Overexpression of vesicle-associated membrane protein PttVAP27-17 as a tool to improve biomass production and the overall saccharification yields in Populus trees

Abstract

Background Bioconversion of wood into bioproducts and biofuels is hindered by the recalcitrance of woody raw material to bioprocesses such as enzymatic saccharification. Targeted modification of the chemical composition of the feedstock can improve saccharification but this gain is often abrogated by concomitant reduction in tree growth. Results In this study, we report on transgenic hybrid aspen (Populus tremula × tremuloides) lines that showed potential to increase biomass production both in the greenhouse and after 5 years of growth in the field. The transgenic lines carried an overexpression construct for Populus tremula × tremuloides vesicle-associated membrane protein (VAMP)-associated protein PttVAP27-17 that was selected from a gene-mining program for novel regulators of wood formation. Analytical-scale enzymatic saccharification without any pretreatment revealed for all greenhouse-grown transgenic lines, compared to the wild type, a 20–44% increase in the glucose yield per dry weight after enzymatic saccharification, even though it was statistically significant only for one line. The glucose yield after enzymatic saccharification with a prior hydrothermal pretreatment step with sulfuric acid was not increased in the greenhouse-grown transgenic trees on a dry-weight basis, but increased by 26–50% when calculated on a whole biomass basis in comparison to the wild-type control. Tendencies to increased glucose yields by up to 24% were present on a whole tree biomass basis after acidic pretreatment and enzymatic saccharification also in the transgenic trees grown for 5 years on the field when compared to the wild-type control. Conclusions The results demonstrate the usefulness of gene-mining programs to identify novel genes with the potential to improve biofuel production in tree biotechnology programs. Furthermore, multi-omic analyses, including transcriptomic, proteomic and metabolomic analyses, performed here provide a toolbox for future studies on the function of VAP27 proteins in plants.

WGCNA analysis revealing molecular mechanism that bio-organic fertilizer improves pear fruit quality by increasing sucrose accumulation and reducing citric acid metabolism

“…ACO-encoded aconitase was the first step of citric acid catabolism, which played a major role in the acidity change of pineapple fruit before harvest ( Saradhuldhat and Paull, 2007 ; Terol et al, 2010 ; Liu et al, 2011 ). The over expression of VAPs increased the plant biomass and carbohydrate products in poplar ( Gandla, 2021 ; Singh et al, 2018 ). WGCNA revealed the sugar and organic acids related metabolism under different fertilization conditions.…”

Saccharification Potential of Transgenic Greenhouse- and Field-Grown Aspen Engineered for Reduced Xylan Acetylation

“…Univariate analyses were performed using JMP ® , Version Pro 14 (SAS Institute Inc., Cary, NC, 1989-2021…”

“…Portions of dry wood powder (50 mg, 0.1–0.5 mm particles) were subjected to analytical saccharification after moisture analysis using an HG63 moisture analyzer (Mettler-Toledo), following Gandla et al (2021) . Pooled samples of the lines (prepared as described above) were analyzed in triplicate.…”

Fluorescence Lifetime Imaging as an In Situ and Label-Free Readout for the Chemical Composition of Lignin

“…The next 4 cm of stem were freeze-dried, milled, and sieved to separate particles of different sizes. Particles with a diameter between 0.1 and 0.5 mm were collected for enzymatic saccharification assay . Particles with diameter lower than 0.1 mm were collected separately for the analysis of the cell wall lignin content and composition by pyrolysis coupled with GC and MS.…”