Journal of Integrative Agriculture最新文献

The velvet protein family plays a key factor in coordinating development and secondary metabolism in many pathogenic fungi. However, no previous research has investigated the function of the velvet protein family in Fusarium oxysporum f. sp. Niveum (FON), which causes a highly destructive disease on watermelon. In this study, ∆fovel1 and ∆folae1 deletion mutants and ∆fovel1-C and ∆folae1-C corresponding complementation mutants of FON were confirmed. Meanwhile, effects of phenotype, biochemistry and virulence of the deletion mutants were protected. Compared with the wild-type strains, the ∆fovel1 and ∆folae1 mutants showed different mycelia phenotype, depressed of conidiation and reduced production of bikaverin and fusaric acid. Moreover, their virulence on watermelon plant roots was significant decreased. In addition, all of these alterations in mutants were restored in corresponding complementation strains. Importantly, yeast two hybrid results indicated an interaction relationship between FoVel1 and FoLae1. The results of this study indicated that FoVEL1 and FoLAE1 play critical roles in secondary metabolisms, conidiation, and virulence in FON. These information will deepen our understanding on the genetic and functional roles of the VEL1 and LAE1 in pathogenic fungi.

Soil microorganisms play critical roles in ecosystem function. However, the relative impact of the potassium (K) fertilizer gradient on the microbial community in wheat‒maize double-cropping systems remains unclear. In this long-term field experiment (2008-2019), we researched bacterial and fungal diversity, composition, and community assemblage in the soil along a K fertilizer gradient (in the wheat season: K0, no K fertilizer; K1, 45 kg ha⁻¹ K₂O; K2, 90 kg ha⁻¹ K₂O; K3, 135 kg ha⁻¹ K₂O; and in the maize season: K0, no K fertilizer; K1, 150 kg ha⁻¹ K₂O; K2, 300 kg ha⁻¹ K₂O; K3, 450 kg ha⁻¹ K₂O) using bacterial 16S rRNA and fungal ITS data. We observed that environmental variables (such as mean annual soil temperature (MAT) and precipitation, available K, ammonium, nitrate, and organic matter) impacted the soil bacterial and fungal communities, and their impacts varied with fertilizer treatments and crop species. Furthermore, the relative abundance of bacteria involved in soil nutrient transformation (phylum Actinobacteria and class Alphaproteobacteria) in the wheat season was significantly increased compared to the maize season, and the optimal K fertilizer dosage (K2 treatment) boosted the relative bacterial abundance of soil nutrient transformation (genus Lactobacillus) and soil denitrification (phylum Proteobacteria) bacteria in the wheat season. The abundance of the soil bacterial community promoting root growth and nutrient absorption (genus Herbaspirillum) in the maize season was improved compared to the wheat season, and the K2 treatment enhanced the bacterial abundance of soil nutrient transformation (genus MND1) and soil nitrogen cycling (genus Nitrospira) genera in the maize season. The results indicated that the bacterial and fungal communities in the double-cropping system exhibited variable sensitivities and assembly mechanisms along a K fertilizer gradient, and microhabitats explained the largest amount of the variation in crop yields, and improved wheat‒maize yields by 11.2-22.6 and 9.2-23.8% with K addition, respectively. These modes are shaped contemporaneously by the different meteorological factors and soil nutrient changes in the K fertilizer gradients.

The nascent polypeptide-associated complex (NAC) is involved in various biological functions in eukaryotes which have been extensively studied in animals and plants, but its role in the biocontrol action of microorganisms needs to be better understood. In this study, we investigated the function of TbNACα, one of the subunits of NAC, in the biocontrol activity of Trichoderma breve T069 against Sclerotium rolfsii. The TbNACα gene was deleted from T. breve T069, and the ΔTbNACα mutant showed significantly reduced mycelial growth, spore production, and spore germination. Additionally, volatile substances from ΔTbNACα had no significant effect on S. rolfsii, while non-volatile substances significantly inhibited the growth of S. rolfsii. Transcriptome sequencing results showed that compared to wild-type T069, the ΔTbNACα mutant had 3,398 differentially expressed genes, mainly regulating the expression of genes related to secondary metabolite biosynthetic enzymes, hydrolases, and membrane transport proteins. Untargeted metabolomics identified 50 upregulated metabolites (27 in positive ion mode and 23 in negative ion mode) in crude extracts from ΔTbNACα mutant metabolite broth. Moreover, the metabolic substances of ethyl caffeate had the strongest activity against S. rolfsii, with an EC₅₀ of 107.15 μg·mL^-1. Quantitative Real-time PCR (qPCR) analysis revealed that genes involved in the ethyl caffeate synthesis pathway were significantly upregulated in ΔTbNACα strains. This study provides a basis for the negative regulation of ethyl caffeate synthesis and elucidates the antagonistic inhibition mechanism of TbNACα in T. breve T069.

