Carotenoid Pigment Accumulation in Horticultural Plants

Carotenoids are a group of widely distributed natural pigments.They give many horticultural plants the bright red,orange,and yellow colors,as well as the aroma and flavor.Carotenoids enhance the health value and represent an essential quality trait of horticultural products.Significant efforts have been made to correlate specific carotenoid production with pathway gene expression.Some transcription factors that directly regulate transcription of the pathway genes have been identified.Horticultural crops have evolved with complicated and multifaceted regulatory mechanisms to generate the enormous diversity in carotenoid content and composition.However,the diverse and complex control of carotenoid accumulation is still not well understood.In this review,we depict carotenoid accumulation pathways and highlight the recent progress in the regulatory control of carotenoid accumulation in horticultural plants.Because of the critical roles of chromoplasts for carotenoid hyperproduction,we evaluate chromoplast ultrastructures and carotenoid sequestrations.A perspective on carotenoid research in horticultural crops is provided.

Heterojunction Incorporating Perovskite and Microporous Metal–Organic Framework Nanocrystals for Efficient and Stable Solar Cells

In this paper,we present a facile approach to enhance the efficiency and stability of perovskite solar cells(PSCs)by incorporating perovskite with microporous indium-based metal–organic framework[In12O(OH)16(H2O)5(btc)6]n(In-BTC)nanocrystals and forming heterojunction light-harvesting layer.The interconnected micropores and terminal oxygen sites of In-BTC allow the preferential crystallization of perovskite inside the regular cavities,endowing the derived films with improved morphology/crystallinity and reduced grain boundaries/defects.Consequently,the In-BTC-modified PSC yields enhanced fill factor of 0.79 and power conversion efficiency(PCE)of 20.87%,surpassing the pristine device(0.76 and 19.52%,respectively).More importantly,over 80%of the original PCE is retained after 12 days of exposure to ambient environment(25°C and relative humidity of^65%)without encapsulation,while only about 35%is left to the pristine device.

Comparative transcriptome analyses shed light on carotenoid production and plastid development in melon fruit

Carotenoids,such asβ-carotene,accumulate in chromoplasts of various fleshy fruits,awarding them with colors,aromas,and nutrients.The Orange(CmOr)gene controlsβ-carotene accumulation in melon fruit by posttranslationally enhancing carotenogenesis and repressingβ-carotene turnover in chromoplasts.Carotenoid isomerase(CRTISO)isomerizes yellow prolycopene into red lycopene,a prerequisite for further metabolism intoβ-carotene.We comparatively analyzed the developing fruit transcriptomes of orange-colored melon and its two isogenic EMS-induced mutants,low-β(Cmor)and yofi(Cmcrtiso).The Cmor mutation in low-βcaused a major transcriptomic change in the mature fruit.In contrast,the Cmcrtiso mutation in yofi significantly changed the transcriptome only in early fruit developmental stages.These findings indicate that melon fruit transcriptome is primarily altered by changes in carotenoid metabolic flux and plastid conversion,but minimally by carotenoid composition in the ripe fruit.Clustering of the differentially expressed genes into functional groups revealed an association between fruit carotenoid metabolic flux with the maintenance of the photosynthetic apparatus in fruit chloroplasts.Moreover,large numbers of thylakoid localized photosynthetic genes were differentially expressed in low-β.CmOR family proteins were found to physically interact with light-harvesting chlorophyll a–b binding proteins,suggesting a new role of CmOR for chloroplast maintenance in melon fruit.This study brings more insights into the cellular and metabolic processes associated with fruit carotenoid accumulation in melon fruit and reveals a new maintenance mechanism of the photosynthetic apparatus for plastid development.

