A novel single-base mutation in CaSGR1 confers the stay-green phenotype in pepper

The stay-green trait is of considerable importance in extending the shelf life of green pepper fruit(Capsicum annuum L.)and in enhancing the appearance of ornamental plants.The study revealed the genetic and regulatory mechanisms of the stay-green trait in pepper,which will aid in the selection of ornamental pepper varieties.In this study,a pepper mutant with stay-green fruit named TNX348 was identified from a germplasm resource bank.Two segregating populations were constructed using the stay-green mutant TNX348 and then used in bulked segregant analysis combined with RNA sequencing and linkage analyses.The causal gene of the stay-green trait was mapped to an approximately 131-kb region,and a senescence-induced chloroplast protein gene,CaSGR1(Capana01g000359),was identified as a candidate gene.Sequencing analysis revealed a G→A single-base mutation of CaSGR1 in TNX348 that led to early termination of translation.Based on the single-base mutation,a single nucleotide polymorphism(SNP)marker co-segregating with the stay-green trait was developed.Furthermore,in transcriptome analysis,expression patterns of 11 hormone transduction-related transcription factors,such as abscisic acid-insensitive(ABI),abscisic acidresponsive element-binding factor(ABF),and NAC transcription factor,were similar or opposite to that of CaSGR1.The results indicated that the transcription factors might mediate chlorophyll degradation by regulating the expression of CaSGR1.

A multi-omics approach identifies bHLH71-like as a positive regulator of yellowing leaf pepper mutants exposed to high-intensity light

Light quality and intensity can have a significant impact on plant health and crop productivity.Chlorophylls and carotenoids are classes of plant pigments that are responsible for harvesting light energy and protecting plants from the damaging effects of intense light.Our understanding of the role played by plant pigments in light sensitivity has been aided by light-sensitive mutants that change colors upon exposure to light of variable intensity.In this study,we conducted transcriptomic,metabolomic,and hormone analyses on a novel yellowing mutant of pepper(yl1)to shed light on the molecular mechanism that regulates the transition from green to yellow leaves in this mutant upon exposure to high-intensity light.Our results revealed greater accumulation of the carotenoid precursor phytoene and the carotenoids phytofluene,antheraxanthin,and zeaxanthin in yl1 compared with wild-type plants under high light intensity.A transcriptomic analysis confirmed that enzymes involved in zeaxanthin and antheraxanthin biosynthesis were upregulated in yl1 upon exposure to high-intensity light.We also identified a single basic helix–loop–helix(bHLH)transcription factor,bHLH71-like,that was differentially expressed and positively correlated with light intensity in yl1.Silencing of bHLH71-like in pepper plants suppressed the yellowing phenotype and led to reduced accumulation of zeaxanthin and antheraxanthin.We propose that the yellow phenotype of yl1 induced by high light intensity could be caused by an increase in yellow carotenoid pigments,concurrent with a decrease in chlorophyll accumulation.Our results also suggest that bHLH71-like functions as a positive regulator of carotenoid biosynthesis in pepper.

Integrated metabolome and transcriptome analysis revealed carotenoid metabolism difference in pepper(Capsicum annuum L.)yellowing mutants under different light quality

Light is an important environmental factor for plant growth and development,different light qualities have different regulatory effects on plants.To investigate the effect of light quality on plants,we determined the physiological characteristics,transcriptome and metabolome analysis of pepper yellowing mutants yl1 treated with blue,red,green,and purple light.Results showed that the leaf of yl1 was obviously yellowing,and the contents of chlorophyll,carotenoid and net photosynthetic rate in yl1 were significantly decreased under purple light.A total of 31,853 genes were quantified under blue,red,green and purple light.The genes related to carotenoid metabolism pathway such as PSY,LUT5 and VDE were significantly increased,while the expression levels of chlorophyll synthesis related genes POR and CAO were significantly decreased under purple light.At the same time,21 carotenoid pathway metabolites were detected under the four light different lights,and 10 metabolites were more abundant in pepper leaves.α-carotene,β-carotene,lutein,neoxanthin,α-cryptoxanthin andβ-cryptoxanthin were significantly accumulated under blue,red and green light.However,zeaxanthin and antheraxanthin were accumulated in large quantities under purple light.After silencing the CaVDE gene under purple light,leaf etiolation degree was significantly weakened,chlorophyll,carotenoids and net photosynthetic rate were significantly increased,and the accumulation of zeaxanthin and antheraxanthin was significantly decreased.These results provide a reference for analyzing the changes of carotenoid components induced by VDE in purple light and provide new insights into the mechanism of leaf color change in plants.

Self-assembled Ag_(4)V_(2)O_(7)/Ag_(3)VO_(4) Z-scheme heterojunction by pH adjustment with efficient photocatalytic performance

Semiconductor heterojunction plays a pivotal role in photocatalysis.However,the construction of a heterojunction with a fine microstructure usually requires complex synthetic procedures.Herein,a pH-adjusted one-step method was employed to controllably synthesize Ag_(4)V_(2)O_(7)/Ag_(3)VO_(4) heterojunction with a well-tuned 0D/1D hierarchical structure for the first time.It is noteworthy that the ordered stacking of vanadium oxide tetrahedron(VO_(3)-)guided by the pH value wisely realizes the in-situ growth of Ag_(4)V_(2)O_(7) nanoparticles on the surface of Ag_(3)VO_(4) nanorods.Furthermore,comprehensive characterization and calculation decipher the electronic structures of Ag_(4)V_(2)O_(7) and Ag_(3)VO_(4) and the formation of Z-scheme heterojunction,benefiting the visible light harvesting and carrier utilization.Such a new Ag_(4)V_(2)O_(7)/Ag_(3)VO_(4) heterojunction exhibits remarkable photocatalytic activity and excellent stability.Complete degradation of Rhodamine B(RhB)can be achieved in 10 min by the Ag_(4)V_(2)O_(7)/Ag_(3)VO_(4) heterojunction under visible light irradiation,demonstrating an outstanding reaction rate of 0.35 min^(−1) that is up to 84-fold higher than those of other silver vanadates.More importantly,this integration of synthesis technology and heterojunction design,based on the intrinsic crystal and electronic structures,could be inspiring for developing novel heterostructured materials with advanced performance.

PepperHub, an Informatics Hub for the Chili Pepper Research Community

Dear Editor Pepper belongs to the Solanaceae family, which includes many important vegetable crops such as tomato, potato, and eggplant. Not only widely used as vegetables and spicy ingredients, pepper also has diverse applications in pharmaceutics, natural coloring agents, cosmetics, defense repellents, and as ornamental plants （Kim et al., 2014; Qin et al., 2014）. Pepper is among the most widely cultivated and consumed vegetables in the world, with annual production reachincl to 38 million tons in 2011 （www.fao.