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Abstract

Two full-length cDNA clones (faEG1 and faEG3, respectively) have been isolated by screening a cDNA library representing transcripts from red strawberry fruits. Southern blot analysis of genomic DNA suggests that the strawberry endo-beta-1,4-glucanases (EGases) are encoded by a multigene family. The cognate genes are predominantly expressed during the ripening process proper, although, in the case of faEG3, some expression has also been observed in large green fruits and, at low amounts, in young vegetative green tissues. In agreement with other ripening-related genes in strawberry, also the expression of faEG1 and faEG3 is down-regulated by treatment with an auxin analogue (1-naphthaleneacetic acid, NAA). Differences in temporal expression of the two EGase genes in fruits are not accompanied by differences in spatial expression. The pattern of expression and the sequence characteristics of the two polypeptides suggest that the two strawberry EGases operate in a synergistic and coordinate manner. The protein encoded by faEG1 looks like one of the usual higher-plant EGases (average molecular mass of 54 kDa), while the protein encoded by faEG3 has a greater deduced molecular mass (about 68 kDa) due to the presence of an extra peptide of about 130 amino acids at the C-terminus. Such unusual peptide shows some features also found in microbial cellulases and contains a putative cellulose-binding domain. We propose that the faEG3-encoded EGase might especially hydrolyse the xyloglucans coating the cellulose microfibrils, thus rendering the cell wall more susceptible to the subsequent hydrolytic activity of the faEG1-encoded EGase.

A Tomato Endo-β-1,4-glucanase, SlCel9C1, Represents a Distinct Subclass with a New Family of Carbohydrate Binding Modules (CBM49)

“…The expression of plant Class C EGase genes has been associated with both degradative processes, such as fruit softening and abscission (20,21), and cell elongation (22), so these proteins may have multiple physiological functions. Studies are now in progress to address this question.…”

Isolation and characterization of the MiCel1 gene from mango: ripening related expression and enhanced endoglucanase activity during softening

“…Sequence analysis of MiCEL1 protein suggested the presence of a CBD at the carboxy terminal end. Although this domain is an essential feature of microbial EGases that act on crystalline cellulose, it is usually absent in plant cellulases with a few exceptions that include fruit species like tomato (Catala and Bennett 1998), peach (Trainotti et al 2006), pear (Hisawa et al 2003) and strawberry (Trainotti et al 1999b). The CBD domain in TomCel8 (now renamed as SlCel9C1) has recently been shown to act on crystalline cellulose under in vitro conditions (Urbanowicz et al 2007).…”

A SHATTERPROOF-like gene controls ripening in non-climacteric strawberries, and auxin and abscisic acid antagonistically affect its expression

“…The F. × ananassa SHATTERPROOF -like ( FaSHP ) full-length cDNA was isolated by screening a strawberry cDNA library (Trainotti et al , 1999). The screening was made following standard procedures using a probe of 200bp prepared by means of a reverse transcription (RT)-PCR experiment using primers [forward (FW) 5′-GGCACAGCAGCAGCAAGCAAATA-3′ and reverse (RV) 5′-AGAGGCGGAATAAATCACCAGACT-3′] designed on expressed sequence tag (EST) sequences (CO380891, EX686940, EX687722) available in public databases.…”