Biology subjects

Naqvi, N. I.

Publications and source records attributed to Naqvi, N. I..

16 recordsLinked to original sources

bioRxiv2026

Syntrophic microbiomes associated with methane-suppressive irrigation in rice

Rice, a staple crop of nearly half of the world population, is grown predominantly in flooded paddies which are one of the largest contributors to methane emissions. An effective approach is to minimise the anaerobic flooded conditions that favour the growth of methanogenic archaea. Empirical measurements showed that controlled irrigation regime reduces methane emissions by 70% to 90%. The soil microbiomes of both flood and drip irrigated soil were characterised using whole-genome shotgun metagenomics. Controlled irrigation was shown to suppress methanogens and lower methane emissions. While emissions are correlated with mcrA gene abundance, empty flooded fields exhibited relatively high mcrA levels above baseline despite undetectable methane emissions. Rice cultivar genotype had no significant effect on the soil microbiomes. Co-occurrence network analysis indicates that soil microbial communities stratify according to their oxygen preferences along a gradient. Methanogens were increased in flooded paddies, and methane production attributed to the microorganisms involved in the anaerobic decay of organic matter. Controlled irrigation altered the microbiome by raising the soil redox potential by enhancing aeration and promoting ammonia oxidation and nitrification pathways. IMPORTANCEThe temporal dynamics of microbial communities in drip-irrigated rice fields remain poorly characterized to-date. Empirical measurements demonstrate that controlled drip irrigation effectively suppresses methanogens and lowers methane emissions by up to 90%. Statistical analysis further revealed a moderate correlation between methane emissions and the mcrA gene with R = 0.6 and p-value = 2.9e-05. The correlation plot showed that the outliers corresponded to samples from empty flooded fields, where high mcrA gene abundance was observed despite low methane emissions. Methane produced in the soil is likely released into the atmosphere via transport through the aerenchyma of rice plants. Controlled irrigation is shown to be climate friendly as it reduces methane emissions by improving soil aeration and increasing the soil redox potential.

microbiology↗

bioRxiv2026

StomaQuant: Deep Learning-Based Quantification for Stomatal Trait Assessment

Stomata are microscopic pores that play a vital role in transpiration and gaseous exchange from leaf surfaces in plants. The stomatal density and size directly influence photosynthesis and hydrodynamics capacity. Conventional approaches for counting and determining stomatal density is labour-intensive and lack scalability. Although there are several AI-based stomata finder tools that were published in the last decade, existing models were trained on model plants like wheat, barley and Arabidopsis. Stomata in such model plants are generally elliptical, but applying a universal model to all plant species is not feasible due to their diverse morphological characteristics. Previous studies have suggested using the stomatal index to quantify the ratio between epidermal cells and total stomatal count. However, this approach can be difficult to apply consistently, as epidermal cell shape and size vary across plant species. Instead, we propose measuring stomatal density based on the number of stomata per total imaged pixel area in the captured images. In this study, a comparison between YOLOv12 and RF-DETR models were made for real-time stomata detection in normal and difficult-to-image and out-of-focus occluded images. The in-house training dataset consisted of images of 300 rice,100 barley and 50 sugarcane leaves that were captured against a dark background. YOLOv12 outperformed RF-DETR with higher mAP50:95 score. The models were trained with image augmentation for 300 epochs and YOLOv12 achieved a peak mean average precision of 98.5% and exceled at detecting stomata across abaxial and adaxial surfaces of leaves of both monocot and dicot plants. StomaQuant has also been shown to be effective for both epidermal peel and ethanol decolorised samples. Thus, StomaQuant can be used to effectively and efficiently estimate the stomatal density and size in a wide range of host plant species.

bioinformatics↗

bioRxiv2025

An Integrated Decarbonising Approach to Mitigate Methane Emissions and Enhance Productivity in Rice Cultivation

