Additive QTLs on three chromosomes control flowering time in woodland strawberry (Fragaria vesca L.)

Flowering time is an important trait that affects survival, reproduction and yield in both wild and cultivated plants. Therefore, many studies have focused on the identification of flowering time quantitative trait locus (QTLs) in different crops, and molecular control of this trait has been extensively investigated in model species. Here we report the mapping of QTLs for flowering time and vegetative traits in a large woodland strawberry mapping population that was phenotyped both under field conditions and in a greenhouse after flower induction in the field. The greenhouse experiment revealed additive QTLs in three linkage groups (LG), two on both LG4 and LG7, and one on LG6 that explain about half of the flowering time variance in the population. Three of the QTLs were newly identified in this study, and one co-localized with the previously characterized FvTFL1 gene. An additional strong QTL corresponding to previously mapped PFRU was detected in both field and greenhouse experiments indicating that gene(s) in this locus can control the timing of flowering in different environments in addition to the duration of flowering and axillary bud differentiation to runners and branch crowns. Several putative flowering time genes were identified in these QTL regions that await functional validation. Our results indicate that a few major QTLs may control flowering time and axillary bud differentiation in strawberries. We suggest that the identification of causal genes in the diploid strawberry may enable fine tuning of flowering time and vegetative growth in the closely related octoploid cultivated strawberry.Peer reviewe

Control of Flowering in Strawberries

Strawberries (Fragaria sp.) are small perennial plants capable of both sexual reproduction through seeds and clonal reproduction via runners. Because vegetative and generative developmental programs are tightly connected, the control of flowering is presented here in the context of the yearly growth cycle. The rosette crown of strawberry consists of a stem with short internodes produced from the apical meristem. Each node harbors one trifoliate leaf and an axillary bud. The fate of axillary buds is dictated by environmental conditions; high temperatures and long days (LDs) promote axillary bud development into runners, whereas cool temperature and short days (SDs) favor the formation of branch crowns. SDs and cool temperature also promote flowering; under these conditions, the main shoot apical meristem is converted into a terminal inflorescence, and vegetative growth is continued from the uppermost axillary branch crown. The environmental factors that regulate vegetative and generative development in strawberries have been reasonably well characterized and are reviewed in the first two chapters. The genetic basis of the physiological responses in strawberries is much less clear. To provide a point of reference for the flowering pathways described in strawberries so far, a short review on the molecular mechanisms controlling flowering in the model plant Arabidopsis is given. The last two chapters will then describe the current knowledge on the molecular mechanisms controlling the physiological responses in strawberries.Peer reviewe

Produção de frutos de morango em função de diferentes períodos de vernalização das mudas Production of strawberry fruits depending on vernalization periods of the transplants

Avaliou-se a produção de frutos de morango da cv. Camarosa em função de diferentes períodos de vernalização das mudas, comparando-a com a de mudas importadas. O experimento foi realizado em Pelotas, utilizando sistema de produção sob túnel. O transplante foi realizado em 18/05/06, utilizando-se mudas produzidas no sul do Rio Grande do Sul, vernalizadas por 0; 7; 14; 21 e 28 dias (4±1ºC, 94±2% UR), e mudas não vernalizadas do Chile. Os tratamentos foram dispostos em delineamento de blocos ao acaso, com quatro repetições. A unidade experimental foi constituída por 21 plantas, avaliadas quanto à produção, número de frutos por planta e massa média dos frutos ao longo de 20 semanas (agosto a dezembro de 2006). As mudas chilenas proporcionaram maiores produção e número de frutos do que as produzidas no RS na ausência de vernalização (1.038,3 e 491,7 g planta-1; 55,1 e 34,3 frutos planta-1, respectivamente). A vernalização das mudas nacionais por cerca de 24 dias otimizou a produção e o número de frutos (1.023,1 g planta-1; 55,6 frutos planta-1). As mudas produzidas no RS apresentaram maior produção em novembro e dezembro, enquanto as chilenas em outubro e novembro.<br>The yield of strawberry fruits cv. Camarosa was evaluated as affected by different vernalization periods of the transplant, in comparison with imported ones. The experiment was carried out in Pelotas, Rio Grande do Sul State, Brazil, using a tunnel as production system. The plants were transplanted on May18, 2006, using transplants produced in the south of Rio Grande do Sul, which were vernalized during 0; 7; 14; 21 and 28 days (4±1ºC, 94±2% RH), and transplants without vernalization coming from Chile. The treatments were disposed according to a randomized complete block design with four replications. The experimental unit were composed of 21 plants. The yield, number of fruits per plant and average fruit mass were analyzed during 20 weeks (August to December). The Chilean transplants provided greater production and number of fruits than transplants produced in Rio Grande do Sul (1,038.3 and 491.7 g plant-1; 55.1 and 34.3 fruits plant-1, respectively). The vernalization of the national transplants during approximately 24 days optimized the yield and number of fruits significantly (1,023.1 g plant-1; 55.6 fruits plant-1). Transplants produced in Rio Grande do Sul presented higher production in November and December, while Chilean ones in October and November

Subclinical Anterior Horn Cell Involvement In Juvenile Myoclonic Epilepsy

WOS: A1994NH70100011PubMed ID: 8156952Although clinical signs of muscle wasting and weakness were not present, electromyographic (EMG) evidence of subclinical anterior horn cell involvement of spinal cord was noted in 5 patients with juvenile myoclonic epilepsy (JME). Quantitative interference pattern analysis of EMG recorded from the anterior tibial muscle showed that the ratio (amplitude:turn/turn:second, A:T/T:S) was significantly increased in 10 patients with JME and 12 patients with lower motor neuron disorders (LMND) as compared with those of 22 normal subjects and 15 patients with frequent generalized tonic-clonic seizures (GTC). Subclinical anterior horn cell involvement detected by EMG techniques can be related to a genetically determined component of JME