The<i>indeterminate gametophyte1</i>Gene of Maize Encodes a LOB Domain Protein Required for Embryo Sac and Leaf Development

Mulenga, Evans

doi:10.1105/tpc.106.047506

Cited by 224 publications

(194 citation statements)

References 59 publications

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“…For many Arabidopsis LBD genes, loss-offunction mutation phenotypes were not apparent with the exception of LBD6, which performs a role in leaf development (Semiarti et al, 2001;Xu et al, 2003). However, several loss-of-function mutants of rice and maize LBD genes have been reported to evidence clear phenotypes (Inukai et al, 2005;Liu et al, 2005;Bortiri et al, 2006;Evans, 2007;Taramino et al, 2007). The ectopic expression of several LBD genes, as wild type or as proteins fused to a transcriptional repression domain, yielded morphological phenotypes, provid- ing clues to the biological functions of these LBD genes (Shuai et al, 2002;Chalfun-Junior et al, 2005;Borghi et al, 2007;Okushima et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

LBD18/ASL20Regulates Lateral Root Formation in Combination withLBD16/ASL18Downstream ofARF7andARF19in Arabidopsis

et al. 2009

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The LATERAL ORGAN BOUNDARIES DOMAIN/ASYMMETRIC LEAVES2-LIKE (LBD/ASL) genes encode proteins harboring a conserved amino acid domain, referred to as the LOB (for lateral organ boundaries) domain. While recent studies have revealed developmental functions of some LBD genes in Arabidopsis (Arabidopsis thaliana) and in crop plants, the biological functions of many other LBD genes remain to be determined. In this study, we have demonstrated that the lbd18 mutant evidenced a reduced number of lateral roots and that lbd16 lbd18 double mutants exhibited a dramatic reduction in the number of lateral roots compared with lbd16 or lbd18. Consistent with this observation, significant b-glucuronidase (GUS) expression in Pro LBD18 :GUS seedlings was detected in lateral root primordia as well as in the emerged lateral roots. Whereas the numbers of primordia of lbd16, lbd18, and lbd16 lbd18 mutants were similar to those observed in the wild type, the numbers of emerged lateral roots of lbd16 and lbd18 single mutants were reduced significantly. lbd16 lbd18 double mutants exhibited additively reduced numbers of emerged lateral roots compared with single mutants. This finding indicates that LBD16 and LBD18 may function in the initiation and emergence of lateral root formation via a different pathway. LBD18 was shown to be localized into the nucleus. We determined whether LBD18 functions in the nucleus using a steroid regulator-inducible system in which the nuclear translocation of LBD18 can be regulated by dexamethasone in the wild-type, lbd18, and lbd16 lbd18 backgrounds. Whereas LBD18 overexpression in the wild-type background induced lateral root formation to some degree, other lines manifested the growth-inhibition phenotype. However, LBD18 overexpression rescued lateral root formation in lbd18 and lbd16 lbd18 mutants without inducing any other phenotypes. Furthermore, we demonstrated that LBD18 overexpression can stimulate lateral root formation in auxin response factor7/19 (arf7 arf19) mutants with blocked lateral root formation. Taken together, our results suggest that LBD18 functions in the initiation and emergence of lateral roots, in conjunction with LBD16, downstream of ARF7 and ARF19.

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Section: Discussionmentioning

confidence: 99%

LBD18/ASL20Regulates Lateral Root Formation in Combination withLBD16/ASL18Downstream ofARF7andARF19in Arabidopsis

et al. 2009

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“…Among these are four transcripts encoding known stem cell regulators, including three CLASS I KNOX genes and a GATA domain protein homologous to HANABA TARANU in Arabidopsis (Figures 4C and 4D; see Supplemental Data Set 8 online) Zhao et al, 2004;Mukherjee et al, 2009;reviewed in Hay and Tsiantis, 2010). Upregulated transcripts encoding proteins that function in organogenesis and cell proliferation of lateral organs include WUSHEL-RELATED HOMEOBOX3A (WOX3A), the YABBY gene DROOPING LEAF2 (DL2), the lateral organ boundary gene INDETERMINATE GA-METOPHYTE1 (IG1), and two GRF-LIKE transcripts (Kim et al, 2003;Nardmann et al, 2004;Yamaguchi et al, 2004;Evans, 2007;Nardmann et al, 2007;Zhang et al, 2007;Zhang et al, 2008). In addition to three AUXIN RESPONSE FACTOR (ARF) class transcription factors, several transcripts that encode hormone biosynthetic proteins are also upregulated in stage 14 SAMs, including seven gibberellin metabolic transcripts implicated in lateral organ growth and development.…”

