Molecular identification of GAPDHs in cassava highlights the antagonism of MeGAPCs and MeATG8s in plant disease resistance against cassava bacterial blight

Identification and expression profiling of GAPDH family genes involved in response to Sclerotinia sclerotiorum infection and phytohormones in Brassica napus

Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is a crucial enzyme in glycolysis, an essential metabolic pathway for carbohydrate metabolism across all living organisms. Recent research indicates that phosphorylating GAPDH exhibits various moonlighting functions, contributing to plant growth and development, autophagy, drought tolerance, salt tolerance, and bacterial/viral diseases resistance. However, in rapeseed (Brassica napus), the role of GAPDHs in plant immune responses to fungal pathogens remains unexplored. In this study, 28 genes encoding GAPDH proteins were revealed in B. napus and classified into three distinct subclasses based on their protein structural and phylogenetic relationships. Whole-genome duplication plays a major role in the evolution of BnaGAPDHs. Synteny analyses revealed orthologous relationships, identifying 23, 26, and 26 BnaGAPDH genes with counterparts in Arabidopsis, Brassica rapa, and Brassica oleracea, respectively. The promoter regions of 12 BnaGAPDHs uncovered a spectrum of responsive elements to biotic and abiotic stresses, indicating their crucial role in plant stress resistance. Transcriptome analysis characterized the expression profiles of different BnaGAPDH genes during Sclerotinia sclerotiorum infection and hormonal treatment. Notably, BnaGAPDH17, BnaGAPDH20, BnaGAPDH21, and BnaGAPDH22 exhibited sensitivity to S. sclerotiorum infection, oxalic acid, hormone signals. Intriguingly, under standard physiological conditions, BnaGAPDH17, BnaGAPDH20, and BnaGAPDH22 are primarily localized in the cytoplasm and plasma membrane, with BnaGAPDH21 also detectable in the nucleus. Furthermore, the nuclear translocation of BnaGAPDH20 was observed under H2O2 treatment and S. sclerotiorum infection. These findings might provide a theoretical foundation for elucidating the functions of phosphorylating GAPDH.

S. A, Raveendran AP, Chaudhary A, Shanmugam A, Arunachalam A. Comparative transcriptomic and weighted gene co-expression network analysis to identify the core genes in the cultivars of Musa acuminata under both infected and chemical perturbated conditions

Banana is a high nutrient crop, which ranks fourth in terms of gross value production. Fusarium wilt of banana, caused by Fusarium oxysporum f. sp. cubense tropical race 4 (FocTR4), is considered the most destructive disease leading to the complete loss of production of the Cavendish cultivars Berangan, Brazilian and Williams, which are vulnerable to the infection of FocTR4. However, the treatment with benzothiadiazole, a synthetic salicylic analog, is aimed to induce resistance in plants. Thus, the treatments pertaining to the banana plants subjected to the Foc infection within the chosen cultivars were compared with chemically treated samples obtained at different time intervals for a short duration (0-4 days). The integrated omics analyses considering the parameters of WGCNA, functional annotation, and protein-protein interactions revealed that many pathways have been negatively influenced in Cavendish bananas under FocTR4 infections and the number of genes influenced also increased over time in Williams cultivar. Furthermore, elevation in immune response and resistance genes were also observed in the roots of the Cavendish banana.

'Candidatus Liberibacter asiaticus' secretory protein SDE3 inhibits host autophagy to promote Huanglongbing disease in citrus

