Mingozzi Marco, Montello Paul, Merkle Scott
Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA.
Tree Physiol. 2009 Mar;29(3):333-43. doi: 10.1093/treephys/tpn029. Epub 2008 Dec 23.
Effects of photoautotrophic and photomixotrophic growth conditions on adventitious shoot regeneration from leaf explants of eastern cottonwood (Populus deltoides Bartr. ex Marsh.) were investigated. Rooting and proliferating shoot cultures (Stage I) were grown in either an elevated (1500 ppm) CO(2) concentration ([CO(2)]) at high photosynthetic photon flux (PPF; ~ 150 micromol m(-2) s(-1)) (photoautotrophic condition) with 0, 10 or 30 g l(-1) sucrose or under standard conditions (ambient (360 ppm) [CO(2)] at low PPF (~ 60 micromol m(-2) s(-1)) with 30 g l(-1) sucrose). Leaves harvested from these cultures were analyzed for soluble sugars and were used as explants for adventitious shoot regeneration (Stage II), which was also carried out under photoautotrophic and standard conditions. Photoautotrophic conditions during Stage I promoted growth of rooting shoots but inhibited axillary shoot proliferation. Photoautotrophic conditions during Stage II suppressed callus and adventitious bud production from leaf explants compared with standard conditions. The regeneration environment appeared to be more important in controlling bud formation than the conditions under which the donor shoots were grown. Regardless of Stage I treatment, bud production was up to 100-fold higher for leaves cultured under standard conditions than under photoautotrophic conditions. Once adventitious buds were differentiated from the leaf tissues, however, their elongation was faster under photoautotrophic conditions than that under standard conditions, with some shoots reaching 10 mm in length on leaf explants cultured under photoautotrophic conditions. Because total leaf soluble sugar concentration was always lowest in shoots under standard conditions, which also yielded the highest bud production, the results suggest that endogenous starvation enhanced shoot production.
研究了光合自养和光合兼养生长条件对东部杨（Populus deltoides Bartr. ex Marsh.）叶片外植体不定芽再生的影响。生根和增殖芽培养物（第一阶段）在高光合光子通量（PPF；约150 μmol m⁻² s⁻¹）下的升高（1500 ppm）二氧化碳浓度（[CO₂]）（光合自养条件）下培养，添加0、10或30 g l⁻¹蔗糖，或在标准条件下（低PPF（约60 μmol m⁻² s⁻¹）下的环境（360 ppm）[CO₂]，添加30 g l⁻¹蔗糖）培养。从这些培养物中收获的叶片用于分析可溶性糖，并用作不定芽再生（第二阶段）的外植体，该阶段也在光合自养和标准条件下进行。第一阶段的光合自养条件促进了生根芽的生长，但抑制了腋芽增殖。与标准条件相比，第二阶段的光合自养条件抑制了叶片外植体的愈伤组织和不定芽产生。再生环境在控制芽形成方面似乎比供体芽生长的条件更重要。无论第一阶段的处理如何，在标准条件下培养的叶片的芽产量比在光合自养条件下高100倍。然而，一旦不定芽从叶片组织中分化出来，它们在光合自养条件下的伸长速度比在标准条件下快，在光合自养条件下培养的叶片外植体上一些芽长到了10毫米。因为在标准条件下芽中的总叶片可溶性糖浓度总是最低的，而标准条件下的芽产量也最高，结果表明内源性饥饿促进了芽的产生。