Flooded rice paddies contribute approximately 12% of global anthropogenic methane emissions, accounting for 1.5% of the total warming effect from all greenhouse gases. With the rising global demand for rice due to population growth, the need for effective methane mitigation strategies in rice cultivation is increasingly critical. This study investigates the combined impact of irrigation methods, fertiliser combinations, and varietal differences on productivity, water use and methane emissions in rice. Field trials were conducted across five land parcels covering 8 Ha in the Sathyamangalam region of Tamil Nadu, India, from October 2024 to January 2025. Results revealed that drip irrigation significantly reduced seasonal methane emissions by up to 68% (128 kg/ha/season) compared to continuous flood irrigation (402.32 kg/ha/season) offering a sustainable solution to address climate change. Furthermore, our modified package of practices coupled with tailored fertiliser combination, led to a 28% reduction in methane emissions (222 kg/ha/season) relative to continuous flooding methods used by the farmers in the region (309 kg/ha/season). Methane emission differences of up to 23.8% were also evident across rice varieties ADT-45 (229.7 kg/ha/season and BPT-5204 (301.7 kg/ha/season) for. Although flood irrigation yielded a 5-6% higher grain productivity than drip irrigation, the TLL fertiliser package under flood irrigation still provided distinct benefits with a yield increase of 5.4%. Notably, water usage under drip irrigation was 42.5% lower on average across the five locations, with minimal impact on yield, resulting in a marked improvement in water use efficiency (0.62 kg.m-3 under drip vs. 0.39 kg.m-3 under flood irrigation). Our findings highlight the value of integrating modern irrigation techniques, optimizing fertiliser management, and appropriate varietal selection with higher environmental sustainability and improved farm productivity to mitigate climate impact in rice cultivation.

plant biology↗

bioRxiv2024

Drip irrigation suppresses methane emissions by reshaping the rhizosphere microbiomes in rice

The rhizosphere microbiomes of rice plants under conventional flood irrigation consist of highly complex consortia of microorganisms and in particular methanogens purportedly associated with methane emissions therein. Controlled irrigation has been proposed as a cultivation method of choice over continuous flooding to reduce water and fertilizer usage in an aerobic environment. However, a systemic understanding of the assembly and function of microbiota in the rhizosphere under drip and flood irrigation remains unclear. Using empirical analyses, we report a significant reduction in methane emissions in controlled irrigation compared to the flooded environment. Genotypic or varietal differences did not influence such methane emissions under conventional flooded cultivation of rice. Using metagenomic sequencing and computational analyses, we provide a deeper understanding of how drip irrigation or continuous flooding affect the root-associated microbiomes in rice. Rhizosphere soil from two different rice varieties, Huanghuazhan and Temasek rice, grown under drip or flood conditions in a greenhouse was collected over 2 months post-transplantation for metagenomic analysis. Our results reveal that drip irrigation favours microbes involved in the nitrifying-denitrifying processes while continuous flooding enriches for methanotrophs and methanogenic archaea. Syntrophic microbiomes associated with methanogenesis were significantly reduced in drip irrigation. Several keystone taxa were evident in the co-occurrence network model related to methanogenic, methanotrophic, nitrifying, sulphur-oxidising and sulphur-reducing activities. Lastly, oxygen availability and redox potential were identified as key drivers that reshape rhizosphere microbiota and the associated metabolic functional differences observed between the two irrigation regimes leading up to the microbial mitigation of climate impact. IMPORTANCEUnlike previous studies in alternate wet-dry irrigation systems, this study characterised the rice microbiomes in a controlled drip irrigation settings where water levels were maintained at low levels and soil remained unflooded throughout the entire season in a greenhouse. A reduction of more than 90% in methane emissions was observed with drip irrigation compared to flood irrigation. Significant correlation was found between levels of methane emitted and mcrA gene copies detected with a Pearson correlation coefficient R of 0.77 and p-value of 2.3e-10. Methanogens are highly abundant in continuous flooded rice soil and are significantly reduced in drip-irrigated soil. Metagenomic profiling indicates that the shifts in microbial diversity under drip irrigation favour nitrifying microorganisms and is likely influenced by increased oxygen availability due to higher soil redox potential.

microbiology↗

bioRxiv2024

Phospholipid signaling and multivesicular endolysosomes modulate membrane dynamics at the biotrophic interface in Rice Blast

Magnaporthe oryzae, the rice blast pathogen, secretes an arsenal of apoplastic and cytoplasmic effector proteins to suppress host immunity during the biotrophy phase. The proposed non-conventional secretion of cytoplasmic effectors into the Biotrophic Interfacial Complex (BIC), remains uncharted except for the involvement of the exocyst complex therein. Recently, the plant endocytic machinery has been implicated in translocation of cytoplasmic effectors to the host. Here, we used live cell imaging and mutant analyses to provide new insight into late endolysosomal mediators as conduits for establishment of the BIC and/or unconventional secretion across the host interface. Rerouting of the late endocytic GTPase Rab7 occurs at the BIC; and the dominant negative Rab7T22N led to significant defects in focal interface formation. FYVE biosensor and pharmacological interventions revealed that Rab7 membrane trafficking and establishment/integrity of the biotrophy interface requires the PI3 kinase Vps34 and phosphoinositide PI3(P) function. Additional pharmacological evidence supports endolysosomal trafficking to the host interface follows a distinct non-conventional secretion route too. Finally, we show that the Multi-Vesicular Bodies and lysosomal membranes act as downstream modules of the Rab7 function in precise sorting and specialised traffic of cytoplasmic effectors across the Magnaporthe-Rice interface during blast disease.

