Transcriptome analysis reveals multiple effects of nitrogen accumulation and metabolism in the roots, shoots, and leaves of potato (Solanum tuberosum L.).

BACKGROUND: Nitrogen (N) is a major element and fundamental constituent of grain yield. N fertilizer plays an essential role in the roots, shoots, and leaves of crop plants. Here, we obtained two N-sensitive potato cultivars. RESULTS: The plants were cultivated in the pots using N-deficient and N-sufficient conditions. Crop height, leaf chlorophyll content, dry matter, and N-accumulation significantly decreased under N-deficient conditions. Furthermore, we performed a comprehensive analysis of the phenotype and transcriptome, GO terms, and KEGG pathways. We used WGCNA of co-expressed genes, and 116 differentially expressed hub genes involved in photosynthesis, nitrogen metabolism, and secondary metabolites to generate 23 modules. Among those modules, six NRT gene families, four pigment genes, two auxin-related genes, and two energy-related genes were selected for qRT-PCR validation. CONCLUSIONS: Overall, our study demonstrates the co-expressed genes and potential pathways associated with N transport and accumulation in potato cultivars' roots, shoots, and leaves under N-deficient conditions. Therefore, this study provides new ideas to conduct further research on improving nitrogen use efficiency in potatoes.

AetMYC1, the Candidate Gene Controlling the Red Coleoptile Trait in Aegilops tauschii Coss. Accession As77.

The red coleoptile trait can help monocotyledonous plants withstand stresses, and key genes responsible for the trait have been isolated from Triticum aestivum, Triticum urartu, and Triticum monococcum, but no corresponding research has been reported for Aegilops tauschii. In this research, transcriptome analysis was performed to isolate the candidate gene controlling the white coleoptile trait in Ae. tauschii. There were 5348 upregulated, differentially-expressed genes (DEGs) and 4761 downregulated DEGs in red coleoptile vs. white coleoptile plants. Among these DEGs, 12 structural genes and two transcription factors involved in anthocyanin biosynthesis were identified. The majority of structural genes showed lower transcript abundance in the white coleoptile of accession 'As77' than in the red coleoptile of accession 'As60', which implied that transcription factors related to anthocyanin biosynthesis could be the candidate genes. The MYB and MYC transcription factors AetMYB7D and AetMYC1 were both isolated from Ae. tauschii accessions 'As60' and 'As77', and their transcript levels analyzed. The coding sequence and transcript level of AetMYB7D showed no difference between 'As60' and 'As77'. AetMYC1p encoded a 567-amino acid polypeptide in 'As60' containing the entire characteristic domains, bHLH-MYC_N, HLH, and ACT-like, belonging to the gene family involved in regulating anthocyanin biosynthesis. AetMYC1w encoded a 436-amino acid polypeptide in 'As77' without the ACT-like domain because a single nucleotide mutation at 1310 bp caused premature termination. Transient expression of AetMYC1p induced anthocyanin biosynthesis in 'As77' with the co-expression of AetMYB7D, while AetMYC1w could not cause induced anthocyanin biosynthesis under the same circumstances. Moreover, the transcript abundance of AetMYC1w was lower than that of AetMYC1p. AetMYC1 appears to be the candidate gene controlling the white coleoptile trait in Ae. tauschii, which can be used for potential biotech applications, such as producing new synthetic hexaploid wheat lines with different coleoptile colors.

Genome-wide identification and expression analysis of the StSWEET family genes in potato (Solanum tuberosum L.).

