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The sugars-will-eventually-be-exported-transporters (SWEET) family is a newly characterized group of sugar transporters, which plays an important role in diverse biological processes, including plant growth, development, and response to abiotic and biotic stresses. SWEET family genes, known as SWEETs, have been characterized in many plant species, but a comprehensive analysis has not been performed on citrus. Here, 27 citrus SWEET genes (CitSWEETs) were identified through homology searches. The phylogenetic relationship, transmembrane helices (TMHs), gene distribution, and gene structure were then investigated. Furthermore, the expression patterns of 27 CitSWEETs were examined in several tissues and under different abiotic stresses. The data revealed that CitSWEET1, CitSWEET2, CitSWEET3, CitSWEET4, CitSWEET7, CitSWEET25, and CitSWEET27 were tissue-specific, and others were ubiquitously expressed. Among 27 genes tested, some members were sensitive to abiotic stress or hormone stimuli, and CitSWEET3 transported glucose in EMY4000 yeast strain. In conclusion, we performed the first comprehensive analysis of the CitSWEET gene family in citrus, which can provide useful information to further analyze their potential roles. [ABSTRACT FROM AUTHOR]

As a novel characteristic sugar transporter group, the sugars-will-eventually-be-exported-transporters (SWEETs) play important roles in plant growth and development and responses to biotic and abiotic stresses. A comprehensive analysis of SWEETs has been performed in a large number of plant species, but has not been done in citrus. In this study, a total of 27 citrus SWEET genes (CitSWEETs) were identified by homology search, then which expression patterns in response to Huanglongbing (HLB) desease and oxytetracycline (OTC) were analyzed. Our data revealed that the expressions of CitSWEET1 and CitSWEET5 were suppressed in severely HLB-infected leaves, whereas CitSWEET2, CitSWEET3, CitSWEET4, CitSWEET7, CitSWEET8, CitSWEET9, CitSWEET10, CitSWEET12, CitSWEET13, CitSWEET14, CitSWEET15, CitSWEET18, CitSWEET20, CitSWEET21, CitSWEET22, CitSWEET23, CitSWEET24, CitSWEET25 and CitSWEET27 expressions were induced. At 30 d after OTC trunk injection, the expressions of 11 CitSWEET genes, especially CitSWEET2, were strongly inhibited. In addition, genetic relationships of the CitSWEET genes in sweet oranges (Citrus sinesis) and clementines (Citrus clementina) were also analyzed. Taken together, our work provided a basis for breeding with molecular resistance to HLB disease. [ABSTRACT FROM AUTHOR]

The sugars-will-eventually-be-exported-transporters (SWEET) family is a newly characterized group of sugar transporters, which plays an important role in diverse biological processes, including plant growth, development, and response to abiotic and biotic stresses. SWEET family genes, known as SWEETs, have been characterized in many plant species, but a comprehensive analysis has not been performed on citrus. Here, 27 citrus SWEET genes (CitSWEETs) were identified through homology searches. The phylogenetic relationship, transmembrane helices (TMHs), gene distribution, and gene structure were then investigated. Furthermore, the expression patterns of 27 CitSWEETs were examined in several tissues and under different abiotic stresses. The data revealed that CitSWEET1, CitSWEET2, CitSWEET3, CitSWEET4, CitSWEET7, CitSWEET25, and CitSWEET27 were tissue-specific, and others were ubiquitously expressed. Among 27 genes tested, some members were sensitive to abiotic stress or hormone stimuli, and CitSWEET3 transported glucose in EMY4000 yeast strain. In conclusion, we performed the first comprehensive analysis of the CitSWEET gene family in citrus, which can provide useful information to further analyze their potential roles. [ABSTRACT FROM AUTHOR]