Transcriptome and Metabolome Analysis of a Late-Senescent Vegetable Soybean during Seed Development Provides New Insights into Degradation of Chlorophyll

Abstract

(1) Background: Senescence represents the final stage of plant growth and development, which transfers nutrients to growing seeds and directly affects the yield and quality of crops. However, little is known about chlorophyll degradation in developing and maturing seeds, in contrast to leaf senescence; (2) Methods: RNA-Seq was used to analyze the differentially expressed genes of different late-senescent germplasms. A widely untargeted metabolic analysis was used to analyze differential metabolites. In addition, qRT-PCR was conducted to detect gene expression levels; (3) Results: Transcriptome analysis revealed that ZX12 seeds have a higher expression level of the chlorophyll synthesis genes in the early stage of maturity, compared with ZX4, and have a lower expression level of chlorophyll degradation genes in the late stage of maturity. Flavonoids were the primary differential metabolites, and ZX12 contains the unique and highest expression of three types of metabolites, including farrerol-7-O-glucoside, cyanidin-3-o-(6′-o-feruloyl) glucoside, and kaempferide-3-o-(6′-malonyl) glucoside. Among them, farrerol-7-O-glucoside and cyanidin-3-o-(6′-o-feruloyl) glucoside are flavonoid derivatives containing mono and dihydroxy-B-ring chemical structures, respectively; and (4) Conclusions: It is speculated that the two metabolites can slow down the degradation process of chlorophyll by scavenging oxygen-free radicals in the chloroplast.

Exploring the interplay between angiosperm chlorophyll metabolism and environmental factors

“…Plastochromanol-8 (PC-8), an efficient scavenger of 1 O 2 , efficiently safeguards lipids against photooxidative damage in Arabidopsis plants (Szymańska and Kruk 2010 ; Rastogi et al 2014 ). Metabolomics research has further demonstrated that three flavonoid metabolites exclusively found in late-maturing soybean seeds (farrerol-7- O -glucoside, cyanidin-3- o -(6′- o -feruloyl) glucoside, and kaempferide-3- o -(6′-malonyl) glucoside) can effectively mitigate Chl degradation by scavenging oxygen free radicals within the chloroplasts (Wang et al 2022a ). However, there is still a need to explore additional mechanisms involved in maintaining equilibrium between Chl and ROS.…”

Comparative Transcriptome-Based Analysis of the Regulation of Leaf Senescence in the Upper and Middle Canopy of Different Soybean Cultivars

“…Different hormones have specific functions in activating/inhibiting and controlling leaf senescence, and photosynthesis [10], hormone transduction [11], MAPK signaling [12], and carbon fixation by photosynthetic organisms all play important regulatory roles in leaf growth and development [13,14]. Different canopy leaves of crops are subjected to different light intensities, resulting in changes in leaf photosynthesis [15] that have a great impact on the subsequent physiological characteristics of leaves in terms of photochemical energy, photosynthesis, and carbon assimilation [16]. One of the most striking features of leaf senescence is the decline in photosynthetic capacity.…”