BACKGROUND: The sugar will eventually be exported transporter (SWEET) family is a novel type of membrane-embedded sugar transporter that contains seven transmembrane helices with two MtN3/saliva domains. The SWEET family plays crucial roles in multiple processes, including carbohydrate transportation, development, environmental adaptability and host-pathogen interactions. Although SWEET genes, especially those involved in response to biotic stresses, have been extensively characterized in many plants, they have not yet been studied in potato. OBJECTIVE: The identification of StSWEET genes provides important candidates for further functional analysis and lays the foundation for the production of good quality and high yield potatoes through molecular breeding. METHODS: In this study, StSWEET genes were identified using a genome-wide search method. A comprehensive analysis of StSWEET family through bioinformatics methods, such as phylogenetic tree, gene structure and promoter prediction analysis. The expression profiles of StSWEET genes in different potato tissues and under P. infestans attack and sugar stress were studied using quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS: Phylogenetic analysis classified 33 StSWEET genes into four groups containing 12, 5, 12 and 4 genes. Furthermore, the gene structures and conserved motifs found that the StSWEET genes are very conservative during evolution. The chromosomal localization pattern showed that the distribution and density of the StSWEETs on 10 potato chromosomes were uneven and basically clustered. Predictive promoter analysis indicated that StSWEET proteins are associated with cell growth, development, secondary metabolism, and response to biotic and abiotic stresses. Finally, the expression patterns of the StSWEET genes in different tissues and the induction of P. infestans and the process of the sugar stress were investigated to obtain the tissue-specific and stress-responsive candidates. CONCLUSION: This study systematically identifies the SWEET gene family in potato at the genome-wide level, providing important candidates for further functional analysis and contributing to a better understanding of the molecular basis of development and tolerance in potato.

Starch synthesis and gelatinization properties of potato tubers / Síntese de amido e propriedades de gelatinização de tubérculos de batata com diferentes teores de amido

Biosynthesis is the only source of potato starch which is an important raw material for food processing, modified starch and biomass energy. However, it is not clear about the evolution of starch synthesis with tuber development in potato. The present study evaluated the differences of starch synthesis and gelatinization properties of potato tubers with different starch content. Relative to cultivars of medium and low starch content, cultivars of high starch content showed significantly higher SBEII gene expression, AGPase and SSS enzyme activity, and total starch content after middle stage of starch accumulation, and had smaller average starch granule size during whole process of tuber development, and had higher pasting temperature before late stages of tuber growth, and had lower pasting temperature after middle stage of starch accumulation. Path analysis showed that, after middle stage of starch accumulation, effects on starch gelatinization of cultivars with high, medium and low starch content represented starch synthesis enzyme activity > starch accumulation > starch granule distribution > starch synthesis enzyme gene expression, starch synthesis enzyme gene expression > starch synthesis enzyme activity > starch accumulation > starch granule distribution, starch synthesis enzyme gene expression > starch granule distribution > starch synthesis enzyme activity > starch accumulation, respectively. In the study, phases existed in the starch biosynthesis of potato tuber, and the starch quality and its formation process were different among varieties with different starch content. The findings might contribute to starch application and potato industries.

A biossíntese é a única fonte de amido de batata que é uma importante matéria-prima para o processamento de alimentos, amido modificado e energia de biomassa. No entanto, não está claro sobre a evolução da síntese do amido com o desenvolvimento do tubérculo na batata. O presente estudo teve como objetivo avaliar as diferenças nas propriedades de síntese e gelatinização do amido de tubérculos de batata com diferentes teores de amido. Em relação às cultivares de médio e baixo teor de amido, as cultivares de alto teor de amido apresentaram expressão do gene SBEII, atividade enzimática AGPase e SSS e teor de amido total significativamente maiores após o estágio intermediário de acúmulo de amido, bem como menor tamanho médio dos grânulos de amido durante todo o processo de desenvolvimento do tubérculo, maior temperatura de colagem antes dos estágios finais de crescimento do tubérculo e menor temperatura de colagem após o estágio intermediário de acúmulo de amido. A análise de trilha mostrou que, após o estágio intermediário de acúmulo de amido, os efeitos na gelatinização do amido de cultivares com alto, médio e baixo teor de amido representaram a atividade da enzima de síntese de amido> acúmulo de amido> distribuição de grânulos de amido> expressão gênica de enzima de síntese de amido; expressão gênica de enzima de síntese de amido > atividade da enzima de síntese de amido> acúmulo de amido> distribuição de grânulos de amido; expressão gênica da enzima de síntese de amido> distribuição de grânulos de amido> atividade de síntese de amido> acúmulo de amido, respectivamente. No estudo, as fases existentes na biossíntese do amido do tubérculo de batata, e a qualidade do amido e seu processo de formação foram diferentes entre as variedades com diferentes teores de amido. As descobertas podem contribuir para a aplicação de amido e as indústrias de batata.