DOI: 10.1093/jxb/erac347 PMCID: PMC4145124

Abstract

Programmed cell death (PCD) is essential for wood development in trees. However, the determination of crucial factors involved in xylem PCD of wood development is still lacking. Here, two Populus trichocarpa typical aspartic protease (AP) genes, AP17 and AP45, modulate xylem maturation, especially fibre PCD, during wood formation. AP17 and AP45 were dominantly expressed in the fibres of secondary xylem, as suggested by GUS expression in APpro::GUS transgenic plants. Cas9/gRNA-induced AP17 or AP45 mutants delayed secondary xylem fibre PCD, and ap17ap45 double mutants showed more serious defects. Conversely, AP17 overexpression caused premature PCD in secondary xylem fibres, indicating a positive modulation in wood fibre PCD. Loss of AP17 and AP45 did not alter wood fibre wall thickness, whereas the ap17ap45 mutants showed a low lignin content in wood. However, AP17 overexpression led to a significant decrease in wood fibre wall thickness and lignin content, revealing the involvement in secondary cell wall synthesis during wood formation. In addition, the ap17ap45 mutant and AP17 overexpression plants resulted in a significant increase in saccharification yield in wood. Overall, AP17 and AP45 are crucial modulators in xylem maturation during wood development, providing potential candidate genes for engineering lignocellulosic wood for biofuel utilization.

Publication Types

Journal Article Research Support, Non-U.S. Gov't

Keywords

Populus trichocarpa Aspartic protease programmed cell death saccharification secondary cell wall wood formation xylem fibre

Grant Support

• Fundamental Research Funds for the Central Universities (): 2572021DT01
• National Natural Science Foundation of China (): 31770637
• Innovation Project of State Key Laboratory of Tree Genetics and Breeding (): 2019A03
• Natural Science Foundation of Heilongjiang Province, China (): ZD2020C004
• Heilongjiang Touyan Innovation Team Program ():

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