Comparative Proteomic and Physiological Analysis Reveals the Variation Mechanisms of Leaf Coloration and Carbon Fixation in a Xantha Mutant of Ginkgo biloba L.

Abstract

Yellow-green leaf mutants are common in higher plants, and these non-lethal chlorophyll-deficient mutants are ideal materials for research on photosynthesis and plant development. A novel xantha mutant of Ginkgo biloba displaying yellow-colour leaves (YL) and green-colour leaves (GL) was identified in this study. The chlorophyll content of YL was remarkably lower than that in GL. The chloroplast ultrastructure revealed that YL had less dense thylakoid lamellae, a looser structure and fewer starch grains than GL. Analysis of the photosynthetic characteristics revealed that YL had decreased photosynthetic activity with significantly high nonphotochemical quenching. To explain these phenomena, we analysed the proteomic differences in leaves and chloroplasts between YL and GL of ginkgo using two-dimensional gel electrophoresis (2-DE) coupled with MALDI-TOF/TOF MS. In total, 89 differential proteins were successfully identified, 82 of which were assigned functions in nine metabolic pathways and cellular processes. Among them, proteins involved in photosynthesis, carbon fixation in photosynthetic organisms, carbohydrate/energy metabolism, amino acid metabolism, and protein metabolism were greatly enriched, indicating a good correlation between differentially accumulated proteins and physiological changes in leaves. The identifications of these differentially accumulated proteins indicates the presence of a specific different metabolic network in YL and suggests that YL possess slower chloroplast development, weaker photosynthesis, and a less abundant energy supply than GL. These studies provide insights into the mechanism of molecular regulation of leaf colour variation in YL mutants.

Cytological, physiological, and transcriptomic analyses of golden leaf coloration in Ginkgo biloba L

“…reported that spectral optical properties change due to retention of carotenoids in yellow leaves in the autumn. Recently, Liu et al 12 analyzed the proteomic profiles of yellow and green G. biloba leaves and identified differentially accumulated proteins involved in energy metabolism, photosynthesis and carbon fixation. To better understand the mechanism of coloration and color variation in G. biloba leaves, it is important to compare yellow mutant leaves with green leaves under the same spatiotemporal and developmental conditions.…”

Proteomic analysis of chloroplasts from chlorophyll-deficient melon mutant

“…Chlorophyll (Chl) is an extremely important pigment that absorbs and converts light energy for plant use (Sandonà et al1998). In Chldeficient mutants, a strong decrease or increase occurs in the abundance of the proteins involved in various metabolic pathways, including Chl biosynthesis and degradation metabolism, nitrogen metabolism, chloroplast development, and carbon and energy metabolism (Rutschow et al 2008, Liu et al 2016. For example, in the Arabidopsis ffc mutant (pale green), the levels of lightharvesting complex I (LHCI) and light-harvesting com-plex II (LHCII) antennae proteins and stromal chaperones (Cpn60, Cpn21, and Hsp70) increased, while the levels of chloroplast-encoded PSII core complex proteins (D1, D2, CP43, CP47, and cytochrome b559α) and nucleus-encoded proteins (OEC16, OEC23, and OEC33) decreased (Rutschow et al 2008).…”

“…APX and SOD are the key enzymes catalyzing the conversion of H2O2 to H2O. This indicates that the mutant is more sensitive to photoinduced damage and ROS accumulation (Liu et al 2016).…”

“…Proteomics is a powerful tool to study the protein networks and molecular regulatory mechanisms of plant development and response to biotic and abiotic stresses (Singh et al 2013, Bansal et al 2016. Proteomic studies based on two-dimensional gel electrophoresis have been applied to investigate the mechanisms underlying leaf color determination in Hosta and Ginkgo biloba (Liu et al 2016. However, 2-D PAGE is time-consuming and not amenable to automation for high-throughput analyses.…”

Preface—Plant Proteomic Research

“…using two-dimensional gel electrophoresis (2-DE) and MALDI-TOF mass spectrometry. Liu et al [ 13 ] provide new insights into the molecular regulation of leaf color variation and carbon fixation in a xantha mutant of Ginkgo biloba L. by exploiting 2-DE coupled with MALDI-TOF/TOF mass spectrometry. Yu et al [ 14 ] present comparative proteomic analysis of chimera Hosta “Gold Standard” leaves from various regions at different development stages and under excess nitrogen fertilization using 2-DE coupled MALDI-TOF/TOF MS.…”