Molecular genetic approaches to leaf development: Knotted and beyond

1994 ◽  
Vol 72 (5) ◽  
pp. 617-625 ◽  
Author(s):  
Laurie G. Smith ◽  
Sarah Hake
Keyword(s):  
Molecular Genetics ◽  
Shoot Apex ◽  
Leaf Development ◽  
Molecular Basis ◽  
Leaf Surface ◽  
Molecular Genetic ◽  
Leaf Morphogenesis ◽  
Promising Alternative ◽  
Recessive Mutations ◽  
Experimental Approaches

Molecular genetics provides a promising alternative to other experimental approaches for furthering our understanding of the mechanisms controlling leaf development. We investigated the molecular basis of dominant Knotted (Kn1) mutations in maize, which cause cells associated with the lateral veins of the leaf blade to acquire characteristics of sheath or auricle and sporadically form outgrowths called knots. The kn1 gene encodes a homeodomain, a DNA-binding domain shared by many transcription factors that regulate developmental processes in animals and fungi. In normal plants, the expression of kn1 is confined to the shoot apex, but in Kn1 mutants, the gene is also expressed ectopically in the veins of developing leaves, apparently causing cells to change their developmental fates. The kn1 gene may function in the shoot apex of normal plants to promote indeterminate growth. Consistent with this hypothesis, when kn1 is expressed constitutively at high levels in the leaves of transgenic tobacco, shoots are formed on the leaf surface. Thus, our results indicate that while the kn1 gene may normally have no function in leaf development, it can alter the development of maize and tobacco leaves when it is expressed in the leaf inappropriately. Genes that normally play a role in leaf development are more likely to be defined by recessive mutations that alter leaf morphogenesis and histogenesis. Key words: leaf development, molecular genetics, Knotted.

scholarly journals Coordination of Leaf Development Across Developmental Axes

Plants ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 433 ◽  
Author(s):  
James W. Satterlee ◽  
Michael J. Scanlon
Keyword(s):  
Leaf Development ◽  
Molecular Genetic ◽  
Transcriptional Network ◽  
Cell Type ◽  
Leaf Morphogenesis ◽  
Apical Meristems ◽  
Shoot Apical Meristems ◽  
Developmental Patterning ◽  
Genetic Mechanisms ◽  
Type Specification

Leaves are initiated as lateral outgrowths from shoot apical meristems throughout the vegetative life of the plant. To achieve proper developmental patterning, cell-type specification and growth must occur in an organized fashion along the proximodistal (base-to-tip), mediolateral (central-to-edge), and adaxial–abaxial (top-bottom) axes of the developing leaf. Early studies of mutants with defects in patterning along multiple leaf axes suggested that patterning must be coordinated across developmental axes. Decades later, we now recognize that a highly complex and interconnected transcriptional network of patterning genes and hormones underlies leaf development. Here, we review the molecular genetic mechanisms by which leaf development is coordinated across leaf axes. Such coordination likely plays an important role in ensuring the reproducible phenotypic outcomes of leaf morphogenesis.

scholarly journals Genome-wide analysis of changes in miRNA and target gene expression reveals key roles in heterosis for Chinese cabbage biomass

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Peirong Li ◽  
Tongbing Su ◽  
Deshuang Zhang ◽  
Weihong Wang ◽  
Xiaoyun Xin ◽  
...  
Keyword(s):  
Chinese Cabbage ◽  
Leaf Development ◽  
Target Genes ◽  
Expression Patterns ◽  
Seedling Stage ◽  
Differentially Expressed ◽  
Small Rna Sequencing ◽  
Leaf Morphogenesis ◽  
Expression Levels ◽  
Parental Lines

AbstractHeterosis is a complex phenomenon in which hybrids show better phenotypic characteristics than their parents do. Chinese cabbage (Brassica rapa L. spp. pekinensis) is a popular leafy crop species, hybrids of which are widely used in commercial production; however, the molecular basis of heterosis for biomass of Chinese cabbage is poorly understood. We characterized heterosis in a Chinese cabbage F1 hybrid cultivar and its parental lines from the seedling stage to the heading stage; marked heterosis of leaf weight and biomass yield were observed. Small RNA sequencing revealed 63 and 50 differentially expressed microRNAs (DEMs) at the seedling and early-heading stages, respectively. The expression levels of the majority of miRNA clusters in the F1 hybrid were lower than the mid-parent values (MPVs). Using degradome sequencing, we identified 1,819 miRNA target genes. Gene ontology (GO) analyses demonstrated that the target genes of the MPV-DEMs and low parental expression level dominance (ELD) miRNAs were significantly enriched in leaf morphogenesis, leaf development, and leaf shaping. Transcriptome analysis revealed that the expression levels of photosynthesis and chlorophyll synthesis-related MPV-DEGs (differentially expressed genes) were significantly different in the F1 hybrid compared to the parental lines, resulting in increased photosynthesis capacity and chlorophyll content in the former. Furthermore, expression of genes known to regulate leaf development was also observed at the seedling stage. Arabidopsis plants overexpressing BrGRF4.2 and bra-miR396 presented increased and decreased leaf sizes, respectively. These results provide new insight into the regulation of target genes and miRNA expression patterns in leaf size and heterosis for biomass of B. rapa.

