Maria Daniela Artigas Ramirez

Soybeans have been cultivated in Poland for more than 140 years. However, Poland’s cold and water-deficient climatic conditions hinder soybean cultivation. Although the availability of suitable soybean varieties in Poland contributes to meeting the demand for soybean production, it is important to identify rhizobial inoculants in Polish soils suitable for soybean cultivation. In this study, we cultivated soybean varieties (Abelina, Merlin, and Sultana) grown in soils taken from four regions in Poland and isolated 330 strains from soybean root nodules. 16S rRNA gene sequencing identified 49 strains of highly stress-tolerant nodule-associated bacteria, including Bradyrhizobium, Rhizobium, Ensifer, Tardiphaga, and Ralstonia spp. Several isolates exhibited positive effects on soybean growth under cold and water-deficient conditions. In particular, the isolate Bradyrhizobium japonicum PSN49, which is phylogenetically similar to B. japonicum USDA 123, increased plant biomass and nodule formation in the soybean cultivar Abelina under abiotic stress conditions due to its high nitrogen-fixing activity. Whole-genome comparisons between PSN49 and other Bradyrhizobium strains revealed that trehalose biosynthesis genes and cold shock proteins contributed to cold stress tolerance. These findings and the strains identified in this study will enhance soybean production and deepen the understanding of the soybean–rhizobium relationship in Poland.

Habenaria and Liparis are well-known orchid genera that grow in terrestrial habitats in the tropics, subtropics or temperate zones. Three species have been found in subtropical regions of China, inhabiting terrestrial to epiphytic habitats. This study focuses on three species, H. dentata (distributed in Asia), H. yachangensis, and L. gigantea. For H. yachangensis and L. gigantea, there is no information about the mycorrhizal community in these species. This study aims to conduct the fungal community screening of Chinese ground orchids from subtropical regions. We performed a comparative analysis of the fungal community among H. dentata, H. yachangensis, and L. gigantea, determining their ITS regions using NGS paired-end sequences. The results clarified the diversity and the predominance of fungal genera. Ascomycota was abundant compared to Basidiomycota or other fungi groups in all communities, with a high dominance in all populations, especially for L. gigantea. At different root spatial locations, the fungal community diversity and richness were higher in the soil than in the rhizosphere or inner root. However, the results suggest that L. gigantea has a different fungal community compared to Habenaria species. In this order, the subtropical terrestrial orchids have a different fungal network compared to the northern terrestrial orchids. Also, there is a high probability of co-existence and co-evolution of endophytic fungi in these terrestrial orchids, indicating the potential role of host plants in selecting an endophytic fungal community. Furthermore, our results highlight the need to elucidate the microbe interactions of these unique orchids for long-term purposes, such as isolating indigenous fungi for suitable inoculants for further orchid propagation, restoration, and conservation.

Many abiotic factors have affected symbiosis effectiveness. However, the responses and interactions vary depending on the plant host, environmental factors, and symbiotic strains. The effect of various environmental factors on the competitiveness of rhizobial strains in host legumes has been examined, but many questions are still unresolved. For example, in the Rhizobia-legume symbiosis, the nitrogen fixation and nodulation processes are strongly related to the physiological state of the host plant. Therefore, a competitive and persistent rhizobial strain is not expected to express its total capacity for nitrogen fixation under limiting factors (e.g., salinity, unfavorable soil pH, nutrient deficiency, mineral toxicity, extreme temperatures, soil moisture problems, and inadequate photoperiods). Moreover, populations of rhizobial species vary in their tolerance to major environmental factors. Furthermore, this chapter emphasizes the studies on symbiosis under abiotic stress and its challenges. Additionally, this can help to understand and establish an effective biological process for improvement in agricultural productivity.

