Regulation of Calvin-Benson cycle enzymes under high temperature stress.

The Calvin-Benson cycle (CBC) consists of three critical processes, including fixation of CO2 by Rubisco, reduction of 3-phosphoglycerate (3PGA) to triose phosphate (triose-P) with NADPH and ATP generated by the light reactions, and regeneration of ribulose 1,5-bisphosphate (RuBP) from triose-P. The activities of photosynthesis-related proteins, mainly from the CBC, were found more significantly affected and regulated in plants challenged with high temperature stress, including Rubisco, Rubisco activase (RCA) and the enzymes involved in RuBP regeneration, such as sedoheptulose-1,7-bisphosphatase (SBPase). Over the past years, the regulatory mechanism of CBC, especially for redox-regulation, has attracted major interest, because balancing flux at the various enzymatic reactions and maintaining metabolite levels in a range are of critical importance for the optimal operation of CBC under high temperature stress, providing insights into the genetic manipulation of photosynthesis. Here, we summarize recent progress regarding the identification of various layers of regulation point to the key enzymes of CBC for acclimation to environmental temperature changes along with open questions are also discussed.

Flavonoid-enriched extract from Millettia speciosa Champ prevents obesity by regulating thermogenesis and lipid metabolism in high-fat diet-induced obese C57BL/6 mice.

Millettia speciosa (M. speciosa) Champ is a medicinal and edible plant. The roots are rich in flavonoids, which possess multiple biological activities, including lipid-lowering effects. This study aimed to explore the effect of flavonoid-enriched extract from M. speciosa (FMS) on obesity. The UPLC-Q-TOF-MS analysis and chromatographic analysis were adopted to identify flavonoid compounds in FMS. Male C57BL/6J mice were fed with a high-fat diet for 3 months and were then treated with FMS (50 or 100 mg/kg/d) or Orlistat (10 mg kg-1 d-1) for another 8 weeks. A total of 35 flavonoids were identified in the extract of M. speciosa root. FMS reduced body weight gain, liver weight gain, white adipose tissue, lipid accumulation, and blood glucose. The levels of TG, ALT, AST, and inflammatory-related adipokines (TNF-α and IL-6) in serum were also reduced by FMS. In addition, FMS promoted thermogenesis in brown adipose tissue and induced the activation of lipolysis, fatty acid oxidation, and oxidative phosphorylation in white adipose tissues. In summary, long-term administration of FMS could ameliorate high-fat diet-induced obesity by stimulating adipose thermogenesis and lipid metabolism.

Novelties on the genus Vaccinium (Ericaceae) from Hainan, China: a new species and a new record for the country.

Here we describe a new species, Vacciniumpseudopubicalyx, and report a new record for the flora of China, V.viscifolium, both from Hainan Province. Vacciniumviscifolium also represents the first record of V.sect.Euepigynium for China. Detailed descriptions and illustrations with analytical photographs of the two taxa are provided.

A second species of Pseuduvaria in China: the identity of the enigmatic species Meiogyne kwangtungensis.

Meiogyne kwangtungensis is a rare species endemic to Hainan, China, known just from two fruiting collections made in the 1930s. Although it was published under the name Meiogyne in 1976, it was suggested that it might be better placed within Pseuduvaria or Mitrephora. For decades, this species was never collected again, thus its true generic affinity remained unresolved due to the lack of flowers. During a field exploration in Hainan, we re-discovered this species and collected a flowering specimen for the first time. The flower immediately confirmed its affinity with Pseuduvaria. Phylogenetic analyses of five chloroplast regions (psbA-trnH, trnL-F, matK, rbcL, and atpB-rbcL; ca. 4.2 kb, 70 accessions) also unambiguously placed Meiogyne kwangtungensis in the Pseuduvaria clade (PP = 1.00, ML BS = 99%). Morphologically, it is most similar to P. multiovulata which is endemic to Myanmar and Thailand, both with often-paired flowers, long pedicels and short peduncles, and often 1-2 monocarps. However, it differs in having smaller flowers with kidney-shaped glands on the inner petals, fewer stamens and carpels, smaller ovoid monocarps with an apicule and fewer seeds. On the basis of the combined molecular phylogenetic and morphological data, we propose a new combination, Pseuduvaria kwangtungensis (P.T.Li) Qing L.Wang & B.Xue. A full description including floral characters and a color plate are provided here for this species. A key to species in the genus Pseuduvaria in China is also provided.

Nuclear-encoded synthesis of the D1 subunit of photosystem II increases photosynthetic efficiency and crop yield.

