RESUMO
This paper reviews the forest resources in Turkey in the light of published literature and summarises extensive fieldwork undertaken in the Mediterranean phytogeograhical region of Turkey. The issues of landscape change and the associated drivers are addressed and the threats to the forest diversity are considered. It notes the impacts of climate change and forest fires and attemepts have been made to put forth future options for sustainable forest development.
Assuntos
Mudança Climática , Incêndios , Árvores , Conservação dos Recursos Naturais , Ecossistema , Região do Mediterrâneo , Fatores de Tempo , TurquiaRESUMO
Boron stress is an environmental factor affecting plant development and production. Recently, microRNAs (miRNAs) have been found to be involved in several plant processes such as growth regulation and stress responses. In this study, miRNAs associated with boron stress were identified and characterized in barley. miRNA profiles were also comparatively analyzed between root and leave samples. A total of 31 known and 3 new miRNAs were identified in barley; 25 of them were found to respond to boron treatment. Several miRNAs were expressed in a tissue specific manner; for example, miR156d, miR171a, miR397, and miR444a were only detected in leaves. Additionally, a total of 934 barley transcripts were found to be specifically targeted and degraded by miRNAs. In silico analysis of miRNA target genes demonstrated that many miRNA targets are conserved transcription factors such as Squamosa promoter-binding protein, Auxin response factor (ARF), and the MYB transcription factor family. A majority of these targets were responsible for plant growth and response to environmental changes. We also propose that some of the miRNAs in barley such as miRNA408 might play critical roles against boron exposure. In conclusion, barley may use several pathways and cellular processes targeted by miRNAs to cope with boron stress.
Assuntos
Boro/farmacologia , Hordeum/genética , Hordeum/fisiologia , MicroRNAs/genética , Estresse Fisiológico/efeitos dos fármacos , Estresse Fisiológico/genética , Sequência de Bases , Relação Dose-Resposta a Droga , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Hordeum/efeitos dos fármacos , Especificidade de Órgãos , Estabilidade de RNA/efeitos dos fármacos , RNA Mensageiro/química , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
Boron (B) is a potential environmental toxicant for plants under excessive conditions. To understand the molecular stress response involved in high B exposure, we focused on the transcript accumulation of three stress-related genes: Hsp90, MT2 and GR1. Transcript accumulations were determined on B-stressed tomato plants by using a quantitative real-time PCR technique. Tomato seedlings were exposed to B ranging from 80 to 5120 µM for 24 h in nutrient solution. Root and shoot transcript accumulations were assessed. Results showed that the genes were over-expressed in B-stressed tomato. The highest relative fold change value was measured on GR1 for both root and shoot (8-10 and 30-34-fold increases, respectively), indicating the activation of the oxidative stress enzyme to tolerate B-stress as an early response. The activation of these genes could be a protection mechanism against to B stress.