Species detection using environmental DNA (eDNA) is a biomonitoring tool that can be widely applied to mangrove restoration and management. Compared to traditional surveys that are taxa-specific and time-consuming, eDNA metabarcoding offers a rapid, non-invasive and cost-efficient method for monitoring mangrove biodiversity and characterising the spatio-temporal distribution of multiple taxa simultaneously. General guidelines for eDNA metabarcoding are well-established for aquatic systems, but habitat-specific guidelines are still lacking. Mangrove habitats, as priority ecosystems for restoration in Southeast Asia, present unique prospects and challenges in these regards. Environmental DNA metabarcoding can be used to (1) track functional recovery in ecological restoration, (2) prioritise conservation areas, (3) provide early warning for threats, (4) monitor threatened taxa, (5) monitor response to climate change, and (6) support community-based restoration. However, these potential applications have yet been realized in Southeast Asia due to (1) technical challenges, (2) lack of standardised methods, (3) spatio-temporal difficulties in defining community, (4) data limitations, and (5) lack of funding, infrastructure and technical capacity. Successful implementation of eDNA metabarcoding in mangrove restoration activities would encourage the development of data-driven coastal management and equitable conservation programs. Eventually, this would promote Southeast Asia’s shared regional interests in food security, coastal defence and biodiversity conservation.

Biofertilizers are agricultural materials capable of reducing the usage amounts of chemical fertilizers. Spore-forming microorganisms (SFM) could be used for plant growth promotion or to improve plant health. Until now, biofertilizers based on SFM have been applied for rice and other crops. In this study, we isolated and characterized SFM, which were colonized on the Oryza sativa L. roots. SFM were analyzed regarding the short-term effects of biofertilization on the nursery growths. Analysis was performed without nitrogen or any inorganic fertilizer and was divided into two groups, including bacteria and fungi. SF-bacteria were dominated by the Firmicutes group, including species from Viridibacillus, Lysinibacillus, Solibacillus, Paenibacillus, Priestia, and mainly Bacillus (50%). The fungi group was classified as Mucoromycota, Basidiomycota, and mainly Ascomycota (80%), with a predominance of Penicillium and Trichoderma species. In plant performance in comparison with B. pumilus TUAT1, some bacteria and fungus isolates significantly improved the early growth of rice, based on 48 h inoculum with 10⁷ CFU mL⁻¹. Furthermore, several SFM showed positive physiological responses under abiotic stress or with limited nutrients such as phosphorous (P). Moreover, the metabolic fingerprint was obtained. The biofertilizer based on SFM could significantly reduce the application of the inorganic fertilizer and improve the lodging resistances of rice, interactively enhancing better plant health and crop production.

Bacillus pumilus strain TUAT1 is a plant growth-promoting bacterium (PGPB) applied as a biofertilizer, containing its spores, for rice. In this study, we analyzed the short-term effects of biofertilization on plant growth in the nursery and long-term effects on plant vegetative growth, yield, and lodging resistance in paddy fields using animal feed rice (‘Fukuhibiki’ and line LTAT-29 which was recently officially registered as a cultivar ‘Monster Nokodai 1′) and fodder rice (line TAT-26). The effects of the biofertilization were analyzed under two nitrogen treatments and at two transplanting distances in the field. The application of 10⁷ colony forming units (CFU) mL⁻¹ bacterial spore solution to seeds on plant box significantly improved the initial growth of rice. The biofertilizer treatment with this strain at 10⁷ CFU g⁻¹ onto seeds in nursery boxes increased the nitrogen uptake at the early growth of rice in the field, resulting in higher growth at the late vegetative growth stage (e.g., tiller number and plant height). Furthermore, the improvement of growth led to increases of not only yield components such as the total panicle number (TPN) and the number of spikelets in a panicle (NSP) in LTAT-29 but also the straw yield and quality of TAT-26. The lodging resistances of these forage rice plants were also improved due to the increased root development and photosynthesis creating tougher culms.

