Planta

Steczkowski, Mackenzi; McClellan, Kyle; Jessup, Russell; Kurouski, Dmitry

doi: 10.1007/s00425-023-04299-6pmid: 38091099

Main conclusionHand-held Raman spectroscopy can be used for highly accurate differentiation between drought, heat and light-triggered stresses in hemp. The differentiation is based on the changes in the biochemistry of plants caused by such stresses.AbstractHemp farming is a rapidly growing industry. This dioecious plant is primarily cultivated for its fibers, seeds, and cannabinoid-rich oils. The yield of these materials can be drastically lowered by many abiotic stresses, such as drought, heat and light. It becomes critically important to develop robust and reliable approaches that can be used to diagnose such abiotic stresses in hemp. In this study, we investigate the accuracy of Raman spectroscopy, an emerging tool within crop monitoring, in the confirmatory identification of drought, heat, and light-induced stresses in three varieties of hemp. Our results showed that mono, double and triple stresses uniquely alter plant biochemistry that results in small spectroscopic changes detected in the Raman spectra acquired from the hemp leaves. These changes could be used for the 80–100% accurate identification of individual abiotic stresses and their combinations in plants. These results demonstrate that a hand-held Raman spectrometer can be used for highly accurate, non-invasive, non-destructive, and label-free diagnostics of hemp stresses directly in the greenhouse or in the field.

Song, Xin; Yu, Yaoguang; Zhu, Jiameng; Li, Chenlong

doi: 10.1007/s00425-023-04283-0pmid: 38019301

Main conclusionThis study reveals that mutations in BRIP1/2 subunits of the BAS complex disrupt root meristem development by decreasing PIN genes expression, affecting auxin transport, and downregulating essential root genes PLT.AbstractSwitch defective/sucrose non-fermentable (SWI/SNF) chromatin remodeling complexes play vital roles in plant development. BRAHMA-interacting proteins1 (BRIP1) and BRIP2 are subunits of BRAHMA (BRM)-associated SWI/SNF complex (BAS) in plants; however, their role and underlying regulatory mechanism in root development are still unknown. Here, we show that brip1 brip2 double mutants have a significantly shortened root meristem and an irregular arrangement in a portion of the root stem cell niche. The mutations in BRIP1 and BRIP2 cause decreased expression of the PIN-FORMED (PIN) genes, which in turn reduces the transport of auxin at the root tip, leading to the disruption of the accurate establishment of normal auxin concentration gradients in the stem cells. Chromatin immunoprecipitation (ChIP) experiments indicated that BRIP1 and BRIP2 directly bind to the PINs. Furthermore, we found a significant down-regulation in the expression of key root development genes, PLETHORA (PLT), in brip1 brip2. The brip1 brip2 plt1 plt2 quadruple mutations do not show further exacerbation in the short-root phenotype compared to plt1 plt2 double mutants. Using a dexamethasone (DEX)-inducible PLT2 transgenic line, we showed that acute overexpression of PLT2 partially rescues root meristem defects of brip1 brip2, suggesting that BRIP1 and BRIP2 act in part through the PLT1/2 pathway. Taken together, our results identify the critical role and the underlying mechanism of BRIP1/2 in maintaining the development of root meristem through the regulation of auxin output and expression of PLTs.