The Elongator complex is conserved in a wide range of species and plays crucial roles in diverse cellular processes. We have previously shown that the Elongator protein PoELp3 was involved in the asexual development, pathogenicity, and autophagy of the rice blast fungus. In this study, we further revealed that PoElp3 functions via tRNA-mediated protein integrity. Phenotypic analyses revealed that overexpression of two of the tRNAs, tK(UUU) and tQ(UUG) could rescue the defects in ΔPoelp3 strain. TMT-based proteomic and transcriptional analyses demonstrated that 386 proteins were down-regulated in ΔPoelp3 strain compared with wild type strain Guy11, in a transcription-independent manner. Codon usage assays revealed an enrichment of Glutamine CAA-biased mRNA in the 386 proteins compared with the 70-15 genome. In addition to those reported previously, we also found that PoErp9, a sphingolipid C9-methyltransferase, was down-regulated in the ΔPoelp3 strain. Through an ILV2-specific integration of PoERP9-GFP into the wild type and ΔPoelp3 strain, we were able to show that PoErp9 was positively regulated by PoElp3 translationally but not transcriptionally. Functional analyses revealed that PoErp9 was involved in the fungal growth, conidial development, pathogenicity, and TOR-related autophagy homeostasis in P. oryzae. Taken together, our results suggested that PoElp3 acts through the tRNA-mediated translational efficiency to regulate asexual development, pathogenicity, sphingolipid metabolism, and autophagy in the rice blast fungus.

Leaves and glumes act as lateral organs and have essential effects on photosynthesis and seed morphology, thus affecting yield. However, the molecular mechanisms controlling their polarity development in rice is still worth further analysis. Here, we isolated a polarity defect of lateral organs 1 (pdl1) mutant in rice, which exhibits twisted/filamentous-shaped leaves and cracked/filamentous-shaped lemmas caused by defects in polarity development. PDL1 encodes a SUPPRESSOR OF GENE SILENCING 3 protein localized in the cytoplasm granules. PDL1 is expressed in the shoot apical meristem, inflorescence meristem, floral meristem, and lateral organs including leaf and floral organs. PDL1 is involved in the synthesis of tasiR-ARF, which may subsequently modulate the expression of OsARFs. Meanwhile, the expression of abaxial miR165/166 and the adaxial identity genes OSHBs was increased and decreased significantly, respectively. The results of this study clarified the molecular mechanism that the PDL1-mediated tasiR-ARF synthesis regulates the lateral organ polarity development in rice.

Planting density is a major limiting factor for maize yield, and breeding for density tolerance breeding has become an urgent issue. The leaf structure of the maize ear leaf is the main factor that restricts planting density and yield composition. In this study, a natural population of 201 maize inbred lines was used for genome-wide association analysis, which identified nine SNPs on chromosomes 2, 5, 8, 9, and 10 that were significantly associated with ear leaf type structure. Further verification through qRT-PCR confirmed the association of five candidate genes with these SNPs, with the Zm00001d008651 gene showing significant differential expression in compact and flat maize inbred lines. Enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) suggested that this gene is involved in the glycolysis process. The analysis of the basic properties of this gene revealed that it encodes a stable, basic protein consisting of 593 amino acids with some hydrophobic ability. The promoter region contains stress and hormone (ABA) related elements. The mutant of this gene increased the uppermost ear leaf angle (eLA) and the first leaf below the uppermost ear (bLA) by 4.96° and 0.97° compared with normal inbred lines. Overall, this research sheds light on the regulatory mechanism of ear and leaf structure that influence density tolerance and provides solid foundational work for the development of new varieties.

It has been reported that C-type lectins (CTLs), which are pattern recognition receptors of the insect innate immunity response, may compete with Cry toxin for the receptor alkaline phosphatase to decrease its toxicity in insects. However, to date, which CTLs affect larval susceptibility to Bt in Spodoptera exigua is not clear. In this study, thirty-three CTL genes were identified from S. exigua. Based on the number of carbohydrate-recognition domains (CRDs) and the domain architectures, they were classified into three groups: (1) nineteen CTL-S (single-CRD), (2) eight immulectin (dual-CRD) and (3) six CTL-X (CRD with other domains). RT-qPCR analysis revealed that expression levels of SeCTL-S15, IML-4 and CTL-X6 were upregulated after challenge with Bt and Cry1Ab. Tissue and developmental stage expression analysis showed that only SeCTL-S15was mainly expressed in the midgut and larva, respectively. Knockdown of SeCTL-S15 significantly increased Bt susceptibility, as indicated by reduced survival and larval weight. These results suggest that CTL-S15 might play a vital role in the low susceptibility of larvae to Bt in S. exigua. Our results provide new insights into CTL function in insects.

Gossypium raimondii (2n=2x=26, D₅), an untapped wild species, is the putative progenitor of the D-subgenome of G. hirsutum (2n=4x=52, AD₁), an extensively cultivated species. Here, we developed a G. hirsutum (recipient)-G. raimondii (donor) introgression population to exploit favorable QTLs/genes and mapped potential quantitative trait loci (QTLs) from wild cotton species. The introgression population consists of 256 lines with an introgression rate of 52.33% of the genome G. raimondii. The range of introgression segment length was 0.03-19.12 Mb, with an average of 1.22 Mb. The coverage of total introgression fragments was 386.98 Mb from G. raimondii. Further genome-wide association analysis (Q+K+MLM) and QTL mapping (RSTEP-LRT) identified 59 common QTLs, including 14 stable QTLs and 6 common QTL (co-QTL) clusters, and one hotspot of MIC. The common QTLs for seed index showed all positive additive effects, while the common QTLs for boll weight were all negative additive effects, indicating that the linkage between seed index and boll weight could be broken. QTLs for lint percentage showed positive effect and could be beneficial for improving cotton yield. Most QTLs for fiber quality had negative additive effects, implying these QTLs were domesticated/improved in G. hirsutum. A few fiber quality QTLs showed positive additive effects, which could be used to improve cotton fiber quality. These introgression lines developed would be useful for molecular marker-assisted breeding and facilitate us to map QTLs precisely for mining desirable genes from the wild species G. raimondii to improve cultivated cotton in future via a design-breeding approach.