STM/BP-Like KNOXI Is Uncoupled from ARP in the Regulation of Compound Leaf Development in<i>Medicago truncatula</i>

Zhou, Chuanen; Han, Li; Li, Guifen; Chai, Maofeng; Fu, Chunxiang; Cheng, Xiaofei; Wen, Jiangqi; Tang, Yuhong; Wang, Zeng‐Yu

doi:10.1105/tpc.114.123885

Cited by 45 publications

(72 citation statements)

References 57 publications

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“…KNOX4 belongs to the class II KNOX family in plants. Different from class I KNOX genes, which are well known for their roles in maintenance of shoot apical meristem (25,(28)(29)(30)(31), class II KNOX genes show diverse expression patterns and few known functions (30,32,33). This study revealed a previously unidentified function of this class II KNOX gene.…”

Section: Discussionmentioning

confidence: 82%

“…The study provides an understanding of the molecular mechanism of physical dormancy and offers a perspective for seed plant evolution. In recent years, Medicago truncatula has been developed into a model legume and effectively used for studying compound leaf development and nitrogen fixation (21)(22)(23)(24)(25). The seeds of M. truncatula belong to a classic hardseededness type.…”

Section: Significancementioning

confidence: 99%

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A class II KNOX gene, KNOX4 , controls seed physical dormancy

Chai

Zhou

Molina

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Physical dormancy of seed is an adaptive trait that widely exists in higher plants. This kind of dormancy is caused by a waterimpermeable layer that blocks water and oxygen from the surrounding environment and keeps embryos in a viable status for a long time. Most of the work on hardseededness has focused on morphological structure and phenolic content of seed coat. The molecular mechanism underlying physical dormancy remains largely elusive. By screening a large number of Tnt1 retrotransposontagged Medicago truncatula lines, we identified nondormant seed mutants from this model legume species. Unlike wild-type hard seeds exhibiting physical dormancy, the mature mutant seeds imbibed water quickly and germinated easily, without the need for scarification. Microscopic observations of cross sections showed that the mutant phenotype was caused by a dysfunctional palisade cuticle layer in the seed coat. Chemical analysis found differences in lipid monomer composition between the wild-type and mutant seed coats. Genetic and molecular analyses revealed that a class II KNOTTED-like homeobox (KNOXII) gene, KNOX4, was responsible for the loss of physical dormancy in the seeds of the mutants. Microarray and chromatin immunoprecipitation analyses identified CYP86A, a gene associated with cutin biosynthesis, as one of the downstream target genes of KNOX4. This study elucidated a novel molecular mechanism of physical dormancy and revealed a new role of class II KNOX genes. Furthermore, KNOX4-like genes exist widely in seed plants but are lacking in nonseed species, indicating that KNOX4 may have diverged from the other KNOXII genes during the evolution of seed plants.S eed dormancy is a complex adaptive trait of higher plants that allows embryos to survive extended periods of unfavorable environmental conditions (1). Over the course of evolution, plant seeds have evolved diverse dormancy forms in response to various climates to maintain viability (2). Physical dormancy, also termed hardseededness, is an exogenous dormancy caused by a water-impermeable hard seed coat. Physical dormancy plays a key role in protecting seeds against microbial attacks and predators and maintaining seed banks in soils (3-5). This type of dormancy has been found in at least 17 plant families and is very common in legume species (2, 6, 7). Seed exhibiting physical dormancy is characterized by specific morphological features, including a water-impermeable palisade cell layer covered by intact cuticles in the hard seed coat. This structure blocks water and oxygen from its surrounding environment and preserves seeds in a viable status for a long time, sometimes for more than hundreds of years (8). Another common type of seed dormancy is physiological dormancy, which is caused by endogenous factors (e.g., abscisic acid) in embryos. Most molecular studies on seed dormancy have focused on physiological dormancy, using model species Arabidopsis thaliana (9, 10).However, A. thaliana seed is water-permeable, and thus not a suitable model to study physical dor...