Huang, Xinru; Zhang, Weiwei; Liao, Yongling; Ye, Jiabao; Xu, Feng

doi: 10.1007/s00425-023-04268-zpmid: 37971670

Key messageThis review summarized how TFs function independently or in response to environmental factors to regulate terpenoid biosynthesis via fine-tuning the expression of rate-limiting enzymes.AbstractTerpenoids are derived from various species and sources. They are essential for interacting with the environment and defense mechanisms, such as antimicrobial, antifungal, antiviral, and antiparasitic properties. Almost all terpenoids have high medicinal value and economic performance. Recently, the control of enzyme genes on terpenoid biosynthesis has received a great deal of attention, but transcriptional factors regulatory network on terpenoid biosynthesis and accumulation has yet to get a thorough review. Transcription factors function as activators or suppressors independently or in response to environmental stimuli, fine-tuning terpenoid accumulation through regulating rate-limiting enzyme expression. This study investigates the advancements in transcription factors related to terpenoid biosynthesis and systematically summarizes previous works on the specific mechanisms of transcription factors that regulate terpenoid biosynthesis via hormone signal–transcription regulatory networks in plants. This will help us to better comprehend the regulatory network of terpenoid biosynthesis and build the groundwork for terpenoid development and effective utilization.

Freitas-Alves, Nayara S.; Moreira-Pinto, Clidia E.; Arraes, Fabrício B. M.; Costa, Lorena S. de L.; de Abreu, Rayane A.; Moreira, Valdeir J. V.; Lourenço-Tessutti, Isabela T.; Pinheiro, Daniele H.; Lisei-de-Sa, Maria E.; Paes-de-Melo, Bruno; Pereira, Bruna M.; Guimaraes, Patricia M.;

Saha, Baisista; Nayak, Jagatjeet; Srivastava, Richa; Samal, Swarnmala; Kumar, Deepak; Chanwala, Jeky; Dey, Nrisingha; Giri, Mrunmay Kumar

doi: 10.1007/s00425-023-04269-ypmid: 38012461

Main conclusionThis review article explores the intricate role, regulation, and signaling mechanisms of WRKY TFs in response to biotic stress, particularly emphasizing their pivotal role in the trophism of plant-pathogen interactions.AbstractTranscription factors (TFs) play a vital role in governing both plant defense and development by controlling the expression of various downstream target genes. Early studies have shown the differential expression of certain WRKY transcription factors by microbial infections. Several transcriptome-wide studies later demonstrated that diverse sets of WRKYs are significantly activated in the early stages of viral, bacterial, and fungal infections. Furthermore, functional investigations indicated that overexpression or silencing of certain WRKY genes in plants can drastically alter disease symptoms as well as pathogen multiplication rates. Hence the new aspects of pathogen-triggered WRKY TFs mediated regulation of plant defense can be explored. The already recognized roles of WRKYs include transcriptional regulation of defense-related genes, modulation of hormonal signaling, and participation in signal transduction pathways. Some WRKYs have been shown to directly bind to pathogen effectors, acting as decoys or resistance proteins. Notably, the signaling molecules like salicylic acid, jasmonic acid, and ethylene which are associated with plant defense significantly increase the expression of several WRKYs. Moreover, induction of WRKY genes or heightened WRKY activities is also observed during ISR triggered by the beneficial microbes which protect the plants from subsequent pathogen infection. To understand the contribution of WRKY TFs towards disease resistance and their exact metabolic functions in infected plants, further studies are required. This review article explores the intrinsic transcriptional regulation, signaling mechanisms, and hormonal crosstalk governed by WRKY TFs in plant disease defense response, particularly emphasizing their specific role against different biotrophic, hemibiotrophic, and necrotrophic pathogen infections.

