Changes in ploidy affect vascular allometry and hydraulic function in Mangifera indica trees.

The enucleated vascular elements of the xylem and the phloem offer an excellent system to test the effect of ploidy on plant function because variation in vascular geometry has a direct influence on transport efficiency. However, evaluations of conduit sizes in polyploid plants have remained elusive, most remarkably in woody species. We used a combination of molecular, physiological and microscopy techniques to model the hydraulic resistance between source and sinks in tetraploid and diploid mango trees. Tetraploids exhibited larger chloroplasts, mesophyll cells and stomatal guard cells, resulting in higher leaf elastic modulus and lower dehydration rates, despite the high water potentials of both ploidies in the field. Both the xylem and the phloem displayed a scaling of conduits with ploidy, revealing attenuated hydraulic resistance in tetraploids. Conspicuous wall hygroscopic moieties in the cells involved in transpiration and transport indicate a role in volumetric adjustments as a result of turgor change in both ploidies. In autotetraploids, the enlargement of organelles, cells and tissues, which are critical for water and photoassimilate transport at long distances, point to major physiological novelties associated with whole-genome duplication.

Multilacunarity as a spatial multiscale multi-mass morphometric of change in the meso-architecture of plant parenchyma tissue.

The lacunarity index (monolacunarity) averages the behavior of variable size structures in a binary image. The generalized lacunarity concept (multilacunarity) on the basis of generalized distribution moments is an appealing model that can account for differences in the mass content at different scales. The model was tested previously on natural images [J. Vernon-Carter et al., Physica A 388, 4305 (2009)]. Here, the computational aspects of multilacunarity are validated using synthetic binary images that consist of random maps, spatial stochastic patterns, patterns with circular or polygonal elements, and a plane fractal. Furthermore, monolacunarity and detrended fluctuation analysis were employed to quantify the mesostructural changes in the intercellular air spaces of frozen-thawed parenchymatous tissue of pome fruit [N. A. Valous et al., J. Appl. Phys. 115, 064901 (2014)]. Here, the aim is to further examine the coherence of the multilacunarity model for quantifying the mesostructural changes in the intercellular air spaces of parenchymatous tissue of pome and stone fruit, acquired with X-ray microcomputed tomography, after storage and ripening, respectively. The multilacunarity morphometric is a multiscale multi-mass fingerprint of spatial pattern composition, assisting the exploration of the effects of metabolic and physiological activity on the pore space of plant parenchyma tissue.

Induction and cryopreservation of embryogenic cultures from nucelli and immature cotyledon cuts of mango (Mangifera indica L. var Zihua).

In this paper, we described the direct somatic embryogenesis from both immature cotyledon cuts and nucelli in the same mango cultivar (Mangifera indica L. var Zihua), studied the effect of growth conditions of embryogenic cultures (EMs) on cryopreservation and compared the cryopreservation response of EMs induced from these two different explants. Histological studies demonstrated that EMs derived from nucelli could be induced directly from epidermal cells of both sides of nucelli, whereas EMs derived from cotyledon cuts were induced only from epidermal cells of the adaxial side of the cotyledons. EMs from either nucelli or cotyledon cuts could be maintained in liquid medium or on solid medium and cryopreserved using a vitrification procedure. Success of cryopreservation of EMs depended on the dehydration treatment and the defined growth conditions during culture but not on their origins. When EMs were sampled during their exponential growth phase in liquid medium and dehydrated with PVS(3) solution for 5 min, survival of the EMs induced from cotyledon cuts and nucelli reached 77.7 and 80%, respectively, after cryopreservation in liquid nitrogen for 24 h. Furthermore, when dehydrated with PVS(3) solution for 30 min, all EMs induced from cotyledon cuts and 96.7% of EMs induced from nucelli could survive after cryopreservation. Cryopreservation did not affect the plant regeneration potential of EMs through somatic embryogenesis. The protocols of somatic embryogenesis and cryopreservation of mango EMs established in this study may offer potential ways to improve mango germplasm conservation and genetic improvement.