RESUMO
Senescence is the process that marks the end of a leaf's lifespan. As it progresses, the massive macromolecular catabolism dismantles the chloroplasts and, consequently, decreases the photosynthetic capacity of these organs. Thus, senescence manipulation is a strategy to improve plant yield by extending the leaf's photosynthetically active window of time. However, it remains to be addressed if this approach can improve fleshy fruit production and nutritional quality. One way to delay senescence initiation is by regulating key transcription factors (TFs) involved in triggering this process, such as the NAC TF ORESARA1 (ORE1). Here, three senescence-related NAC TFs from tomato (Solanum lycopersicum) were identified, namely SlORE1S02, SlORE1S03, and SlORE1S06. All three genes were shown to be responsive to senescence-inducing stimuli and posttranscriptionally regulated by the microRNA miR164 Moreover, the encoded proteins interacted physically with the chloroplast maintenance-related TF SlGLKs. This characterization led to the selection of a putative tomato ORE1 as target gene for RNA interference knockdown. Transgenic lines showed delayed senescence and enhanced carbon assimilation that, ultimately, increased the number of fruits and their total soluble solid content. Additionally, the fruit nutraceutical composition was enhanced. In conclusion, these data provide robust evidence that the manipulation of leaf senescence is an effective strategy for yield improvement in fleshy fruit-bearing species.
Assuntos
Frutas/crescimento & desenvolvimento , Solanum lycopersicum/crescimento & desenvolvimento , Solanum lycopersicum/genética , Proteínas de Arabidopsis , Biomassa , Senescência Celular , Técnicas de Silenciamento de Genes , Genoma de Planta , Fenótipo , Fotossíntese , Folhas de Planta/fisiologia , Terpenos/metabolismo , Fatores de TranscriçãoRESUMO
PURPOSE: Inconsistent data exist on long-term visual outcomes in survivors of retinoblastoma. No studies have been reported on role of ocular coherence tomography (OCT) in predicting visual acuity. We assessed visual acuity in patients with retinoblastoma treated at our center in whom affected eyes were preserved. METHODS: Patients who had completed a 2-year follow-up and were more than 5 years of age at assessment were included. Clinical data were obtained from database and factors predicting visual acuity were analyzed. OCT was performed in these patients to assess central macular thickness (CMT). RESULTS: Visual outcomes were assessed in 45 eyes of 43 patients, of which 38 (88 %) had bilateral retinoblastoma. The median age at diagnosis was 12 months. Sixty percent (27/45) had International classification of retinoblastoma group C or D disease with 40 % eyes showing macular lesions. The far visual acuity was better than 6/12 in 53 % (24/45), 6/12 to 6/60 in 40 % (18/45) and 6/60 in 7 % (6/60). Macular location and International classification of retinoblastoma predicted poor vision (p = 0.06 and 0.07, respectively). CMT was less than 200 µm in 3 of 36 eyes (8 %) and 1 eye showed epiretinal membrane. Radiotherapy was associated with foveal thinning (p = 0.003). Two of 3 eyes with foveal thinning had a vision of 6/60. CONCLUSIONS: Good visual outcomes were observed in half of retinoblastoma patients treated with eye preservation. Macular location and International classification of retinoblastoma group C and D predicted poor visual acuity, while previous radiotherapy predicted foveal thinning, which was associated with poor visual acuity.