Muhammad Saleem

Publications (4)22.69 Total impact

• Source

  Available from: plantphysiol.org

  Article: Specification of cortical parenchyma and stele of maize primary roots by asymmetric levels of auxin, cytokinin, and cytokinin-regulated proteins.

  Muhammad Saleem, Tobias Lamkemeyer, André Schützenmeister, Johannes Madlung, Hajime Sakai, Hans-Peter Piepho, Alfred Nordheim, Frank Hochholdinger
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  ABSTRACT: In transverse orientation, maize (Zea mays) roots are composed of a central stele that is embedded in multiple layers of cortical parenchyma. The stele functions in the transport of water, nutrients, and photosynthates, while the cortical parenchyma fulfills metabolic functions that are not very well characterized. To better understand the molecular functions of these root tissues, protein- and phytohormone-profiling experiments were conducted. Two-dimensional gel electrophoresis combined with electrospray ionization tandem mass spectrometry identified 59 proteins that were preferentially accumulated in the cortical parenchyma and 11 stele-specific proteins. Hormone profiling revealed preferential accumulation of indole acetic acid and its conjugate indole acetic acid-aspartate in the stele and predominant localization of the cytokinin cis-zeatin, its precursor cis-zeatin riboside, and its conjugate cis-zeatin O-glucoside in the cortical parenchyma. A root-specific beta-glucosidase that functions in the hydrolysis of cis-zeatin O-glucoside was preferentially accumulated in the cortical parenchyma. Similarly, four enzymes involved in ammonium assimilation that are regulated by cytokinin were preferentially accumulated in the cortical parenchyma. The antagonistic distribution of auxin and cytokinin in the stele and cortical parenchyma, together with the cortical parenchyma-specific accumulation of cytokinin-regulated proteins, suggest a molecular framework that specifies the function of these root tissues that also play a role in the formation of lateral roots from pericycle and endodermis cells.
  Plant physiology 11/2009; 152(1):4-18. · 6.53 Impact Factor
• Article: Tissue specific control of the maize (Zea mays L.) embryo, cortical parenchyma, and stele proteomes by RUM1 which regulates seminal and lateral root initiation.

  Muhammad Saleem, Tobias Lamkemeyer, André Schützenmeister, Claudia Fladerer, Hans-Peter Piepho, Alfred Nordheim, Frank Hochholdinger
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  ABSTRACT: The different root types of maize (Zea mays L.) originate from distinct tissues during development. The maize mutant rum1 (rootless with undetectable meristems 1) does not initiate seminal roots and lateral roots in the primary root. While seminal roots are laid down during embryogenesis, endodermis cells of the parenchyma, and pericycle cells of the stele contribute to the postembryonic initiation of lateral roots. In this study, tissue specific protein profiles of immature embryo, cortical parenchyma which includes endodermis, cortex and epidermis cell layers, and stele tissues were compared between wild-type and rum1 via 2-DE. Electrospray ionization tandem mass spectrometry (ESI-MS/MS) identified 86 proteins encoded by 69 genes that were differentially accumulated between wild-type and rum1 (Fc>or=2; FDR<10%) demonstrating that RUM1 affects the proteome composition of cortical parenchyma, stele and embryo tissues. While several protein isoforms, protein families or members of biochemical pathways regulated by RUM1 were differentially accumulated in at least two tissues, other proteins displayed tissue specific expression differences. Multiple members of the globulin gene family displayed, for example, embryo specific expression differences, while different glycolysis related enzymes were differentially expressed in all three analyzed tissues. Proteins related to signal transduction and cell fate were overrepresented in cortical parenchyma versus embryo and embryo versus stele tissues, respectively, and might imply tissue specific functions of these protein classes.
  Journal of Proteome Research 04/2009; 8(5):2285-97. · 5.11 Impact Factor
• Source

  Available from: iastate.edu

  Article: Transcriptomic and proteomic analyses of pericycle cells of the maize primary root.

  Diana Dembinsky, Katrin Woll, Muhammad Saleem, Yan Liu, Yan Fu, Lisa A Borsuk, Tobias Lamkemeyer, Claudia Fladerer, Johannes Madlung, Brad Barbazuk, Alfred Nordheim, Dan Nettleton, Patrick S Schnable, Frank Hochholdinger
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  ABSTRACT: Each plant cell type expresses a unique transcriptome and proteome at different stages of differentiation dependent on its developmental fate. This study compared gene expression and protein accumulation in cell-cycle-competent primary root pericycle cells of maize (Zea mays) prior to their first division and lateral root initiation. These are the only root cells that maintain the competence to divide after they leave the meristematic zone. Pericycle cells of the inbred line B73 were isolated via laser capture microdissection. Microarray experiments identified 32 genes preferentially expressed in pericycle versus all other root cells that have left the apical meristem; selective subtractive hybridization identified seven genes preferentially expressed in pericycle versus central cylinder cells of the same root region. Transcription and protein synthesis represented the most abundant functional categories among these pericycle-specific genes. Moreover, 701 expressed sequence tags (ESTs) were generated from pericycle and central cylinder cells. Among those, transcripts related to protein synthesis and cell fate were significantly enriched in pericycle versus nonpericycle cells. In addition, 77 EST clusters not previously identified in maize ESTs or genomic databases were identified. Finally, among the most abundant soluble pericycle proteins separated via two-dimensional electrophoresis, 20 proteins were identified via electrospray ionization-tandem mass spectrometry, thus defining a reference dataset of the maize pericycle proteome. Among those, two proteins were preferentially expressed in the pericycle. In summary, these pericycle-specific gene expression experiments define the distinct molecular events during the specification of cell-cycle-competent pericycle cells prior to their first division and demonstrate that pericycle specification and lateral root initiation might be controlled by a different set of genes.
  Plant physiology 12/2007; 145(3):575-88. · 6.53 Impact Factor
• Article: Proteomic dissection of plant development.

  Frank Hochholdinger, Michaela Sauer, Diana Dembinsky, Nadine Hoecker, Nils Muthreich, Muhammad Saleem, Yan Liu
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  ABSTRACT: Plant development is controlled by complex endogenous genetic programs and responses to environmental cues. Proteome analyses have recently been introduced to plant biology to identify proteins instrumental in these developmental processes. To date most plant proteome studies have been employed to generate reference maps of the most abundant soluble proteins of plant organs at a defined developmental stage. However, proteomics is now also utilized for genetic studies comparing the proteomes of different plant genotypes, for physiological studies analyzing the influences of exogenous signals on a particular plant organ, and developmental studies investigating proteome changes during development. Technical advances are now beginning to allow a proteomic dissection of individual cell types, thus greatly increasing the information revealed by proteome analyses.
  PROTEOMICS 08/2006; 6(14):4076-83. · 4.51 Impact Factor