A Vitis vinifera basic helix–loop–helix transcription factor enhances plant cell size, vegetative biomass and reproductive yield

Abstract

SummaryStrategies for improving plant size are critical targets for plant biotechnology to increase vegetative biomass or reproductive yield. To improve biomass production, a codon‐optimized helix–loop–helix transcription factor (VvCEB1 opt) from wine grape was overexpressed in Arabidopsis thaliana resulting in significantly increased leaf number, leaf and rosette area, fresh weight and dry weight. Cell size, but typically not cell number, was increased in all tissues resulting in increased vegetative biomass and reproductive organ size, number and seed yield. Ionomic analysis of leaves revealed the VvCEB1 opt‐overexpressing plants had significantly elevated, K, S and Mo contents relative to control lines. Increased K content likely drives increased osmotic potential within cells leading to greater cellular growth and expansion. To understand the mechanistic basis of VvCEB1 opt action, one transgenic line was genotyped using RNA‐Seq mRNA expression profiling and revealed a novel transcriptional reprogramming network with significant changes in mRNA abundance for genes with functions in delayed flowering, pathogen–defence responses, iron homeostasis, vesicle‐mediated cell wall formation and auxin‐mediated signalling and responses. Direct testing of VvCEB1 opt‐overexpressing plants showed that they had significantly elevated auxin content and a significantly increased number of lateral leaf primordia within meristems relative to controls, confirming that cell expansion and organ number proliferation were likely an auxin‐mediated process. VvCEB1 opt overexpression in Nicotiana sylvestris also showed larger cells, organ size and biomass demonstrating the potential applicability of this innovative strategy for improving plant biomass and reproductive yield in crops.

CAM emerges in a leaf metabolic model under water-saving constraints in different environments

“…Barrera Zambrano et al proposed that Clusia might overcome this discrepancy by having a high % IAS in the spongy mesophyll for efficient CO 2 diffusion in C 3 mode, and large palisade cells for carboxylic acid storage in CAM mode and suggested this as a potential engineering strategy for transferring inducible CAM into a C 3 plant 48 . Of particular relevance is a study which attempted to increase leaf cell size by overexpressing a grape berry transcription factor ( VvCEB1 opt ) in Arabidopsis thaliana and Nicotiana sylvestris 49 . This approach increased cell size — but not number — in both species with a 1.8-to 2.3-fold increase in the palisade mesophyll and 2.0-to 2.5-fold increase in the spongy mesophyll in A. thaliana.…”

Alternative Crassulacean Acid Metabolism Modes Provide Environment-Specific Water-Saving Benefits in a Leaf Metabolic Model

“…They suggested this as a potential engineering strategy for transferring inducible CAM into a C3 plant (Barrera Zambrano et al, 2014); however engineering such tissue differentiation into a C3 crop would be a major challenge. Of particular relevance is a study which attempted to increase leaf cell size by overexpressing a grape berry (Vitis vinifera) transcription factor (VvCEB1opt) in Arabidopsis (Arabidopsis thaliana) and tobacco (Nicotiana sylvestris) (Lim et al, 2018). This approach increased cell size-but not number-in both species, with a 1.8-to 2.3-fold increase in the palisade mesophyll and 2.0-to 2.5-fold increase in the spongy mesophyll in Arabidopsis.…”

Arabidopsis and sunflower plants with increased xylem area show enhanced seed yield

“…Many research groups worldwide have obtained transgenic or mutant plants exhibiting higher yields than controls (Zhao et al, 2015;Cabello et al, 2017;Wang et al, 2017;Jiang et al, 2018;Lim et al, 2018). However, the evaluation of stems width and the number of vascular bundles in these plants was not investigated or associated with seed yield.…”