cell biology↗

bioRxiv2023

Mycorrhizal symbiont provides growth benefits in host plants via phosphate and phenylpropanoid metabolism

Using functional interaction assays, Tinctoporellus species isolate AR8 was identified as a plant growth-promoting fungus from Arabidopsis roots. Confocal microscopy revealed interstitial growth and intracellular endophytic colonization within root cortex by AR8 hyphae prior to induction of beneficial effects. AR8 improved plant growth and fitness across a broad range of monocot and dicot host species. AR8 solubilized inorganic phosphate and enabled macronutrient phosphorus assimilation into the host plants, and the resultant growth promotion required an intact phosphate starvation response therein. Metabolomics analysis identified a highly specific subset of primary and secondary metabolites such as sugars, organic acids, sugar alcohols, amino acids, and phenylpropanoids, which were found to be essential for the plant growth-promoting activities of AR8. trans-Cinnamic acid was identified as a novel AR8-induced plant growth promoting metabolite.

plant biology↗

bioRxiv2023

A mitochondrial regulon for developmental ferroptosis in rice blast

Ferroptosis remains an underexamined iron- and lipid peroxides-driven cell death modality despite its importance to several human- and plant-diseases and to immunity thereof. Here, we utilized a range of chemical biological tools, genetic mutants and biochemical analyses to gain insights into how the fungal pathogen Magnaporthe oryzae undergoes Ferroptosis strictly in the spore cells to successfully transit to infectious development. We reveal a functional dependency between such intrinsic Ferroptosis and autophagy-mediated mitochondrial degradation. Mechanistically, the requirement of mitophagy for ferroptotic cell death was attributed to its ability to maintain a pool of metabolically active mitochondria. Pharmacological disruption of the electron transport chain or membrane potential led to complete inhibition of ferroptosis, thus simulating the loss of mitophagy phenotypes. Conversely, increased mitochondrial membrane potential in a mitophagy-defective mutant alleviated the Ferroptosis defects therein. Graded inhibition of mitochondrial Coenzyme Q (CoQ) biosynthesis with or without ferroptosis inhibitor Liproxstation-1 distinguished its antioxidant function in such regulated cell death. Membrane potential-dependent regulation of ATP synthesis and iron homeostasis, as well as dynamics of Aconitase in the Tricarboxylic acid cycle in the presence or absence of mitophagy, mitochondrial poisoning or iron chelation further linked mitochondrial metabolism to Ferroptosis. Lastly, we present an important mitochondrial bioenergetics and redox-regulatory network regulon essential for intrinsic Ferroptosis and its precise role in fungal pathogenesis leading up to the establishment of the devastating rice blast disease.

cell biology↗

bioRxiv2022

Rab7/Retromer-based endolysosomal trafficking facilitates effector secretion and host invasion in rice blast

Secretion is a fundamental process in all living organisms. Using conventional secretion pathways, many plant pathogens release effectors into the host plants to downregulate immunity and promote infection. However, this does not always constitute the only way that effectors are sorted and tracked to their final destination such as the biotrophic interfacial complex-associated effectors produced by the blast fungus Magnaporthe oryzae. Here, we uncover a novel unconventional route originating from fungal vacuolar membrane to the host interface and plasma membrane. We found that a GFP-MoRab7 labeled vacuole is closely associated with the interface structure throughout M. oryzae invasive growth. Conditional inactivation of MoRab7 impaired the establishment of the biotrophy interface and secretion of Pwl2 effector. To perform the vacuolar trafficking pathway, MoRab7 first recruits the retromer complex to the vacuole membrane, enabling it recognizes a batch of SNARE proteins, including the v-SNARE MoSnc1. Live-cell imaging supports both retromer complex component and MoSnc1 protein labeled vesicles showing the trafficking dynamics toward the interface or plasma membrane, and then fusion with target membranes. Lastly, disruption of the MoRab7/Retromer/MoSnc1-based endolysosomal cascade affects effector secretion and fungal pathogenicity. Taken together, we discovered an unconventional protein and membrane trafficking route starting from the fungal endolysosomes to the M. oryzae-rice interaction interface, and dissect the role of MoRab7/Retromer/MoSnc1 constituent sorting machinery in effector secretion during invasive growth in M. oryzae.

