RESUMO
Nectar is one of the key rewards mediating plant-mutualist interactions. In addition to sugars, nectars often contain many other compounds with important biological functions, including proteins. This study was undertaken to assess the proteinaceous content of Brassica rapa nectar. SDS-PAGE analysis of raw B. rapa nectar revealed the presence of ~10 proteins, with a major band at ~10 kDa. This major band was found to contain a non-specific lipid transfer protein encoded by B. rapa locus Bra028980 and subsequently termed BrLTP2.1. Sequence analysis of BrLTP2.1 predicted the presence of a signal peptide required for secretion from the cell, eight cysteines, and a mature molecular mass of 7.3 kDa. Constitutively expressed BrLTP2.1-GFP in Arabidopsis displayed accumulation patterns consistent with secretion from nectary cells. BrLTP2.1 was also found to have relatively high sequence similarity to non-specific lipid-transfer proteins with known functions in plant defense, including Arabidopsis DIR1. Heterologously expressed and purified BrLTP2.1 was extremely heat stable and bound strongly to saturated free fatty acids, but not methyl jasmonate. Recombinant BrLTP2.1 also had direct antimicrobial activity against an extensive range of plant pathogens, being particularly effective against necrotrophic fungi. Taken together, these results suggest that BrLTP2.1 may function to prevent microbial growth in nectars.
Assuntos
Antifúngicos/química , Brassica rapa/genética , Proteínas de Transporte/genética , Néctar de Plantas/química , Proteínas de Plantas/genética , Sequência de Aminoácidos , Brassica rapa/metabolismo , Proteínas de Transporte/metabolismo , Filogenia , Proteínas de Plantas/metabolismoRESUMO
The PIN family of proteins is best known for its involvement in polar auxin transport and tropic responses. PIN6 (At1g77110) is one of the remaining PIN family members in Arabidopsis thaliana to which a biological function has not yet been ascribed. Here we report that PIN6 is a nectary-enriched gene whose expression level is positively correlated with total nectar production in Arabidopsis, and whose function is required for the proper development of short stamens. PIN6 accumulates in internal membranes consistent with the ER, and multiple lines of evidence demonstrate that PIN6 is required for auxin-dependent responses in nectaries. Wild-type plants expressing auxin-responsive DR5:GFP or DR5:GUS reporters displayed intense signal in lateral nectaries, but pin6 lateral nectaries showed little or no signal for these reporters. Further, exogenous auxin treatment increased nectar production more than tenfold in wild-type plants, but nectar production was not increased in pin6 mutants when treated with auxin. Conversely, the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA) reduced nectar production in wild-type plants by more than twofold, but had no significant effect on pin6 lines. Interestingly, a MYB57 transcription factor mutant, myb57-2, closely phenocopied the loss-of-function mutant pin6-2. However, PIN6 expression was not dependent on MYB57, and RNA-seq analyses of pin6-2 and myb57-2 mutant nectaries showed little overlap in terms of differentially expressed genes. Cumulatively, these results demonstrate that PIN6 is required for proper auxin response and nectary function in Arabidopsis. These results also identify auxin as an important factor in the regulation of nectar production, and implicate short stamens in the maturation of lateral nectaries.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Ácidos Indolacéticos/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Fatores de Transcrição/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Transporte Biológico , Flores/efeitos dos fármacos , Flores/genética , Flores/crescimento & desenvolvimento , Flores/metabolismo , Genes Reporter , Homeostase , Ácidos Indolacéticos/farmacologia , Proteínas de Membrana Transportadoras/genética , Mutagênese Insercional , Fenótipo , Reguladores de Crescimento de Plantas/farmacologia , Néctar de Plantas/metabolismo , Regiões Promotoras Genéticas , Fatores de Transcrição/genéticaRESUMO
PURPOSE: To evaluate whether the postponement of dental elective procedures at the start of the COVID-19 pandemic was associated with an increased number of simple dental extractions, and/or decreased restorative procedures by analyzing data obtained from state-funded insurance dental claims. METHODS: Paid dental claims collected from March 2019 to December 2019 and from March 2020 to December 2020 for children ages two to 13 years old were analyzed. Dental procedures were selected based on Current Dental Terminology (CDT) codes for simple dental extractions and restorative procedures. Statistical analyses were performed to compare the rates of procedure types between 2019 and 2020. RESULTS: No differences in dental extractions but full-coverage restoration procedure rates per month and child were significantly lower than pre-pandemic (P=0.016). CONCLUSION: Further study required to determine the impact of COVID-19 on pediatric restorative procedures and access to pediatric dental care in the surgical setting.