Co-chaperoning of chlorophyll and carotenoid biosynthesis by ORANGE family proteins in plants

Chlorophylls and carotenoids are essential photosynthetic pigments.Plants spatiotemporally coordinate the needs of chlorophylls and carotenoids for optimal photosynthesis and fitness in response to diverse environmental and developmental cues.However,how the biosynthesis pathways of these two pigments are coordinated,particularly at posttranslational level to allow rapid control,remains largely unknown.Here,we report that the highly conserved ORANGE(OR)family proteins coordinate both pathways via posttranslationally mediating the first committed enzyme in each pathway.We demonstrate that OR family proteins physically interact with magnesium chelatase subunit I(CHLI)in chlorophyll biosynthesis pathway in addition to phytoene synthase(PSY)in carotenoid biosynthesis pathway and concurrently stabilize CHLI and PSY enzymes.We show that loss of OR genes hinders both chlorophyll and carotenoid biosynthesis,limits light-harvesting complex assembly,and impairs thylakoid grana stacking in chloroplasts.Overexpression of OR safeguards photosynthetic pigment biosynthesis and enhances thermotolerance in both Arabidopsis and tomato plants.Our findings establish a novel mechanism by which plants coordinate chlorophyll and carotenoid biosynthesis and provide a potential genetic target to generate climate-resilient crops.

中国省域视角下对外直接投资、逆向技术溢出与创新能力研究

"一带一路"建设成为新时代对外开放的最鲜明特征,为我国新时代改革开放指明了新方向,注入了新活力。伴随中国新一轮改革开放质量的不断深化、扩展、拓宽,对外开放的质量提出了更高、更深的新要求。对外直接投资的逆向技术溢出效应是近年来国际直接投资领域研究的热点。如何更深入探究三者发展关系?为新时期提高省域创新能力同时共赢对外直接投资的逆向技术溢出效应。在构建理论框架基础上,详细解析三者之间的机制机理,根据2001-2018年可获得数据,实证显示对外直接投资逆向技术溢出对创新能力具有一定的"门槛效应",并进一步解析不同变量作用力量。在瞄准制造强国2025背景下,在如何深度融合作用的过程中,进一步提出了应从宏观和微观两个视角协同发力以实现新时代经济发展效益提升。

High-purity helical carbon nanotubes by trace-water- assisted chemical vapor deposition： Large-scale synthesis and growth mechanism

Helical carbon nanotubes （HCNTs） are highly desirable due to their unique geometrical elegance and inherent physical properties; however, high-efficiency synthesis of high-purity HCNTs with high yield and full elucidation of their growth mechanism remains challenging. Traditional methods to achieve the high-yield growth of HCNTs mainly focus on controlling the size of catalytic particles. Herein, we found that addition of trace water greatly benefits large-scale synthesis of HCNTs. Uniform HCNTs with - 100% purity can be obtained, and the yield of HCNTs can reach ~ 8,078% in a run of 6 h, much higher than that obtained without trace water and any of the reported yields. Experiments and theoretical simulations are performed to reveal that the trace water can react with the dangling bond on carbon, thus inhibiting the generation of amorphous species. Furthermore, the trace water can enhance the anisotropy of the catalyst surface. This results in different segregation rates of carbon atoms coming out of different crystal planes and further periodic mismatch of the graphite layers, thus leading to the formation of HCNTs. Therefore, this new and efficient method is promising for practical, large-scale production of HCNTs.

Plant carotenoids: recent advances and future perspectives

Carotenoids are isoprenoid metabolites synthesized de novo in all photosynthetic organisms.Carotenoids are essential for plants with diverse functions in photosynthesis,photoprotection,pigmentation,phytohormone synthesis,and signaling.They are also critically important for humans as precursors of vitamin A synthesis and as dietary antioxidants.The vital roles of carotenoids to plants and humans have prompted significant progress toward our understanding of carotenoid metabolism and regulation.New regulators and novel roles of carotenoid metabolites are continuously revealed.This review focuses on current status of carotenoid metabolism and highlights recent advances in comprehension of the intrinsic and multi-dimensional regulation of carotenoid accumulation.We also discuss the functional evolution of carotenoids,the agricultural and horticultural application,and some key areas for future research.