Antimicrobial acroautophagy/autophagy plays a vital role in degrading intracellular pathogens or microbial molecules in host-microbe interactions. However, microbes evolved various mechanisms to hijack or modulate autophagy to escape elimination. Vector-transmitted phloem-limited bacteria, Candidatus Liberibacter (Ca. Liberibacter) species, cause Huanglongbing (HLB), one of the most catastrophic citrus diseases worldwide, yet contributions of autophagy to HLB disease proliferation remain poorly defined. Here, we report the identification of a virulence effector in "Ca. Liberibacter asiaticus" (Las), SDE3, which is highly conserved among the "Ca. Liberibacter". SDE3 expression not only promotes the disease development of HLB and canker in sweet orange (Citrus sinensis) plants but also facilitates Phytophthora and viral infections in Arabidopsis, and Nicotiana benthamiana (N. benthamiana). SDE3 directly associates with citrus cytosolic glyceraldehyde-3-phosphate dehydrogenases (CsGAPCs), which negatively regulates plant immunity. Overexpression of CsGAPCs and SDE3 significantly inhibits autophagy in citrus, Arabidopsis, and N. benthamiana. Intriguingly, SDE3 undermines autophagy-mediated immunity by the specific degradation of CsATG8 family proteins in a CsGAPC1-dependent manner. CsATG8 degradation is largely rescued by treatment with an inhibitor of the late autophagic pathway, E64d. Furthermore, ectopic expression of CsATG8s enhances Phytophthora resistance. Collectively, these results suggest that SDE3-CsGAPC interactions modulate CsATG8-mediated autophagy to enhance Las progression in citrus.Abbreviations: ACP: asian citrus psyllid; ACD2: ACCELERATED CELL DEATH 2; ATG: autophagy related; Ca. Liberibacter: Candidatus Liberibacter; CaMV: cauliflower mosaic virus; CMV: cucumber mosaic virus; Cs: Citrus sinensis; EV: empty vector; GAPC: cytosolic glyceraldehyde-3-phosphate dehydrogenase; HLB: huanglongbing; H2O2: hydrogen peroxide; Las: liberibacter asiaticus; Laf: liberibacter africanus; Lam: liberibacter americanus; Pst: Pseudomonas syringae pv. tomato; PVX: potato virus X; ROS: reactive oxygen species; SDE3: sec-delivered effector 3; TEM: transmission electron microscopy; VIVE : virus-induced virulence effector; WT: wild-type; Xcc: Xanthomonas citri subsp. citri.

Heat Shock Transcription Factor GhHSFB2a Is Crucial for Cotton Resistance to Verticillium dahliae

Heat shock transcription factors (HSFs) play a critical regulatory role in many plant disease resistance pathways. However, the molecular mechanisms of cotton HSFs involved in resistance to the soil-borne fungus Verticillium dahliae are limited. In our previous study, we identified numerous differentially expressed genes (DEGs) in the transcriptome and metabolome of V. dahliae-inoculated Arabidopsis thaliana. In this study, we identified and functionally characterized GhHSFB2a, which is a DEG belonging to HSFs and related to cotton immunity to V. dahliae. Subsequently, the phylogenetic tree of the type two of the HSFB subfamily in different species was divided into two subgroups: A. thaliana and strawberry, which have the closest evolutionary relationship to cotton. We performed promoter cis-element analysis and showed that the defense-reaction-associated cis-acting element-FC-rich motif may be involved in the plant response to V. dahliae in cotton. The expression pattern analysis of GhHSFB2a displayed that it is transcriptional in roots, stems, and leaves and significantly higher at 12 h post-inoculation (hpi). Subcellular localization of GhHSFB2a was observed, and the results showed localization to the nucleus. Virus-induced gene silencing (VIGS) analysis exhibited that GhHSFB2a silencing increased the disease index and fungal biomass and attenuated resistance against V. dahliae. Transcriptome sequencing of wild-type and GhHSFB2a-silenced plants, followed by Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, protein-protein interaction, and validation of marker genes revealed that ABA, ethylene, linoleic acid, and phenylpropanoid pathways are involved in GhHSFB2a-mediated plant disease resistance. Ectopic overexpression of the GhHSFB2a gene in Arabidopsis showed a significant increase in the disease resistance. Cumulatively, our results suggest that GhHSFB2a is required for the cotton immune response against V. dahliae-mediated ABA, ethylene, linoleic acid, and phenylpropanoid pathways, indicating its potential role in the molecular design breeding of plants.

Autophagy in the Lifetime of Plants: From Seed to Seed

Autophagy is a highly conserved self-degradation mechanism in eukaryotes. Excess or harmful intracellular content can be encapsulated by double-membrane autophagic vacuoles and transferred to vacuoles for degradation in plants. Current research shows three types of autophagy in plants, with macroautophagy being the most important autophagic degradation pathway. Until now, more than 40 autophagy-related (ATG) proteins have been identified in plants that are involved in macroautophagy, and these proteins play an important role in plant growth regulation and stress responses. In this review, we mainly introduce the research progress of autophagy in plant vegetative growth (roots and leaves), reproductive growth (pollen), and resistance to biotic (viruses, bacteria, and fungi) and abiotic stresses (nutrients, drought, salt, cold, and heat stress), and we discuss the application direction of plant autophagy in the future.

