ITRAQ-based comparative proteomic analysis of differences in the protein profiles of stems and leaves from two alfalfa genotypes

Hao Sun,Jie Yu,Qingchuan Yang,Wenwen Liu,Fan Zhang,Mingna Li,Jiaju Zhang,Junmei Kang,Zhen Wang,Ruicai Long

doi:10.1186/s12870-020-02671-2

Abstract

BackgroundTo explore the molecular regulatory mechanisms of early stem and leaf development, proteomic analysis was performed on leaves and stems of F genotype alfalfa, with thin stems and small leaves, and M genotype alfalfa, with thick stems and large leaves.ResultsBased on fold-change thresholds of > 1.20 or < 0.83 (p < 0.05), a large number of proteins were identified as being differentially enriched between the M and F genotypes: 249 downregulated and 139 upregulated in stems and 164 downregulated and 134 upregulated in leaves. The differentially enriched proteins in stems were mainly involved in amino acid biosynthesis, phenylpropanoid biosynthesis, carbon fixation, and phenylalanine metabolism. The differentially enriched proteins in leaves were mainly involved in porphyrin and chlorophyll metabolism, phenylpropanoid biosynthesis, starch and sucrose metabolism, and carbon fixation in photosynthetic organisms. Six differentially enriched proteins were mapped onto the porphyrin and chlorophyll metabolism pathway in leaves of the M genotype, including five upregulated proteins involved in chlorophyll biosynthesis and one downregulated protein involved in chlorophyll degradation. Eleven differentially enriched proteins were mapped onto the phenylpropanoid pathway in stems of the M genotype, including two upregulated proteins and nine downregulated proteins.ConclusionEnhanced chlorophyll synthesis and decreased lignin synthesis provided a reasonable explanation for the larger leaves and lower levels of stem lignification in M genotype alfalfa. This proteomic study aimed to classify the functions of differentially enriched proteins and to provide information on the molecular regulatory networks involved in stem and leaf development.

Highlights

To explore the molecular regulatory mechanisms of early stem and leaf development, proteomic analysis was performed on leaves and stems of F genotype alfalfa, with thin stems and small leaves, and M genotype alfalfa, with thick stems and large leaves
Six differentially enriched proteins (DEPs) were mapped onto the porphyrin and chlorophyll metabolism pathway, including porphobilinogen deaminase (PBGD), uroporphyrinogen decarboxylase (UPOD), bacteriochlorophyll synthase (BchG), red chlorophyll catabolite reductase (RCCR), CHLI, and magnesium-protoporphyrin IX monomethyl ester cyclase (MPEC), which were significantly enriched in leaves (Fig. 8b)
Leaf and stem development, responsible for plant morphology and establishment, is a complicated process that runs throughout the whole life history of plants

Summary

Introduction

To explore the molecular regulatory mechanisms of early stem and leaf development, proteomic analysis was performed on leaves and stems of F genotype alfalfa, with thin stems and small leaves, and M genotype alfalfa, with thick stems and large leaves. Land plants constantly produce new tissues and organs to complete their life cycle, and the formation of stems and leaves is a crucial aspect of plant growth and development. The plant shoot, which includes leaves, stems, and flowers, differentiates from the shoot apical meristem (SAM) [1]. Leaves, which originate from the SAM [2], are the central organs of photosynthesis and photoperception. They are the first barriers for plant defense, protecting plants against photochemical damage from UV rays, maintaining plant mechanical properties, and preventing damage from biotic and abiotic factors [3]. The plant stem is essential for maintaining plant height and rigidity and responds to environmental stress through the release of signaling molecules [5]

Methods

Results

Discussion

Conclusion