Comparison of carotenoid,chlorophyll concentrations and their biosynthetic transcript levels in different coloured cauliflower

Carotenoids and chlorophylls are among the most widely distributed pigments in nature that play essential roles in the photosynthetic apparatus and confer diverse colours in plants.Among all vegetables,cauliflower(Brassica oleracea L.ssp.var.botrytis)is rich in phytochemicals and is an important crop grown all over the world.This study investigates carotenoid and chlorophyll concentrations in differently pigmented cultivars and elucidates the role of transcriptional regulation of carotenoid accumulation including lutein andβ-carotene.Here,we characterised changes in pigments by UHPLC-DAD-ToF-MS and changes in transcript levels of carotenoid metabolic genes by qRT-PCR in florets and leaves of orange(‘Jaffa'and‘Sunset'),purple(‘Di Sicilia Violetto'and‘Graffiti'),green(‘Trevi')and white(‘Clapton')cultivars.Transcript levels of all carotenoid metabolic genes showed different transcript level patterns in the leaves and florets.Compared to the other cultivars,the orange cultivars had the highest levels ofβ-carotene in the florets and lutein in the leaves resulting in changes lutein/β-carotene ratios.In the green cultivar,higher transcript levels were also found,especially for phytoene synthase and phytoene desaturase genes of the core biosynthesis pathway.However,no increased carotenoid concentrations were observed,possibly due to a higher carotenoid turnover induced by the carotenoid cleavage dioxygenase 4 in the green cultivar.In the white(‘Clapton')and purple(‘Di Sicilia Violetto'and‘Graffiti')cultivars the phytoene desaturase transcript levels as well as carotenoid concentrations were low.Chlorophyll concentrations changed in trend comparable to the carotenoid concentrations and were only significantly lower in the leaves of the orange cultivar‘Jaffa'.Also,the chlorophyll a/b ratio changed in‘Jaffa'.In florets the highest chlorophylls concentrations were observed for the green cultivar(‘Trevi')and the purple cultivar(‘Di Sicilia Violetto').Taken together,the study demonstrates the complex source-sink relationship of carotenoid accumulation in different coloured cauliflower.

Integrated proteomic and metabolomic analyses reveal the importance of aroma precursor accumulation and storage in methyl jasmonate-primed tea leaves

In response to preharvest priming with exogenous methyl jasmonate(MeJA),tea plants adjust their physiological behavior at the molecular level.The whole-organism reconfiguration of aroma formation from the precursor to storage is poorly understood.In this study,we performed iTRAQ proteomic analysis and identified 337,246,and 413 differentially expressed proteins in tea leaves primed with MeJA for 12 h,24h,and 48 h,respectively.Furthermore,a total of 266 nonvolatile and 100 volatile differential metabolites were identified by utilizing MS-based metabolomics.A novel approach that incorporated the integration of extended self-organizing map-based dimensionality was applied.The vivid time-scale changes tracing physiological responses in MeJA-primed tea leaves are marked in these maps.Jasmonates responded quickly to the activation of the jasmonic acid pathway in tea leaves,while hydroxyl and glycosyl jasmonates were biosynthesized simultaneously on a massive scale to compensate for the exhausted defense.The levels ofα-linolenic acid,geranyl diphosphate,farnesyl diphosphate,geranylgeranyl diphosphate,and phenylalanine,which are crucial aroma precursors,were found to be significantly changed in MeJA-primed tea leaves.Green leaf volatiles,volatile terpenoids,and volatile phenylpropanoids/benzenoids were spontaneously biosynthesized from responding precursors and subsequently converted to their corresponding glycosidic forms,which can be stably stored in tea leaves.This study elucidated the physiological response of tea leaves primed with exogenous methyl jasmonate and revealed the molecular basis of source and sink changes on tea aroma biosynthesis and catabolism in response to exogenous stimuli.The results significantly enhance our comprehensive understanding of tea plant responses to exogenous treatment and will lead to the development of promising biotechnologies to improve fresh tea leaf quality.

