Enhanced Axillary Branching and Pigment Development of Double-Node Explants of Bigtooth Maple

Abstract

<jats:p>Bigtooth maple (<jats:italic>Acer grandidentatum</jats:italic> Nutt.) is indigenous to the southwestern United States. This species is not widely used in managed landscapes but the plant holds promise as a useful ornamental tree. Micropropagation might provide additional sources of selected genotypes for the nursery industry, but tissue culture has not been used successfully to propagate this species. We cultured double-node explants from greenhouse-grown, 2-year old seedlings of bigtooth maples that originated from Utah, Texas and New Mexico. Seedling height ranged from 15-90 cm. The shoot region was divided into three equal zones designated as terminal, intermediate and basal. Explants were selected from each of those zones. Explants were established on Murashige-Skoog (MS), Linsmaier-Skoog (LS), Woody Plant Medium (WPM) and Driver-Kuniyuki (DKW) tissue culture media. Shoot proliferation, area of the plate covered by callus and foliar pigment development (hue as determined by Royal Horticultural Society Color charts) were monitored for 17 weeks. Media affected shoot proliferation (<jats:italic>P</jats:italic> = 0.0042) but the zone of origin (<jats:italic>P</jats:italic> = 0.6664) of the explant did not. Callus area showed no significant difference among the four media and three zones (<jats:italic>P</jats:italic> = 0.2091) and averaged 3.60 centimeters<jats:sup>2</jats:sup>. After four subcultures, each lasting 30 days, explants on DKW media produced 10 shoots per explant. This media might hold promise for the micropropagation of bigtooth maple. Twenty-nine percent of all explants expressed foliar pigmentation, which ranged from red-purple to orange-red. Whether foliar pigment development in tissue culture correlates with expressed pigmentation in nature warrants further investigation.</jats:p>