PbMC1a/1b regulates lignification during stone cell development in pear (Pyrus bretschneideri) fruit

Abstract

Programmed cell death (PCD) and secondary cell wall (SCW) thickening in pear fruit are accompanied by the deposition of cellulose and lignin to form stone cells. Metacaspase is an important protease for development, tissue renewal and PCD. The understanding of the molecular mechanism whereby pear (Pyrus) metacaspase promotes PCD and cell wall lignification is still limited. In this study, the Metacaspases gene family (PbMCs) from P. bretschneideri was identified. PbMC1a/1b was associated with lignin deposition and stone cell formation by physiological data, semiquantitative real-time polymerase chain reaction (RT-PCR) and quantitative RT-PCR (qRT-PCR). Relative to wildtype (WT) Arabidopsis, the overexpression of PbMC1a/1b increased lignin deposition and delayed growth, thickened the cell walls of vessels, xylary fibers and interfascicular fibers, and increased the expression of lignin biosynthetic genes. Yeast two-hybrid (Y2H), bimolecular fluorescence complementation (BiFC) and GST pull-down assays indicated that the PbMC1a/1b protein physically interacted with PbRD21. Simultaneously, the transient expression of PbMC1a/1b and PbRD21 led to significant changes in the expression of genes and lignin contents in pear fruits and flesh calli. These results indicate that PbMC1a/1b plays an important role in cell wall lignification, possibly by interacting with PbRD21 to increase the mRNA levels of some lignin synthesis-associated genes and promote the formation of stone cells in pear fruit.

CAD Genes: Genome-Wide Identification, Evolution, and Their Contribution to Lignin Biosynthesis in Pear (Pyrus bretschneideri)

“…In our study, the stone cell content exhibited a rise-fall tendency, which was consistent with the results reported by Tao et al (2015) and Ma et al (2017) [ 22 , 25 ]. The inhibition of the synthesis of lignin in pear fruit may reduce the content of stone cells [ 26 ]. Members of the CAD gene family have been identified in many species, such as the observation of nine CAD genes in Arabidopsis [ 16 ], 12 in rice [ 17 ], 15 in hybrid Populus ( Populus deltoides × Populus Nigra ) [ 14 ], and five in Cucumis melo [ 27 ].…”

Characterization and Interaction Analysis of the Secondary Cell Wall Synthesis-Related Transcription Factor PmMYB7 in Pinus massoniana Lamb.

“…In Pyrus bretschneideri, the PbMC1a/1b protein was located in the cytoplasm and nucleus, and PbRD21 was only found in the nucleus. Through subcellular localization analysis, both PbMC1a/1b and PbRD21 were found in the nucleus, which may indicate the possibility of their interaction [47]. In Heterodera schachtii, Hs4E02 is located in the nucleus, causing RD21A to accumulate in different cell compartments, and interaction is observed in the cytoplasm as well as the nucleus [48].…”

The Metacaspase TaMCA-Id Negatively Regulates Salt-Induced Programmed Cell Death and Functionally Links With Autophagy in Wheat

“…But the underlying regulating mechanisms are less clear. The MCAs act to regulate plant growth, development, and multiple stress responses (Gong et al, 2020;Roohollah et al, 2020). This study acquired a novel TaMCA-Id that had typical characteristics of type I MCA family, which could contribute to the regulation of NaCl-caused PCD and activity of caspase 3like proteases in wheat seedlings.…”