Characteristics and molecular identification of glyceraldehyde-3-phosphate dehydrogenases in poplar

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), an essential enzyme of the glycolysis metabolic pathway, plays a vital role in carbon metabolism, plant development, and stress resistance. As a kind of woody plant, poplars are widely cultivated for afforestation. Although the whole genome data of poplars have been published, little information is known about the GAPDH family of genes in poplar. This study performed a genome-wide identification of the poplar GAPDH family, and 13 determined PtGAPDH genes were identified from poplar genome. Phylogenetic tree showed that the PtGAPDH members were divided into PtGAPA/B, PtGAPC, PtGAPCp, and PtGAPN groups. A total of 13 PtGAPDH genes were distributed on eight chromosomes, 13 gene pairs belonging to segmented replication events were detected in poplar, and 23 collinearity gene pairs were determined between poplar and willow. The PtGAPDHcis-acting elements associated with growth and development as well as stress resistance revealed that PtGAPDHs might be involved in these processes. The phosphoglycerate kinase (PGK) and triose-phosphate isomerase (TPI) were predicted as the putative interaction proteins of PtGAPDHs. Gene ontology (GO) analysis showed that PtGAPDHs play a crucial role in the oxidation and reduction processes. PtGAPDH expression levels were induced by NaCl and PEG treatments, which implied that PtGAPDHs might be involved in stress response. Overexpression of PtGAPC1 significantly changed the contents of lipid and carbohydrate metabolites, which indicated that PtGAPC1 plays an essential role in metabolic regulation. This study highlights the characterizations and profiles of PtGAPDHs and reveals that PtGAPC1 is involved in the loop of lipid and carbohydrate metabolisms.

A bacterial effector counteracts host autophagy by promoting degradation of an autophagy component

Beyond its role in cellular homeostasis, autophagy plays anti‐ and promicrobial roles in host–microbe interactions, both in animals and plants. One prominent role of antimicrobial autophagy is to degrade intracellular pathogens or microbial molecules, in a process termed xenophagy. Consequently, microbes evolved mechanisms to hijack or modulate autophagy to escape elimination. Although well‐described in animals, the extent to which xenophagy contributes to plant–bacteria interactions remains unknown. Here, we provide evidence that Xanthomonas campestris pv. vesicatoria (Xcv) suppresses host autophagy by utilizing type‐III effector XopL. XopL interacts with and degrades the autophagy component SH3P2 via its E3 ligase activity to promote infection. Intriguingly, XopL is targeted for degradation by defense‐related selective autophagy mediated by NBR1/Joka2, revealing a complex antagonistic interplay between XopL and the host autophagy machinery. Our results implicate plant antimicrobial autophagy in the depletion of a bacterial virulence factor and unravel an unprecedented pathogen strategy to counteract defense‐related autophagy in plant–bacteria interactions.

Linking Autophagy to Potential Agronomic Trait Improvement in Crops

Autophagy is an evolutionarily conserved catabolic process in eukaryotic cells, by which the superfluous or damaged cytoplasmic components can be delivered into vacuoles or lysosomes for degradation and recycling. Two decades of autophagy research in plants uncovers the important roles of autophagy during diverse biological processes, including development, metabolism, and various stress responses. Additionally, molecular machineries contributing to plant autophagy onset and regulation have also gradually come into people’s sights. With the advancement of our knowledge of autophagy from model plants, autophagy research has expanded to include crops in recent years, for a better understanding of autophagy engagement in crop biology and its potentials in improving agricultural performance. In this review, we summarize the current research progress of autophagy in crops and discuss the autophagy-related approaches for potential agronomic trait improvement in crop plants.

Homologous Drought-Induced 19 Proteins, PtDi19-2 and PtDi19-7, Enhance Drought Tolerance in Transgenic Plants

