Petal and Sepal Epidermal Micromorphology of Six Lathyrus Taxa (Fabaceae) and their Systematic Value

Abstract

In this study, the epidermal types and their distribution on dorsal and lateral petals, the trichome types and their density on sepals of Lathyrus chloranthus, L. digitatus, L. laxiflorus subsp. laxiflorus, L. roseus subsp. roseus, L. sativus, and L. tuberosus, belonging to sections Lathyrus, Lathyrostylis, Pratensis, and Orobon of the genus Lathyrus in Turkey were investigated using light microscopy (LM) and scanning electron microscopy (SEM), and the systematic significance of these characters was evaluated. These taxa, except L. sativus, are studied for the first time under aspects of the petal and sepal micromorphology. Three major epidermal types were recognized on the petal: tabular rugose striate cells (TRS), areolate cells with more or less striations (AS), and papillose conical striate cells (PCS). TRS and AS were further subdivided into three subtypes. TRS was found on the dorsal and lateral petals of L. chloranthus, L. sativus, and L. tuberosus: the dorsal petals of L. roseus subsp. roseus and the lateral petals of L. laxiflorus subsp. laxiflorus, while AS was present on the dorsal and lateral petals of L. digitatus and the lateral petals of L. roseus subsp. roseus. PCS was found only on the dorsal petals of L. digitatus. Three main types of trichomes on the sepal were observed: peltate glandular, capitate glandular, and nonglandular trichomes. The capitate glandular and nonglandular trichomes were further subdivided into three subtypes. The peltate glandular trichomes were present only in L. chloranthus, but absent in the others. The capitate glandular trichomes were found in L. chloranthus, L. laxiflorus subsp. laxiflorus, L. roseus subsp. roseus, and L. tuberosus. The nonglandular trichomes were always present in L. chloranthus and L. laxiflorus subsp. laxiflorus. The present results show that the petal and sepal micromorphology can be used in delimitation of the taxa based on petal and sepal micromorphology.

Micromorphological studies on the genus Lotus L. (Fabaceae: Loteae) from Egypt

“…There is evidence that the Fabaceae members have the highest degree of variation of epidermal cell types within the flowers (Barthlott, 1990;Ojeda et al, 2009;Çildir et al, 2012). In this study, the anticlinal cell wall boundaries of calyces varied between the studied taxa ( (Figure 4).…”

Grain Legumes

“…The production of conical cells is controlled by an MYB-related transcription factor and the mutant mixta that has a null allele of this factor was found in Antirrhinum majus. In legumes, conical petal epidermal cells have been used as a marker for petal identity but there is no evidence of mixta homologues that play a role in differentiation of petal conical cells (Ojeda et al 2009;Çildir et al 2012).…”

Intraspecific variation in the petal epidermal cell morphology of Vicia faba L. (Fabaceae)

“…Previously, intraspecific differences in the petal epidermal morphology have only been reported between two subspecies of Echium wildpretii with different functional groups of pollinators ( Ojeda et al, 2016 ). “Negligible” intraspecific petal micro-morphological variation has been identified within the legume species Lotus japonicus (Regel) K.Larsen, and Trifolium repens L. (3–4 plants; Ojeda et al, 2009 ), and while multiple plants of six Lathyrus L. species were examined by Çildir et al (2012 ; 3–6 plants), they do not describe any intraspecific differences between individuals. Here, we report a much higher level of intraspecific variation in the distribution of a functionally important cell type for the interaction of a flower with pollinators; conical cells.…”

“…Previous investigations into the distribution of petal epidermal cell morphology have largely focused on differences between broad taxonomic groups ( Kay et al, 1981 ; Christensen and Hansen, 1998 ; Papiorek et al, 2014 ) or within specific families ( Baagøe, 1977 , 1980 ; Ojeda et al, 2009 ). A handful of studies have also examined differences in petal epidermal morphology within genera, particularly in genera with more than one functional group of pollinators ( Di Stilio et al, 2009 ; Çildir et al, 2012 ; Ojeda et al, 2012 , 2016 ). From these previous studies we know that substantial variation can occur in the petal epidermal cell types present between flowers of different species, even within a genus.…”

“…However, despite these investigations into the distribution of petal epidermal cell types across flowering plant families, there is little discussion of intraspecific variation. Those studies that have examined multiple individuals from a single species have generally found no significant variation between individuals ( Ojeda et al, 2009 ; Çildir et al, 2012 ), with the exception of two subspecies of Echium wildpretii H.Pearson ex Hook.f. with different functional groups of pollinators ( Ojeda et al, 2016 ).…”