RESUMEN
The tapetum is a specialized layer of cells within the anther, adjacent to the sporogenous tissue. During its short life, it provides nutrients, molecules and materials to the pollen mother cells and microsporocytes, being essential during callose degradation and pollen wall formation. The interaction between the tapetum and sporogenous cells in Solanum lycopersicum (tomato) plants, despite its importance for breeding purposes, is poorly understood. To investigate this process, gene editing was used to generate loss-of-function mutants that showed the complete and specific absence of tapetal cells. These plants were obtained targeting the previously uncharacterized Solyc03g097530 (SlTPD1) gene, essential for tapetum specification in tomato plants. In the absence of tapetum, sporogenous cells developed and callose deposition was observed. However, sporocytes failed to undergo the process of meiosis and finally degenerated, leading to male sterility. Transcriptomic analysis conducted in mutant anthers lacking tapetum revealed the downregulation of a set of genes related to redox homeostasis. Indeed, mutant anthers showed a reduction in the accumulation of reactive oxygen species (ROS) at early stages and altered activity of ROS-scavenging enzymes. The results obtained highlight the importance of the tapetal tissue in maintaining redox homeostasis during male gametogenesis in tomato plants.
Asunto(s)
Solanum lycopersicum , Solanum lycopersicum/genética , Solanum lycopersicum/metabolismo , Regulación de la Expresión Génica de las Plantas , Flores/genética , Flores/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Fitomejoramiento , Homeostasis , Oxidación-ReducciónRESUMEN
The formation of fruits is an important step in the life cycle of flowering plants. The process of fruit development is highly regulated and involves the interaction of a complex regulatory network of genes in both space and time. To identify regulatory genes involved in fruit initiation in tomato we analyzed the transcriptomic profile of ovaries from the parthenocarpic PsEND1:barnase transgenic line. This line was generated using the cytotoxic gene barnase targeted to the anthers with the PsEND1 anther-specific promoter from pea. Among the differentially expressed genes we identified SlDOF10, a gene coding a DNA-binding with one finger (DOF) transcription factor which is activated in unpollinated ovaries of the parthenocarpic plants. SlDOF10 is preferentially expressed in the vasculature of the cotyledons and young leaves and in the root tip. During floral development, expression is visible in the vascular tissue of the sepals, the flower pedicel and in the ovary connecting the placenta with the developing ovules. The induction of the gene was observed in response to exogenous gibberellins and auxins treatments. To evaluate the gene function during reproductive development, we have generated SlDOF10 overexpressing and silencing stable transgenic lines. In particular, down-regulation of SlDOF10 activity led to a decrease in the area occupied by individual vascular bundles in the flower pedicel. Associated with this phenotype we observed induction of parthenocarpic fruit set. In summary, expression and functional analyses revealed a role for SlDOF10 gene in the development of the vascular tissue specifically during reproductive development highlighting the importance of this tissue in the process of fruit set.
RESUMEN
RESEARCH QUESTION: Is higher antral follicle count (AFC) in healthy young women associated with higher oocyte developmental competence? DESIGN: Retrospective study of 1985 first oocyte donation cycles, corresponding to 3210 fresh embryo transfers in oocyte recipients, conducted between January 2010 and May 2014. RESULTS: Donors with higher AFC who underwent ovarian stimulation, produced both more cumulus-oocyte complexes (COC) (B coefficientâ¯=â¯0.47, 95% CI 0.41 to 0.53;Pâ¯≤â¯0.001) and MII oocytes (B coefficientâ¯=â¯0.36, 95% CI 0.32 to 0.41;Pâ¯≤â¯0.001) at linear regression analysis. Donors with low AFC had a higher risk of cancellation (OR 4.79, 95% CI 2.99 to 7.69;Pâ¯<â¯0.001) or obtaining fewer than four metaphase II (MII) at ovum retrieval (OR 3.87, 95% CI 2.38 to 6.27;Pâ¯<â¯0.001). No association was found between AFC and biochemical (OR 1.13, 95% CI 0.93 to 1.36), clinical (OR 1.05, 95% CI 0.87 to 1.28), ongoing pregnancy (OR 1.00, 95%, CI 0.82 to 1.21) or live birth rates (OR 0.97, 95% CI 0.8 to 1.19), when at least four MII were obtained at ovum retrieval. CONCLUSIONS: AFC does not relate to the developmental competence of oocytes in women younger than 35 years.