Drought-induced 19 (Di19) proteins play important roles in abiotic stress responses. Thus far, there are no reports about Di19 family in woody plants. Here, eight Di19 genes were identified in poplar. We analyzed phylogenetic tree, conserved protein domain, and gene structure of Di19 gene members in seven species. The results showed the Di19 gene family was very conservative in both dicotyledonous and monocotyledonous forms. On the basis of transcriptome data, the expression patterns of Di19s in poplar under abiotic stress and ABA treatment were further studied. Subsequently, homologous genes PtDi19-2 and PtDi19-7 with strong response to drought stress were identified. PtDi19-2 functions as a nuclear transcriptional activator with a transactivation domain at the C-terminus. PtDi19-7 is a nuclear and membrane localization protein. Additionally, PtDi19-2 and PtDi19-7 were able to interact with each other in yeast two-hybrid system. Overexpression of PtDi19-2 and PtDi19-7 in Arabidopsis was found. Phenotype identification and physiological parameter analysis showed that transgenic Arabidopsis increased ABA sensitivity and drought tolerance. PtDi19-7 was overexpressed in hybrid poplar 84K (Populus alba × Populus glandulosa). Under drought treatment, the phenotype and physiological parameters of transgenic poplar were consistent with those of transgenic Arabidopsis. In addition, exogenous ABA treatment induced lateral bud dormancy of transgenic poplar and stomatal closure of transgenic Arabidopsis. The expression of ABA/drought-related marker genes was upregulated under drought treatment. These results indicated that PtDi19-2 and PtDi19-7 might play a similar role in improving the drought tolerance of transgenic plants through ABA-dependent signaling pathways.

Cassava diseases caused by Xanthomonas phaseoli pv. manihotis and Xanthomonas cassavae

Xanthomonas phaseoli pv. manihotis (Xpm) and X. cassavae (Xc) are two bacterial pathogens attacking cassava. Cassava bacterial blight (CBB) is a systemic disease caused by Xpm, which might have dramatic effects on plant growth and crop production. Cassava bacterial necrosis is a nonvascular disease caused by Xc with foliar symptoms similar to CBB, but its impacts on the plant vigour and the crop are limited. In this review, we describe the epidemiology and ecology of the two pathogens, the impacts and management of the diseases, and the main research achievements for each pathosystem. Because Xc data are sparse, our main focus is on Xpm and CBB.

Comparative RNA-Seq Analysis Reveals Potentially Resistance-Related Genes in Response to Bacterial Canker of Tomato

Tomato is one of the most important crops for human consumption. Its production is affected by the actinomycete Clavibacter michiganensis subsp. michiganensis (Cmm), one of the most devastating bacterial pathogens of this crop. Several wild tomato species represent a source of natural resistance to Cmm. Here, we contrasted the transcriptomes of the resistant wild tomato species Solanum arcanum LA2157 and the susceptible species Solanum lycopersicum cv. Ailsa Craig, during the first 24 h of challenge with Cmm. We used three analyses approaches which demonstrated to be complementary: mapping to S. lycopersicum reference genome SL3.0; semi de novo transcriptome assembly; and de novo transcriptome assembly. In a global context, transcriptional changes seem to be similar between both species, although there are some specific genes only upregulated in S. arcanum during Cmm interaction, suggesting that the resistance regulatory mechanism probably diverged during the domestication process. Although S. lycopersicum showed enriched functional groups related to defense, S. arcanum displayed a higher number of induced genes related to bacterial, oomycete, and fungal defense at the first few hours of interaction. This study revealed genes that may contribute to the resistance phenotype in the wild tomato species, such as those that encode for a polyphenol oxidase E, diacyl glycerol kinase, TOM1-like protein 6, and an ankyrin repeat-containing protein, among others. This work will contribute to a better understanding of the defense mechanism against Cmm, and the development of new control methods.

Analysis of SI-Related BoGAPDH Family Genes and Response of BoGAPC to SI Signal in Brassica oleracea L

Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is not only involved in carbohydrate metabolism, but also plays an important role in stress resistance. However, it has not been reported in Brassica oleracea. In this study, we performed a genome-wide identification of BoGAPDH in B. oleracea and performed cloning and expression analysis of one of the differentially expressed genes, BoGAPC. A total of 16 members of the BoGAPDH family were identified in B. oleracea, which were conserved, distributed unevenly on chromosomes and had tandem repeat genes. Most of the genes were down-regulated during self-pollination, and the highest expression was found in stigmas and sepals. Different transcriptome data showed that BoGAPDH genes were differentially expressed under stress, which was consistent with the results of qRT-PCR. We cloned and analyzed the differentially expressed gene BoGAPC and found that it was in the down-regulated mode 1 h after self-pollination, and the expression was the highest in the stigma, which was consistent with the result of GUS staining. The promoter region of the gene not only has stress response elements and plant hormone response elements, but also has a variety of specific elements for regulating floral organ development. Subcellular localization indicates that the BoGAPC protein is located in the cytoplasm and belongs to the active protein in the cytoplasm. The results of prokaryotic expression showed that the size of the BoGAPC protein was about 37 kDa, which was consistent with the expected results, indicating that the protein was induced in prokaryotic cells. The results of yeast two-hybrid and GST pull-down showed that the SRK kinase domain interacted with the BoGAPC protein. The above results suggest that the BoGAPDH family of B. oleracea plays an important role in the process of plant stress resistance, and the BoGAPC gene may be involved in the process of self-incompatibility in B. oleracea, which may respond to SI by encoding proteins directly interacting with SRK.