In photosynthetic organisms, the photosystem II (PSII) complex is the primary target of thermal damage. Plants have evolved a repair process to prevent the accumulation of damaged PSII. The repair of PSII largely involves de novo synthesis of proteins, particularly the D1 subunit protein encoded by the chloroplast gene psbA. Here we report that the allotropic expression of the psbA complementary DNA driven by a heat-responsive promoter in the nuclear genome sufficiently protects PSII from severe loss of D1 protein and dramatically enhances survival rates of the transgenic plants of Arabidopsis, tobacco and rice under heat stress. Unexpectedly, we found that the nuclear origin supplementation of the D1 protein significantly stimulates transgenic plant growth by enhancing net CO2 assimilation rates with increases in biomass and grain yield. These findings represent a breakthrough in bioengineering plants to achieve efficient photosynthesis and increase crop productivity under normal and heat-stress conditions.

[Present situation and development strategy of Alpinia oxyphylla].

Alpinia oxyphylla is mainly produced in Hainan,and also one of the four famous traditional Chinese medicines in South China with increasing importance in traditional Chinese medicine industry. Field surveys and literatures show that A. oxyphylla has widely used as a medicinal and edible plant,it is an important raw material for many Chinese patent medicines,health products and food,with a long history of artificial cultivation and application. The future development is prospected on health market. But A. oxyphylla industry has faced a lot of problems,including unreasonable planting layout,lack of good varieties,imperfect seed breeding system,low level of standardization,inconsistent quality of medicinal materials,low level of industry,and so on. The suggestions for sustainable development are listed below.First,it is essential to strengthen the research on the basis and application technology of A. oxyphylla,speed up the selection and breeding of improved varieties,and popularize standardized cultivation techniques. Secondly,it is important to strengthen the research on quality standards,improve the quality evaluation system of medicinal materials. Thirdly,it is necessary to take full advantage of the functional components to develop functional products with Hainan characteristics,find out the unique product characteristics of A. oxyphylla,build a famous brand and improve the product competitiveness in the market. It is also important to strengthen policy support and industrial supervision,promote the healthy and rapid development of A. oxyphylla industry.

SPL6 represses signalling outputs of ER stress in control of panicle cell death in rice.

Inositol-requiring enzyme 1 (IRE1) is the most conserved transducer of the unfolded protein response that produces either adaptive or death signals depending on the amplitude and duration of its activation. Here, we report that SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE 6 (SPL6)-deficient plants displayed hyperactivation of the endoplasmic reticulum (ER) stress sensor IRE1, leading to cell death in rice panicles, indicating that SPL6 is an essential survival factor for the suppression of persistent or intense ER stress conditions. Importantly, knockdown of the hyperactivated mRNA level of IRE1 rescues panicle apical abortion in the spl6-1 transgenic plants harbouring the IRE1-RNAi constructs, establishing the genetic linkage between the hyperactivation of IRE1 and cell death in spl6-1. Our findings reveal a novel cell survival machinery in which SPL6 represses the transcriptional activation of the ER stress sensor IRE1 in control of ER stress signalling outputs that hinge on a balance between adaptive and death signals for determining cell fates during ER stress.

Metabolic Reprogramming in Chloroplasts under Heat Stress in Plants.

Increases in ambient temperatures have been a severe threat to crop production in many countries around the world under climate change. Chloroplasts serve as metabolic centers and play a key role in physiological adaptive processes to heat stress. In addition to expressing heat shock proteins that protect proteins from heat-induced damage, metabolic reprogramming occurs during adaptive physiological processes in chloroplasts. Heat stress leads to inhibition of plant photosynthetic activity by damaging key components functioning in a variety of metabolic processes, with concomitant reductions in biomass production and crop yield. In this review article, we will focus on events through extensive and transient metabolic reprogramming in response to heat stress, which included chlorophyll breakdown, generation of reactive oxygen species (ROS), antioxidant defense, protein turnover, and metabolic alterations with carbon assimilation. Such diverse metabolic reprogramming in chloroplasts is required for systemic acquired acclimation to heat stress in plants.

Putative zeatin O-glucosyltransferase OscZOG1 regulates root and shoot development and formation of agronomic traits in rice.

As a ubiquitous reaction, glucosylation controls the bioactivity of cytokinins in plant growth and development. Here we show that genetic manipulation of zeatin-O-glucosylation regulates the formation of important agronomic traits in rice by manipulating the expression of OscZOG1 gene, encoding a putative zeatin O-glucosyltransferase. We found that OscZOG1 was preferentially expressed in shoot and root meristematic tissues and nascent organs. The growth of lateral roots was stimulated in the overexpression lines, but inhibited in RNA interference lines. In shoots, knockdown of OscZOG1 expression by RNA interference significantly improved tillering, panicle branching, grain number per panicle and seed size, which are important agronomic traits for grain yield. In contrast, constitutive expression of OscZOG1 leads to negative effects on the formation of the grain-yielding traits with a marked increase in the accumulation levels of cis-zeatin O-glucoside (cZOG) in the transgenic rice plants. In this study, our findings demonstrate the feasibility of improving the critical yield-determinant agronomic traits, including tiller number, panicle branches, total grain number per panicle and grain weight by downregulating the expression level of OscZOG1. Our results suggest that modulating the levels of cytokinin glucosylation can function as a fine-tuning switch in regulating the formation of agronomic traits in rice.