Premium
Higher expression of the strawberry xyloglucan endotransglucosylase/hydrolase genes Fv XTH 9 and Fv XTH 6 accelerates fruit ripening
Author(s) -
Witasari Lucia D.,
Huang FongChin,
Hoffmann Thomas,
Rozhon Wilfried,
Fry Stephen C.,
Schwab Wilfried
Publication year - 2019
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14512
Subject(s) - xyloglucan , ripening , cell wall , biology , chemistry , biochemistry , botany
Summary Fruit softening in Fragaria (strawberry) is proposed to be associated with the modification of cell wall components such as xyloglucan by the action of cell wall‐modifying enzymes. This study focuses on the in vitro and in vivo characterization of two recombinant xyloglucan endotransglucosylase/hydrolases ( XTH s) from Fragaria vesca , Fv XTH 9 and Fv XTH 6. Mining of the publicly available F. vesca genome sequence yielded 28 putative XTH genes. Fv XTH 9 showed the highest expression level of all Fv XTH s in a fruit transcriptome data set and was selected with the closely related Fv XTH 6 for further analysis. To investigate their role in fruit ripening in more detail, the coding sequences of Fv XTH 9 and Fv XTH 6 were cloned into the vector pYES 2 and expressed in Saccharomyces cerevisiae . Fv XTH 9 and Fv XTH 6 displayed xyloglucan endotransglucosylase ( XET ) activity towards various acceptor substrates using xyloglucan as the donor substrate. Interestingly, Fv XTH 9 showed activity of mixed‐linkage glucan:xyloglucan endotransglucosylase ( MXE ) and cellulose:xyloglucan endotransglucosylase ( CXE ). The optimum pH of both Fv XTH 9 and Fv XTH 6 was 6.5. The prediction of subcellular localization suggested localization to the secretory pathway, which was confirmed by localization studies in Nicotiana tabacum . Overexpression showed that Fragaria × ananassa fruits infiltrated with Fv XTH 9 and Fv XTH 6 ripened faster and showed decreased firmness compared with the empty vector control pBI 121. Thus Fv XTH 9 and also Fv XTH 6 might promote strawberry fruit ripening by the modification of cell wall components.