High frequency direct plant regeneration from leaf, internode, and root segments of Eastern Cottonwood (Populus deltoides)

Abstract

Simple, reproducible, high frequency, improved plant regeneration protocol in Eastern Cottonwood (Populus deltoides) clones, WIMCO199 and L34, has been reported. Initially, aseptic cultures established from axillary buds of nodal segments from mature plus trees on MS liquid medium supplemented with 0.25 mg l -1 KIN and 0.25 mg l -1 IAA. Nodal and internodal segments were found to be extraprolific over shoot apices during course of aseptic culture establishment, while 0.25 mg l -1 KIN concentration played a stimulatory role in high frequency plant regeneration. Diverse explants, such as various leaf segments, internodes, and roots from in vitro raised cultures, were employed. Direct plant regeneration was at high frequency of 92% in internodes, 88% in leaf segments, and 43% in root segments. This led to the formation of multiple shoot clusters on established culture media with rapid proliferation rates. Many-fold enhanced shoot elongation and growth of the clusters could be achieved on liquid MS medium supplemented with borosilicate glass beads, which offer physical support for proliferating shoots leading to faster growth in comparison to semi-solid agar or direct liquid medium. SEM examination of initial cultures confirmed direct plant regeneration events without intervening calli. In vitro regenerated plants induced roots on half-strength MS medium with 0.15 mg l -1 IAA. Rooted 5-to 6-week-old in vitro regenerated plants were transferred into a transgenic greenhouse in pots containing 1:1 mixture of vermicompost and soil at 27 ± 2°C for hardening and acclimatization.14-to 15-week-old well-established hardened plants were transplanted to the field and grown to maturity. The mature in vitro raised poplar trees exhibited a high survival rate of 85%; 4-year-old healthy trees attained an average height of 8 m and an average trunk diameter of 25 cm and have performed well under field conditions. The regeneration protocol presented here will be very useful for undertaking genetic manipulation, providing a value addition to Eastern Cottonwood propagation in future.

An Improved System for Shoot Regeneration from Stem Explants of Lombardy Poplar (Populus nigra L. var. italica Koehne)

“…Similar procedure is reported in Eastern Cottonwood (P. deltoides) [17][18][19] and male Himalayan poplar (P. ciliata) [20]. No callus induction in this method might be another advantage, because it is well known that plants regenerated via a callus phase may differ from the mother plant due to somaclonal variations [21].…”

Regeneration via Direct Organogenesis from Leaf Segments of Eggplant (Solanum melongena L.)

“…Magioli et al (1998) advised half strength MS medium suitable for shoot induction and well supported by the results of Franklin et al (2004). In cottonwood (Populus deltoides), IAA has been used to induce roots after shoot multiplication (Yadav et al, 2009). The production of basal callus at the base of explants was higher for those explants grown with BAP at full strength MS medium, an indication that tissue differentiation in the zone of contact with the medium is related to the IAA/cytokinins ratio.…”

Direct and indirect plant regeneration from various explants of eastern cottonwood clones (Populus deltoides Bartram ex Marsh.) with tissue culture

“…Similarly, in this study, the nodal culture directly produced organogenesis in 3 weeks. Yadav et al (2009), studied direct plant regeneration from leaf and root segments and internodes of the eastern cottonwood (P. deltoides). The study showed that, direct plant regeneration was at the high frequencies of 92% in internodes, 88% in leaf segments and 43% in root segments.…”

“…There are several studies on in vitro organogenesis with Populus spp. including P. deltoides or its hybrids (Rutledge and Douglas, 1988;Sellmer et al, 1989;Coleman and Ernst, 1990;Noël et al, 2002;Yadav et al, 2009). However, with several of the known Populus genotypes, it was found that they are hard to perpetuate and difficult to work with for in vitro culture studies (Yadav et al, 2009).…”