# Phytomicrobiones: A Potential Approach for Sustainable Pesticide Biodegradation
## 3 Phytomicrobiome and Pesticide Biodegradation
### Translocation and Accumulation  
The capacity of phytomicrobes to degrade pesticides is inextricably linked with the uptake and translocation of these chemical compounds within plants. The physical and chemical properties of pesticides, as well as the biological attributes of the plant, collectively influence this process. This journey begins at the plant's roots [139], where pesticides, upon application, dissolve into soil solutions readily accessible to the plant's root system. It is crucial to note that pesticide uptake by plant roots typically follows a passive or diffusive process, albeit with some exceptions, such as hormone-like herbicides, including phenoxyacid herbicides [140]; although, size matters--the molecular mass of a pesticide below 1000 is readily absorbed by plant roots [141]. However, pesticide uptake and translocation are significantly affected by factors like dissolved organic carbon (DOC) concentration, pH, temperature, and organic matter (OM) content of the soil. Importantly, two distinct pathways of pesticide transportation have been observed: (i) intracellular or intercellular transport and (ii) tissue transport. The choice between these pathways hinges on the size of pesticide molecules, with smaller molecules able to traverse the xylem and phloem, while larger ones are restricted from phloem transport [142]. This intricate system of pesticide uptake and translocation leaves an indelible mark on phytomicrobial diversity. For instance, a study by [PERSON] et al. (2018) investigated the impact of various pesticides on the phytomicrobiome composition, revealing that nitrogen (N) and sulfur (S) cycling bacteria proved most sensitive to pesticide exposure [143]. Ammonia-oxidizing microorganisms exhibited a negative response to pesticide presence while denitrifying bacteria were stimulated by these chemical compounds. Remarkably, the combined application of biofertilizers and pesticides has been shown to promote phytomicrobial growth [144]. In a study of sugarcane phytomicrobiota, the combined application of pesticides and biofertilizer led to higher microbial diversity than the control, illustrating the intricate interplay between pesticide movement and fertilizer application. It is evident that phytomicrobiome diversity is shaped not only by pesticide dynamics but also by the influence of fertilizer application. The accumulation of pesticides within plant tissues opens yet another chapter in our exploration of pesticide degraders. In the case of tobacco plants, the application of N-(3,5-dichlorophenyl) succinimide, a fungicide, results in pesticide accumulation within the phylosphere, consequently bolstering the abundance of Enterobacteriaceae relative to control conditions [145]. This Enterobacteriaceae family, a common inhabitant of plant phylospheres in pesticide-applied settings, exhibits remarkable pesticide-degrading capabilities [146; 147]. However, the identification of pesticide degraders in relation to pesticide accumulation within plants remains a fledgling field [148]. While various studies have illuminated the plant's ability to modulate its microbiome in response to pesticide applications, creating niches for potential pesticide degraders [145; 146], the mechanisms governing the abundance and roles of pesticide degraders in relation to pesticide accumulation within the plant remain veiled in mystery. To date, no comprehensive studies have explored these intricate facets of pesticide degradation. Consequently, it is paramount to initiate further research aimed at unearthing potential pesticide degraders and deciphering their roles in the context of pesticide accumulation within plant tissues. This endeavor holds the potential to unveil new dimensions of pesticide biodegradation within the intricate phytomicrobiome.