A Rice PECTATE LYASE-LIKE Gene Is Required for Plant Growth and Leaf Senescence

Abstract

To better understand the molecular mechanisms behind plant growth and leaf senescence in monocot plants, we identified a mutant exhibiting dwarfism and an early-senescence leaf phenotype, termed dwarf and early-senescence leaf1 (del1). Histological analysis showed that the abnormal growth was caused by a reduction in cell number. Further investigation revealed that the decline in cell number in del1 was affected by the cell cycle. Physiological analysis, transmission electron microscopy, and TUNEL assays showed that leaf senescence was triggered by the accumulation of reactive oxygen species. The DEL1 gene was cloned using a map-based approach. It was shown to encode a pectate lyase (PEL) precursor that contains a PelC domain. DEL1 contains all the conserved residues of PEL and has strong similarity with plant PelC. DEL1 is expressed in all tissues but predominantly in elongating tissues. Functional analysis revealed that mutation of DEL1 decreased the total PEL enzymatic activity, increased the degree of methylesterified homogalacturonan, and altered the cell wall composition and structure. In addition, transcriptome assay revealed that a set of cell wall function-and senescence-related gene expression was altered in del1 plants. Our research indicates that DEL1 is involved in both the maintenance of normal cell division and the induction of leaf senescence. These findings reveal a new molecular mechanism for plant growth and leaf senescence mediated by PECTATE LYASE-LIKE genes.

Premature leaf senescence 3, encoding a methyltransferase, is required for melatonin biosynthesis in rice

“…Although a growing number of leaf senescence‐associated genes have been identified and characterized in model plants (Liang et al ., ; Lin et al ., ; Wu et al ., ), the molecular mechanism underlying rice methyltransferase‐mediated leaf senescence remains poorly understood. In this study, we cloned and characterized OsMTS1 from the rice premature leaf senescence 3 mutant, which was different from previously reported mutants (Liang et al ., ; Yang et al ., ,b,c; Bi et al ., ; Leng et al ., ). First, the alteration of leaf colour and degradation of Chl content mainly occurred during the heading stage (Figure c and d).…”

“…Additionally, ROS bursts are one of the most important factors triggering early leaf senescence. If the ROS level is not reduced in a timely and effective way within the plant cell, the cell membrane can get destroyed, which can then accelerate nucleic acid, protein and chloroplast degradation, thereby causing early leaf senescence (Lee et al, 2009;Jiao et al, 2012;Chen et al, 2013;Wang et al, 2015;Wu et al, 2016;Yang et al, 2016c;Leng et al, 2017). For example, overexpression of the plasma membrane-localized S-domain receptor-like kinase (OsSIK2) exhibited delayed leaf senescence via increasing the peroxidase activity to eliminate H 2 O 2 .…”

Increase in Cell Wall Thickening and Biomass Production by Overexpression of PmCesA2 in Poplar

“…The cell wall in plant cells provides structural support, underpinning plant growth and development (Leng et al, 2017). Cellulose, a major load-bearing structure of growing cell walls, has drawn much research attention for its various industrial applications.…”

OsPG1 encodes a polygalacturonase that determines cell wall architecture and affects resistance to bacterial blight pathogen in rice

“…A rice mutant Leaf Tip Senescence 1 (LTS1) resulted in dwar sm and withered leaf tips, ultimately causing early leaf senescence (Wu et al 2016). The loss of function of DEL1 resulted in the leaf apex and leaf margin exhibiting a faint yellow color after germinating for 5 days, while leaf tips exhibited withering and cracking at the maturity stage (Leng et al 2017). The phenotype of necrotic leaf tips correlates with plant resistance.…”