Section: Morphological and Molecular Maturation Of The Maize Sammentioning

confidence: 99%

Ontogeny of the Maize Shoot Apical Meristem

Takacs

et al. 2012

Plant Cell

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The maize (Zea mays) shoot apical meristem (SAM) arises early in embryogenesis and functions during stem cell maintenance and organogenesis to generate all the aboveground organs of the plant. Despite its integral role in maize shoot development, little is known about the molecular mechanisms of SAM initiation. Laser microdissection of apical domains from developing maize embryos and seedlings was combined with RNA sequencing for transcriptomic analyses of SAM ontogeny. Molecular markers of key events during maize embryogenesis are described, and comprehensive transcriptional data from six stages in maize shoot development are generated. Transcriptomic profiling before and after SAM initiation indicates that organogenesis precedes stem cell maintenance in maize; analyses of the first three lateral organs elaborated from maize embryos provides insight into their homology and to the identity of the single maize cotyledon. Compared with the newly initiated SAM, the mature SAM is enriched for transcripts that function in transcriptional regulation, hormonal signaling, and transport. Comparisons of shoot meristems initiating juvenile leaves, adult leaves, and husk leaves illustrate differences in phase-specific (juvenile versus adult) and meristem-specific (SAM versus lateral meristem) transcript accumulation during maize shoot development. This study provides insight into the molecular genetics of SAM initiation and function in maize.

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“…Members of this gene family can be divided into different classes and subtypes, which are involved in distinct aspects of plant development (Majer and Hochholdinger, 2011). Most LBD genes studied thus far are involved in aboveground development, including adaxial-abaxial patterning of Arabidopsis leaves (Lin et al, 2003), proximal-distal patterning in Arabidopsis petals (Chalfun et al, 2005), embryo sac and leaf development in maize (Evans, 2007), leaf expansion in Arabidopsis (Iwakawa et al, 2007), and glume formation in rice (Li et al, 2008). However, it has also been demonstrated that LBD genes are involved in different aspects of root formation, including lateral root formation in Arabidopsis (Okushima et al, 2007), shootborne root formation in rice (Inukai et al, 2005;Liu et al, 2005), and shoot-borne and seminal root initiation in maize (Taramino et al, 2007).…”

Section: Rtcs-dependent Regulation Of Lob Domain Genes and Transcriptmentioning

confidence: 99%

Comparative Transcriptome Profiling of Maize Coleoptilar Nodes during Shoot-Borne Root Initiation

et al. 2013

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Maize (Zea mays) develops an extensive shoot-borne root system to secure water and nutrient uptake and to provide anchorage in the soil. In this study, early coleoptilar node (first shoot node) development was subjected to a detailed morphological and histological analysis. Subsequently, microarray profiling via hybridization of oligonucleotide microarrays representing transcripts of 31,355 unique maize genes at three early stages of coleoptilar node development was performed. These pairwise comparisons of wild-type versus mutant rootless concerning crown and seminal roots (rtcs) coleoptilar nodes that do not initiate shoot-borne roots revealed 828 unique transcripts that displayed RTCS-dependent expression. A stage-specific functional analysis revealed overrepresentation of "cell wall," "stress," and "development"-related transcripts among the differentially expressed genes. Differential expression of a subset of 15 of 828 genes identified by these microarray experiments was independently confirmed by quantitative real-time-polymerase chain reaction. In silico promoter analyses revealed that 100 differentially expressed genes contained at least one LATERAL ORGAN BOUNDARIES domain (LBD) motif within 1 kb upstream of the ATG start codon. Electrophoretic mobility shift assay experiments demonstrated RTCS binding for four of these promoter sequences, supporting the notion that differentially accumulated genes containing LBD motifs are likely direct downstream targets of RTCS.

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Theindeterminate gametophyte1Gene of Maize Encodes a LOB Domain Protein Required for Embryo Sac and Leaf Development

Cited by 224 publications

References 59 publications

LBD18/ASL20Regulates Lateral Root Formation in Combination withLBD16/ASL18Downstream ofARF7andARF19in Arabidopsis

LBD18/ASL20Regulates Lateral Root Formation in Combination withLBD16/ASL18Downstream ofARF7andARF19in Arabidopsis

Ontogeny of the Maize Shoot Apical Meristem

Comparative Transcriptome Profiling of Maize Coleoptilar Nodes during Shoot-Borne Root Initiation

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