Phytophthora sojae zoospores differ in chemotaxis to the root and root exudates of host soybean and nonhost common bean

Phytophthora sojae does not infect nonhost maize (Zea mays) but infects nonhost common bean (Phaseolus vulgaris) under inoculation. Soybean seed exudates participate in mediating host resistance to P. sojae prior to infection. This study aims to elucidate the role of seed exudates in mediating the nonhost resistance to P. sojae prior to infection. The behaviors of P. sojae zoospores in response to the seed exudates were determined using an assay chamber and a concave slide. The proteomes of P. sojae zoospores in response to the seed exudates were analyzed with the tandem mass tag (TMT) method. The key proteins were quantitatively verified by parallel reaction monitoring (PRM). Maize seed exudates exerted a repellent effect on zoospores. This result explains why zoospores sense repelling signaling molecules that weaken and strongly inhibit chemotaxis signals in the phosphatidylinositol signaling pathway and arachidonic acid metabolism pathway. Common bean seed exudates did not exhibit any attraction to the zoospores because the G protein signaling pathway, had no significant change. The proteins protecting the cell membrane structure were significantly downregulated, and the early apoptosis signal glutathione was enhanced in zoospores responding to common bean seed exudates, which resulted in dissolution of the cysts. Maize and common bean seed exudates mediate part of the nonhost resistance to P. sojae via different mechanisms prior to infection. The immunity of maize to P. sojae is due to the repellent effect of maize seed exudates on zoospores. Common bean seed exudates participate in mediating nonhost resistance by dissolving cysts.

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Transcriptomic Responses of Rhizobium phaseoli to Root Exudates Reflect Its Capacity to Colonize Maize and Common Bean in an Intercropping System

Frontiers in Microbiology ◽

10.3389/fmicb.2021.740818 ◽

2021 ◽

Vol 12 ◽

Author(s):

José Luis Aguirre-Noyola ◽

Mónica Rosenblueth ◽

Michel Geovanni Santiago-Martínez ◽

Esperanza Martínez-Romero

Keyword(s):

Ferulic Acid ◽

Common Bean ◽

Root Exudates ◽

Dicarboxylic Acids ◽

Rna Seq ◽

Rhizobium Phaseoli ◽

Gene Encoding ◽

Genomic Expression ◽

Microbe Interactions ◽

Hydroponic Conditions

Corn and common bean have been cultivated together in Mesoamerica for thousands of years in an intercropping system called “milpa,” where the roots are intermingled, favoring the exchange of their microbiota, including symbionts such as rhizobia. In this work, we studied the genomic expression of Rhizobium phaseoli Ch24-10 (by RNA-seq) after a 2-h treatment in the presence of root exudates of maize and bean grown in monoculture and milpa system under hydroponic conditions. In bean exudates, rhizobial genes for nodulation and degradation of aromatic compounds were induced; while in maize, a response of genes for degradation of mucilage and ferulic acid was observed, as well as those for the transport of sugars, dicarboxylic acids and iron. Ch24-10 transcriptomes in milpa resembled those of beans because they both showed high expression of nodulation genes; some genes that were expressed in corn exudates were also induced by the intercropping system, especially those for the degradation of ferulic acid and pectin. Beans grown in milpa system formed nitrogen-fixing nodules similar to monocultured beans; therefore, the presence of maize did not interfere with Rhizobium–bean symbiosis. Genes for the metabolism of sugars and amino acids, flavonoid and phytoalexin tolerance, and a T3SS were expressed in both monocultures and milpa system, which reveals the adaptive capacity of rhizobia to colonize both legumes and cereals. Transcriptional fusions of the putA gene, which participates in proline metabolism, and of a gene encoding a polygalacturonase were used to validate their participation in plant–microbe interactions. We determined the enzymatic activity of carbonic anhydrase whose gene was also overexpressed in response to root exudates.

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Maize and Common Bean Seed Exudates Mediate Part of Nonhost Resistance to Phytophthora Sojae before Infection

10.21203/rs.3.rs-190759/v1 ◽

2021 ◽

Author(s):

Zhuoqun Zhang ◽

Yifan Zhao ◽

Tai An ◽

Han Yu ◽

Xiangqi Bi ◽

...

