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Publication
Influência do declínio amarelo das Apiáceas sobre diferentes variedades de cenoura
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Advisor(s)
Abstract(s)
O controlo de pragas e doenças constitui, atualmente, um dos grandes desafios da
produção agrícola, especialmente na horticultura do Oeste. Além das doenças-chave como
por exemplo, o míldio, oídio e podridões, cuja incidência aumenta devido ao clima da
região, existem outras doenças menos conhecidas e que dependem de outros fatores para
além do clima, como é o caso da bactéria de quarentena “Candidatus Liberibacter
solanacearum” (Ca. L. solanacearum) na cultura da cenoura, detetada pela primeira vez em
Portugal em 2017.
Por conseguinte, este trabalho teve como principal objetivo detetar a presença desta
bactéria em diferentes variedades de cenoura, num campo agrícola do concelho de Óbidos,
região Oeste de Portugal.
Este estudo realizou-se, por um lado, em campo, ao ar livre, onde a cultura esteve
exposta às condições climáticas e o produtor utilizou as técnicas culturais habituais. Por
outro lado, realizou-se um ensaio em vasos, com as mesmas variedades, em estufa, onde as
condições foram mais controladas de forma a verificar a sanidade das sementes no que diz
respeito à presença da bactéria.
Em ambos os ensaios, campo e estufa, foi avaliado o possível aparecimento de
sintomas causados por “Ca. L. solanacearum”, como folhas avermelhadas e douradas e
extremidades enroladas e também a presença dos insetos vetores responsáveis pela
transmissão da doença.
Também foram monitorizados, em ambos os locais, através da colocação semanal
de placas cromotrópicas de cor amarela, a presença dos vetores responsáveis pela
transmissão da doença.
Os insetos vetores de “Ca. L. solanacearum” identificados neste trabalho foram os
psilídeos Bactericera cockerelli. Trioza apicalis e Bactericera trigonica.
A partir dos 71 dias após sementeira todas as variedades manifestavam sintomas
sugestivos da “Ca. L. solanacearum” em algumas das repetições. Decorridos 88 dias após
sementeira foi verificado que todas as repetições de todas as variedades já manifestavam
sintomas sugestivos desta doença.IV
Na fase final do ensaio de campo, foram recolhidas amostras foliares de plantas
com sintomas, para confirmação da presença da bactéria através de PCR. Os resultados
obtidos mostram que todas as amostras testadas deram negativo para a presença da
bactéria. Os resultados foram confirmados por NGS.
Desta forma, os sintomas observados podem estar associados a outro agente,
possivelmente ao vírus da folha vermelha, no entanto serão necessários testes para
confirmar esta hipótese.
Este estudo é bastante relevante para as regiões produtoras de cenoura tendo em
conta que sempre que possam surgir sintomas associados à bactéria “Ca. L. solanacearum”
as plantas devem ser monitorizadas e devem ser efetuados os testes necessários para
confirmar se efetivamente se trata desta doença ou de outra com sintomas semelhantes, tal
como, o vírus da folha vermelha da cenoura. Estes resultados contribuem para que
trabalhos semelhantes possam considerar várias perspetivas.
