| Congresso Brasileiro de Microbiologia 2023 | Resumo: 1397-2 | ||||
Resumo:The low availability of phosphorus (P) in the soil is one of the main constraints for crop production. Plants developed different strategies to increase P use efficiency, such as root morphology modifications, exudation of signaling compounds for mycorrhizal colonization and association with microorganisms, such as arbuscular mycorrhizal fungi (AMF). The objective of this work was to investigate the effect of AMF colonization on sorghum growth and P uptake, influenced by sorgoleone, one of the most studied allelochemicals and predominant compound of sorghum root exudates. The experiment was carried out in a greenhouse, using sorghum genotype P9401 (low sorgoleone production), in a completely randomized experimental design with four replicates, with inoculum of the fungus Rhizophagus clarus (500 spores/plant) and without inoculum (negative control). In addition, three doses of purified sorgoleone (20 micromolar, 40 micromolar and 80 micromolar) were added to the low-P soil (P=2.8 mg.dm−3 Mehlich 1). The plants were collected 45 days after planting and the biomass, P content, AMF colonization, gene expression and rhizosphere soil were analyzed. For terminal restriction fragment length polymorphism (T-RFLP) analysis total DNA was extracted and 16S (for bacteria) and 28S rRNA (for fungi) genes were amplified and digested with the restriction enzymes AluI, HpaII and HaeIII. PCR digested products were genotyped on Genetic Analyzer 3500XL with GeneMapper 5.0 software and analyzed with T-REX program. The relative abundances of the microbial species were determined by the average T-RF size values of digestions with the restriction enzymes. The diversity profile of bacteria and AMF was evaluated by a multidimensional non-metric scale (NMDS) based on the Bray-Curtis distance matrix and the unidirectional similarity analysis test (ANOSIM) with p≤0.05 was used to test whether the sample groups had significantly different mean differences. The results showed a significant increase in total plant biomass and P content in the treatment with inoculation of 20 micromolar of sorgoleone and R. clarus. There was a significant increase on the expression of the genes related to AMF colonization (SbAM3), sorgoleone biosynthesis (N21G12) and P transport (SbPT8, SbPT9, SbPT10 and SbPT11) under this condition. Moreover, a significant difference on sorghum microbiota was observed in the fungal communities in treatments inoculated and non-inoculated with R. clarus (p<0.05). However, no difference was observed for bacteria genetic diversity. Our results indicated that 20 micromolar sorgoleone was able to influence mycorrhizal colonization in sorghum under low-P, suggesting that sorghum genotypes with higher sorgoleone exudation may develop a denser mycorrhizal network, promote greater nutrient uptake and higher grain yield.
Palavras-chave: Sorghum bicolor, phosphorus, arbuscular mycorrhizal fungi Agência de fomento:Embrapa, Capes, CNPq, Fapemig and Finep | |||||