scholarly journals Molecular genetics of bipolar disorder

2001 ◽  
Vol 178 (S41) ◽  
pp. s128-s133 ◽  
Author(s):  
Nick Craddock ◽  
Ian Jones
Keyword(s):  
Bipolar Disorder ◽  
Candidate Gene ◽  
Molecular Genetics ◽  
Ethical Issues ◽  
Association Studies ◽  
Single Gene ◽  
Molecular Genetic ◽  
Genetic Dissection ◽  
Adoption Studies ◽  
Candidate Gene Association

BackgroundA robust body of evidence from family, twin and adoption studies demonstrates the importance of genes in the pathogenesis of bipolar disorder. Recent advances in molecular genetics have made it possible to identify these susceptibility genes.AimsTo present an overview for clinical psychiatrists.MethodReview of current molecular genetics approaches and emerging findings.ResultsOccasional families may exist in which a single gene plays a major role in determining susceptibility, but the majority of bipolar disorder involves more complex genetic mechanisms such as the interaction of multiple genes and environmental factors. Molecular genetic positional and candidate gene approaches are being used for the genetic dissection of bipolar disorder. No gene has yet been identified but promising findings are emerging. Regions of interest include chromosomes 4p16, 12q23–q24, 16p13, 21q22, and Xq24–q26. Candidate gene association studies are in progress but no robust positive findings have yet emerged.ConclusionIt is almost certain that over the next few years the identification of bipolar susceptiblity genes will have a major impact on our understanding of disease pathophysiology. This is likely to lead to major improvements and treatment in patient care, but will also raise important ethical issues.

scholarly journals Molecular genetic analysis of porcine von Willebrand disease: tight linkage to the von Willebrand factor locus

Blood ◽  
1988 ◽  
Vol 72 (1) ◽  
pp. 308-313 ◽  
Author(s):  
WF Bahou ◽  
EJ Bowie ◽  
DN Fass ◽  
D Ginsburg
Keyword(s):  
Von Willebrand Factor ◽  
Molecular Basis ◽  
Gene Deletion ◽  
Molecular Genetic ◽  
Molecular Genetic Analysis ◽  
Von Willebrand Disease ◽  
Molecular Defect ◽  
Human Disorder ◽  
Von Willebrand ◽  
Willebrand Factor

von Willebrand disease (vWD), one of the most common bleeding disorders in humans, is manifested as a quantitative or qualitative defect in von Willebrand factor (vWF), an adhesive glycoprotein (GP) with critical hemostatic functions. Except for the rare severely affected patient with a gene deletion as etiology of the disease, the molecular basis for vWD is not known. We studied the molecular basis for vWD in a breeding colony of pigs with a disease closely resembling the human disorder. The porcine vWF gene is similar in size and complexity to its human counterpart, and no gross gene deletion or rearrangement was evident as the pathogenesis of porcine vWD. A restriction fragment- length polymorphism (RFLP) within the porcine vWF gene was identified with the restriction endonuclease HindIII, and 22/35 members of the pedigree were analyzed for the polymorphic site. Linkage between the vWF locus and the vWD phenotype was established with a calculated LOD score of 5.3 (1/200,000 probability by chance alone), with no crossovers identified. These findings indicate that porcine vWD is due to a molecular defect within (or near) the vWF locus, most likely representing a point mutation or small insertion/deletion within the vWF gene.

Behavior and Molecular Genetics of the Five Factor Model

2015 ◽  
Author(s):  
Amber M. Jarnecke ◽  
Susan C. South
Keyword(s):  
Molecular Genetics ◽  
Behavior Genetics ◽  
Factor Model ◽  
Five Factor Model ◽  
Molecular Genetic ◽  
Future Directions ◽  
Genetics Research ◽  
Genetic Mechanisms ◽  
Genetic Techniques ◽  
Related Personality

Behavior and molecular genetics informs knowledge of the etiology, structure, and development of the Five Factor Model (FFM) of personality. Behavior genetics uses quantitative modeling to parse the relative influence of nature and nurture on phenotypes that vary within the population. Behavior genetics research on the FFM has demonstrated that each domain has a heritability (proportion of variation due to genetic influences) of 40–50%. Molecular genetic methods attempt to identify specific genetic mechanisms associated with personality variation. To date, findings from molecular genetics are tentative, with significant results failing to replicate and accounting for only a small percentage of the variance. However, newer techniques hold promise for finding the “missing heritability” of FFM and related personality domains. This chapter presents an overview of commonly used behavior and molecular genetic techniques, reviews the work that has been done on the FFM domains and facets, and offers a perspective for future directions.

