Applying a non-GMO breeding approach with an identified natural variation to reduce food allergen Len c3 in Lens culinaris seeds.

Lentils (Lens culinaris) are produced in diverse agroecological regions and are consumed as one of the most important food legumes worldwide. Lentils possess a nutritional profile from a human health perspective that is not only nutrient dense but also offers a better balance between protein and carbohydrates. However, lentil causes food allergy, which has been a significant concern due to increased consumption in parts of the world. Len c3, a non-specific lipid transfer protein (LTP), was identified as one of the allergens in lentil seeds. In this study, we identified an LTP gene Lcu.2RBY.4g013600 that encodes the lentil allergen Len c3. We then focused on gene screening from a collection of natural accessions to search for natural mutations of the Len c3 allergen-encoding gene. A natural lentil line M11 was identified with mutations at LcLTP3b and low accumulation of vicilin through genomic-assisted approaches. Furthermore, we generated a pool of lentil germplasms with LcLTP3b mutation background through crossing the identified lentil plant M11 with two lentil cultivars, CDC Redmoon and CDC Gold. These generated lentil hybrids can be used as a breeding resource targeting at reducing allergen risk in lentil consumption.

A chloroplast diacylglycerol lipase modulates glycerolipid pathway balance in Arabidopsis.

Two parallel pathways compartmentalized in the chloroplast and the endoplasmic reticulum contribute to thylakoid lipid synthesis in plants, but how these two pathways are coordinated during thylakoid biogenesis and remodeling remains unknown. We report here the molecular characterization of a homologous ADIPOSE TRIGLYCERIDE LIPASE-LIKE gene, previously referred to as ATGLL. The ATGLL gene is ubiquitously expressed throughout development and rapidly upregulated in response to a wide range of environmental cues. We show that ATGLL is a chloroplast non-regioselective lipase with a hydrolytic activity preferentially towards 16:0 of diacylglycerol (DAG). Comprehensive lipid profiling and radiotracer labeling studies revealed a negative correlation of ATGLL expression and the relative contribution of the chloroplast lipid pathway to thylakoid lipid biosynthesis. Additionally, we show that genetic manipulation of ATGLL expression resulted in changes in triacylglycerol levels in leaves. We propose that ATGLL, through affecting the level of prokaryotic DAG in the chloroplast, plays important roles in balancing the two glycerolipid pathways and in maintaining lipid homeostasis in plants.

Comprehensive compositional assessment of bioactive compounds in diverse pea accessions.

Pea (Pisum sativum L.) is an important legume crop providing a good source of protein, vitamins, minerals and bioactive compounds with health benefits for humans. In this study, an improved method for simultaneous analysis of multiple phytoestrogens among 100 pea accessions was developed. Ipriflavone, (a synthetic isoflavone), was used as an internal standard for the semiquantitative analysis of 17 phytoestrogens including isoflavone aglycones and conjugates, allowing direct analysis of isoflavones in their naturally occurring forms. This comprehensive dataset demonstrated that the isoflavones varied greatly and some accessions tended to have high levels of multiple phytoestrogens among the 100 accessions analyzed. Isoliquiritigenin followed by glycitein were the predominant compounds detected in the accessions and showed the highest correlation with the total phytoestrogens content. Secoisolariciresinol content was consistently higher in yellow cotyledon peas than in green cotyledon peas, whereas the contents of coumestrol, genestein and secoisolariciresinol were significantly correlated with seed coat color. The total phenolics and saponins showed a wide range of variability among the accessions with higher concentrations of total phenolics observed in seeds with pigmented seed coat or yellow cotyledon seeds, suggesting the synthesis of saponins and phenolics are significantly affected by metabolic pathway genes controlling cotyledon color or seed coat color. This study profiled the variability of bioactive compounds of pea seed quality traits in diverse pea accessions and provides an immense resource for continued research, breeding and selection of genotypes for a wide range of applications.

Spatiotemporal transcriptomics and metabolic profiling provide insights into gene regulatory networks during lentil seed development.