Tian, Jinfu; Zhang, Jiahui; Francis, Frédéric

doi: 10.1007/s00425-023-04292-zpmid: 38078967

Main conclusionThis review provides a detailed description of the function and mechanism of VQ family gene, which is helpful for further research and application of VQ gene resources to improve crops.AbstractValine-glutamine (VQ) motif-containing proteins are a large class of transcriptional regulatory cofactors. VQ proteins have their own unique molecular characteristics. Amino acids are highly conserved only in the VQ domain, while other positions vary greatly. Most VQ genes do not contain introns and the length of their proteins is less than 300 amino acids. A majority of VQ proteins are predicted to be localized in the nucleus. The promoter of many VQ genes contains stress or growth related elements. Segment duplication and tandem duplication are the main amplification mechanisms of the VQ gene family in angiosperms and gymnosperms, respectively. Purification selection plays a crucial role in the evolution of many VQ genes. By interacting with WRKY, MAPK, and other proteins, VQ proteins participate in the multiple signaling pathways to regulate plant growth and development, as well as defense responses to biotic and abiotic stresses. Although there have been some reports on the VQ gene family in plants, most of them only identify family members, with little functional verification, and there is also a lack of complete, detailed, and up-to-date review of research progress. Here, we comprehensively summarized the research progress of VQ genes that have been published so far, mainly including their molecular characteristics, biological functions, importance of VQ motif, and working mechanisms. Finally, the regulatory network and model of VQ genes were drawn, a precise molecular breeding strategy based on VQ genes was proposed, and the current problems and future prospects were pointed out, providing a powerful reference for further research and utilization of VQ genes in plant improvement.

Su, Jiangshuo; Lu, Zhaowen; Zeng, Junwei; Zhang, Xuefeng; Yang, Xiuwei; Wang, Siyue; Zhang, Fei; Jiang, Jiafu; Chen, Fadi

doi: 10.1007/s00425-023-04297-8pmid: 38063918

Main conclusionMulti-locus GWAS detected several known and candidate genes responsible for flowering time in chrysanthemum. The associations could greatly increase the predictive ability of genome selection that accelerates the possible application of GS in chrysanthemum breeding.AbstractTimely flowering is critical for successful reproduction and determines the economic value for ornamental plants. To investigate the genetic architecture of flowering time in chrysanthemum, a multi-locus genome-wide association study (GWAS) was performed using a collection of 200 accessions and 330,710 single-nucleotide polymorphisms (SNPs) via 3VmrMLM method. Five flowering time traits including budding (FBD), visible colouring (VC), early opening (EO), full-bloom (OF) and senescing (SF) stages, plus five derived conditional traits were recorded in two environments. Extensive phenotypic variations were observed for these flowering time traits with coefficients of variation ranging from 6.42 to 38.27%, and their broad-sense heritability ranged from 71.47 to 96.78%. GWAS revealed 88 stable quantitative trait nucleotides (QTNs) and 93 QTN-by-environment interactions (QEIs) associated with flowering time traits, accounting for 0.50–8.01% and 0.30–10.42% of the phenotypic variation, respectively. Amongst the genes around these stable QTNs and QEIs, 21 and 10 were homologous to known flowering genes in Arabidopsis; 20 and 11 candidate genes were mined by combining the functional annotation and transcriptomics data, respectively, such as MYB55, FRIGIDA-like, WRKY75 and ANT. Furthermore, genomic selection (GS) was assessed using three models and seven unique marker datasets. We found the prediction accuracy (PA) using significant SNPs identified by GWAS under SVM model exhibited the best performance with PA ranging from 0.90 to 0.95. Our findings provide new insights into the dynamic genetic architecture of flowering time and the identified significant SNPs and candidate genes will accelerate the future molecular improvement of chrysanthemum.

Kaduchová, Kateřina; Čmiel, Vratislav; Koláčková, Veronika; Pecinka, Ales

doi: 10.1007/s00425-023-04293-ypmid: 38095727

Main conclusionWe describe a user-optimized sample holder EasyClick for medium-sized plants that reduces root side movements and thus greatly extends the duration of live cell confocal microscopy.AbstractPreparation and mounting of the samples are key factors for successful live cell microscopy. To acquire biologically relevant data, it is necessary to minimize stress and avoid physical damage to plant tissues during the installation of the sample into the microscope. This is challenging, particularly when the whole plant is mounted as the living sample needs to be properly anchored in the microscopic system to obtain high-quality and high-resolution data. Here, we present a user-optimized sample holder EasyClick for live cell inverted confocal microscopic analysis of plant roots with diameters from 0.3 to 0.7 mm. The EasyClick holder was tested on an inverted confocal microscope using germinating plants of several cereals. Nevertheless, it can be directly used on other types of inverted microscopes from various producers and on different plant species. The EasyClick holder effectively restricts root lateral and vertical movements. This greatly improves the conditions for time-lapse microscopy of the samples of interest.

