Differences In Leaf Form Research Articles

Establishment of an Agrobacterium mediated transformation protocol for the detection of cytokinin in the heterophyllous plant Hygrophila difformis (Acanthaceae).

This is the first report of a highly efficient Agrobacterium tumefaciens-mediated transformation protocol for Acanthaceae and its utilization in revealing important roles of cytokinin in regulating heterophylly in Hygrophila difformis. Plants show amazing morphological differences in leaf form in response to changes in the surrounding environment, which is a phenomenon called heterophylly. Previous studies have shown that the aquatic plant Hygrophila difformis (Acanthaceae) is an ideal model for heterophylly study. However, low efficiency and poor reproducibility of genetic transformation restricted H. difformis as a model plant. In this study, we reported successful induction of callus, shoots and the establishment of an efficient stable transformation protocol as mediated by Agrobacterium tumefaciens LBA4404. We found that the highest callus induction efficiency was achieved with 1mg/L 1-Naphthaleneacetic acid (NAA) and 2mg/L 6-benzyladenine (6-BA), that efficient shoot induction required 0.1mg/L NAA and 0.1mg/L 6-BA and that high transformation efficiency required 100µM acetosyringone. Due to the importance of phytohormones in the regulation of heterophylly and the inadequate knowledge about the function of cytokinin (CK) in this process, we analyzed the function of CK in the regulation of heterophylly by exogenous CK applicationand endogenous CK detection. By using our newly developed transformation system to detect CK signals, contents and distribution in H. difformis, we revealed an important role of CK in environmental mediated heterophylly.

Natural revegetation potential of Japanese wild thyme (Thymus quinquecostatus Celak.) on serpentine quarries

AbstractQuarrying is an important industry that supports human infrastructure, but it has negative effects on human health, environments, and plant communities. In the case of the serpentine quarry on Sugashima Island (Sugashima), Japan, rapid remediation using native plants is necessary to restore the serpentine ecosystem. According to our previous work, we revealed high adaptability of Japanese wild thyme (Thymus quinquecostatus Celak.) to the severe environment of serpentine areas, and we desired to utilize this species for revegetation. However, basic information on Japanese thyme was extremely limited, in comparison with well‐investigated European thymes that have been used for revegetation experiments. The aims of this work were to identify the plant functional traits of wild thymes collected from different areas of Japan and to test their potential for revegetation of serpentine quarry soil. We collected four types of wild thyme from Sugashima and other areas of serpentine, calcareous, and tuff breccia soil, and revealed varietal differences in leaf form, branching patterns, flowers, and also blooming season, seed formation ability, and seed germination percentages. Thymes from serpentine and calcareous areas could grow on soil of the serpentine quarry, and a small number of plants were able to cover the experimental plots. Among the Japanese thymes investigated, Sugashima thyme had the longest branches, and spread rapidly by forming many branches. These data suggest that Japanese thymes, especially Sugashima thyme, have good potential for revegetation of serpentine quarries.

Relationships between specific leaf area and leaf composition in succulent and non-succulent species of contrasting semi-desert communities in south-eastern Spain

Much attention has been paid to differences in leaf form and composition among vegetation types, but less to the frequently substantial variation within vegetation types. We focused on the extent to which correlations between variables are the same in both succulent-poor and succulent-rich vegetation in semi-arid SE Spain. Mean foliar [N] of perennials varied among species over a 5-fold range. Across species, [N] was positively correlated with specific leaf area (i.e., leaf area divided by dry mass; SLA) and with water concentration at saturation (WCS) in the grasslands, excluding the one succulent species. In succulent-rich vegetation on marl, SLA was correlated with [N] but not WCS, and there was a wedge-shaped relationship between [N] and WCS. Foliar [N] and [P] were positively correlated in the grasslands, but not in succulent-rich vegetation on marl. The N/P quotient varied from 8 to 29, with mean 14 in grassland on limestone and mean 26 in grassland on deep soil over gypsum. Our chief finding is that most correlations among SLA, WCS, [N] and [P] found in the non-succulent vegetation are not found in the succulent-rich vegetation. The results are discussed in relation to global patterns and the problems of defining succulence.