Lentil (Lens culinaris Medik.) is a nutritious legume with seeds rich in protein, minerals and an array of diverse specialized metabolites. The formation of a seed requires regulation and tight coordination of developmental programs to form the embryo, endosperm and seed coat compartments, which determines the structure and composition of mature seed and thus its end-use quality. Understanding the molecular and cellular events and metabolic processes of seed development is essential for improving lentil yield and seed nutritional value. However, such information remains largely unknown, especially at the seed compartment level. In this study, we generated high-resolution spatiotemporal gene expression profiles in lentil embryo, seed coat and whole seeds from fertilization through maturation. Apart from anatomic differences between the embryo and seed coat, comparative transcriptomics and weighted gene co-expression network analysis revealed embryo- and seed coat-specific genes and gene modules predominant in specific tissues and stages, which highlights distinct genetic programming. Furthermore, we investigated the dynamic profiles of flavonoid, isoflavone, phytic acid and saponin in seed compartments across seed development. Coupled with transcriptome data, we identified sets of candidate genes involved in the biosynthesis of these metabolites. The global view of the transcriptional and metabolic changes of lentil seed tissues throughout development provides a valuable resource for dissecting the genetic control of secondary metabolism and development of molecular tools for improving seed nutritional quality.

Kinase CIPK9 integrates glucose and abscisic acid signaling to regulate seed oil metabolism in rapeseed.

Rapeseed (Brassica napus), an important oil crop worldwide, provides large amounts of lipids for human requirements. Calcineurin B-like (CBL)-interacting protein kinase 9 (CIPK9) was reported to regulate seed oil content in the plant. Here, we generated gene-silenced lines through RNA interference biotechnology and loss-of-function mutant bnacipk9 using CRISPR/Cas9 to further study BnaCIPK9 functions in the seed oil metabolism of rapeseeds. We discovered that compared with wild-type (WT) lines, gene-silenced and bnacipk9 lines had substantially different oil contents and fatty acid compositions: seed oil content was improved by 3%-5% and 1%-6% in bnacipk9 lines and gene-silenced lines, respectively; both lines were with increased levels of monounsaturated fatty acids and decreased levels of polyunsaturated fatty acids. Additionally, hormone and glucose content analyses revealed that compared with WT lines the bnacipk9 lines showed significant differences: in bnacipk9 seeds, indoleacetic acid and abscisic acid (ABA) levels were higher; glucose and sucrose contents were higher with a higher hexose-to-sucrose ratio in bnacipk9 mid-to-late maturation development seeds. Furthermore, the bnacipk9 was less sensitive to glucose and ABA than the WT according to stomatal aperture regulation assays and the expression levels of genes involved in glucose and ABA regulating pathways in rapeseeds. Notably, in Arabidopsis (Arabidopsis thaliana), exogenous ABA and glucose imposed on developing seeds revealed the effects of ABA and glucose signaling on seed oil accumulation. Altogether, our results strongly suggest a role of CIPK9 in mediating the interaction between glucose flux and ABA hormone signaling to regulate seed oil metabolism in rapeseed.

Asymmetric gene expression in grain development of reciprocal crosses between tetraploid and hexaploid wheats.

Production of viable progeny from interploid crosses requires precise regulation of gene expression from maternal and paternal chromosomes, yet the transcripts contributed to hybrid seeds from polyploid parent species have rarely been explored. To investigate the genome-wide maternal and paternal contributions to polyploid grain development, we analyzed the transcriptomes of developing embryos, from zygote to maturity, alongside endosperm in two stages of development, using reciprocal crosses between tetraploid and hexaploid wheats. Reciprocal crosses between species with varied levels of ploidy displayed broad impacts on gene expression, including shifts in alternative splicing events in select crosses, as illustrated by active splicing events, enhanced protein synthesis and chromatin remodeling. Homoeologous gene expression was repressed on the univalent D genome in pentaploids, but this suppression was attenuated in crosses with a higher ploidy maternal parent. Imprinted genes were identified in endosperm and early embryo tissues, supporting predominant maternal effects on early embryogenesis. By systematically investigating the complex transcriptional networks in reciprocal-cross hybrids, this study presents a framework for understanding the genomic incompatibility and transcriptome shock that results from interspecific hybridization and uncovers the transcriptional impacts on hybrid seeds created from agriculturally-relevant polyploid species.

Computational genomics insights into cold acclimation in wheat.

