Changes in Acetylene Reduction Activities and nifH Genes Associated with Field-Grown Sweet Potatoes with Different Nursery Farmers and Cultivars

Itoh, Kazuhito; Ohashi, Keisuke; Yakai, Nao; Adachi, Fumihiko; Hayashi, Shinobu

doi:10.3390/horticulturae5030053

Cited by 4 publications

(2 citation statements)

References 23 publications

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“…The biological nitrogen fixation of plants, rather than by association with microorganisms, can generate crops that are less dependent on synthetic nitrogen fertilizers and can increase agricultural productivity and sustainability [ 50 ]. The sweet potato, the seventh largest food crop in the world [ 2 ], grows well in nitrogen-poor infertile soils, and it is believed that sweet potato endo- and epiphytic microorganisms play important roles in acting upon this growth ability in this plant [ 21 , 22 , 23 , 24 ]. Are these all the reasons?…”

Section: Discussionmentioning

confidence: 99%

“…The sweet potato, as a low-nitrogen-tolerant crop, grows well in nitrogen-poor infertile soils. Previous studies have shown that the growth ability of the sweet potato is partially due to the functions of diazotrophic growth-promoting bacteria that contain endo- and epiphytic microorganisms of this plant [ 21 , 22 , 23 , 24 ]. Various endophytic bacteria were isolated from sweet potatoes [ 18 ], such as Azospirillum sp.…”

Section: Introductionmentioning

confidence: 99%

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Genome-Wide Characterization of Nitrogenase Reductase (nifH) Genes in the Sweet Potato [Ipomoea batatas (L.) Lam] and Its Wild Ancestors

Wang

Zhao

et al. 2022

Genes

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The sweet potato (Ipomoea batatas (L.) Lam.) is an important and widely grown crop, and the nitrogenase reductase (nifH) gene is the most widely sequenced marker gene used to identify nitrogen-fixing bacteria and archaea. There have been many examples of the isolation of the diazotrophic endophytes in sweet potatoes, and there has been no report on whether sweet potatoes and their wild ancestors harbored nifH genes. In this study, a comprehensive analysis of nifH genes has been conducted on these species by using bioinformatics and molecular biology methods. A total of 20, 19 and 17 nifH genes were identified for the first time in sweet potatoes, I. trifida and I. triloba, respectively. Based on a phylogenetic analysis, all of the nifH genes, except for g10233.t1, itf14g14040.t1 and itb14g15470.t1, were clustered into five independent clades: I, II, III, IV and V. The nifH genes clustered in the same phylogenetic branch showed a more similar distribution of conserved motifs and exons–introns than those of the other ones. All of the identified genes were further mapped on the 15 chromosomes of the sweet potato, I. trifida and I. triloba. No segmental duplication was detected in each genome of three Ipomoea species, and 0, 8 and 7 tandemly duplicated gene pairs were detected in the genome of the sweet potato, I. trifida and I. triloba, respectively. Synteny analysis between the three Ipomoea species revealed that there were 7, 7 and 8 syntenic gene pairs of nifH genes detected between the sweet potato and I. trifida, between the sweet potato and I. triloba and between I. trifida and I. triloba, respectively. All of the duplicated and syntenic nifH genes were subjected to purifying selection inside duplicated genomic elements during speciation, except for the tandemly duplicated gene pair itf11g07340.t2_itf11g07340.t3, which was subjected to positive selection. Different expression profiles were detected in the sweet potato, I. trifida and I. triloba. According to the above results, four nifH genes of the sweet potato (g950, g16683, g27094 and g33987) were selected for quantitative real-time polymerase chain reaction (qRT-PCR) analysis in two sweet potato cultivars (Eshu 15 and Long 9) under nitrogen deficiency (N0) and normal (N1) conditions. All of them were upregulated in the N1 treatment and were consistent with the analysis of the RNA-seq data. We hope that these results will provide new insights into the nifH genes in the sweet potato and its wild ancestors and will contribute to the molecular breeding of sweet potatoes in the future.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Genome-Wide Characterization of Nitrogenase Reductase (nifH) Genes in the Sweet Potato [Ipomoea batatas (L.) Lam] and Its Wild Ancestors