plant biology↗

bioRxiv2022

Fission yeast Smi1p participates in the synthesis of the primary septum by regulating β-1,3-glucan synthase Bgs1p function

Cytokinesis is the concluding step of the cell cycle. Coordination between multiple cellular processes is essential for the success of cytokinesis. The fission yeast, Schizosaccharomyces pombe, like other fungal cells is contained within a cell wall. During cell division, the external cell wall is extended inwards to form a special septum wall structure in continuity with the cell wall. The primary septum, the central component of the three-layered division septum, is enriched with linear {beta}-1,3-glucan formed by Bgs1p, a {beta}-1,3-glucan synthase. In this study we uncover a novel essential protein, Smi1p, that functions as a suppressor of the Bgs1p temperature-sensitive mutant, cps1-191. We observe a rescue in the cell wall composition and ultrastructure and also in actomyosin ring dynamics. Further, we identify a colocalization and physical association between Bgs1p and Smi1p. Altogether, our results indicate that Smi1p regulates the function of Bgs1p during cytokinesis.

cell biology↗

bioRxiv2021

Fungal auxin is a quorum-based modulator of blast disease severity

Auxin is an important phytohormone regulating plant growth and development, and can also be produced by microbial pathogens including the rice-blast fungus Magnaporthe oryzae. However, the detailed biosynthesis pathway, biological function(s), and cellular distribution of such fungal auxin in M. oryzae remain largely unknown. Here, we report a sequential accumulation of intrinsic auxin in the three conidial cells, the infection structure (appressorium), and the invasive hyphae in M. oryzae. Such fungus-derived auxin was also secreted out and perceived by the host plants. A mitochondria-associated Indole-3-pyruvate decarboxylase, Ipd1, is essential for auxin/Indole-3-acetic acid biosynthesis in M. oryzae. The ipd1{Delta} was defective in pathogenicity whereas overexpression of IPD1 led to enhanced virulence in rice. Chemical inhibition of fungal IAA biosynthesis, or its increase via external supplementation decreased or increased the severity of blast disease, respectively, in a dose-dependent manner. Furthermore, the IAA produced and secreted by M. oryzae governed the incidence and severity of blast disease in a quorum-dependent manner. Appressorium formation, conidial cell death critical for appressorium function, and the transcription of infection-related genes, MPG1 and INV1, directly correlated with cell density and/or IAA levels within the conidial population at the early stages of pathogenic development. Overall, our study revealed that the severity of blast disease is regulated via quorum sensing with intrinsic IAA serving as an associated signal transducer in rice blast.

microbiology↗

bioRxiv2021

Fungal jasmonate as a novel morphogenetic signal for pathogenesis

A key question that has remained unanswered is how pathogenic fungi switch from vegetative growth to infection-related morphogenesis during a disease cycle. Here, we identify a fungal oxylipin analogous to the well-known phytohormone jasmonic acid, as the principal morphogenesis signal responsible for such a developmental switch to pathogenicity in the rice-blast fungus Magnaporthe oryzae. We explored the molecular function(s) of such intrinsic jasmonic acid during pathogenic differentiation in M. oryzae via OPR1, which encodes a 12-Oxo-phytodienoic Acid Reductase essential for its biosynthesis. Loss of OPR1 led to prolonged vegetative growth, and a delayed initiation and improper development of infection structures in M. oryzae, reminiscent of phenotypes observed in mutants (e.g. pth11{Delta} and cpka{Delta}) that are compromised for cyclic AMP signaling. Genetic- or chemical-complementation completely restored proper germ tube growth and appressorium formation in opr1{Delta}. Liquid chromatography mass spectrometry-based quantification revealed increased OPDA accumulation and a significant decrease in JA levels in the opr1{Delta}. Most interestingly, exogenous jasmonic acid also restored appressorium formation in the pth11{Delta} mutant that lacks G protein/cyclic AMP signaling. Epistasis analysis placed fungal jasmonate upstream of the cyclic AMP signaling in rice blast. Lastly, we show that intrinsic jasmonate orchestrates the cessation of vegetative phase and initiates pathogenic development via a regulatory interaction with the cyclic AMP cascade and redox signaling in rice blast.