Development of cold acclimation in crops involves transcriptomic reprograming, metabolic shift, and physiological changes. Cold responses in transcriptome and lipid metabolism has been examined in separate studies for various crops. In this study, integrated computational approaches was employed to investigate the transcriptomics and lipidomics data associated with cold acclimation and vernalization in four wheat genotypes of distinct cold tolerance. Differential expression was investigated between cold treated and control samples and between the winter-habit and spring-habit wheat genotypes. Collectively, 12,676 differentially expressed genes (DEGs) were identified. Principal component analysis of these DEGs indicated that the first, second, and third principal components (PC1, PC2, and PC3) explained the variance in cold treatment, vernalization and cold hardiness, respectively. Differential expression feature extraction (DEFE) analysis revealed that the winter-habit wheat genotype Norstar had high number of unique DEGs (1884 up and 672 down) and 63 winter-habit genes, which were clearly distinctive from the 64 spring-habit genes based on PC1, PC2 and PC3. Correlation analysis revealed 64 cold hardy genes and 39 anti-hardy genes. Cold acclimation encompasses a wide spectrum of biological processes and the involved genes work cohesively as revealed through network propagation and collective association strength of local subnetworks. Integration of transcriptomics and lipidomics data revealed that the winter-habit genes, such as COR413-TM1, CIPKs and MYB20, together with the phosphatidylglycerol lipids, PG(34:3) and PG(36:6), played a pivotal role in cold acclimation and coordinated cohesively associated subnetworks to confer cold tolerance.

Endosperm-Embryo Communications: Recent Advances and Perspectives.

Seed maturation depends on well-coordinated communications between the processes of endosperm and embryo development. The endosperm is considered to be destined to support embryo development and the timing of endosperm cellularization is critical for embryo growth. Recent findings suggest that the endosperm development and the onset of embryo maturation are two independent processes during seed development. Meanwhile, it is lately reported that several mobile regulators originating from the endosperm are needed to ensure proper embryo growth and seed maturation. In this opinion article, we highlight processes on how endosperm communicates with embryo during seed development and discuss some intriguing questions in light of the latest advancements.

LEAFY COTYLEDON1 expression in the endosperm enables embryo maturation in Arabidopsis.

The endosperm provides nutrients and growth regulators to the embryo during seed development. LEAFY COTYLEDON1 (LEC1) has long been known to be essential for embryo maturation. LEC1 is expressed in both the embryo and the endosperm; however, the functional relevance of the endosperm-expressed LEC1 for seed development is unclear. Here, we provide genetic and transgenic evidence demonstrating that endosperm-expressed LEC1 is necessary and sufficient for embryo maturation. We show that endosperm-synthesized LEC1 is capable of orchestrating full seed maturation in the absence of embryo-expressed LEC1. Inversely, without LEC1 expression in the endosperm, embryo development arrests even in the presence of functional LEC1 alleles in the embryo. We further reveal that LEC1 expression in the endosperm begins at the zygote stage and the LEC1 protein is then trafficked to the embryo to activate processes of seed maturation. Our findings thus establish a key role for endosperm in regulating embryo development.

Integrative Modeling of Gene Expression and Metabolic Networks of Arabidopsis Embryos for Identification of Seed Oil Causal Genes.

Fatty acids in crop seeds are a major source for both vegetable oils and industrial applications. Genetic improvement of fatty acid composition and oil content is critical to meet the current and future demands of plant-based renewable seed oils. Addressing this challenge can be approached by network modeling to capture key contributors of seed metabolism and to identify underpinning genetic targets for engineering the traits associated with seed oil composition and content. Here, we present a dynamic model, using an Ordinary Differential Equations model and integrated time-course gene expression data, to describe metabolic networks during Arabidopsis thaliana seed development. Through in silico perturbation of genes, targets were predicted in seed oil traits. Validation and supporting evidence were obtained for several of these predictions using published reports in the scientific literature. Furthermore, we investigated two predicted targets using omics datasets for both gene expression and metabolites from the seed embryo, and demonstrated the applicability of this network-based model. This work highlights that integration of dynamic gene expression atlases generates informative models which can be explored to dissect metabolic pathways and lead to the identification of causal genes associated with seed oil traits.

Alternative splicing dynamics and evolutionary divergence during embryogenesis in wheat species.

