Molecular Pathogens, 2025, Vol.16, No.6, 294-302 http://microbescipublisher.com/index.php/mp 298 5.2 Expression regulation of resistance-related genes in roots The names of PR genes and NS-LRR genes sound rather "technical", but they are indeed the "main force" in the defense mechanism. Whether they are opened or not often depends on the signal sent first by the root. For example, for genes such as PR-1 and PR-2, after microbial pretreatment, the expression in the roots will increase significantly, followed by the reaction in the leaves (Songsaeng et al., 2024). Some signals are derived through transcription factors, while others are regulated by root hormones. Whether NBS-LRR genes like RPM1 can be expressed smoothly sometimes depends on whether the "epigenetic mechanism" of DNA methylation allows it (Xie et al., 2025). In other words, the root actually functions as a signal converter, and even the resistance of the leaves may be affected by it. 5.3 Coordinated networks of root-mediated local leaf immunity Disease resistance does not rely on any single tissue to fight alone, especially for problems like leaf spot disease - the interaction mechanism between roots and leaves is actually the key point. For instance, some studies have found that certain rootstocks can transfer defensition-related transcriptional information to the scion and also affect the methylation pattern of leaf DNA (Liu et al., 2024). Coupled with regulatory factors such as WRKY transcription factor and VQ protein leading the way, the expression of a whole set of hormone pathways and resistance genes was also driven (Dong et al., 2024). These complex signaling pathways interweave, ultimately enabling plants to respond more quickly and accurately when facing pathogen attacks. Although it seems that the main battlefield is in the leaves, the dispatching ability of the roots is clearly not to be ignored. 6 Case Study: Field Trials of Rhizosphere Microbial Modulation of Wheat Leaf Spot Resistance 6.1 Field efficacy of microbial consortia Conducting experiments in the fields is often more complicated than in the laboratory, but it is also closer to reality. Some microbial combinations, such as the combined inoculation of Paenibacillus sp. And Arthrobacter spp., were once used to control leaf spot disease in actual wheat fields. The results showed that the disease control effect was good, even exceeding 47% (Wang et al., 2021; Samain et al., 2023). Some studies have also shown that biological control agents can reduce the severity of diseases in the field by up to over 80%. Of course, the effectiveness of such control measures is not fixed. The combination of strains and the variety of wheat can both have a considerable impact on the outcome. Interestingly, these microbial agents not only resist diseases but also have a certain positive effect on promoting crop growth. 6.2 Field monitoring of root samples and leaf disease progression It is not only necessary to see if the disease has decreased, but also to observe exactly what has happened to the root system and leaves. The research team will take samples regularly throughout the wheat growing season to inspect the root system and also assess the condition of the disease spots on the leaves. The diversity of rhizosphere microorganisms in the plots inoculated with microbial agents was either maintained or higher than that in the control plots, and the original microorganisms in the soil were not significantly destroyed (Wang et al., 2021). When measuring the degree of leaf spot development by disease index, it can be found that the side with microbial "auxiliary injection" is always less affected than the untreated side (Samain et al., 2023). 6.3 Empirical data analysis of root-leaf immune response indicators Based on the existing field data, the inoculation of microorganisms not only alters the underground microecology but also benefits the above-ground parts. For instance, both the biomass of the root system and the plant have increased, while the abundance of "good friends" groups such as Bacillus, sphingosinomonas, and Streptomyces has significantly improved (Samain et al., 2023). Meanwhile, the proportion of fungi that cause headaches for plants, such as Fusarium and Trichoderma, has decreased, while biocontrol fungi like Trichoderma and Penicillium have increased instead (Wang et al., 2021). These changes seem to be part of the "root-leaf interaction", and it is not surprising that they are ultimately reflected in the improvement of disease resistance and the stability of yield. Rhizosphere microbial agents are not merely about regulating microorganisms; they are more like adjusting the rhythm of a crop's immune system (Figure 2).
RkJQdWJsaXNoZXIy MjQ4ODYzNA==