cell biology↗

bioRxiv2020

Crosskingdom growth benefits of fungus-derived phytohormones in Choy Sum

Soil-borne beneficial microbes establish symbioses with plant hosts, and play key roles during growth and development therein. In this study, fungal strains FLP7 and B9 were isolated from the rhizosphere microbiome associated with Choy Sum (Brassica rapa var. parachinen-sis) and barley (Hordeum vulgare), respectively. Sequence analyses of the internal transcribed spacer and 18S ribosomal RNA genes combined with colony and conidial morphology identified FLP7 and B9 to be isolates of Penicillium citrinum. Plant-fungus interaction assays revealed that B9, but not FLP7, showed significant growth promotion effect in Choy Sum cultivated in normal soil, whereas FLP7 enhanced Choy Sum growth under phosphate-limiting condition. In comparison to the mock control, B9-inoculated plants showed a 34% increase in growth in aerial parts, and an 85% upsurge in the fresh weight of roots when cultivated in sterilized soil. The dry biomass of inoculated Choy Sum increased by 39% and 74% for the shoots and roots, respectively. Root colonization assays showed that P. citrinum associates directly with the root surface but does not enter/invade the roots of inoculated Choy Sum plants. Preliminary results also indicated that P. citrinum can promote growth in Choy Sum via volatile metabolites too. Interestingly, we detected relatively higher amounts of indole acetic acid and cytokinins in axenic P. citrinum culture filtrate through liquid-chromatography mass-spectrometry analyses. This could plausibly explain the overall growth promotion in Choy Sum. Furthermore, the phenotypic growth defects associated with the Arabidopsis ga1 mutant could be chemically complemented by the exogenous application of P. citrinum culture filtrate, which also showed accumulation of fungus-derived active gibberellins. Our study underscores the importance of trans-kingdom beneficial effects of such mycobiome-derived phytohormone-like metabolites in host plant growth.

microbiology↗

bioRxiv2019

Ferroptosis contributes to developmental cell death in rice blast

We identified that ferroptosis, an iron-dependent non-apoptotic cell death process, occurs in the rice blast fungus Magnaporthe oryzae, and plays a key role in infection-related development therein. Ferroptosis in the blast fungus was confirmed based on the four basic criteria. We confirmed the dependence of ferroptosis on ferric ions, and optimized C11-BODIPY581/591 as a key sensor for subcellular detection and quantification of lipid peroxides that mediate ferroptotic cell death during the pathogenic growth phase of M. oryzae. In addition, we uncovered an important regulatory function for reduced glutathione and the NADPH oxidases in generating/modulating the superoxide moieties for ferroptotic cell death in Magnaporthe. Ferroptosis was found to be necessary for the specific developmental cell death in conidia during appressorium maturation in rice blast. Such ferroptotic cell death initiated first in the terminal cell and progressed sequentially to the entire conidium. Chelation of iron or chemical inhibition of ferroptosis caused conidial cells to remain viable and led to strong defects in host invasion by M. oryzae. Precocious induction of ferroptosis in a blast-susceptible rice cultivar led to resistance against M. oryzae invasion. Interestingly, ferroptosis and autophagy were found to play inter-reliant or codependent roles in contributing to such precise cell death in M. oryzae conidia during pathogenic differentiation. Our study provides significant molecular insights into understanding the role of developmental cell death and iron homeostasis in infection-associated morphogenesis and in fungus-plant interaction in the blast pathosystem.

cell biology↗

bioRxiv2019

Mitochondrial dynamics and mitophagy are necessary for proper invasive growth in Rice Blast

Magnaporthe oryzae causes Blast disease, which is one of the most devastating infections in rice and several important cereal crops. M. oryzae needs to coordinate gene regulation, morphological changes, nutrient acquisition, and host evasion, in order to invade and proliferate within the plant tissues. Thus far, the molecular mechanisms underlying the regulation of invasive growth in planta have remained largely unknown. We identified a precise filamentous-punctate-filamentous cycle in mitochondrial morphology during Magnaporthe-Rice interaction. Interestingly, loss of either the mitochondrial fusion (MoFzo1) or fission (MoDnm1) machinery, or inhibition of mitochondrial fission using Mdivi-1 caused significant reduction in M. oryzae pathogenicity. Furthermore, exogenous carbon source(s) but not antioxidant treatment delayed such mitochondrial dynamics/transition during invasive growth. Such nutrient-based regulation of organellar dynamics preceded MoAtg24-mediated mitophagy, which was found to be essential for proper biotrophic development and invasive growth in planta. We propose that precise mitochondrial dynamics and mitophagy occur during the transition from biotrophy to necrotrophy, and are required for proper induction and establishment of the blast disease in rice.

