RAPISARDA Viviana Andrea
congresos y reuniones científicas
Fruit maturation induces closure of plasmodesmata in flavedo of lemons
ALBORNOZ, P.; INTERDONATO, R.; ROSA, M.; PRADO, F. E.; RAPISARDA, V. A.; HILAL, M.
Congreso; IX Congreso Argentino de Citricultura; 2019
Sucrose produced by plants is transported thought the phloem and get into to sink cells through two ways: a) symplastic pathway, through plasmodesmata (PD) that connect the cytoplasm of neighboring cells through interrupted regions of the cell wall; and/or b) transcellular pathway, through plasmatic membrane, by transporters of sucrose or hexoses after sucrose cleavage in the apoplast by cell wall-bound invertase (WI). Previously, high WI activity has been detected in flavedo tissue of postharvest yellow lemons, which could be associated to a low participation of symplastic pathway in sugar transport. Thus, the aim was correlate the WI activity with the absence/presence of PD in lemons harvested in different maturation stages. Immature (green) and mature (yellow) fruit were hand collected during the winter season (June to August) from commercial orchards located in Tucumán, Argentina. WI activity from albedo and flavedo tissues was determined by spectrophotometry. Structural and ultrastructural anatomy studies from lemon peel tissues were performed using different microscopy techniques. WI activity in flavedo of mature lemons dramatically increased in respect to that of immature lemons. Cell wall of flavedo parenchymatic tissue of green lemons presented a noticeable discontinuity, which gives an aspect of beads on a string, due to the large amount of PD. However, cell wall of yellow lemons was homogeneous without interruptions. Closure of PD in mature lemons, which correlated with increasing WI activity, indicates that the symplastic pathway was cancelled in these fruit. This phenomenon is maybe related to develop of a protection mechanism, with a major control of transport and/or with the maintenance of osmotic potential of the fruit during the last stages of maturation, senescence and/or abscission.