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Rocha, L. O.

Publications and source records attributed to Rocha, L. O..

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Altered bacteria community dominance reduces tolerance to resident fungus and seed to seedling growth performance in maize (Zea mays L. var. DBK 177).

Seeds are reservoirs of beneficial and harmful microorganism that modulates plant growth and health. Here, we access seed to seedling bacteriome assembly modified by seed-disinfection and the underlined effect over maize germination performance and root-seedlings microbial colonization. Seed-disinfection was performed with sodium hypochlorite (1.25%, 30 min), resulting in a reduction of the cultivable-dependent fraction of seed-borne bacteria population, but not significantly detected by real-time PCR, microscopy, and biochemical analysis of the roots on germinated seeds. 16S rRNA sequencing revealed that the seed and root bacteriome exhibited similar diversity and did not differ in the structure concerning seed-disinfection. On the other hand, the abundance reduction of the genera f_Enterobacteriaceae_922761 (unassigned genus), Azospirillum, and Acinetobacter in disinfected-seed prior germination seems to display changes in prominence of several new taxa in the roots of germinated seeds. Interestingly, this reduction in the bacteriome negatively affected the germination speed and growth of maize plantlets. Additionally, bacteriome re-shape increased the maize var DKB 177 susceptible to the seed-borne plant pathogen Penicillium sp. Such changes in the natural seed-borne composition removed the natural barrier, increasing susceptibility to pathogens, impairing disinfected seeds to germinate, and develop. We conclude that bacteria borne in seeds modulate the relative abundance of taxa in the root, promote germination, seedling growth, and protect the maize against fungal pathogens.

microbiology

Wild rice (O. latifolia) from natural ecosystems in the Pantanal region of Brazil: host to Fusarium incarnatum-equiseti species complex and highly contaminated by zearalenone.

We assessed the mycobiota diversity and mycotoxin levels present in wild rice (Oryza latifolia) from the Pantanal region of Brazil; fundamental aspects of which are severely understudied as an edible plant from a natural ecosystem. We found a variety of fungal species contaminating the rice samples; the most frequent genera being Fusarium, Nigrospora and Cladosporium (35.9%, 26.1% and 15%, respectively). Within the Fusarium genus, the wild rice samples were mostly contaminated by the Fusarium incarnatum-equiseti species complex (FIESC) (80%) along with Fusarium fujikuroi species complex (20%). Phylogenetic analysis supported multiple FIESC species and gave strong support to the presence of two previously uncharacterized lineages within the complex (LN1 and LN2). Deoxynivalenol (DON) and zearalenone (ZEA) chemical analysis showed that most of the isolates were DON/ZEA producers and some were defined as high ZEA producers, displaying abundant ZEA levels over DON (over 19 times more). Suggesting that ZEA likely has a key adaptive role for FIESC in wild rice (O. latifolia). Mycotoxin determination in the rice samples revealed high frequency of ZEA, and 85% of rice samples had levels >100 μg/kg; the recommended limit set by regulatory agencies. DON was only detected in 5.2% of the samples. Our data shows that FIESC species are the main source of ZEA contamination in wild rice and the excessive levels of ZEA found in the rice samples raises considerable safety concerns regarding wild rice consumption by humans and animals.Competing Interest StatementThe authors have declared no competing interest.View Full Text

microbiology