Among polyploid species with complex genomic architecture, variations in the regulation of alternative splicing (AS) provide opportunities for transcriptional and proteomic plasticity and the potential for generating trait diversities. However, the evolution of AS and its influence on grain development in diploid grass and valuable polyploid wheat crops are poorly understood. To address this knowledge gap, we developed a pipeline for the analysis of alternatively spliced transcript isoforms, which takes the high sequence similarity among polyploid wheat subgenomes into account. Through analysis of synteny and detection of collinearity of homoeologous subgenomes, conserved and specific AS events across five wheat and grass species were identified. A global analysis of the regulation of AS in diploid grass and polyploid wheat grains revealed diversity in AS events not only between the endosperm, pericarp and embryo overdevelopment, but also between subgenomes. Analysis of AS in homoeologous triads of polyploid wheats revealed evolutionary divergence between gene-level and transcript-level regulation of embryogenesis. Evolutionary age analysis indicated that the generation of novel transcript isoforms has occurred in young genes at a more rapid rate than in ancient genes. These findings, together with the development of comprehensive AS resources for wheat and grass species, advance understanding of the evolution of regulatory features of AS during embryogenesis and grain development in wheat.

Elucidating the biochemical basis of trans-16:1 fatty acid change in leaves during cold acclimation in wheat.

In plant cells, phosphatidylglycerol (PG) in the chloroplast has a characteristic trans-∆3-hexadecenoic acid (t16:1) at the sn-2 position. The t16:1 content in wheat leaf tissues decreases during cold treatment, but the significance of this fatty acid compositional change and the underlying biochemical mechanism remains poorly understood. Using a large collection of wheat cultivars displaying a varying capacity of freezing tolerance, we show for the first time under field conditions that this low temperature induced t16:1 change is associated with winter hardiness. To explore the metabolic mechanism responsible for the reduction of t16:1, we performed detailed lipid analysis and comparative transcriptome study with four selected wheat lines under cold acclimation. Our results show that wheat leaf tissues experience a gradual decrease in chloroplast lipid pathway activity during cold acclimation and that the decline in chloroplast lipid synthesis manifests itself in the decrease of t16:1 in PG. Comparative RNA-seq analyses with leaf tissues further reveal concerted transcriptome shifts indicating a rebalancing of chloroplast and cytosolic lipid synthesis during cold acclimation. Our study, thus, provides mechanistic understanding on chloroplast lipid adjustments as a "molecular ideotype" and the t16:1 change as a specific metabolite marker for screening freezing tolerance in wheat.

On the Role of DGAT1 in Seed Glycerolipid Metabolic Network and Critical Stages of Plant Development in Arabidopsis.

Studies on the model plant Arabidopsis thaliana have uncovered the identities of most enzymatic components involved in seed storage lipid biosynthesis. However, much remains to be learned on how pathway interactions operate in the seed metabolic network. In this study, we dissected seed glycerolipid molecular compositional changes in the Arabidopsis mutant deficient in diacylglycerol acyltransferase 1 (DGAT1). Our results indicate that metabolic adjustments occurred in both phosphatidylcholine synthesis and deacylation in developing seeds. Ultrastructural changes of perturbed oil and protein bodies were also evident in cotyledon parenchyma cells. To unmask the physiological and developmental role associated with DGAT1-mediated neutral lipid biosynthesis, we attempted to combine dgat1 mutation with lpcat2 that harbors a defect in lysophosphatidylcholine acyltransferase 2 (LPCAT2). Disruption in both DGAT1 and LPCAT2 led to an apparent defect in pollen development that manifested as pollen sterility. Collectively, our results highlight a role of DGAT1 in both storage lipid synthesis and plant development.

Molecular identification and functional characterization of a cyanogenic glucosyltransferase from flax (Linum unsitatissimum).

Flax seed has become consumers' choice for not only polyunsaturated alpha-linolenic fatty acid but also nutraceuticals such as lignans and soluble fiber. There is, however, a major drawback of flax as a source of functional food since the seeds contain significant level of cyanogenic glucosides. The final step of cyanogenic glucoside biosynthesis is mediated by UDP-glucose dependent glucosyltransferase. To date, no flax cyanogenic glucosyl transferase genes have been reported with verified biochemical functionality. Here we present a study on the identification and enzymatic characterization of a first flax cyanogenic glucosyltransferase, LuCGT1. We show that LuCGT1 was highly active towards both aliphatic and aromatic substrates. The LuCGT1 gene is expressed in leaf tissues as well as in developing seeds, and its expression level was drastically reduced in flax mutant lines low in cyanogenic glucosides. Identification of LuCGT1 provides a molecular handle for developing gene specific markers for targeted breeding of low cyanogenic glucosides in flax.

Genome-Wide Identification and Characterization of the Wheat Remorin (TaREM) Family during Cold Acclimation.