The management of pests and diseases affecting crops is currently one of the major challenges faced by agricultural production, particularly in the horticultural sector of Western Portugal. In addition to key diseases such as downy mildew, powdery mildew, and rots—whose incidence is increasing due to the region’s climate—there are other, lesserknown diseases that are influenced by factors beyond climatic conditions. One such example is the quarantine bacterium “Candidatus Liberibacter solanacearum” (Ca. L. solanacearum), which was first detected in carrot crops in Portugal in 2017. The primary objective of this study was to detect the presence of this bacterium in different carrot varieties cultivated in an agricultural field in the municipality of Óbidos, located in the Western region of Portugal. This study was carried out, on one hand, in an open field where the crop was exposed to natural climatic conditions and standard cultivation practices were applied by the grower. On the other hand, a pot trial was conducted in a greenhouse using the same cultivars, under more controlled conditions, to assess seed health regarding the presence of the bacterium. In both settings—field and greenhouse—the possible appearance of symptoms caused by “Ca. L. solanacearum” was assessed, including reddish or golden-colored leaves and curled leaf tips. Additionally, the presence of insect vectors responsible for transmitting the disease was monitored. Vector populations were monitored weekly at both locations using yellow chromotropic sticky traps. The insect vectors of Ca. L. solanacearum identified in this study were the psyllid species Bactericera cockerelli, Trioza apicalis, and Bactericera trigonica. From 71 days after sowing, all carrot varieties showed symptoms suggestive of “Ca. L. solanacearum” in some of the replicates. By 88 days after sowing, all replicates of all varieties exhibited symptoms indicative of this disease. At the final stage of the field trial, foliar samples were collected from symptomatic plants to confirm the presence of the bacterium through PCR analysis. The results showedVI that all tested samples were negative for the bacterium. These findings were further confirmed by Next-Generation Sequencing (NGS). Thus, the symptoms observed may be associated with another causal agent, possibly the red leaf virus. However, additional testing is required to confirm this hypothesis. This study is highly relevant for carrot-producing regions, as it highlights the importance of monitoring plants whenever symptoms potentially associated with “Ca. L. solanacearum” appear. Appropriate diagnostic tests should be conducted to confirm whether the disease is indeed caused by this bacterium or by another pathogen with similar symptomatology, such as carrot red leaf virus. These findings provide valuable insights and encourage future studies to adopt broader diagnostic perspectives.
The management of pests and diseases affecting crops is currently one of the major challenges faced by agricultural production, particularly in the horticultural sector of Western Portugal. In addition to key diseases such as downy mildew, powdery mildew, and rots—whose incidence is increasing due to the region’s climate—there are other, lesserknown diseases that are influenced by factors beyond climatic conditions. One such example is the quarantine bacterium “Candidatus Liberibacter solanacearum” (Ca. L. solanacearum), which was first detected in carrot crops in Portugal in 2017. The primary objective of this study was to detect the presence of this bacterium in different carrot varieties cultivated in an agricultural field in the municipality of Óbidos, located in the Western region of Portugal. This study was carried out, on one hand, in an open field where the crop was exposed to natural climatic conditions and standard cultivation practices were applied by the grower. On the other hand, a pot trial was conducted in a greenhouse using the same cultivars, under more controlled conditions, to assess seed health regarding the presence of the bacterium. In both settings—field and greenhouse—the possible appearance of symptoms caused by “Ca. L. solanacearum” was assessed, including reddish or golden-colored leaves and curled leaf tips. Additionally, the presence of insect vectors responsible for transmitting the disease was monitored. Vector populations were monitored weekly at both locations using yellow chromotropic sticky traps. The insect vectors of Ca. L. solanacearum identified in this study were the psyllid species Bactericera cockerelli, Trioza apicalis, and Bactericera trigonica. From 71 days after sowing, all carrot varieties showed symptoms suggestive of “Ca. L. solanacearum” in some of the replicates. By 88 days after sowing, all replicates of all varieties exhibited symptoms indicative of this disease. At the final stage of the field trial, foliar samples were collected from symptomatic plants to confirm the presence of the bacterium through PCR analysis. The results showedVI that all tested samples were negative for the bacterium. These findings were further confirmed by Next-Generation Sequencing (NGS). Thus, the symptoms observed may be associated with another causal agent, possibly the red leaf virus. However, additional testing is required to confirm this hypothesis. This study is highly relevant for carrot-producing regions, as it highlights the importance of monitoring plants whenever symptoms potentially associated with “Ca. L. solanacearum” appear. Appropriate diagnostic tests should be conducted to confirm whether the disease is indeed caused by this bacterium or by another pathogen with similar symptomatology, such as carrot red leaf virus. These findings provide valuable insights and encourage future studies to adopt broader diagnostic perspectives.
Description
Dissertação, Mestrado, Engenharia Agronómica, Instituto Politécnico de Santarém, Escola Superior Agrária, 2025
Keywords
Candidatus Liberibacter solanacearum Bacteria vetor sintomas PCR Bacterium vector symptoms
Citation
Marques, Cristiana dos Santos (2025). Influência do declínio amarelo das Apiáceas sobre diferentes variedades de cenoura. Dissertação de Mestrado na área da Engenharia Agronómica, apresentada na Escola Superior Agrária de Santarém