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Section: Discussionmentioning

confidence: 82%

Section: Significancementioning

confidence: 99%

A class II KNOX gene, KNOX4 , controls seed physical dormancy

Chai

Zhou

Molina

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…Therefore, it appears that the core mechanism regulating leaf form in R. aquatica differs from that of L. arcuata and P. nodosus. Parallels are seen between this situation and that of leaf complexity, where other mechanisms besides the KNOX-GA gene module have been shown to operate in a derived clade of Fabaceae (Hofer et al, 1997;Champagne et al, 2007;Zhou et al, 2014). Since the acquisition of heterophylly has also occurred independently multiple times (Wells and Pigliucci, 2000;Wanke, 2011;Nakayama et al, 2012a), the core regulatory mechanisms for acquisition of heterophylly may not be conserved during evolution.…”

Section: Regulation Of Ga Level Via Knox1 Genes Induces Heterophyllymentioning

confidence: 90%

Regulation of the KNOX-GA Gene Module Induces Heterophyllic Alteration in North American Lake Cress

et al. 2014

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Plants show leaf form alteration in response to changes in the surrounding environment, and this phenomenon is called heterophylly. Although heterophylly is seen across plant species, the regulatory mechanisms involved are largely unknown. Here, we investigated the mechanism underlying heterophylly in Rorippa aquatica (Brassicaceae), also known as North American lake cress. R. aquatica develops pinnately dissected leaves in submerged conditions, whereas it forms simple leaves with serrated margins in terrestrial conditions. We found that the expression levels of KNOTTED1-LIKE HOMEOBOX (KNOX1) orthologs changed in response to changes in the surrounding environment (e.g., change of ambient temperature; below or above water) and that the accumulation of gibberellin (GA), which is thought to be regulated by KNOX1 genes, also changed in the leaf primordia. We further demonstrated that exogenous GA affects the complexity of leaf form in this species. Moreover, RNA-seq revealed a relationship between light intensity and leaf form. These results suggest that regulation of GA level via KNOX1 genes is involved in regulating heterophylly in R. aquatica. The mechanism responsible for morphological diversification of leaf form among species may also govern the variation of leaf form within a species in response to environmental changes.

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“…KNOX genes have also been characterized in legume species such as PsKN1 and PsKN2 in P. sativum (Tattersall et al, 2005), orthologues of STM and KNAT1/BP, respectively, and LjKN1, LjKN2 and LjKN3 in Lotus japonicus (Luo et al, 2005). In Medicago truncatula KNOX genes present important differences compared with other characterised legume KNOXs (Di Giacomo et al, 2008;Zhou et al, 2014). (Sharma et al, 2014).…”

Section: Class 1 Knox Homeodomain Transcription Factorsmentioning

confidence: 99%

“…KNOX genes fall into two subclasses, Class I KNOX (KNOXI) and Class II KNOX (KNOXII) based on sequence similarity, gene structure, and expression pattern (Scofield and Murray, 2006;Hay and Tsiantis, 2010;Arnaud and Pautot, 2014;Zhou et al, 2014 (Gibbs et al, 2014). AtMYB93 homologues have been found in diverse crop species.…”

Section: Class 1 Knox Homeodomain Transcription Factorsmentioning

confidence: 99%

Plant development regulation: Overview and perspectives

Yruela

2015

Journal of Plant Physiology

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Plant development, as occur in other eukaryotes, is conducted through a complex network of hormones, transcription factors, enzymes and micro RNAs, among other cellular components.They control developmental processes such as embryo, apical root and shoot meristem, leaf, flower, or seed formation, among others. The research in these topics has been very active in last decades. Recently, an explosion of new data concerning regulation mechanisms as well as the response of these processes to environmental changes has emerged. Initially, most of investigations were carried out in the model eudicot Arabidopsis but currently data from other plant species are available in the literature, although they are still limited. The aim of this review is focused on the current knowledge of main molecular actors involved in plant development regulation in diverse plant species. A special attention will be given to the major families of genes and proteins participating in these mechanisms. The information on the regulatory pathways where they participate will be briefly cited. Additionally, he importance of certain structural features of such proteins that confer ductility and flexibility to these mechanisms will also be reported and discussed.

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STM/BP-Like KNOXI Is Uncoupled from ARP in the Regulation of Compound Leaf Development inMedicago truncatula

Cited by 45 publications

References 57 publications

A class II KNOX gene, KNOX4 , controls seed physical dormancy

A class II KNOX gene, KNOX4 , controls seed physical dormancy

Regulation of the KNOX-GA Gene Module Induces Heterophyllic Alteration in North American Lake Cress

Plant development regulation: Overview and perspectives

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