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

Abstract

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.

Diversity of Endophytic Bacteria in Hybrid Maize Seeds With Genetic Correlation and the Strain of Bacillus Mojavensis Isolated as a Potential Microorganism Capable of Vertical Transmission

“…Vertical transmission across generations has a profound impact on plant ecology. However, few studies are linking the diversity of endophytic bacteria in maize seeds with generational transmission, and most studies tend to be female parents (Santos et al, 2021). Based on the traditional separation method, this study found that Bacillus and Pantoea were the dominant bacteria of maize and the pollen at the genus level.…”

“…As a medium for carrying and transmitting plant genetic information, plant seeds also contain abundant endophytic bacteria resources (Wang et al, 2021). Santos et al (2021) found that the germination rate of seeds with surface disinfection was signi cantly lower than that of the control group. The endophytic bacteria in the seeds coordinated the microbial balance of the seeds and promoted corn germination and seedling growth.…”

Maize seed endophytes

“…Many different microbes can grow in seed, and the maize seed community is distinct from other parts of the plant (Johnston‐Monje & Raizada, 2011 ). Only a handful of studies have looked at the maize seed endophyte community with modern deep sequencing methods (Johnston‐Monje et al, 2021 ; Liu et al, 2017 , 2020 ; Majumdar et al, 2021 ; Santos et al, 2021 ), so most of our knowledge comes from isolation studies. However, based on both sequencing (Figure 1 ) and isolation (Tables 1 and 2 ), the bacteria of the maize seed are dominated by Proteobacteria, Actinobacteria, and Firmicutes, with the majority of fungi placed in the Ascomycota phylum.…”

“…Transmission across multiple generations (see below) implies they must at least be in the stalk and aboveground vasculature. Electron microscopy of sterile, germinating seeds shows microbes in the pericarp, endosperm, radicle, and germinating root surface (Santos et al, 2021 ), and the beneficial microbe B. mojavensis RCC101 was seen to cover the root epidermis after germination (Bacon et al, 2001 ). The presence of endophytes on the root surface implies that microbes can move from the seed out into the rhizoplane and rhizosphere, a conclusion supported by other work (Johnston‐Monje & Raizada, 2011 ; White et al, 2019 ).…”