Remorins (REMs) are plant-specific proteins that play an essential role in plant-microbe interactions. However, their roles in vernalization and abiotic stress responses remain speculative. Most remorins have a variable proline-rich -half and a more conserved -half that is predicted to form coils. A search of the wheat ( L.) database revealed the existence of 20 different genes, which we classified into six groups on the basis of whether they shared a common phylogenetic and structural origin. Analysis of the physical genomic distributions demonstrated that genes are dispersed in the wheat genome and have one to seven introns. Promoter analysis of genes revealed the presence of putative -elements related to diverse functions like development, hormonal regulation, and biotic and abiotic stress responsiveness. Expression levels of genes were measured in plants grown under field and controlled conditions and in response to hormone treatment. Our analyses revealed that 12 members of the REM family are regulated during cold acclimation in wheat in four different tissues (roots, crowns, stems, and leaves), with the highest expression in roots. Differential gene expression was found between wheat cultivars with contrasting degrees of cold tolerance, suggesting the implication of genes in cold response and tolerance. Additionally, eight genes were induced in response to abscisic acid and methyl jasmonate treatment. This genome-wide analysis of genes provides valuable resources for functional analysis aimed at understanding their role in stress adaptation.

Tapetal Expression of BnaC.MAGL8.a Causes Male Sterility in Arabidopsis.

Monoacylglycerol lipase (MAGL) hydrolyzes monoacylglycerol, producing free fatty acid and glycerol. Although this enzyme has been shown to play important roles in mammal, its potential function in plants remains poorly understood. In a survey of the MAGL genes in Brassica napus, we found tapetal expression of BnaC.MAGL8.a, a homolog of AtMAGL8, results in male sterility in Arabidopsis thaliana. Retarded tapetal PCD and defective pollen wall were observed in the transgenic plants. The tapetal cells became vacuolated at stage 9, and then degenerated at stage 11. Most microspores degenerated with the tapetal cells, and only few pollen grains with an irregular-shaped exine layer were produced in the transgenic plants. Transcriptome analysis identified 398 differentially expressed genes. Most of them are involved in pollen development and stress response. ABORTED MICROSPORES and its downstream pollen wall biosynthesis genes were down-regulated, but genes related with reactive oxygen species homeostasis and jasmonates signaling were up-regulated in the transgenic plants. These results suggest that expression of BnaC.MAGL8.a in tapetum invokes stress response and impairs pollen development. The apparent phenotypic similarity between atgpat1 mutant and BnA9::BnaC.MAGL8.a transgenic plants lead us to propose a role for monoacylglycerol (MAG) in pollen development in Arabidopsis. Our study provides insights on not only the biological function of plant MAGL genes but also the role of MAG in pollen development.

Roles of Cytosolic Glutamine Synthetases in Arabidopsis Development and Stress Responses.

Glutamine (Gln) has as a central role in nitrogen (N) and carbon (C) metabolism. It is synthesized during assimilation of ammonium by cytosolic and plastidial glutamine synthetases (GS; EC 6.1.1.3). Arabidopsis thaliana has five cytosolic GS (GS1) encoding genes designated as GLN1;1-GLN1;5 and one plastidial GS (GS2) gene. In this report that concerns cytosolic GS, we show by analyzing single, double and triple mutants that single genes were dispensable for growth under laboratory conditions. However, loss of two or three GS1 isoforms impacted plant form, function and the capacity to tolerate abiotic stresses. The loss of GLN1;1, GLN1;2 and GLN1;3 resulted in a significant reduction of vegetative growth and seed size. In addition, we infer that GLN1;4 is essential for pollen viability but only in the absence of GLN1;1 and GLN1;3. Transcript profiling revealed that expression of GLN1;1, GLN1;2, GLN1;3 and GLN1;4 was repressed by salinity and cold stresses. Among all single gln1 mutants, growth of gln1;1 seedlings showed an enhanced sensitivity to the GS inhibitor phosphinothricin (PPT), as well as to cold and salinity treatments, suggesting a non-redundant role for GLN1;1. Furthermore, the increased sensitivity of gln1;1 mutants to methyl viologen was associated with an accelerated accumulation of reactive oxygen species (ROS) in the thylakoid of chloroplasts. Our data demonstrate, for the first time, an involvement of the cytosolic GS1 in modulating ROS homeostasis in chloroplasts. Collectively, the current study establishes a link between cytosolic Gln production and plant development, ROS production and stress tolerance.

CIPK9 is involved in seed oil regulation in Brassica napus L. and Arabidopsis thaliana (L.) Heynh.