The genetic basis for differences in leaf form between Arabidopsis thaliana and its wild relative Cardamine hirsuta

A key question in biology is how differences in gene function or regulation produce new morphologies during evolution. Here we investigate the genetic basis for differences in leaf form between two closely related plant species, Arabidopsis thaliana and Cardamine hirsuta. We report that in C. hirsuta, class I KNOTTED1-like homeobox (KNOX) proteins are required in the leaf to delay cellular differentiation and produce a dissected leaf form, in contrast to A. thaliana, in which KNOX exclusion from leaves results in a simple leaf form. These differences in KNOX expression arise through changes in the activity of upstream gene regulatory sequences. The function of ASYMMETRIC LEAVES1/ROUGHSHEATH2/PHANTASTICA (ARP) proteins to repress KNOX expression is conserved between the two species, but in C. hirsuta the ARP-KNOX regulatory module controls new developmental processes in the leaf. Thus, evolutionary tinkering with KNOX regulation, constrained by ARP function, may have produced diverse leaf forms by modulating growth and differentiation patterns in developing leaf primordia.

Phenotypic plasticity and stability of leaf form in Plantago paradoxa Hook, f. in mosaic environments

Phenotypic polymorphisms in leaves are correlated with three distinct microhabitats that occur in each of two populations of Plantago paradoxa. Progeny testing demonstrates that there are differences in leaf form between the populations but that these are masked by canalization within populations. In one of the populations, plants from all three microhabitats exhibit phenotypic plasticity of leaf form, both transplants and progeny adopting the same form in a common environment. However, plants having one of the three leaf forms in the second population are stable. Foliar applications of gibberellic acid show that about two-thirds of the phenotypically plastic plants subsequently produce leaf forms that mimic the stable leaf form in the glasshouse. The occurrence of leaf forms which are stable or subject to phenotypic modification is dependent on the particular microhabitat the plants occupy.

Heterophyllous Shoots in Betula papyrifera

LEAVES of two morphological types occur on long shoots of tree crowns in many species of Betula. Those at the shoot base frequently differ from leaves closer to the shoot tip in venation, size, toothing and other characteristics. The first group of leaves (early leaves) appears at or shortly after bud opening, and the second (late leaves) later in the growing season after the first leaves are well expanded. Early leaves are also found on short shoots, that is, shoots the internodes of which fail to elongate more than a few mm. Late leaves are lacking on short shoots. In a report on leaf dimorphism in Populus trichocarpa, Critchfield1 stated that differences in leaf form were due to differences in ontogeny between early and late leaves. Early leaves formed in the growing season preceding their expansion. Their development was arrested and they over-wintered as embryonic leaves, continuing development the following spring. Late leaves over-wintered as leaf primordia or were not initiated until the growing season in which they expanded. Consequently their formation was not interrupted in the embryonic stage and their form differed from that of early leaves. These investigations have now been extended to an evaluation of bud contents, shoot growth, and heterophylly in Betula papyrifera Marsh. growing in north central Wisconsin (U.S.A.).

MORPHOLOGY OF MARSILEA VESTITA. II. MORPHOLOGY OF THE ADULT LAND AND SUBMERGED LEAVES

Two distinct adult leaf forms, i.e., land and submerged leaves, of the aquatic fern Marsilea vestita were collected from nature and were obtained from plants in sterile culture. The venation patterns and anatomy of these 2 adult leaf forms are presented in detail. Pinna development and the morphology of a third leaf form, i.e., floating leaves, are briefly considered. The differences in leaf form are ascribed to differences in the activity of the marginal meristem of the leaf.

ALTERATION OF LEAF SIZE AND STRUCTURE IN CONVALLARIA MAJALIS CAUSED BY EXTREME SHADE

This paper presents a comparative anatomical study of normal shade and extreme shade leaves of a common garden plant (Convallaria majalis L.). Striking differences in leaf form, shape, size, thickness, and internal structure were observed. The failure of the mesophyll cells to enlarge is thought to account for the marked thinness and peculiarly folded condition of extreme shade leaves.