Wang

Zhao

et al. 2022

Genes

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Endophytic N2 fixation in sweet potato: responses to N, P, and K inputs and visualization of 15N2 utilizing bacterial cells via Raman spectroscopy

Ueda

Yano

2023

Biol Fertil Soils

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Fertilizer-N strongly limits non-leguminous crop yields; however, sweet potato (Ipomoea batatas) is an exception, likely due to its ability to acquire atmospheric N2 via endophytic diazotrophs. Using Raman spectroscopy, we found that in 15N2-fed sweet potato, some endophytic bacteria contained 15N, providing direct evidence of N2 fixation in planta. To assess N2-fixing capability, pot experiments were conducted by varying N, P, and K fertilizer inputs. Sweet potato showed higher N content than the non-N2-fixing Ipomoea aquatica; additionally, it showed increased N content which was 1.4-fold higher than the fertilizer-N input. Its δ15N values were closer to those of N2-fixing soybean, with an estimated 11–56% of plant N derived from N2. The estimated amount of fixed-N in sweet potato was negligible without fertilizer-N; however, a gradual accumulation leading to an immediate saturation was observed with increasing fertilizer-N. During this state, increasing P supply linearly enhanced the capability, reaching 13 g N m−2, comparable to that of legumes. However, K inputs affected neither N2 fixation nor growth owing to strong K acquisition from the soil even without fertilizer-K. Our results indicate extensive N2 fixation in sweet potato, depending on its nutritional status, particularly P; resonance Raman spectroscopy facilitates the visualization of active N2-fixing bacteria on a single-cell scale.

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Effects of Inoculating the Diazotrophic Endophyte Bradyrhizobium sp. AT1 on Different Cultivars of Sweet Potato (Ipomoea batatas [L.] Lam.)

et al. 2023

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Owing to the worldwide shortage of nitrogen (N) fertilizers, diazotrophic endophytes have received increasing attention as biofertilizers. In this study, we investigated the inoculation effects of a diazotrophic endophyte (Bradyrhizobium sp. AT1) on three different cultivars of sweet potato (cvs. Beniazuma, Ayamurasaki, and Kokei No. 14) under pot, container, and different field conditions. Following inoculation, the root length was increased in cvs. Beniazuma and Ayamurasaki but suppressed in cv. Kokei No. 14 in pots, filled with a mixture of vermiculite, potting soil, and pearlite. AT1 inoculation also increased shoot growth in cv. Beniazuma and tuber formation in cv. Ayamurasaki in containers filled with vermiculite, potting soil, and light-colored Andosol. In field experiments, carried out at two field sites with the three cultivars, AT1 inoculation increased the growth of cvs. Beniazuma and Ayamurasaki, but it had almost no effect on cv. Kokei No. 14. In addition to growth promotion, inoculation of micropropagated sweet potato cv. Beniazuma with AT1 led to N derived from air (Ndfa) and acetylene reduction activity (ARA) five months after inoculation. Our studies indicate that AT1 inoculation can enhance the growth of sweet potato and promote N2 fixation.

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Changes in Acetylene Reduction Activities and nifH Genes Associated with Field-Grown Sweet Potatoes with Different Nursery Farmers and Cultivars

Cited by 4 publications

References 23 publications

Genome-Wide Characterization of Nitrogenase Reductase (nifH) Genes in the Sweet Potato [Ipomoea batatas (L.) Lam] and Its Wild Ancestors

Genome-Wide Characterization of Nitrogenase Reductase (nifH) Genes in the Sweet Potato [Ipomoea batatas (L.) Lam] and Its Wild Ancestors

Endophytic N2 fixation in sweet potato: responses to N, P, and K inputs and visualization of 15N2 utilizing bacterial cells via Raman spectroscopy

Effects of Inoculating the Diazotrophic Endophyte Bradyrhizobium sp. AT1 on Different Cultivars of Sweet Potato (Ipomoea batatas [L.] Lam.)

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