Interaction of negative regulator OsWD40-193 with OseEF1A1 inhibits Oryza sativa resistance to Hirschmanniella mucronata infection.

Rice is a crucial food crop worldwide, but it is highly susceptible to Hirschmanniella mucronata, a migratory parasitic nematode. No rice variety has been identified that could resist H. mucronata infection. Therefore, it is very important to study the interaction between rice and H. mucronata to breed resistant rice varieties. Here, we demonstrated that protein OsWD40-193 interacted with the extension factor OseEF1A1 and both were negative regulators inhibiting rice resistance to H. mucronata infection. Overexpression of either OsWD40-193 or OseEF1A1 led to enhance susceptibility to H. mucronata, whereas the absence of OsWD40-193 or OseEF1A1 led to resistance. Further transcriptomic analysis showed that OseEF1A1 deletion altered the expression of genes association with salicylic acid, jasmonic acid and abolic acid signaling pathways and increased the accumulation of secondary metabolites to enhance resistance in rice. Our study showed that H. mucronata infection affected the expression of negative regulators in rice and inhibited rice resistance, which was conducive to the infection of nematode. Together, our data showed that H. mucronata affected the expression of negative regulators to facilitate its infection and provided potential target genes to engineering resistance germplasm via gene editing of the negative regulators.

Integrated transcriptome and metabolome analysis revealed that flavonoids enhanced the resistance of Oryza sativa against Meloidogyne graminicola.

Rice is a crucial food crop worldwide, but its yield and quality are significantly affected by Meloidogyne graminicola is a root knot nematode. No rice variety is entirely immune to this nematode disease in agricultural production. Thus, the fundamental strategy to combat this disease is to utilize rice resistance genes. In this study, we conducted transcriptome and metabolome analyses on two rice varieties, ZH11 and IR64. The results indicated that ZH11 showed stronger resistance than IR64. Transcriptome analysis revealed that the change in gene expression in ZH11 was more substantial than that in IR64 after M. graminicola infection. Moreover, GO and KEGG enrichment analysis of the upregulated genes in ZH11 showed that they were primarily associated with rice cell wall construction, carbohydrate metabolism, and secondary metabolism relating to disease resistance, which effectively enhanced the resistance of ZH11. However, in rice IR64, the number of genes enriched in disease resistance pathways was significantly lower than that in ZH11, which further explained susceptibility to IR64. Metabolome analysis revealed that the metabolites detected in ZH11 were enriched in flavonoid metabolism and the pentose phosphate pathway, compared to IR64, after M. graminicola infection. The comprehensive analysis of transcriptome and metabolome data indicated that flavonoid metabolism plays a crucial role in rice resistance to M. graminicola infection. The content of kaempferin, apigenin, and quercetin in ZH11 significantly increased after M. graminicola infection, and the expression of genes involved in the synthetic pathway of flavonoids also significantly increased in ZH11. Our study provides theoretical guidance for the precise analysis of rice resistance and disease resistance breeding in further research.

Transcriptome Analysis of Protein Kinase MoCK2, which Affects Acetyl-CoA Metabolism and Import of CK2-Interacting Mitochondrial Proteins into Mitochondria in the Rice Blast Fungus Magnaporthe oryzae.

