Premium
Aerenchyma and lenticel formation in pine seedlings: A possible avoidance mechanism to anaerobic growth conditions
Author(s) -
Topa Mary A.,
McLeod Kenneth W.
Publication year - 1986
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1986.tb03394.x
Subject(s) - aerenchyma , lenticel , shoot , rhizosphere , botany , pinus radiata , biology , anaerobic exercise , pericycle , horticulture , biochemistry , genetics , arabidopsis , bacteria , mutant , gene , physiology
Seedlings of pond pine ( Pinus serotina Michx.), sand pine [ P. clausa (Engelm.) Sarg.], and loblolly pine ( P. taeda L., wet‐site and drought‐hardy seed sources) were grown in hydroponic solution culture using a non‐circulating, continuously flowing design under anaerobic or aerobic conditions to determine whether flooding tolerance was correlated with enhanced internal root aeration. Transport of atmospheric O 2 from the shoot to the root of anaerobically grown loblolly and pond pine seedlings was demonstrated via rhizosphere oxidation, using both reduced indigo‐carmine solution and a polarographic, ensheathing Pt‐electrode. Stem and root collar lenticels were the major sites of atmospheric O 2 entry for submerged roots in these seedlings. No O 2 leakage was detected from roots of aerobically grown pine seedlings. Longitudinal and radial pathways for gaseous diffusion via intercellular air spaces in the pericycle and between ray parenchyma cells, respectively, were demonstrated histo‐logically in anaerobically grown loblolly and pond pines. Rhizosphere oxidation, and lenticel and aerenchyma development in roots of flood‐intolerant sand pine seedlings grown in anaerobic solutions were minimal. Only 15 days of anaerobic growth conditions were necessary to increase internal root porosities of loblolly and pond pine seedlings – although not to the extent found in seedlings treated for 30 or 75 days. Histological results indicated that root tissue in the secondary stage of growth was capable of forming intercellular air spaces, demonstrating a degree of internal plasticity – at least in the more flood‐tolerant loblolly and pond pine seedlings.