Vein patterning and evolution in C4 plants

Botany ◽  
2010 ◽  
Vol 88 (9) ◽  
pp. 775-786 ◽  
Author(s):  
Athena D. McKown ◽  
Nancy G. Dengler

The C4 photosynthetic pathway provides a platform to gain insight into the formation, regulation, and biological consequences of leaf vein pattern modification. This review examines the functional role of the vascular system in C4 photosynthesis and the development of veins in C3 and C4 plants, highlighting the contribution of vasculature in the evolution of the C4 pathway. With interest in developing C3 plant crops into C4 systems, it is essential to understand vascular patterning as a necessary element for C4 functioning. Leaf venation in C4 plants generally shows a higher vein density through a greater network complexity (more veins) compared with the ancestral C3 condition. Thus, C4 plants can provide a model that links the development of vein patterning with evolutionary selection pressures and molecular mechanisms (i.e., modifications of different components of vascular development). Numerous studies, including a comparative C3 and C4 Flaveria case study, highlight that the overall process of vein formation and patterning is complex, involving interactions between procambium and ground meristem during leaf ontogeny, and points to potential roles of changes in auxin production, transport, and perception.

Author(s):  
Irina Kneuper ◽  
William Teale ◽  
Jonathan Edward Dawson ◽  
Ryuji Tsugeki ◽  
Eleni Katifori ◽  
...  

Abstract Our current understanding of vein development in leaves is based on canalization of the plant hormone auxin into self-reinforcing streams which determine the sites of vascular cell differentiation. By comparison, how auxin biosynthesis affects leaf vein patterning is less well understood. Here, after observing that inhibiting polar auxin transport rescues the sparse leaf vein phenotype in auxin biosynthesis mutants, we propose that the processes of auxin biosynthesis and cellular auxin efflux work in concert during vein development. By using computational modeling, we show that localized auxin maxima are able to interact with mechanical forces generated by the morphological constraints which are imposed during early primordium development. This interaction is able to explain four fundamental characteristics of midvein morphology in a growing leaf: (i) distal cell division; (ii) coordinated cell elongation; (iii) a midvein positioned in the center of the primordium; and (iv) a midvein which is distally branched. Domains of auxin biosynthetic enzyme expression are not positioned by auxin canalization, as they are observed before auxin efflux proteins polarize. This suggests that the site-specific accumulation of auxin, as regulated by the balanced action of cellular auxin efflux and local auxin biosynthesis, is crucial for leaf vein formation.


2017 ◽  
Author(s):  
Irina Kneuper ◽  
William Teale ◽  
Jonathan Edward Dawson ◽  
Ryuji Tsugeki ◽  
Klaus Palme ◽  
...  

SummaryThe plant hormone auxin (indole-3-acetic acid, IAA) has a profound influence over plant cell growth and differentiation. Current understanding of vein development in leaves is based on the canalization of auxin into self-reinforcing streams which determine the sites of vascular cell differentiation. However, the role of auxin biosynthesis during leaf development in the context of leaf vein patterning has not been much studied so far. Here we characterize the context specific importance of auxin biosynthesis, auxin transport and mechanical regulations in a growing leaf. We show that domains of auxin biosynthesis predict the positioning of vascular cells. In mutants that have reduced capacity in auxin biosynthesis, leaf vein formation is decreased. While exogenous application of auxin does not compensate the loss of vein formation in auxin biosynthesis mutants, inhibition of polar auxin transport does compensate the vein-less phenotype, suggesting that the site-specific accumulation of auxin, which is likely to be mainly caused by the local auxin biosynthesis, is important for leaf vein formation. Our computational model of midvein development brings forth the interplay of cell stiffness and auxin dependent cell division. We propose that local auxin biosynthesis has the integral role in leaf vascular development.HighlightsBuilt spatially and temporally resolved auxin biosynthesis map in growing leaf primordium of Arabidopsis.Expression domains of auxin biosynthetic enzymes within primordia strongly correlated with leaf vein initiation.Results show that domains of auxin biosynthesis within primordia drive leaf vein initiation and patterning.Highlights and eTOC BlurbUsing modelling and a spatiotemporal analysis of auxin biosynthesis and transport, Kneuper et al. show that tissue specific auxin biosynthesis defines places of vein initiation hence underlining the importance of auxin concentration in vein initiation.


Antioxidants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 706
Author(s):  
Aishwarya R. Vaidya ◽  
Nina Wolska ◽  
Dina Vara ◽  
Reiner K. Mailer ◽  
Katrin Schröder ◽  
...  

