(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.

NAC (NAM/ATAF1/2/CUC2) transcription factors regulate plant growth and development and stress responses. Because NAC transcription factors are known to play important roles in the regulation of salt tolerance in many plants, we aimed to explore their roles in the halophyte Suaeda glauca. Based on transcriptome sequencing data, we identified 25 NAC transcription factor gene family members. In a phylogenetic tree analysis with Arabidopsis thaliana NAC transcription factors, the SgNACs were divided into 10 groups. The physicochemical properties and conserved domains of the putative proteins, as well as the transcript profiles of their encoding genes, were determined for the 25 SgNAC genes using bioinformatic methods. Most of the S. glauca NAC genes were upregulated to some extent after 24 h of salt stress, suggesting that they play an important role in regulating the salt tolerance of S. glauca. These findings lay the foundation for further research on the functions and mechanisms of the NAC gene family in S. glauca.

Betaine aldehyde dehydrogenases (BADHs) are key enzymes in the biosynthesis of glycine betaine, which is an important organic osmolyte that maintains cell structure and improves plant tolerance to abiotic stresses, especially in halotolerant plants. Improving the drought tolerance of crops will greatly increase their yield. In this study, a novel BADH gene named SgBADH from Suaeda glauca was induced by drought stress or abscisic acid. To explore the biological function of SgBADH, the SgBADH gene was transformed into Arabidopsis. Then, we found SgBADH-overexpressing Arabidopsis seedlings showed enhanced tolerance to drought stress. SgBADH transgenic Arabidopsis seedlings also had longer roots compared with controls under drought stress, while SgBADH-overexpressing Arabidopsis exhibited increased glycine betaine accumulation and decreased malondialdehyde (MDA) under drought stress. Our results suggest that SgBADH might be a positive regulator in plants during the response to drought.