose layers from the inner cell wall lamellae. A comparison with other nut species showed that an extended network during sclerification seemed to be linked to high cell wall lignification and that the connectivity between cells got reduced with maturation. In contrast, intercellular spaces between cells remained unchanged during the entire sclerification process, allowing air and water to flow through the walnut shell tissue when mature. The connectivity between inner tissue and environment was essential during shell drying in the last month of nut development to avoid mould formation. The findings highlight how connectivity and transport work in developing walnut shell tissue and how finally in the mature state these structures influence shell mechanics, permeability, conservation and germination.

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Comparative transcriptome profiling provides insights into endocarp lignification of walnut (Juglans Regia L.)

Cited by 7 publications

References 58 publications

The role of JrLACs in the lignification of walnut endocarp

The role of JrLACs in the lignification of walnut endocarp

Mechanism of Stone (Hardened Endocarp) Formation in Fruits: An Attempt toward Pitless Fruits, and Its Advantages and Disadvantages

The walnut shell network: 3D visualisation of symplastic and apoplastic transport routes in sclerenchyma tissue

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