The rice pathogen Magnaporthe oryzae causes severe losses to rice production. Previous studies have shown that the protein kinase MoCK2 is essential for pathogenesis, and this ubiquitous eukaryotic protein kinase might affect several processes in the fungus that are needed for infection. To better understand which cellular processes are affected by MoCK2 activity, we performed a detailed transcriptome sequencing analysis of deletions of the MoCK2 b1 and b2 components in relation to the background strain Ku80 and connected this analysis with the abundance of substrates for proteins in a previous pulldown of the essential CKa subunit of CK2 to estimate the effects on proteins directly interacting with CK2. The results showed that MoCK2 seriously affected carbohydrate metabolism, fatty acid metabolism, amino acid metabolism, and the related transporters and reduced acetyl-CoA production. CK2 phosphorylation can affect the folding of proteins and especially the effective formation of protein complexes by intrinsically disordered or mitochondrial import by destabilizing soluble alpha helices. The upregulated genes found in the pulldown of the b1 and b2 mutants indicate that proteins directly interacting with CK2 are compensatorily upregulated depending on their pulldown. A similar correlation was found for mitochondrial proteins. Taken together, the classes of proteins and the changes in regulation in the b1 and b2 mutants suggest that CK2 has a central role in mitochondrial metabolism, secondary metabolism, and reactive oxygen species (ROS) resistance, in addition to its previously suggested role in the formation of new ribosomes, all of which are processes central to efficient nonself responses as innate immunity. IMPORTANCE The protein kinase CK2 is highly expressed and essential for plants, animals, and fungi, affecting fatty acid-related metabolism. In addition, it directly affects the import of essential mitochondrial proteins into mitochondria. These effects mean that CK2 is essential for lipid metabolism and mitochondrial function and, as shown previously, is crucial for making new translation machinery proteins. Taken together, our new results combined with previously reported results indicate that CK2 is an essential protein necessary for the capacities to launch efficient innate immunity responses and withstand the negative effects of such responses necessary for general resistance against invading bacteria and viruses as well as to interact with plants, withstand plant immunity responses, and kill plant cells.

First report of spotting disease caused by Fusarium proliferatum infection of Alisma orientale in China.

Alisma orientale (Alismatidae) is highly valued for both its pharmaceutical and nutritional properties. The tubers are in Chinese herbal medicine and the leaves and stems for several Chinese delicacies. Intercropping A. orientale and Nelumbo nucifera may increase quality, yield, and other economic benefits. In July 2021, a novel spotting disease was observed in these plants in the White Lotus Science and Technology Expo Park in Guangchang County, Fuzhou City, Jiangxi Province (26.79°N, 116.31°E). The symptom was round to regular black spots on the stems during the early stage of infection. Over time, the larger spots merged, resulting in stem breakage and eventually death. A. orientale spot disease arose in July of 2021, causing approximately 50% of leaves to die, and leading to 10 to 25% yield loss. To identify the pathogenic organism, 5×5 mm samples were taken from affected tissue adjoining healthy tissue, sterilized in 75% ethanol for 30 s, and immersed in 0.1% mercury chloride for a further 30 s, before washing in sterile water and transfer to potato glucose agar (PDA) plates. After culturing at 28℃±1℃ for seven days, aerial mycelia were identified. At the start of culture, the mycelia were white but later turned purple-red. Three to five straight or partially bent septa were visible on the macroconidia, which were 28.8(19.1~38.6) ×2.9(1.9~4.0) µm in size (n=50). In contrast, the microconidia appeared glassy and elliptical, with sizes of 9.8(4.9~14.8) ×2.7(1.2~4.1) µm (n=50). These features suggested F. proliferatum (Zhao et al., 2019). To verify this, various primers, including universal ITS1/ITS4, Fusarium-specific EF1T/EF2T, PRO1/PRO2 (Mulè et al., 2004), and Bt2a/Bt2b (Glass and Donaldson, 1995; O'Donnell and Cigelnik, 1998) primers were used for amplification of the 5.8S rRNA/ITS, α-elongation factor, calmodulin, and ß-tubulin genes. The resulting sequences were between 99% and 100% identical to those of F. proliferatum in GenBank (accession numbers MW721116.1, KR071735.1, KU604008.1, and MH398186.1, respectively). The present sequences were uploaded with accession numbers of OK047496, OL448294, OL448295, and OM280358, with sequence lengths of 549 bp, 725 bp, 594 bp, and 325bp, respectively. A maximum likelihood-phylogenetic tree was created in MEGA5 based on ITS+TEF+PRO sequences. Pathogenicity was tested by hyphal inoculation. Needles, cotton, and water were sterilized under high temperature and pressure. Five-millimeter punches were taken from infected and uninfected PDA plates and three uninfected stems of A. orientale were inoculated with the pathogen with a fourth used as the control. Plants were maintained in experimental field of the Bailian Science and Technology Expo Park. Infected wounds were gently wetted with sterile water and sealed with sellotape. After 10 days, the infected stems displayed symptoms while the controls did not. The same pathogen was recovered from the infected stems, fulfilling Koch's requirements. This appears to be the only report describing F. proliferatum infection of A. orientale stems. These results are useful for the recognition and avoidance of F. proliferatum infections in A. orientale and other plants.