pathology↗

bioRxiv2018

Cellular dynamics and genomic identity of centromeres in Rice Blast

A series of well-synchronized events mediated by kinetochore-microtubule interactions ensure faithful chromosome segregation in eukaryotes. Centromeres scaffold kinetochore assembly and are among the fastest evolving chromosomal loci in terms of the DNA sequence, length, and organization of intrinsic elements. Neither the centromere structure nor the kinetochore dynamics is well studied in plant pathogenic fungi. Here, we sought to understand the process of chromosome segregation in the rice blast fungus, Magnaporthe oryzae. High-resolution confocal imaging of GFP-tagged inner kinetochore proteins, CenpA and CenpC, revealed an unusual albeit transient declustering of centromeres just before anaphase separation in M. oryzae. Strikingly, the declustered centromeres positioned randomly at the spindle midzone without an apparent metaphase plate per se. Using chromatin immunoprecipitation followed by deep sequencing, all seven centromeres were identified as CenpA-rich regions in the wild-type Guy11 strain of M. oryzae. The centromeres in M. oryzae are regional and span 57 to 109 kb transcriptionally poor regions. No centromere-specific DNA sequence motif or repetitive elements could be identified in these regions suggesting an epigenetic specification of centromere function in M. oryzae. Highly AT-rich and heavily methylated DNA sequences were the only common defining features of all the centromeres in the Rice Blast. Detailed gene synteny analyses helped identify and compare the centromere regions in distinct isolates of M. oryzae and its related species Magnaporthe poae. Overall, this study identifies unusual centromere dynamics and maps the centromere DNA sequences in the top model fungal pathogen M. oryzae, which causes severe losses in global rice production.\n\nSignificanceMagnaporthe oryzae is an important fungal pathogen that causes an annual loss of 10-30% rice crop due to the devastating blast disease. In most organisms, kinetochores are arranged either in the metaphase plate or are clustered together to facilitate synchronized anaphase separation of chromosomes. In this study, we show that the initially clustered kinetochores separate and position randomly prior to anaphase in M. oryzae. Centromeres, identified as the site of kinetochore assembly, are regional type without any shared sequence motifs in M. oryzae. Together, this study reveals atypical kinetochore dynamics and identifies functional centromeres in M. oryzae, thus paving the way to define heterochromatin boundaries and understand the process of kinetochore assembly on epigenetically specified centromere loci.

genetics↗

bioRxiv2017

Cpk2, a catalytic subunit of cyclic AMP-PKA, regulates growth and pathogenesis in rice blast

The cAMP-Protein Kinase A signalling, anchored on CpkA, is necessary for appressorium development and host penetration, but indispensable for infectious growth in Magnaporthe oryzae. In this study, we identified and characterized the gene encoding the second catalytic subunit, CPK2, whose expression was found to be lower compared to CPKA at various stages of pathogenic growth in M. oryzae. Deletion of CPK2 caused no alterations in vegetative growth, conidiation, appressorium formation, or pathogenicity. Surprisingly, the cpkA{Delta}cpk2{Delta} double deletion strain displayed significant reduction in growth rate and conidiation compared to the single deletion mutants. Interestingly, loss of CPKA and CPK2 resulted in morphogenetic defects in germ tubes (with curled/wavy and serpentine growth pattern) on hydrophobic surfaces, and a complete failure to produce appressoria therein, thus suggesting an important role for CPK2-mediated cAMP-PKA in surface sensing and response pathway. CPKA promoter-driven CPK2 expression partially suppressed the defects in host penetration and pathogenicity in the cpkA{Delta}. Such ectopic CPK2 expressing strain successfully penetrated the rice leaves, but was unable to produce proper secondary invasive hyphae, thus underscoring the importance of CpkA in growth and differentiation in planta. The Cpk2-GFP localized to the nucleus and cytoplasmic vesicles in conidia and the germ tubes. The Cpk2-GFP colocalized with CpkA-mCherry on vesicles in the cytosol, but such overlap was not evident in the nucleus. Our studies indicate that CpkA and Cpk2 share overlapping functions, but also play distinct roles during pathogenesis-associated signalling and morphogenesis in the rice blast fungus.

cell biology↗