Proteomic analysis of early-stage incompatible and compatible interactions between grapevine and P. viticola

Wild grapevines can show strong resistance to the downy mildew pathogen P. viticola, but the associated mechanisms are poorly described, especially at early stages of infection. Here, we performed comparative proteomic analyses of grapevine leaves from the resistant genotype V. davidii "LiuBa-8" (LB) and susceptible V. vinifera "Pinot Noir" (PN) 12 h after inoculation with P. viticola. By employing the iTRAQ technique, a total of 444 and 349 differentially expressed proteins (DEPs) were identified in LB and PN, respectively. The majority of these DEPs were related to photosynthesis, respiration, cell wall modification, protein metabolism, stress, and redox homeostasis. Compared with PN, LB showed fewer downregulated proteins associated with photosynthesis and more upregulated proteins associated with metabolism. At least a subset of PR proteins (PR10.2 and PR10.3) was upregulated upon inoculation in both genotypes, whereas HSP (HSP70.2 and HSP90.6) and cell wall-related XTH and BXL1 proteins were specifically upregulated in LB and PN, respectively. In the incompatible interaction, ROS signaling was evident by the accumulation of H₂O₂, and multiple APX and GST proteins were upregulated. These DEPs may play crucial roles in the grapevine response to downy mildew. Our results provide new insights into molecular events associated with downy mildew resistance in grapevine, which may be exploited to develop novel protection strategies against this disease.

Potential Biotechnological Applications of Autophagy for Agriculture

Autophagy is a genetically regulated, eukaryotic cellular degradation system that sequestrates cytoplasmic materials in specialised vesicles, termed autophagosomes, for delivery and breakdown in the lysosome or vacuole. In plants, autophagy plays essential roles in development (e.g., senescence) and responses to abiotic (e.g., nutrient starvation, drought and oxidative stress) and biotic stresses (e.g., hypersensitive response). Initially, autophagy was considered a non-selective bulk degradation mechanism that provides energy and building blocks for homeostatic balance during stress. Recent studies, however, reveal that autophagy may be more subtle and selectively target ubiquitylated protein aggregates, protein complexes and even organelles for degradation to regulate vital cellular processes even during favourable conditions. The selective nature of autophagy lends itself to potential manipulation and exploitation as part of designer protein turnover machinery for the development of stress-tolerant and disease-resistant crops, crops with increased yield potential and agricultural efficiency and reduced post-harvest losses. Here, we discuss our current understanding of autophagy and speculate its potential manipulation for improved agricultural performance.

The Meloidogyne incognita Nuclear Effector MiEFF1 Interacts With Arabidopsis Cytosolic Glyceraldehyde-3-Phosphate Dehydrogenases to Promote Parasitism

Root-knot nematodes are obligate endoparasites that maintain a biotrophic relationship with their hosts over a period of several weeks. They induce the differentiation of root cells into specialized multinucleate hypertrophied feeding cells known as giant cells. Nematode effectors synthesized in the esophageal glands and injected into the plant tissue through the syringe-like stylet play a key role in giant cell ontogenesis. The Meloidogyne incognita MiEFF1 is one of the rare effectors of phytopathogenic nematodes to have been located in vivo in feeding cells. This effector specifically targets the giant cell nuclei. We investigated the Arabidopsis functions modulated by this effector, by using a yeast two-hybrid approach to identify its host targets. We characterized a universal stress protein (USP) and cytosolic glyceraldehyde-3-phosphate dehydrogenases (GAPCs) as the targets of MiEFF1. We validated the interaction of MiEFF1 with these host targets in the plant cell nucleus, by bimolecular fluorescence complementation (BiFC). A functional analysis with Arabidopsis GUS reporter lines and knockout mutant lines showed that GAPCs were induced in giant cells and that their non-metabolic functions were required for root-knot nematode infection. These susceptibility factors are potentially interesting targets for the development of new root-knot nematode control strategies.