Diabetes mellitus is the fifth most common cause of death worldwide. Due to its chronic nature, diabetes is a debilitating disease for the patient and a relevant cost for the national health system. Type 2 diabetes mellitus is the most common form of diabetes mellitus (90% of cases) and is characteristically multifactorial, with both genetic and environmental causes. Diabetes patients display a significant increase in the risk of developing cardiovascular disease compared to the rest of the population. This is associated with increased blood clotting, which results in circulatory complications and vascular damage. Platelets are circulating cells within the vascular system that contribute to hemostasis. Their increased tendency to activate and form thrombi has been observed in diabetes mellitus patients (i.e., platelet hyperactivity). The oxidative damage of platelets and the function of pro-oxidant enzymes such as the NADPH oxidases appear central to diabetes-dependent platelet hyperactivity. In addition to platelet hyperactivity, endothelial cell damage and alterations of the coagulation response also participate in the vascular damage associated with diabetes. Here, we present an updated interpretation of the molecular mechanisms underlying vascular damage in diabetes, including current therapeutic options for its control.


Forests ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 737
Author(s):  
Ernesto C. Rodríguez-Ramírez ◽  
Jeymy Adriana Valdez-Nieto ◽  
José Antonio Vázquez-García ◽  
Gregg Dieringer ◽  
Isolda Luna-Vega

The Mexican tropical montane cloud forest trees occur under special and limited climatic conditions; many of these species are particularly more sensitive to drought stress. Hydric transport in leaf veins and wood features are influenced by climatic variations and individual intrinsic factors, which are essential processes influencing xylogenesis. We assessed the plastic response to climatic oscillation in two relict-endangered Magnolia schiedeana Schltdl. populations and associated the architecture of leaf vein traits with microenvironmental factors and wood anatomy features with climatic variables. The microenvironmental factors differed significantly between the two Magnolia populations and significantly influenced variation in M. schiedeana leaf venation traits. The independent chronologies developed for the two study forests were dated back 171–190 years. The climate-growth analysis showed that M. schiedeana growth is strongly related to summer conditions and growth responses to Tmax, Tmin, and precipitation. Our study highlights the use of dendroecological tools to detect drought effects. This association also describes modifications in vessel traits recorded before, during, and after drought events. In conclusion, our results advance our understanding of the leaf vein traits and wood anatomy plasticity in response to microenvironmental fluctuations and climate in the tropical montane cloud forest.


1999 ◽  
Vol 82 (08) ◽  
pp. 865-869 ◽  
Author(s):  
Thomas Sato

IntroductionThe vascular system is one of the first organ systems to develop in our bodies. Normal development and maturation of the physiological functions of almost all of the other organs are critically dependent on the accurate and tightly controlled establishment of the vascular system. Our understanding of the mechanisms underlying the formation of the vascular system during development is still in its infancy. With further understanding of these mechanisms, we may eventually be able to correct the abnormal development and the malfunctioning of many organs by therapeutically modulating the morphology and/or physiological function of the vascular system.Our further understanding of the vascular development can, in part, be achieved by discovering the molecules that play critical roles in this process. We could also achieve this goal by learning more about the functions of previously identified molecules in the vascular system. Discovery of new processes underlying the development of the vascular system will also contribute to further understanding of these molecular mechanisms.Recent advances, using the whole genome approach, have resulted in a flood of new information. This trend will continue, and fortunately, a number of molecular reagents will become available. Therefore, the field will likely experience an exponential growth in terms of novel biological insights and discovering the mechanisms of vascular system development.Occasionally, reductionistic approaches help to systematically address a number of biological problems, including the problems associated with vascular system development. One such approach is to choose an organism that allows us to systematically address these biological questions. The choice of animal models that are well-suited for the study of a particular question has led to a large number of discoveries. To address questions in vascular system development, current research has focused on animal models, including fish, frog, bird, and mouse, and also studies involving humans. It is also worthwhile to note that the branching morphogenesis of the fly trachea system has been utilized to address fundamental questions of vascular morphogenesis.This chapter will summarize the genomic manipulation of the murine vascular system to address questions regarding vascular development. In addition, the advances that have been made in this field using such methods will be summarized.


2008 ◽  
Vol 3 (5) ◽  
pp. 286-289 ◽  
Author(s):  
Megan G. Sawchuk ◽  
Tyler J. Donner ◽  
Enrico Scarpella

2020 ◽  
Vol 8 (1) ◽  
pp. 76
Author(s):  
Jian-Yu Meng ◽  
Mbuya Sylvain Ntambo ◽  
Philippe C. Rott ◽  
Hua-Ying Fu ◽  
Mei-Ting Huang ◽  
...  

