Untitled

Abstract

Three cDNA clones (pCel 10, pCel 20 and pCel 30), each encoding different endo-beta-1,4-glucanases in peach, were obtained by RT-PCR and their expression investigated by northern analysis during leaf and fruit abscission and during fruit development. This analysis allowed the detection of only the pCel 10-related mRNA. A 2.2 kb transcript accumulated in ethylene activated abscission zones of leaves and fruits, and ppEG1 (Prunus persica endoglucanase 1) the gene coding for pCel 10, was isolated and characterized. A cDNA (termed pCel 1), containing the entire open reading frame of ppEGC1, was obtained and its sequence used to define the structure of the gene and the exon/intron boundaries. ppEG1 consists of 7 exons and encodes a 497 amino acid polypeptide including a putative signal peptide at the N-terminus. The similarity of this peach endo-beta-1,4-glucanase (EGase, EC 3.2.1.4) is high (76.3%) with the ripening avocado and low (47.3%) with the bean abscission EGase. A 1639 bp region at the 5' of the transcription start site shows regulatory functions in transgenic tobacco plants, as judged by its ability to drive GUS expression in cell separation-related events.

The HD-Zip transcription factor LcHB2 regulates litchi fruit abscission through the activation of two cellulase genes

“…Compared to cellulases in other plants (Supplementary Fig. S7), LcCEL8 had higher similarity to abscission-related cellulases in citrus (CitCEL6; Merelo et al , 2017), peach (PpEG1; Trainotti et al , 1997), tomato (SlCel5; Kalaitzis et al , 1999), and pepper (cCel2; Trainotti et al , 1998b), while LcCEL2 was more closely related to cotton ( Gossypium hirsutum ) GhCel1 (Mishra et al , 2008) and peach PpEG4 (Trainotti et al , 2006). These data might not seem surprising if the comparisons refer only to the structure of the polypeptides rather than to their functions in vivo .…”

“…The accumulation of a cellulase-encoding mRNA induced by ethylene treatment was first reported in abscising bean leaves (Tucker et al , 1988). Since then, several studies have demonstrated that cellulase activity and gene expression are correlated with events in AZs during shedding of plant organs (in avocado, Tonutti et al , 1995; in tomato, del Campillo and Bennett, 1996; in pepper, Capsicum annuum , Trainotti et al , 1997; and in citrus, Kazokas and Burns, 1998). Cellulases are encoded by a multigene family, as confirmed in our study that identified 20 cellulase genes in the litchi genome.…”

“…3). Although many abscission-related cellulase genes have also been identified in the FAZ tissues of several other fruit crop species (Trainotti et al , 1997; Li et al , 2010; Merelo et al , 2017), our understanding of the functions of these cellulases during fruit abscission is limited. Here, overexpression of LcCEL2 and LcCEL8 in Arabidopsis was able to accelerate floral organ abscission, and analysis of GUS-promoter fusion lines further showed that these genes were expressed in cells in the AZ during floral organ abscission and silique dehiscence (Figs 4D, E, 5; Supplementary Fig.…”

“…To date, at least 10 different abscission-associated cellulase genes have been found in fruit crops, including ppEG1 and ppEG4 in peach ( Prunus persica ) (Trainotti et al , 1997, 2006), PaCel1 in avocado ( Persea americana ) (Tonutti et al , 1995), MdEG1 in apple ( Malus × domestica ) (Li and Yuan, 2008), and CitCEL3 , CitCEL6 ( CsCEL-a1 ), CitCEL10 , CitCEL22 , and CsCEL-b1 in citrus ( Citrus sinensis ) (Kazokas and Burns, 1998; Merelo et al , 2017). However, the functions of these cellulases during abscission as well as their underlying mechanisms are still largely unknown.…”

Secretion, purification and activity of two recombinant pepper endo‐β‐1,4‐glucanases expressed in the yeast Pichia pastoris

“…This variability is the consequence of different genetic programmes, but also reflects the biochemical complexity of the plant cell wall structure [3]. A very important consequence of this complexity is that plants require a large set of different enzymes to carry out the physiological processes where modifications of the cell wall properties are required [4–9].…”