In rice production, early growth is often slow in direct‐seeded system. Techniques to overcome this barrier are needed. This study evaluated the effectiveness of Kikuichi—a biofertilizer containing Bacillus pumilus TUAT1 spore—in promoting rice growth in a direct‐sowing system. Oxygen, iron, and molybdenum as coating materials were also evaluated to combine with biofertilizer. The seeds were coated with powdered Kikuichi with polyvinyl alcohol followed by a coating with calcium peroxide (CALPER), molybdenum (Benmoly), and iron powder. Double coating with the biofertilizer and Benmoly promoted plant growth. We applied amounts of Kikuichi equivalent to one, two and a half, and five times the weight of the seeds and found that the growth‐promoting effect was dependent on the amount applied. The best timing of application of the coating, specifically during sprouting, was before the coleoptile emerged. Bacillus pumilus TUAT1 can enhance the growth of rice when it exists in high concentration on the spermosphere by coating with molybdenum, but double coating with neither calcium peroxide nor iron powder contributed to the initial growth of the seeds. Kikuichi coating with Benmoly has positive effects on the rice growth. This coating method is suitable to apply biofertilizer for direct sowing cultivation of rice.

Aluminum (Al) toxicity is a major problem affecting soil fertility, microbial diversity, and nutrient uptake of plants. Rhizobia response and legume interaction under Al conditions are still unknown; it is important to understand how to develop and improve legume cultivation under Al stress. In this study, rhizobia response was recorded under different Al concentrations. Al effect on rhizobial cells was characterized by combination with different two pH conditions. Symbiosis process was compared between α- and β-rhizobia inoculated onto soybean varieties. Rhizobial cell numbers was decreased as Al concentration increased. However, induced Al tolerance considerably depended on rhizobia types and their origins. Accordingly, organic acid results were in correlation with growth rate and cell density which suggested that citric acid might be a positive selective force for Al tolerance and plant interaction on rhizobia. Al toxicity delayed and interrupted the plant–rhizobia interaction and the effect was more pronounced under acidic conditions. Burkholderia fungorum VTr35 significantly improved plant growth under acid–Al stress in combination with all soybean varieties. Moreover, plant genotype was an important factor to establish an effective nodulation and nitrogen fixation under Al stress. Additionally, tolerant rhizobia could be applied as an inoculant on stressful agroecosystems. Furthermore, metabolic pathways have still been unknown under Al stress.

Antecedentes y Objetivos: Las especies de Meliaceae son extremadamente recalcitrantes durante la germinación y en los procesos in vitro. Por lo tanto, este estudio está enfocado en caracterizar y optimizar un sistema altamente eficiente de propagación a través de embriogénesis somática secundaria en Azadirachta indica, paso importante para la producción de metabolitos secundarios, la propagación o regeneración de estas especies recalcitrantes.Materiales y Métodos: Las secciones de hojas y cotiledones fueron inducidos en medio MS suplementado con bencil-aminopurina (BAP) sola o combinada con ácido 1-naftalenacético (NAA) y ácido abscísico (BA) con tidiazuron (TDZ).Resultados clave: Azadirachta indica desarrolla embriones somáticos primarios con BAP. La formación de tallos y raíces ocurre en bajas concentraciones de BAP, mientras la embriogénesis somática es favorecida a altos niveles de BAP o TDZ. Los embriones somáticos primarios y secundarios fueron evidenciados continuamente y sincrónicamente o asincrónicamente. Una gran cantidad de embriones somáticos fueron obtenidos con citoquininas. Sin embargo, la concentración tiene un rol importante en la diferenciación entre embriones primarios y secundarios. Además, las auxinas son la clave para inducir la histo-diferenciación en los embriones. La inducción de tallo ocurrió después de que los embriones somáticos se transfirieron a un medio libre de hormonas (MS). Estos tallos fueron enraizados con MS1/2.Conclusiones: Los embriones somáticos secundarios fueron distinguidos y caracterizados durante todo el proceso y el sistema fue establecido con segmentos de cotiledones en corto tiempo; esto ofrece oportunidades ventajosas como la producción de metabolitos.