CAMTA3 negatively regulates disease resistance through modulating immune response and extensive transcriptional reprogramming in cassava

As one of the important crops in the world, cassava production is seriously threatened by Xanthomonas axonopodis pv. manihotis (Xam) all year round. Calmodulin-binding transcription activators (CAMTAs) play key roles in biotic stress and abiotic stress in plants, however, their roles in cassava remain elusive. In this study, six MeCAMTAs were identified, and MeCAMTA3 with the highest induction upon Xam infection was confirmed as a transcription factor that binds to the vCGCGb motif. MeCAMTA3 negatively regulates plant disease resistance against Xam. On the one hand, MeCAMTA3 negatively regulated endogenous salicylic acid and reactive oxygen species accumulation, pathogenesis-related genes MePRs' transcripts and callose deposition during cassava-Xam interaction but not under control conditions. On the other hand, RNA sequencing showed extensive transcriptional reprogramming by MeCAMTA3, especially 18 genes with a vCGCGb motif in the promoter region in hormone signaling, antioxidant signaling and other disease resistance signaling. Notably, chromatin immunoprecipitation-polymerase chain reaction showed that eight of these genes might be directly regulated by MeCAMTA3 through transcriptional repression. In summary, MeCAMTA3 negatively regulates plant disease resistance against cassava bacterial blight through modulation of multiple immune responses during cassava-Xam interaction and extensive transcriptional reprogramming.

Transient Gene Expression is an Effective Experimental Tool for the Research into the Fine Mechanisms of Plant Gene Function: Advantages, Limitations, and Solutions

A large data array on plant gene expression accumulated thanks to comparative omic studies directs the efforts of researchers to the specific or fine effects of the target gene functions and, as a consequence, elaboration of relatively simple and concurrently effective approaches allowing for the insight into the physiological role of gene products. Numerous studies have convincingly demonstrated the efficacy of transient expression strategy for characterization of the plant gene functions. The review goals are (i) to consider the advantages and limitations of different plant systems and methods of transient expression used to find out the role of gene products; (ii) to summarize the current data on the use of the transient expression approaches for the insight into fine mechanisms underlying the gene function; and (iii) to outline the accomplishments in efficient transient expression of plant genes. In general, the review discusses the main and critical steps in each of the methods of transient gene expression in plants; areas of their application; main results obtained using plant objects; their contribution to our knowledge about the fine mechanisms of the plant gene functions underlying plant growth and development; and clarification of the mechanisms regulating complex metabolic pathways.

The specific W-boxes of GAPC5 promoter bound by TaWRKY are involved in drought stress response in wheat

Drought is one of the most common abiotic stresses, and can limit wheat yield, crops and productivity. GAPCs play vital roles under drought stress conditions in multiple species. The aim of this experiment was to determine the regulatory mechanism of TaGAPC5 under drought stress. In this study, the genes and promoters of TaGAPC5 in diverse drought-tolerant cultivars were cloned. The amino acid sequences were conserved, while the promoter fragments were not identical. Under abiotic stress, the expression level of TaGAPC5 was substantially different among the diverse drought-tolerant cultivars and the promoter activities were significantly improved. The yeast one-hybrid system and Electrophoretic mobility shift assay (EMSA) demonstrated that TaWRKYs bound to specific W-boxes: TaWRKY28, TaWRKY33, TaWRKY40 and TaWRKY47 bind to G/ATGACG/C/A, C/G/ATGACG, C/ATGACC and C/ATGACC/G, respectively. By analyzing different 5' deletion mutants of these promoters, it was determined that these W-boxes in CW-TaGAPC5 promoter (-1262, -1202, -904, -880 and -207) and ZY-TaGAPC5 promoter (-697 and -220) bound by these four TaWRKYs and were functional under drought stress. The deletion or addition of specific W-boxes in the promoter fragments significantly restrained or advanced the promoter activity under drought stress, and these results further confirmed that these W-boxes play vital roles in improving transcription levels under drought stress. The W-boxes in CW-TaGAPC5P (-1262, -1202, -904, -880 and -207) and ZY-TaGAPC5P (-697 and -220) were identified as the key cis-elements for responding to drought stress and were bound by the transcription factor TaWRKY.