Zhou, Shuangshuang; Lin, Ya; Cai, Yu; Li, Linfang; Yao, Xiaohui; Sun, Kuan; Song, Qin; Zhang, Qingwei

doi: 10.1007/s00425-023-04306-wpmid: 38112830

Main conclusionIntegrated transcriptome and metabolome analysis have unveiled the physiological and molecular responses of rhubarb to infection by smut fungi.AbstractRhubarb is an important medicinal plant that is easily infected by smut fungi during its growth. Thus far, no research on the influence of smut fungi on the growth of rhubarb and its secondary metabolism has been conducted. In this study, petioles of Chinese rhubarb (Rheum officinale) [healthy or infected with smut fungus (Thecaphora schwarzmaniana)] were characterized. Microscopic structure, global gene expression profiling, global metabolic profiling, and key enzyme activity and metabolite levels in infected plants were analyzed. Infection by smut fungi resulted in numerous holes inside the petiole tissue and led to visible tumors on the external surface of the petiole. Through metabolic changes, T. schwarzmaniana induced the production of specific sugars, lipids, and amino acids, and inhibited the metabolism of phenolics and flavonoids in R. officinale. The concentrations of key medicinal compounds (anthraquinones) were decreased because of smut fungus infection. In terms of gene expression, the presence of T. schwarzmaniana led to upregulation of the genes associated with nutrient (sugar, amino acid, etc.) transport and metabolism. The gene expression profiling showed a stimulated cell division activity (the basis of tumor formation). Although plant antioxidative response was enhanced, the plant defense response against pathogen was suppressed by T. schwarzmaniana, as indicated by the expression profiling of genes involved in biotic and abiotic stress-related hormone signaling and the synthesis of plant disease resistance proteins. This study demonstrated physiological and molecular changes in R. officinale under T. schwarzmaniana infection, reflecting the survival tactics employed by smut fungus for parasitizing rhubarb.

Wang, Dan; Yang, Zaijun; Feng, Mengying; Yang, Wenwen; Qu, Rui; Nie, Shuming

doi: 10.1007/s00425-023-04288-9pmid: 38047928

Main conclusionOverexpression of SlBRI1 driven by the Atrd29A promoter could increase the cold resistance of tomato plants during chilling stress but did not improve the expression of SlBRI1 and plant growth under normal conditions.AbstractLow temperature is the main limiting factor severely affecting tomato plant development, growth, and fruit quality in winter and spring. Brassinosteroids (BRs) and key BR signaling genes positively regulate tomato plant development and response to chilling stress. Brassinosteroid-insensitive 1 (BRI1) is a major BR receptor that initiates BR signaling. Our results showed that overexpression of SlBRI1 driven by the Atrd29A promoter in transgenic plants did not increase the expression of SlBRI1 under normal conditions but rapidly induced the expression of SlBRI1 during chilling stress. The degree of wilting was lower in Atrd29A promoter-transgenic plants than in wild-type (WT) plants after chilling stress. Atrd29A promoter-transgenic plants exhibited low relative electrolyte leakage and reactive oxygen species (ROS) accumulation under chilling stress. Transgenic plants showed higher photosynthetic ability and antioxidant enzyme activity than WT plants under chilling stress. The BR content and expression levels of key genes involved in BR biosynthesis in Atrd29A-promoter transgenic plants were significantly lower than those in WT plants during chilling stress. The abscisic acid (ABA) content and expression levels of key ABA biosynthesis genes in the Atrd29A promoter-transgenic plants were significantly higher than those in the WT plants during chilling stress. In addition, Atrd29A promoter-transgenic plants positively enhanced the expression levels of ICE–CBF–COR cold-responsive pathway genes. Therefore, the overexpression of SlBRI1 driven by the Atrd29A promoter in transgenic plants can be a valuable tool for reducing chilling stress.