Acquisition of callogenic capacity in date palm leaf tissues in response to 2,4-D treatment

Abstract

While callogenesis in date palm can be initiated by culturing immature leaf segments on medium containing 2,4-dichlorophenoxyacetic acid (2,4-D), it is difficult to obtain callus from certain genotypes. To better understand the mechanisms of callogenesis in date palm, we studied the developmental events underlying this process at the cellular level. The callogenic capacity of leaf segments depends on the state of cell differentiation. The most callogenic segments were within the leaf elongation zone, required polar auxin transport to initiate callogenesis and contained the highest quantities of free endogenous indole-3-acetic acid. At the cellular level, callus induction involves two spatially and temporally separated events. The first event involves cells from the fascicular parenchyma in an equatorial plane perpendicular to the vascular axis that within 2 days of culture in the presence of 2,4-D, acquire structural and ultrastructural features typically observed in meristematic cells. The second event occurs 3 days later and is characterised by the modification of adjacent perivascular sheath cells. The latter cells become callogenic in that they reinitiated their cell cycles and undergo cell division leading to callus formation. These data provide evidence that callus initiation in leaf vascular tissue of date palm involves a sequential response of two distinct cell types to auxin and requires polar auxin transport.

Somatic embryogenesis in Acrocomia aculeata Jacq. (Lodd.) ex Mart using the thin cell layer technique

“…In Phoenix dactilyfera, leaf explants showed cellular alterations in the fascicular parenchyma after two days of in vitro culture in the presence of NAA (Gueye et al 2009b) or 2,4-D (Gueye et al 2009a). In leaf TCLs of Bactris gasipaes cultured in the presence of picloram, Steinmacher et al (2007c) observed the first cell divisions after 30 days located near vascular bundles.…”

Improving date palm (phoenix dactylifera l. cv. estamaran) calogenesis by the use of zinc oxide nanoparticles

“…Traditional method of date palm propagation is through offshoots. However, various limitation such as very slow growth, less number of offshoots in mother palm trees (Sharma, 1990) and has the risk of contamination of pests and emergence of diseases (Gueye et al, 2009). Therefore, tissue culture technique or in vitro regeneration can be used as an alternative method for date palm mass propagation.…”

“…Among indirect embryogenesis processes, callus induction is very difficult because the date palm is a monoecious, perennial woody plant (Gueye et al, 2009). Therefore, need of a suitable and optimized protocol in order to prepare a nutrient medium for date palm callus induction by the researchers, it would be very helpful for large scale date palm propagation.…”

The effect of the orientation of stem segments of grapevine (Vitis vinifera) cv. Chardonnay on callus development in vitro

“…2). Callus cells proliferated from the peripheral zones of the stem segments and gradually covered the cut surface, suggesting that they originated from vascular parenchyma or cambium cells (Gueye et al 2009b; Fig. 2).…”