Blue Light Acclimation Reduces the Photoinhibition of Phalaenopsis aphrodite (Moth Orchid)

Interactions between root endophytic microorganisms and the reduced negative ion release capacity of Phalaenopsis aphrodite Rchb. f. under high temperature stress

Introduction

Negative oxygen ions are produced by plants through photosynthesis, utilizing "tip discharge" or the photoelectric effect, which has various functions such as sterilization, dust removal, and delaying aging. With global warming, high temperatures may affect the ability of Phalaenopsis aphrodite Rchb. f. to produce negative oxygen ions. P. aphrodite is commonly used in modern landscape planning and forest greening.

Methods

In this study, P. aphrodite was selected as the research object. By artificially simulating the climate, the control group (CK) and the high temperature stress group (HS) were set up in the experiment.

Results

The study found that compared with the control group, the ability of P. aphrodite to produce negative oxygen ions significantly decreased when exposed to high temperature stress. Meanwhile, under high temperature stress treatment, peroxidase content increased by 102%, and proline content significantly increased by 35%.

Discussion

Redundancy analysis results indicated a significant correlation between the root endophytic microbial community of P. aphrodite and negative oxygen ions, as well as physiological indicators. Under high temperature stress, P. aphrodite may affect the regulation of physiological indicators by modifying the composition of root endophytic microbial communities, thereby influencing the ability to release negative oxygen ions.

BAG8 positively regulates cold stress tolerance by modulating photosystem, antioxidant system and protein protection in Solanum lycopersicum

The B-cell lymphoma 2 (Bcl-2)-associated athanogene (BAG) family is a relatively conserved and multifunctional co-chaperones in animals and plants, which can flexibly interact with a variety of proteins and regulate various processes from growth and development to stress response. However, compared with animals, the function of BAG family in plant remains largely unknown, especially in response to cold stress. In this study, we have found that the expression of BAG8 was significantly induced in tomato under cold stress. Results showed that bag8 mutants exhibit significantly reduced tolerance towards cold stress, while BAG8 overexpressing lines were relatively resistant as reflected by the phenotype and membrane peroxidation. Measuring of gas exchange parameters, photosystem I (PSI) and photosystem II (PSII) of tomato leaves under cold stress further revealed that BAG8 mitigated cold-induced damage in photosynthetic system. Additionally, bag8 mutants exhibited more cold-induced reactive oxygen species, which were substantially normalized in BAG8 overexpressing plants. Nevertheless, the activities of antioxidant enzymes which were compromised in bag8 mutants were improved in BAG8 overexpressing plants facing cold stress. Additionally, BAG8 interacted with heat shock protein Hsp70 and protein phosphatase PP2A both in vitro and in vivo. Our results demonstrate that BAG8 plays a positive role in cold tolerance in tomato probably by the improvement of photosystems and antioxidant systems, and by interacting with Hsp70 involved in photosynthesis and PP2A involved in stomatal development.

Identification, Biological Function Profiling and Biosynthesis of Secondary Metabolites in Medicinal Orchids

The secondary metabolites present in medicinal orchids are diverse and possess a vast array of biological activities. They represent valuable raw materials for modern pharmaceuticals and clinical medicine and have tremendous potential for future development. A systematic collation of secondary metabolites' composition and a summary of the biological activities of medicinal orchids represent a crucial step in unlocking the potential of these valuable resources in drug development. Furthermore, such information can provide essential guidance for comprehensively analyzing the pharmacological and therapeutic mechanisms of these valuable herbs in traditional Chinese herbal medicine. This review article presents an overview of the types and main biological functions of the secondary metabolites found in medicinal orchids, as well as the conventional synthesis methods for these compounds. Our aim is to provide a useful reference for future research and the drug development of secondary metabolic products of medicinal orchids.

A Single Nucleotide Variation of CRS2 Affected the Establishment of Photosynthetic System in Rice

Chloroplasts are essential sites for plant photosynthesis, and the biogenesis of the photosynthetic complexes involves the interaction of nuclear genes and chloroplast genes. In this study, we identified a rice pale green leaf mutant, crs2. The crs2 mutant showed different degrees of low chlorophyll phenotypes at different growth stages, especially at the seedling stage. Fine mapping and DNA sequencing of crs2 revealed a single nucleotide substitution (G4120A) in the eighth exons of CRS2, causing a G-to-R mutation of the 229th amino acid of CRS2 (G229R). The results of complementation experiments confirmed that this single-base mutation in crs2 is responsible for the phenotype of the crs2 mutant. CRS2 encodes a chloroplast RNA splicing 2 protein localized in the chloroplast. Western blot results revealed an abnormality in the abundance of the photosynthesis-related protein in crs2. However, the mutation of CRS2 leads to the enhancement of antioxidant enzyme activity, which could reduce ROS levels. Meanwhile, with the release of Rubisco activity, the photosynthetic performance of crs2 was improved. In summary, the G229R mutation in CRS2 causes chloroplast protein abnormalities and affects photosystem performance in rice; the above findings facilitate the elucidation of the physiological mechanism of chloroplast proteins affecting photosynthesis.

Blue Light Mediates Chloroplast Avoidance and Enhances Photoprotection of Vanilla Orchid

Vanilla orchid, which is well-known for its flavor and fragrance, is cultivated in tropical and subtropical regions. This shade-loving plant is very sensitive to high irradiance. In this study, we show that vanilla chloroplasts started to have avoidance movement when blue light (BL) was higher than 20 μmol m-2s-1 and significant avoidance movement was observed under BL irradiation at 100 μmol m-2s-1 (BL100). The light response curve indicated that when vanilla was exposed to 1000 μmol m-2s-1, the electron transport rate (ETR) and photochemical quenching of fluorescence (qP) were significantly reduced to a negligible amount. We found that if a vanilla orchid was irradiated with BL100 for 12 days, it acquired BL-acclimation. Chloroplasts moved to the side of cells in order to reduce light-harvesting antenna size, and chloroplast photodamage was eliminated. Therefore, BL-acclimation enhanced vanilla orchid growth and tolerance to moderate (500 μmol m-2s-1) and high light (1000 μmol m-2s-1) stress conditions. It was found that under high irradiation, BL-acclimatized vanilla maintained higher ETR and qP capacity than the control without BL-acclimation. BL-acclimation induced antioxidant enzyme activities, reduced ROS accumulation, and accumulated more carbohydrates. Moreover, BL-acclimatized orchids upregulated photosystem-II-associated marker genes (D1 and PetC), Rubisco and PEPC transcripts and sustained expression levels thereof, and also maximized the photosynthesis rate. Consequently, BL-acclimatized orchids had higher biomass. In short, this study found that acclimating vanilla orchid with BL before transplantation to the field might eliminate photoinhibition and enhance vanilla growth and production.