BACKGROUND: Accumulation of storage compounds during seed development plays an important role in the life cycle of oilseed plants; these compounds provide carbon and energy resources to support the establishment of seedlings. RESULTS: In this study, we show that BnCIPK9 has a broad expression pattern in Brassica napus L. tissues and that wounding stress strongly induces its expression. The overexpression of BnCIPK9 during seed development reduced oil synthesis in transgenic B. napus compared to that observed in wild-type (WT) plants. Functional analysis revealed that seed oil content (OC) of complementation lines was similar to that of WT plants, whereas OC in Arabidopsis thaliana (L.) Heynh. Atcipk9 knockout mutants (cipk9) was higher than that of WT plants. Seedling of cipk9 mutants failed to establish roots on a sugar-free medium, but root establishment could be rescued by supplementation of sucrose or glucose. The phenotype of complementation transgenic lines was similar to that of WT plants when grown on sugar-free medium. Mutants, cipk9, cbl2, and cbl3 presented similar phenotypes, suggesting that CIPK9, CBL2, and CBL3 might work together and play similar roles in root establishment under sugar-free condition. CONCLUSION: This study showed that BnCIPK9 and AtCIPK9 encode a protein kinase that is involved in sugar-related response and plays important roles in the regulation of energy reserves. Our results suggest that AtCIPK9 negatively regulates lipid accumulation and has a significant effect on early seedling establishment in A. thaliana. The functional characterization of CIPK9 provides insights into the regulation of OC, and might be used for improving OC in B. napus. We believe that our study makes a significant contribution to the literature because it provides information on how CIPKs coordinate stress regulation and energy signaling.

Transcriptomic Insights into Phenological Development and Cold Tolerance of Wheat Grown in the Field.

Cold acclimation and winter survival in cereal species is determined by complicated environmentally regulated gene expression. However, studies investigating these complex cold responses are mostly conducted in controlled environments that only consider the responses to single environmental variables. In this study, we have comprehensively profiled global transcriptional responses in crowns of field-grown spring and winter wheat (Triticum aestivum) genotypes and their near-isogenic lines with the VRN-A1 alleles swapped. This in-depth analysis revealed multiple signaling, interactive pathways that influence cold tolerance and phenological development to optimize plant growth and development in preparation for a wide range of over-winter stresses. Investigation of genetic differences at the VRN-A1 locus revealed that a vernalization requirement maintained a higher level of cold response pathways while VRN-A1 genetically promoted floral development. Our results also demonstrated the influence of genetic background on the expression of cold and flowering pathways. The link between delayed shoot apex development and the induction of cold tolerance was reflected by the gradual up-regulation of abscisic acid-dependent and C-REPEAT-BINDING FACTOR pathways. This was accompanied by the down-regulation of key genes involved in meristem development as the autumn progressed. The chromosome location of differentially expressed genes between the winter and spring wheat genetic backgrounds showed a striking pattern of biased gene expression on chromosomes 6A and 6D, indicating a transcriptional regulation at the genome level. This finding adds to the complexity of the genetic cascades and gene interactions that determine the evolutionary patterns of both phenological development and cold tolerance traits in wheat.

The D-lactate dehydrogenase MoDLD1 is essential for growth and infection-related development in Magnaporthe oryzae.

Rice blast disease caused by Magnaporthe oryzae is initiated by the attachment of conidia to plant surfaces. Germ tubes emerging from conidia develop melanized appressoria to physically penetrate the host surface. Previous studies revealed that appressorium development requires the breakdown of storage lipids and glycogen that occur in peroxisomes and the cytosol respectively, culminating in production of pyruvate. However, the downstream product(s) entering the mitochondria for further oxidation is unclear. In this study, we aimed to investigate the molecular basis underlying the metabolic flux towards the mitochondria associated with the infectious-related development in M. oryzae. We showed that D-lactate is a key intermediate metabolite of the mobilization of lipids and glycogen, and its oxidative conversion to pyruvate is catalysed by a mitochondrial D-lactate dehydrogenase MoDLD1. Deletion of MoDLD1 caused defects in conidiogenesis and appressorium formation, and subsequently the loss of fungal pathogenicity. Further analyses demonstrated that MoDLD1 activity is involved in the maintenance of redox homeostasis during conidial germination. Thus, MoDLD1 is a critical modulator that channels metabolite flow to the mitochondrion coupling cellular redox state, and contributes to development and virulence of M. oryzae.