Two independent and polarized processes of cell elongation regulate leaf blade expansion in Arabidopsis thaliana (L.) Heynh

Development ◽  
1996 ◽  
Vol 122 (5) ◽  
pp. 1589-1600 ◽  
Author(s):  
T. Tsuge ◽  
H. Tsukaya ◽  
H. Uchimiya
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Elongation ◽  
Leaf Development ◽  
Cellular Level ◽  
Leaf Length ◽  
Specific Cell ◽  
Wild Type ◽  
Leaf Morphogenesis ◽  
Length Direction ◽  
Number Of Cells

For genetic analysis of mechanisms of leaf morphogenesis, we chose Arabidopsis thaliana (L.) Heynh. as a model for leaf development in dicotyledonous plants. Leaves of the angustifolia mutant were the same length as but narrower and thicker than wild-type leaves. The total number of cells in leaf blades of angustifolia plants was the same as in the wild type. At the cellular level in the angustifolia mutant it was found that the cells were smaller in the leaf-width direction and larger in the leaf-thickness direction than in wild type, revealing the function of the ANGUSTIFOLIA gene, which is to control leaf morphology by regulating polarity-specific cell elongation. The existence of similar genes that regulate leaf development in the length direction was, therefore, predicted. Three loci and several alleles associated with short-leaved mutants were newly isolated as rotundifolia mutants. The rotundifolia3 mutant had the same number of cells as the wild type, with reduced cell elongation in the leaf-length direction. The features of the angustifolia rotundifolia3 double mutant indicated that ANGUSTIFOLIA and ROTUNDIFOLIA3 genes act independently. We propose that leaf expansion in Arabidopsis involves at least two independent developmental processes: width development and length development, with the ANGUSTIFOLIA and ROTUNDIFOLIA3 genes playing different polarity-specific roles in cell elongation.

Molecular breeding for improving heat stress tolerance in wheat.

2021 ◽  
pp. 82-89
Author(s):  
Kuo-hai Yu ◽  
Hui-ru Peng ◽  
Zhong-fu Ni ◽  
Ying-yin Yao ◽  
Zhao-rong Hu ◽  
...  
Keyword(s):  
Heat Stress ◽  
Heat Tolerance ◽  
Molecular Basis ◽  
Molecular Genetic ◽  
Wheat Breeding ◽  
Heat Response ◽  
Breeding Programmes ◽  
Resource Exploration ◽  
Heat Stress Tolerance

Abstract This paper discusses wheat responses to heat stress (including morphological and growth, cellular structure and physiological responses) and the molecular-genetic bases of heat response in wheat (including topics on mapping quantitative trait loci related to heat tolerance and the role of functional genes in response to heat stress). The improvement of heat tolerance of wheat by comprehensive strategies is also described. It is believed that with the emphasis on genetic resource exploration and with better understanding of the molecular basis, heat tolerance will be improved during wheat breeding programmes in the future.

Genetic epidemiology 2: molecular genetics

2003 ◽  
pp. 335-356
Author(s):  
David Collier ◽  
Tao Li
Keyword(s):  
Molecular Genetics ◽  
Single Gene ◽  
Molecular Genetic ◽  
Molecular Genetic Analysis ◽  
Primary Objective ◽  
Great Success ◽  
Complex Disorder ◽  
Single Gene Disorders ◽  
Human Disorders ◽  
Rapid Pace

The previous chapter has focused on methods for identifying familial clustering of disorders or traits, and on methods for distinguishing between shared genetic and environmental influences. The primary objective for this chapter is to outline techniques for identifying specific genes responsible for an observed phenotype. The theoretical basis of complex and quantitative traits was established many decades ago. However practical methods for the efficient molecular analysis of the human genome have only recently emerged. Alongside these developments, the molecular genetic analysis of human disorders has moved at a rapid pace. Molecular genetics has focused on single gene disorders with great success, whereas for complex psychiatric disorders, few genetic risk factors have been identified. However the tools used by the complex disorder geneticist have evolved rapidly in the last few years and better strategies and statistical methods continue to appear. This chapter outlines some established and novel approaches to the analysis of the genetics of complex human disorders. A basic understanding of genetical statistics will be useful.

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