Oil bodies in leaf mesophyll cells of angiosperms: overview and a selected survey

Abstract

Neutral (storage) oil bodies occur in leaf mesophyll cells of many angiosperms, but their literature has been largely forgotten. We review this literature and provide a survey of 302 species and hybrids from mostly north-central US species representing 113 families. Freehand cross sections of fresh leaves stained with Sudan IV verified the presence of oil. In 71 species from 24 families we observed 1-15 oil bodies per mesophyll cell. The eudicot families Asteraceae, Caprifoliaceae, Lamiaceae, and Rosaceae had the highest number of species with oil bodies, whereas few or no species in the Apiaceae, Betulaceae, Fabaceae, and Scrophulariaceae had them. Only three of 19 monocot species sampled had oil bodies. Repeat sampling of a Malus (crabapple) cultivar and a Euonymus species showed conspicuous oil bodies in mid-summer and also in mid-autumn in both attached and recently shed leaves. Oil bodies in leaf mesophyll cells are conspicuous (visible in hand cross sections using moderate magnification in unstained water mounts) in numerous species, and they occur throughout the growing season in at least some species. Neutral oil bodies in leaf mesophyll cells are not mentioned in contemporary textbooks and advanced works, but they deserve recognition as significant cellular components of many taxa, in which they may be significant sources of commercial oils.

The SUGAR-DEPENDENT1 Lipase Limits Triacylglycerol Accumulation in Vegetative Tissues of Arabidopsis

“…The accumulation of TAG in sdp1 also raises a number of questions concerning the physiological role of TAG in plant vegetative tissues. Oil bodies have been found in the leaves of many plant species (Lersten et al, 2006), and roles for cytosolic TAG in carbon storage and membrane lipid remodeling have previously been proposed in a number of studies (Murphy, 2001;James et al, 2010). However, more evidence is required to support or refute these theories.…”

“…Lipid bodies have been observed in the leaves of many plants (Lersten et al, 2006), and oil in vegetative tissues has previously been proposed to play a role in carbon storage and membrane lipid remodeling (Murphy, 2001;James et al, 2010). Nevertheless, the oil content of leaves, stems, and roots is extremely low in all but a very few plant species (Durrett et al, 2008).…”

Oil Bodies and Oleosins in Physcomitrella Possess Characteristics Representative of Early Trends in Evolution

“…Lipid droplets are present in green leaves of diverse species, although they are less obvious and abundant (Lersten et al, 2006). Whether these lipid droplets possess oleosins and other characteristics and play a similar physiological role of food storage as do Physcomitrella gametophyte OBs remain to be elucidated.…”

“…In fruits of some species, such as olive (Olea europaea), avocado (Persea americana), and oil palm (Syagrus cocoides), the fleshy mesocarp possesses much larger (10-50-mm diameter) subcellular lipid particles of TAGs, which are devoid of surface oleosins and apparently are for attracting animals for seed dispersal (Murphy, 2001;Hsieh and Huang, 2004). OBs are also present, although generally in low abundance, in leaves of diverse plant species, and their structures and functions are unknown (Lersten et al, 2006).…”

Leaf Oil Body Functions as a Subcellular Factory for the Production of a Phytoalexin in Arabidopsis

“…The lipids stored in seeds supply energy for seed germination and have drawn attention as a bioenergy resource. However, vegetative organs, including leaves, which do not require storage lipids for growth, also develop oil bodies (Lersten et al, 2006), suggesting that these structures may have unknown function(s) in addition to acting as a source of energy. The physiological roles of oil bodies are poorly understood, especially in vegetative tissues.…”