A comparative study of early leaf development in the Viola albida complex

Abstract

Early leaves within the Viola albida complex were investigated by scanning electron microscopy in order to determine the morphological segments during morphogenesis. The early leaf development of V. albida var. albida could be morphologically divided into the eight stages in the following order: I, the initiation of shoot germination; II, the conical growth directionally of the leaf; III, the adaxial and abaxial formation of the leaf; IV, the initiation of the stipule; V, the formation of a transitional zone between the leaf blade and petiole; VI, the expansion of the upper part of the leaf blade; VII, the formation of almost all parts of the early leaf; VIII, the early simple leaf. Viola albida var. takahashii differs from V. albida var. albida by additional stages, i.e., V-1, the initiation of the first lateral lobe at the both lateral parts of the leaf after the stage V and an early lobed leaf. Viola albida var. chaerophylloides is also distinguished from two taxa by two developmental features, V-2, the initiation of a second lateral lobe below of the first lateral lobe, and an early palmately compound leaf. These findings suggest that the Viola albida complex would be in the process of peramorphosis, showing developmental changes in a chain of events, leading to a different leaf shape. These data would also be useful for isolating genes that give rise to different leaf morphogenesis outcomes among the taxa in the Viola albida complex.

Speciation of <i>Viola albida</i> var. <i>takahashii</i> based on both artificial and natural hybridization between <i>V. albida</i> var. <i>albida</i> and <i>V. albida</i> var. <i>chaerophylloides</i>

“…However, they could be grouped into the V. albida var. albida leaf type in light of the morphological distinctions that the leaf primordium starts from the apical meristem and gradually develops into mature leaves (Choi and Whang, 2019). On the other hand, typical V. albida var.…”

A complete chloroplast genome sequence of Viola albida Palibin 1899 (Violaceae), a member of VIOLA ALBIDA complex

“…takahashii (Nakai) Nakai (Nakai 1916 ), and V. chaerophylloides (Regel) W. Becker (Becker 1902 ) exhibit morphological continuity in leaves: from undivided ( V. albida ) through deeply lobed ( V. albida var. takahashii ) to fully divided (compound leaves; V. chaerophylloides ) (Choi and Whang 2019 ). Since they have a complex taxonomic history, often recognized as independent species or varieties of V. albida , these taxa are recognized as the VIOLA ALBIDA complex (Whang 2006 ; Choi and Whang 2019 ).…”

“…takahashii ) to fully divided (compound leaves; V. chaerophylloides ) (Choi and Whang 2019 ). Since they have a complex taxonomic history, often recognized as independent species or varieties of V. albida , these taxa are recognized as the VIOLA ALBIDA complex (Whang 2006 ; Choi and Whang 2019 ). Various approaches have been conducted to understand the evolution of VIOLA ALBIDA complex: leaf morphological (Kim et al.…”

“… 1998 ; Koo et al. 2010 ), developmental (Choi and Whang 2019 ), transcriptome (Srikanth et al. 2019 ), and phylogenetic (Whang 2006 ) studies.…”