Identification of Differentially Expressed Proteins in Sugarcane in Response to Infection by Xanthomonas albilineans Using iTRAQ Quantitative Proteomics

Sugarcane can suffer severe yield losses when affected by leaf scald, a disease caused by Xanthomonas albilineans. This bacterial pathogen colonizes the vascular system of sugarcane, which can result in reduced plant growth and plant death. In order to better understand the molecular mechanisms involved in the resistance of sugarcane to leaf scald, a comparative proteomic study was performed with two sugarcane cultivars inoculated with X. albilineans: one resistant (LCP 85-384) and one susceptible (ROC20) to leaf scald. The iTRAQ (isobaric tags for relative and absolute quantification) approach at 0 and 48 h post-inoculation (hpi) was used to identify and annotate differentially expressed proteins (DEPs). A total of 4295 proteins were associated with 1099 gene ontology (GO) terms by GO analysis. Among those, 285 were DEPs during X. albilineans infection in cultivars LCP 85-384 and ROC20. One hundred seventy-two DEPs were identified in resistant cultivar LCP 85-384, and 113 of these proteins were upregulated and 59 were downregulated. One hundred ninety-two DEPs were found in susceptible cultivar ROC20 and half of these (92) were upregulated, whereas the other half corresponded to downregulated proteins. The significantly upregulated DEPs in LCP 85-384 were involved in metabolic pathways, the biosynthesis of secondary metabolites, and the phenylpropanoid biosynthesis pathway. Additionally, the expression of seven candidate genes related to photosynthesis and glycolytic pathways, plant innate immune system, glycosylation process, plant cytochrome P450, and non-specific lipid transfer protein was verified based on transcription levels in sugarcane during infection by X. albilineans. Our findings shed new light on the differential expression of proteins in sugarcane cultivars in response to infection by X. albilineans. The identification of these genes provides important information for sugarcane variety improvement programs using molecular breeding strategies.

TaWRKY40 transcription factor positively regulate the expression of TaGAPC1 to enhance drought tolerance

BACKGROUNDS

Drought stress is one of the major factors that affects wheat yield. Glyceraldehyde-3-Phosphate dehydrogenase (GAPDH) is a multifunctional enzyme that plays the important role in abiotic stress and plant development. However, in wheat, limited information about drought-responsive GAPC genes has been reported, and the mechanism underlying the regulation of the GAPC protein is unknown.

RESULTS

In this study, we evaluated the potential role of GAPC1 in drought stress in wheat and Arabidopsis. We found that the overexpression of TaGAPC1 could enhance the tolerance to drought stress in transgenic Arabidopsis. Yeast one-hybrid library screening and EMSA showed that TaWRKY40 acts as a direct regulator of the TaGAPC1 gene. A dual luciferase reporter assay indicated that TaWRKY40 improved the TaGAPC1 promoter activity. The results of qRT-PCR in wheat protoplast cells with instantaneous overexpression of TaWRKY40 indicated that the expression level of TaGAPC1 induced by abiotic stress was upregulated by TaWRKY40. Moreover, TaGAPC1 promoted H2O2 detoxification in response to drought.

CONCLUSION

These results demonstrate that the inducible transcription factor TaWRKY40 could activate the transcription of the TaGAPC1 gene, thereby increasing the tolerance of plants to drought stress.

Genome-wide identification of growth-regulating factors in moso bamboo (Phyllostachys edulis): in silico and experimental analyses

Growth-regulating factor (GRF), a small plant-specific transcription factor (TF) family, is extensively involved in the regulation of growth and developmental processes. However, the GRF family has not been comprehensively studied in moso bamboo (Phyllostachys edulis), a typical non-timber forest member. Here, 18 GRF genes were identified and characterized from the moso bamboo genome, and they clustered into three subfamilies (A, B and C). PeGRF genes were analyzed to determine their gene structures, conserved motifs and promoter. The non-synonymous/synonymous substitution ratios of paralogous and orthologous were less than 1, indicating that the GRF family mainly experienced purifying selection during evolution. According to the analysis of tissue-specific expression patterns, the participation of moso bamboo GRFs might be required during the formation and development of these five tissues. Moreover, PeGRF proteins might be involved in the regulation of plant development in biological processes. The qRT-PCR analysis demonstrated that PeGRF genes played essential roles in combating hormonal stresses and they might be involved in hormone regulation. PeGRF11, a nuclear localized protein as assessed by a subcellular localization assay, could interact with PeGIF3 in yeast and in planta according to yeast two-hybridization and bimolecular fluorescence complementation assays (BiFC) assays. But PeGRF11, as a TF, had no transcriptional activity in yeast. These results provide useful information for future functional research on the GRF genes in moso bamboo.

