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Abstract(s)
A parte área das plantas (filosfera) é colonizada por uma comunidade microbiana diversa, que pode crescer tanto epifiticamente na superfície dos órgãos como endofiticamente no interior dos tecidos. Estes microrganismos contribuem para uma melhoria do crescimento e da saúde das plantas. A maioria dos trabalhos relacionados com a microbiologia da filosfera foi realizada nas folhas, sendo os frutos muito pouco estudados. Neste trabalho foi avaliada, pela primeira vez, a diversidade da comunidade microbiana endofítica e epifítica associada a azeitonas de três cultivares Portuguesas (Madural, Cobrançosa e Verdeal Transmontana). A influência da cultivar na comunidade microbiana presente no fruto foi igualmente avaliada. As bactérias e os fungos foram isolados de azeitonas em meio de cultura batata dextrose agar e agar padrão para contagem, respectivamente, e os isolados obtidos foram identificados por sequenciação da região 16S (para bactérias) e ITS (para fungos) dos genes RNAr. Um total de 270 isolados (122 bactérias, 151 fungos filamentosos) pertencentes a 41 taxa (6 bactérias, 35 fungos filamentosos) foram isolados a partir das azeitonas das três cultivares. No geral, a comunidade epifítica foi mais diversa (35 taxa) e abundante (227 isolados) face à comunidade endofítica (13 taxa, 43 isolados). Em ambas as comunidades a espécie mais abundante foi a bactéria sp. 6, cuja identificação não foi possível de efectuar, seguida pelos fungos Davidiella tassiana e Penicillium expansum ao nível dos epifíticos, ou por Pyronema domesticum e Fusarium lateritium ao nível dos endofíticos. As duas comunidades apresentaram uma reduzida similaridade ao nível da composição de espécies, com um índice de Sørensen de 0,260. A cultivar demonstrou influenciar a estrutura da comunidade microbiana. A diversidade e a riqueza de fungos endófitos foram superiores nas azeitonas das cvs. Verdeal Transmontana (5 taxa, 12 isolados) e Madural (5 taxa, 10 isolados); enquanto que nos endófitos foi superior nas azeitonas das cvs. Cobrançosa (16 taxa, 32,68 ufc/cm2) e Madural (13 taxa, 32,88 ufc/cm2). A frequência de colonização pelos fungos endofíticos foi superior nas azeitonas das cvs. Verdeal Transmontana e Madural (17% cada), e a colonização por bactérias foi superior nas azeitonas das cvs. Cobrançosa (10%) e Madural (8%). Os resultados indicam que tanto as propriedades do habitat (endófito vs. epífito) como a cultivar são importantes na determinação da estrutura e da diversidade da comunidade bacteriana e fúngica associada às azeitonas.
The above-ground parts of plants (phyllosphere) harbor a diverse microbial community, both as epiphytes on the plant surface and within plant tissues as endophytes, that play a crucial role for plant health and growth. Much of the work on phyllosphere microbiology has been focused on leaves, whereas fruits have been rarely studied. In this work the diversity of endophytic and epiphytic microbial community associated with olive fruit of three Portuguese cultivars (Madural, Cobrançosa and Verdeal Transmontana) was assessed for the first time. The effect of plant cultivar on microbial community inhabiting olive fruit was also evaluated. Bacteria and fungi were isolated from fresh olive fruits in plate count agar and in potato dextrose agar medium, respectively, and the isolates obtained were identified by sequencing the 16S (for bacteria) and the ITS region (for fungi) of rRNA genes. A total of 270 isolates (122 bacteria, 151 filamentous fungi) belonging to 41 taxa (6 bacteria, 35 filamentous fungi) were isolated from olives of the three cultivars. Overall, the epiphytic community was most diverse (35 taxa) and rich (227 isolates) than endophytic community (13 taxa, 43 isolates). In both communities the specie most abundant was the unidentified bacteria sp. 6, followed by Davidiella tassiana and Penicillium expansum within epiphytes, or by Pyronema domesticum and Fusarium lateritium within endophytes. Both communities showed low similarity on species composition, with a Sørensen index of 0.26. Olive tree cultivar was found to influence microbial community structure. The diversity and richness of fungal endophytes was higher on olives of cvs. Verdeal Transmontana (5 taxa, 12 isolates) and Madural (5 taxa, 10 isolates); whereas of epiphytes was on olives of cvs. Cobrançosa (16 taxa, 32.68 cfu/cm2) and Madural (13 taxa, 32.88 cfu/cm2). The frequency of fungal colonization was highest in olives of cv. Verdeal Transmontana and Madural (17% each) whereas of bacteria was in olives of cv. Cobrançosa (10%) and Madural (8%). The results show that both the habitat (endophyte vs. epiphyte) properties and the plant cultivar are important in determining the structure and diversity of the bacterial and fungal community associated to olive fruit.
The above-ground parts of plants (phyllosphere) harbor a diverse microbial community, both as epiphytes on the plant surface and within plant tissues as endophytes, that play a crucial role for plant health and growth. Much of the work on phyllosphere microbiology has been focused on leaves, whereas fruits have been rarely studied. In this work the diversity of endophytic and epiphytic microbial community associated with olive fruit of three Portuguese cultivars (Madural, Cobrançosa and Verdeal Transmontana) was assessed for the first time. The effect of plant cultivar on microbial community inhabiting olive fruit was also evaluated. Bacteria and fungi were isolated from fresh olive fruits in plate count agar and in potato dextrose agar medium, respectively, and the isolates obtained were identified by sequencing the 16S (for bacteria) and the ITS region (for fungi) of rRNA genes. A total of 270 isolates (122 bacteria, 151 filamentous fungi) belonging to 41 taxa (6 bacteria, 35 filamentous fungi) were isolated from olives of the three cultivars. Overall, the epiphytic community was most diverse (35 taxa) and rich (227 isolates) than endophytic community (13 taxa, 43 isolates). In both communities the specie most abundant was the unidentified bacteria sp. 6, followed by Davidiella tassiana and Penicillium expansum within epiphytes, or by Pyronema domesticum and Fusarium lateritium within endophytes. Both communities showed low similarity on species composition, with a Sørensen index of 0.26. Olive tree cultivar was found to influence microbial community structure. The diversity and richness of fungal endophytes was higher on olives of cvs. Verdeal Transmontana (5 taxa, 12 isolates) and Madural (5 taxa, 10 isolates); whereas of epiphytes was on olives of cvs. Cobrançosa (16 taxa, 32.68 cfu/cm2) and Madural (13 taxa, 32.88 cfu/cm2). The frequency of fungal colonization was highest in olives of cv. Verdeal Transmontana and Madural (17% each) whereas of bacteria was in olives of cv. Cobrançosa (10%) and Madural (8%). The results show that both the habitat (endophyte vs. epiphyte) properties and the plant cultivar are important in determining the structure and diversity of the bacterial and fungal community associated to olive fruit.
Description
Keywords
Olea europaea L. Bactéria Fungo Madural Verdeal Transmontana Cobrançosa