Transcriptome and Proteomics Analysis of Wheat Seedling Roots Reveals That Increasing NH4+/NO3– Ratio Induced Root Lignification and Reduced Nitrogen Utilization

Wheat growth and nitrogen (N) uptake gradually decrease in response to high NH4+/NO3– ratio. However, the mechanisms underlying the response of wheat seedling roots to changes in NH4+/NO3– ratio remain unclear. In this study, we investigated wheat growth, transcriptome, and proteome profiles of roots in response to increasing NH4+/NO3– ratios (Na: 100/0; Nr1: 75/25, Nr2: 50/50, Nr3: 25/75, and Nn: 0/100). High NH4+/NO3– ratio significantly reduced leaf relative chlorophyll content, Fv/Fm, and ΦII values. Both total root length and specific root length decreased with increasing NH4+/NO3– ratios. Moreover, the rise in NH4+/NO3– ratio significantly promoted O2– production. Furthermore, transcriptome sequencing and tandem mass tag-based quantitative proteome analyses identified 14,376 differentially expressed genes (DEGs) and 1,819 differentially expressed proteins (DEPs). The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis indicated that glutathione metabolism and phenylpropanoid biosynthesis were the main two shared enriched pathways across ratio comparisons. Upregulated DEGs and DEPs involving glutathione S-transferases may contribute to the prevention of oxidative stress. An increment in the NH4+/NO3– ratio induced the expression of genes and proteins involved in lignin biosynthesis, which increased root lignin content. Additionally, phylogenetic tree analysis showed that both A0A3B6NPP6 and A0A3B6LM09 belong to the cinnamyl-alcohol dehydrogenase subfamily. Fifteen downregulated DEGs were identified as high-affinity nitrate transporters or nitrate transporters. Upregulated TraesCS3D02G344800 and TraesCS3A02G350800 were involved in ammonium transport. Downregulated A0A3B6Q9B3 is involved in nitrate transport, whereas A0A3B6PQS3 is a ferredoxin-nitrite reductase. This may explain why an increase in the NH4+/NO3– ratio significantly reduced root NO3–-N content but increased NH4+-N content. Overall, these results demonstrated that increasing the NH4+/NO3– ratio at the seedling stage induced the accumulation of reactive oxygen species, which in turn enhanced root glutathione metabolism and lignification, thereby resulting in increased root oxidative tolerance at the cost of reducing nitrate transport and utilization, which reduced leaf photosynthetic capacity and, ultimately, plant biomass accumulation.

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The Effect of Salicylic Acid on Resistance in Wheat (Triticum aestivum) Seedling Roots Against the Take-All Fungus, Gaeumannomyces graminis var tritici

Australian Journal of Botany ◽

10.1071/bt9960499 ◽

1996 ◽

Vol 44 (4) ◽

pp. 499 ◽

Cited By ~ 9

Author(s):

S Seah ◽

K Sivasithamparam ◽

DW Turner

Keyword(s):

Triticum Aestivum ◽

Salicylic Acid ◽

Wheat Seedling ◽

Triticum Aestivum L ◽

Gaeumannomyces Graminis ◽

Resistance Response ◽

Wheat Seedlings ◽

Seedling Roots ◽

Wheat Seedling Roots ◽

Take All

The effect of salicylic acid (SA) applied as foliar dip, foliar wipe, root drench or pre-germination soak on the susceptibility of wheat (Triticum aestivum L.) seedlings to Gaeumannomyces graminis (Sacc.) Arx & Olivier var. tritici Walker (take-all fungus, Ggt) was studied. It was hypothesised that an increase in SA concentration applied using these methods would increase the resistance in wheat seedling roots against Ggt. Leaves (by foliar wipe and foliar dip) and roots (by root drench) of 1-2-week-old wheat seedlings grown in Lancelin sand, were treated with 0, 0.1 or 1 mM SA, and treatments of 0, 0.1 or 0.5 mM SA were applied in a pre-germination soak method. Ggt infection reduced (P Ͱ4 0.05) chlorophyll content and concentration and root length (P Ͱ4 0.10). Experiments that were conducted suggested that the SA treatments failed to induce a resistance response because they did not stimulate phenylalanine ammonia-lyase and peroxidase activities in the wheat seedling roots. Therefore, SA applied using these methods was not effective in reducing the susceptibility of wheat seedlings to Ggt. The chemical or biological induction of resistance in plant roots and its applicability as a root disease control strategy requires further clarification.

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Study of the Effect of Azospirillum Lectins on the Formation of Hydrogen Peroxide in Wheat Seedling Roots

Izvestiya of Saratov University New Series Series Chemistry Biology Ecology ◽

10.18500/1816-9775-2012-12-4-56-63 ◽

2012 ◽

Vol 12 (4) ◽

pp. 56-63

Author(s):

S. A. Alen’kina ◽

◽

K. A. Trutneva ◽

V. А. Velikov ◽

V. E. Nikitina ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Azospirillum Brasilense ◽

Wheat Seedling ◽

Oxalate Oxidase ◽

Lectin Activity ◽

Production Of Hydrogen ◽

Seedling Roots ◽

Azospirillum Brasilense Sp7 ◽

Wheat Seedling Roots ◽

Adaptation Processes

We show that the lectins isolated from the surface of the nitrogenfixing soil bacterium Azospirillum brasilense Sp7 and its mutant defective in lectin activity, A. brasilense Sp7.2.3., can regulate the production of hydrogen peroxide in wheat seedling roots, which is associated with the activation of superoxide dismutase, peroxidase and oxalate oxidase, as well as with the inhibition of catalase activity. We show that activation of oxalate oxidase is the most rapidly inducible pathway for the formation of hydrogen peroxide in wheat seedling roots under the effect of lectins. The obtained data indicate that the Azospirillum lectins can act as inducers of adaptation processes in wheat seedling roots.

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