The specific MYB binding sites bound by TaMYB in the GAPCp2/3 promoters are involved in the drought stress response in wheat

BACKGROUND

Drought stress is one of the major abiotic stresses that affects plant growth and productivity. The GAPCp genes play important roles in drought stress tolerance in multiple species. The aim of this experiment was to identify the core cis-regulatory elements that may respond to drought stress in the GAPCp2 and GAPCp3 promoter sequences.

RESULTS

In this study, the promoters of GAPCp2 and GAPCp3 were cloned. The promoter activities were significantly improved under abiotic stress via regulation of Rluc reporter gene expression, while promoter sequence analysis indicated that these fragments were not almost identical. In transgenic Arabidopsis with the expression of the GUS reporter gene under the control of one of these promoters, the activities of GUS were strong in almost all tissues except the seeds, and the activities were induced after abiotic stress. The yeast one-hybrid system and EMSA demonstrated that TaMYB bound TaGAPCp2P/3P. By analyzing different 5' deletion mutants of these promoters, it was determined that TaGAPCp2P (- 1312~ - 528) and TaGAPCp3P (- 2049~ - 610), including the MYB binding site, contained enhancer elements that increased gene expression levels under drought stress. We used an effector and a reporter to co-transform tobacco and found that TaMYB interacted with the specific MYB binding sites of TaGAPCp2P (- 1197~ - 635) and TaGAPCp3P (- 1456~ - 1144 and - 718~ - 610) in plant cells. Then, the Y1H system and EMSA assay demonstrated that these MYB binding sites in TaGAPCp2P (- 1135 and - 985) and TaGAPCp3P (- 1414 and - 665) were the target cis-elements of TaMYB. The deletion of the specific MYB binding sites in the promoter fragments significantly restrained the drought response, and these results confirmed that these MYB binding sites (AACTAAA/C) play vital roles in improving the transcription levels under drought stress. The results of qRT-PCR in wheat protoplasts transiently overexpressing TaMYB indicated that the expression of TaGAPCp2/3 induced by abiotic stress was upregulated by TaMYB.

CONCLUSION

The MYB binding sites (AACTAAA/C) in TaGAPCp2P/3P were identified as the key cis-elements for responding to drought stress and were bound by the transcription factor TaMYB.

Chia Seed (Salvia hispanica L.) as a Source of Proteins and Bioactive Peptides with Health Benefits: A Review

The consumption of chia seed (Salvia hispanica L.) has increased in recent years due its high content of omega-3 fatty acids and dietary fiber. This seed also has a high concentration of proteins and essential amino acids, becoming a promising source of bioactive peptides. The objective of this review was to identify the composition and the beneficial effects of chia seeds (S. hispanica L.), their proteins, peptides, and their potential impact on human health. The UniProt database was used to identify the chia proteins and their amino acid sequences. The BIOPEP database was used to analyze the peptides's bioactive potential. A total of 20 proteins were cataloged in chia seed, 12 of those were involved in the regular metabolic processes of the plant cells. However, eight proteins were specifically related to production and storage of plant lipids, thus explaining the high concentration of lipids in chia seeds (around 30%), especially omega-3 fatty acids (around 20%). The analyses of amino acid sequences showed peptides with bioactive potential, including dipeptidyl peptidase-IV inhibitors, angiotensin-converting enzyme inhibitors, and antioxidant capacity. These results correlated with the main health benefits of whole chia seed in humans such as antioxidant capacity, and hypotensive, hypoglycemic, and anticholesterolemic effects. Such relation can be associated with chia protein and peptide compositions and therefore needs further investigation in vitro and in vivo.

Autophagy in crop plants: what's new beyond Arabidopsis?

Autophagy is a major degradation and recycling pathway in plants. It functions to maintain cellular homeostasis and is induced by environmental cues and developmental stimuli. Over the past decade, the study of autophagy has expanded from model plants to crop species. Many features of the core machinery and physiological functions of autophagy are conserved among diverse organisms. However, several novel functions and regulators of autophagy have been characterized in individual plant species. In light of its critical role in development and stress responses, a better understanding of autophagy in crop plants may eventually lead to beneficial agricultural applications. Here, we review recent progress on understanding autophagy in crops and discuss potential future research directions.