Keyword(s):

Common Bean ◽

Soybean Seed ◽

Phytophthora Sojae ◽

Nonhost Resistance ◽

Bean Seed ◽

Repellent Effect ◽

Maize Seed ◽

Tandem Mass Tag ◽

Assay Chamber ◽

Acid Pathway

Abstract Purpose: Phytophthora sojae does not infect the nonhost maize (Zea mays L.) but could infect the nonhost common bean (Phaseolus vulgaris L.). Soybean seed exudates participate in mediating host resistance to P. sojae before infection. This study aimed to elucidate the role of nonhost seed exudates in mediating nonhost resistance to P. sojae before infection. Methods: The response behavior of P. sojae zoospores to the seed exudates was determined using an assay chamber and a concave slide, and the proteomes of P. sojae zoospores treated with the seed exudates were analysed with the tandem mass tag (TMT) method. The key proteins were quantified by parallel reaction monitoring (PRM).Results: Maize seed exudates exerted a repellent effect on zoospores, whereas common bean seed exudates did not exhibit any attraction to zoospores but could dissolve the cysts. The key proteins related to zoospores chemotaxis showed no significant changes in response to maize seed exudates, but the key proteins in arachidonic acid pathway were downregulated and controlled the repellent behavior of zoospores. Proteins protecting the cell membrane structure were significantly downregulated in zoospores responding to common bean seed exudates, which confirmed the bacteriolytic effect of common bean seed exudates on cysts. Conclusion: Maize and common bean seed exudates mediate part of the nonhost resistance via different mechanisms prior to P. sojae infection. The immune of maize to P. sojae is due to the repellent effect of maize seed exudates on zoospores. Common bean seed exudates participate in mediating nonhost resistance by dissolving cysts.

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Changes in biochemistry and cellular ultrastructure support different resistance mechanisms to Phytophthora sojae in nonhost common bean and host soybean

Plant Pathology ◽

10.1111/ppa.13527 ◽

2022 ◽

Author(s):

Xiangqi Bi ◽

Guangmei Song ◽

Han Yu ◽

Zhuoqun Zhang ◽

Haixu Liu ◽

...

Keyword(s):

Common Bean ◽

Resistance Mechanisms ◽

Phytophthora Sojae ◽

Cellular Ultrastructure

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Combination of developmental behaviors and transcriptome reveals differential response mechanisms of Phytophthora sojae to aspartic acid and glucose in seed exudates

Phytopathology ◽

10.1094/phyto-08-21-0332-r ◽

2021 ◽

Author(s):

Xinying Gao ◽

Haixu Liu ◽

Han Yu ◽

Zhuoqun Zhang ◽

Xiangqi Bi ◽

...

Keyword(s):

Amino Acids ◽

Signaling Pathway ◽

G Protein ◽

Aspartic Acid ◽

Root Exudates ◽

Soybean Seed ◽

Mapk Signaling ◽

Phytophthora Sojae ◽

Signal Molecules ◽

Protein Signaling

Isoflavones in soybean seed and root exudates are host specific signal molecules for Phytophthora sojae to recognize host soybean. G protein and calcium signaling pathway are involved in the chemotaxis of zoospores in the recognition of isoflavones. To investigate the role of host non-specific signaling molecules (sugars and amino acids) in seed and root exudates in zoospore chemotaxis and mycelial growth, the transcriptome of P. sojae responding to aspartic acid (Asp) and glucose (Glc) was analyzed by RNA-seq method. We found that the relative in situ concentrations of amino acids and sugars significantly promoted zoospore chemotaxis, as do isoflavones. Transcriptomics showed that both similarity and difference existed in response mechanisms of P. sojae to Asp and Glc. Asp and Glc activated MAPK signaling pathway and phosphatidylinositol signaling system but not G-protein signaling pathway, which have been reported to be responsible for zoospore chemotaxis. In addition, ubiquitin mediated proteolysis and ABC transporters were also activated by Asp and Glc. Meanwhile, glutathione signaling pathway uniquely participated in the response of P. sojae to Asp but not involved in the response process to Glc, which is waiting for further study. Our results provide new insights into the molecular mechanism of zoospore response to Asp and Glc.

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