Sugarcane can suffer severe yield losses when affected by leaf scald, a disease caused by Xanthomonas albilineans. This bacterial pathogen colonizes the vascular system of sugarcane, which can result in reduced plant growth and plant death. In order to better understand the molecular mechanisms involved in the resistance of sugarcane to leaf scald, a comparative proteomic study was performed with two sugarcane cultivars inoculated with X. albilineans: one resistant (LCP 85-384) and one susceptible (ROC20) to leaf scald. The iTRAQ (isobaric tags for relative and absolute quantification) approach at 0 and 48 h post-inoculation (hpi) was used to identify and annotate differentially expressed proteins (DEPs). A total of 4295 proteins were associated with 1099 gene ontology (GO) terms by GO analysis. Among those, 285 were DEPs during X. albilineans infection in cultivars LCP 85-384 and ROC20. One hundred seventy-two DEPs were identified in resistant cultivar LCP 85-384, and 113 of these proteins were upregulated and 59 were downregulated. One hundred ninety-two DEPs were found in susceptible cultivar ROC20 and half of these (92) were upregulated, whereas the other half corresponded to downregulated proteins. The significantly upregulated DEPs in LCP 85-384 were involved in metabolic pathways, the biosynthesis of secondary metabolites, and the phenylpropanoid biosynthesis pathway. Additionally, the expression of seven candidate genes related to photosynthesis and glycolytic pathways, plant innate immune system, glycosylation process, plant cytochrome P450, and non-specific lipid transfer protein was verified based on transcription levels in sugarcane during infection by X. albilineans. Our findings shed new light on the differential expression of proteins in sugarcane cultivars in response to infection by X. albilineans. The identification of these genes provides important information for sugarcane variety improvement programs using molecular breeding strategies.


2009 ◽  
Vol 104 (6) ◽  
pp. 1085-1098 ◽  
Author(s):  
Athena D. McKown ◽  
Nancy G. Dengler

Author(s):  
H. Xu ◽  
B. Blonder ◽  
M. Jodra ◽  
Y. Malhi ◽  
M.D. Fricker

SummaryLeaf vein network geometry can predict levels of resource transport, defence, and mechanical support that operate at different spatial scales. However, it is challenging to quantify network architecture across scales, due to the difficulties both in segmenting networks from images, and in extracting multi-scale statistics from subsequent network graph representations.Here we develop deep learning algorithms using convolutional neural networks (CNNs) to automatically segment leaf vein networks. Thirty-eight CNNs were trained on subsets of manually-defined ground-truth regions from >700 leaves representing 50 southeast Asian plant families. Ensembles of 6 independently trained CNNs were used to segment networks from larger leaf regions (~100 mm2). Segmented networks were analysed using hierarchical loop decomposition to extract a range of statistics describing scale transitions in vein and areole geometry.The CNN approach gave a precision-recall harmonic mean of 94.5% ± 6%, outperforming other current network extraction methods, and accurately described the widths, angles, and connectivity of veins. Multi-scale statistics then enabled identification of previously-undescribed variation in network architecture across species.We provide a LeafVeinCNN software package to enable multi-scale quantification of leaf vein networks, facilitating comparison across species and exploration of the functional significance of different leaf vein architectures.


2020 ◽  
Author(s):  
Xin Ye ◽  
Hui-Yu Huang ◽  
Feng-Lin Wu ◽  
Li-Ya Cai ◽  
Ning-Wei Lai ◽  
...  

Abstract Citrus sinensis (L.) Osbeck seedlings were fertigated with nutrient solution containing 2 [magnesium (Mg)-sufficiency] or 0 mM (Mg-deficiency) Mg(NO3)2 for 16 weeks. Thereafter, RNA-Seq was used to investigate Mg-deficiency-responsive genes in the veins of upper and lower leaves in order to understand the molecular mechanisms for Mg-deficiency-induced vein lignification, enlargement and cracking, which appeared only in the lower leaves. In this study, 3065 upregulated and 1220 downregulated, and 1390 upregulated and 375 downregulated genes were identified in Mg-deficiency veins of lower leaves (MDVLL) vs Mg-sufficiency veins of lower leaves (MSVLL) and Mg-deficiency veins of upper leaves (MDVUL) vs Mg-sufficiency veins of upper leaves (MSVUL), respectively. There were 1473 common differentially expressed genes (DEGs) between MDVLL vs MSVLL and MDVUL vs MSVUL, 1463 of which displayed the same expression trend. Magnesium-deficiency-induced lignification, enlargement and cracking in veins of lower leaves might be related to the following factors: (i) numerous transciption factors and genes involved in lignin biosynthesis pathways, regulation of cell cycle and cell wall metabolism were upregulated; and (ii) reactive oxygen species, phytohormone and cell wall integrity signalings were activated. Conjoint analysis of proteome and transcriptome indicated that there were 287 and 56 common elements between DEGs and differentially abundant proteins (DAPs) identified in MDVLL vs MSVLL and MDVUL vs MSVUL, respectively, and that among these common elements, the abundances of 198 and 55 DAPs matched well with the transcript levels of the corresponding DEGs in MDVLL vs MSVLL and MDVUL vs MSVUL, respectively, indicating the existence of concordances between protein and transcript levels.


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