Propagation and characterization of viable arbuscular mycorrhizal fungal spores within maize plant (Zea mays L.)

Apple-arbuscular mycorrhizal symbiosis confers resistance to Fusarium solani by inducing defense response and elevating nitrogen absorption

Fusarium solani exerts detrimental effects on plant growth, which is one of the reasons for the incidence of apple replant disease. Arbuscular mycorrhizal fungi (AMF) enhance plant resistance to Fusarium wilt; however, the mechanism remains poorly understood. Therefore, the present study investigated the symbiosis between apple and AMF and explored the physiology, especially nitrate metabolism, antioxidant defense, and photosynthetic performance, when infected by F. solani. The experiment was carried out with four treatments, namely -AMF - F. solani, -AMF + F. solani, -AMF + F. solani, and + AMF + F. solani. In this study, the -AMF + F. solani treatment increased the activity of enzymes associated with nitrogen metabolism, such as the nitrate and nitrite reductases, in the apple root system. The +AMF + F. solani treatment showed higher antioxidant enzyme activities than the -AMF + F. solani by F. solani infection. The apple seedlings of the +AMF + F. solani treatment decreased reactive oxygen accumulation and reduced the oxidative damages triggered by F. solani infection. The improvement in antioxidant capacity due to the +AMF + F. solani treatment was closely associated with the upregulation of genes related to the antioxidant system. The F. solani infection greatly damaged the photosynthetic process, while the +AMF + F. solani treatment significantly improved it compared to the -AMF + F. solani treatment. In conclusion, the study demonstrated that the apple-AMF symbiosis plays an active role in regulating the resistance against F. solani infection by enhancing defense response and nitrogen metabolism.

Legacy Effects of Biochar and Compost Addition on Arbuscular Mycorrhizal Fungal Community and Co-Occurrence Network in Black Soil

Compost and biochar are beneficial soil amendments which derived from agricultural waste, and their application was proven to be effective practices for promoting soil fertility. Arbuscular mycorrhizal (AM) fungi form symbiotic associations with most crop plant species, and are recognized as one group of the most important soil microorganisms to increase food security in sustainable agriculture. To understand the legacy effects of compost and biochar addition on AM fungal communities, a field study was conducted on the Songnen Plain, Northeast China. Two years after application, compost addition improved soil aggregate stability, but we did not detect a legacy effect of compost addition on AM fungal community. Our results indicated that AM fungal Shannon diversity and Pielou evenness indices were significantly increased by one-time biochar addition, but unaffected by compost addition after two year’s application. PERMANOVA analysis also revealed a legacy effect of biochar addition on AM fungal community. Network analysis revealed a dramatically simplified AM fungal co-occurrence network and small network size in biochar added soils, demonstrated by their topological properties (e.g., low connectedness and betweenness). However, AM fungal community did not differ among aggregate fractions, as confirmed by the PERMANOVA analysis as well as the fact that only a small number of AM fungal OTUs were shared among aggregate fractions. Consequently, the current study highlights a stronger legacy effect of biochar than compost addition on AM fungi, and have implications for agricultural practices.

Relationship between nitrifying microorganisms and other microorganisms residing in the maize rhizosphere

The microbial network of rhizosphere is unique as a result of root exudate. Insights into the relationship that exists with the energy metabolic functional groups will help in biofertilizer production. We hypothesize that there exists a relationship between nitrifying microorganisms and other energy metabolic functional microbial groups in the maize rhizosphere across different growth stages. Nucleospin soil DNA extraction kit was used to extract DNA from soil samples collected from maize rhizosphere. The 16S metagenomics sequencing was carried out on Illumina Miseq. The sequence obtained was analyzed on MG-RAST. Nitrospira genera were the most abundant in the nitrifying community. Nitrifying microorganisms were more than each of the studied functional groups except for nitrogen-fixing bacteria. Also, majority of the microorganisms were noticed at the fruiting stage and there was variation in the microbial structure across different growth stages. The result showed that there exists a substantial amount of both negative and positive correlation within the nitrifying microorganisms, and between them and other energy metabolic functional groups. The knowledge obtained from this study will help improve the growth and development of maize through modification of the rhizosphere microbial community structure.

Sustainable Intensification of Maize in the Industrial Revolution: Potential of Nitrifying Bacteria and Archaea

Sustainable intensification is a means that proffer a solution to the increasing demand for food without degrading agricultural land. Maize is one of the most important crops in the industrial revolution era, there is a need for its sustainable intensification. This review discusses the role of maize in the industrial revolution, progress toward sustainable production, and the potential of nitrifying bacteria and archaea to achieve sustainable intensification. The era of the industrial revolution (IR) uses biotechnology which has proven to be the most environmentally friendly choice to improve crop yield and nutrients. Scientific research and the global economy have benefited from maize and maize products which are vast. Research on plant growth-promoting microorganisms is on the increase. One of the ways they carry out their function is by assisting in the cycling of geochemical, thus making nutrients available for plant growth. Nitrifying bacteria and archaea are the engineers of the nitrification process that produce nitrogen in forms accessible to plants. They have been identified in the rhizosphere of many crops, including maize, and have been used as biofertilizers. This study's findings could help in the development of microbial inoculum, which could be used to replace synthetic fertilizer and achieve sustainable intensification of maize production during the industrial revolution.

Constraints and Prospects of Improving Cowpea Productivity to Ensure Food, Nutritional Security and Environmental Sustainability

Providing safe and secure food for an increasing number of people globally is challenging. Coping with such a human population by merely applying the conventional agricultural production system has not proved to be agro-ecologically friendly; nor is it sustainable. Cowpea (Vigna unguiculata (L) Walp) is a multi-purpose legume. It consists of high-quality protein for human consumption, and it is rich in protein for livestock fodder. It enriches the soil in that it recycles nutrients through the fixation of nitrogen in association with nodulating bacteria. However, the productivity of this multi-functional, indigenous legume that is of great value to African smallholder farmers and the rural populace, and also to urban consumers and entrepreneurs, is limited. Because cowpea is of strategic importance in Africa, there is a need to improve on its productivity. Such endeavors in Africa are wrought with challenges that include drought, salinity, the excessive demand among farmers for synthetic chemicals, the repercussions of climate change, declining soil nutrients, microbial infestations, pest issues, and so forth. Nevertheless, giant strides have already been made and there have already been improvements in adopting sustainable and smart biotechnological approaches that are favorably influencing the production costs of cowpea and its availability. As such, the prospects for a leap in cowpea productivity in Africa and in the enhancement of its genetic gain are good. Potential and viable means for overcoming some of the above-mentioned production constraints would be to focus on the key cowpea producer nations in Africa and to encourage them to embrace biotechnological techniques in an integrated approach to enhance for sustainable productivity. This review highlights the spectrum of constraints that limit the cowpea yield, but looks ahead of the constraints and seeks a way forward to improve cowpea productivity in Africa. More importantly, this review investigates applications and insights concerning mechanisms of action for implementing eco-friendly biotechnological techniques, such as the deployment of bio inoculants, applying climate-smart agricultural (CSA) practices, agricultural conservation techniques, and multi-omics smart technology in the spheres of genomics, transcriptomics, proteomics, and metabolomics, for improving cowpea yields and productivity to achieve sustainable agro-ecosystems, and ensuring their stability.