Assessment and selection of fungal antagonists against Rhizoctonia solani

The soil-borne pathogen Rhizoctonia solani Kühn (teleomorph, Thanatephorus cucumeris [A.B. Frank] Donk) is worldwide responsible for serious damage of many economically important agricultural and horticultural crops. Control of Rhizoctonia diseases is difficult because this pathogen survives for many years as sclerotia in soil or as mycelium in organic matter under numerous environmental conditions. Furthermore, the pathogen has an extremely wide host range. To date, no effective control strategies against Rhizoctonia diseases are available in either organic farming or horticulture. In integrated pest management systems (IPM), mainly fungicides are used as control method. However, the European Union has decided that 60% of the chemical pesticides that were allowed in 1996 should be banned from 2003. Hence, new strategies to control one of the most important soil-borne pathogen R. solani are urgently needed. It is well-documented that an environmentally friendly alternative to protect plants against soil borne pathogens is biological control. Our work is concentrated on the development of a fungal biological control agent (BCA) especially selected against diseases caused by R. solani.. Based on a combination of in vitro and in vivo assays 339 fungal plant-associated strains was evaluated against R. solani. The following characteristics were tested in vitro: antagonistic activity at 20 ℃ and 12 ℃, the ability to produce cell wall-degrading enzymes (chitinase, β-1,3-glucanase, protease), and influence on sclerotia germination. The ability of spore production was also of importance under consideration of formulation of possible candidates. As results of the note characteristics six isolates were selected. Taxonomical characterization using molecular methods like BOX-PCR and sequencing of the 18S rDNA resulted in genetically diverse Trichoderma isolates. The disease suppression effect of the six fungal isolates were tested against bottom rot on lettuce and black scurf on potato in pot experiments in climate chamber. The conditions were favourable for the disease development by R. solani on both crops. All six isolates were able to suppress the disease severity on lettuce and potato. According to their biocontrol effect under field conditions the most efficient isolate will be commercialised as BCA product.

Tissue-specific signatures of metabolites and proteins in asparagus roots and exudates

Comprehensive untargeted and targeted analysis of root exudate composition has advanced our understanding of rhizosphere processes.However,little is known about exudate spatial distribution and regulation.We studied the specific metabolite signatures of asparagus root exudates,root outer(epidermis and exodermis),and root inner tissues(cortex and vasculature).The greatest differences were found between exudates and root tissues.In total,263 non-redundant metabolites were identified as significantly differentially abundant between the three root fractions,with the majority being enriched in the root exudate and/or outer tissue and annotated as‘lipids and lipid-like molecules’or‘phenylpropanoids and polyketides’.Spatial distribution was verified for three selected compounds using MALDI-TOF mass spectrometry imaging.Tissue-specific proteome analysis related root tissue-specific metabolite distributions and rhizodeposition with underlying biosynthetic pathways and transport mechanisms.The proteomes of root outer and inner tissues were spatially very distinct,in agreement with the fundamental differences between their functions and structures.According to KEGG pathway analysis,the outer tissue proteome was characterized by a high abundance of proteins related to‘lipid metabolism’,‘biosynthesis of other secondary metabolites’and‘transport and catabolism’,reflecting its main functions of providing a hydrophobic barrier,secreting secondary metabolites,and mediating water and nutrient uptake.Proteins more abundant in the inner tissue related to‘transcription’,‘translation’and‘folding,sorting and degradation’,in accord with the high activity of cortical and vasculature cell layers in growth-and development-related processes.In summary,asparagus root fractions accumulate specific metabolites.This expands our knowledge of tissue-specific plant cell function.

The proteome landscape of the root cap reveals a role for the jacalin-associated lectin JAL10 in the salt-induced endoplasmic reticulum stress pathway

Rapid climate change has led to enhanced soil salinity,one of the major determinants of land degradation,resulting in low agricultural productivity.This has a strong negative impact on food security and environmental sustainability.Plants display various physiological,developmental,and cellular responses to deal with salt stress.Recent studies have highlighted the root cap as the primary stress sensor and revealed its crucial role in halotropism.The root cap covers the primary root meristem and is the first cell type to sense and respond to soil salinity,relaying the signal to neighboring cell types.However,it remains unclear how root-cap cells perceive salt stress and contribute to the salt-stress response.Here,we performed a root-cap cell-specific proteomics study to identify changes in the proteome caused by salt stress.The study revealed a very specific salt-stress response pattern in root-cap cells compared with non-rootcap cells and identified several novel proteins unique to the root cap.Root-cap-specific protein–protein interaction(PPI)networks derived by superimposing proteomics data onto known global PPI networks revealed that the endoplasmic reticulum(ER)stress pathway is specifically activated in root-cap cells upon salt stress.Importantly,we identified root-cap-specific jacalin-associated lectins(JALs)expressed in response to salt stress.A JAL10-GFP fusion protein was shown to be localized to the ER.Analysis of jal10 mutants indicated a role for JAL10 in regulating the ER stress pathway in response to salt.Taken together,our findings highlight the participation of specific root-cap proteins in salt-stress response pathways.Furthermore,root-cap-specific JAL proteins and their role in the salt-mediated ER stress pathway open a new avenue for exploring tolerance mechanisms and devising better strategies to increase plant salinity tolerance and enhance agricultural productivity.