scholarly journals Structural Maintenance of Chromosomes 5/6 Complex Is Necessary for Tetraploid Genome Stability in Arabidopsis thaliana

2021 ◽  
Vol 12 ◽  
Author(s):  
Fen Yang ◽  
Nadia Fernández Jiménez ◽  
Joanna Majka ◽  
Mónica Pradillo ◽  
Ales Pecinka
Keyword(s):  
Arabidopsis Thaliana ◽  
Genome Stability ◽  
Flowering Plants ◽  
Common Phenomenon ◽  
Loss Of Function ◽  
Homologous Chromosomes ◽  
Maternal Genome ◽  
Important Player ◽  
Polyploid Genome ◽  
Structural Maintenance Of Chromosomes

Polyploidization is a common phenomenon in the evolution of flowering plants. However, only a few genes controlling polyploid genome stability, fitness, and reproductive success are known. Here, we studied the effects of loss-of-function mutations in NSE2 and NSE4A subunits of the Structural Maintenance of Chromosomes 5/6 (SMC5/6) complex in autotetraploid Arabidopsis thaliana plants. The diploid nse2 and nse4a plants show partially reduced fertility and produce about 10% triploid offspring with two paternal and one maternal genome copies. In contrast, the autotetraploid nse2 and nse4a plants were almost sterile and produced hexaploid and aneuploid progeny with the extra genome copies or chromosomes coming from both parents. In addition, tetraploid mutants had more severe meiotic defects, possibly due to the presence of four homologous chromosomes instead of two. Overall, our study suggests that the SMC5/6 complex is an important player in the maintenance of tetraploid genome stability and that autotetraploid Arabidopsis plants have a generally higher frequency of but also higher tolerance for aneuploidy compared to diploids.

scholarly journals Cytokinin signalling regulates two-stage inflorescence arrest in Arabidopsis

2022 ◽  
Author(s):  
Catriona H Walker ◽  
Alexander Ware ◽  
Jan Šimura ◽  
Karin Ljung ◽  
Zoe A Wilson ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Reproductive Success ◽  
Flowering Plants ◽  
Loss Of Function ◽  
Inflorescence Meristem ◽  
Fruit Removal ◽  
Cytokinin Receptor ◽  
Developmental Arrest ◽  
Cytokinin Treatment ◽  
Floral Primordia

To maximise their reproductive success, flowering plants must correctly time their entry into and exit from the reproductive phase (flowering). While much is known about the mechanisms that regulate the initiation of flowering, the regulation of end-of-flowering remains largely uncharacterised. End-of-flowering in Arabidopsis thaliana consists of the quasi-synchronous arrest of individual inflorescences, but it is unclear how this arrest is correctly timed with respect to environmental stimuli and ongoing reproductive success. Here we show that Arabidopsis inflorescence arrest is a complex developmental phenomenon which includes a decline in size and cessation of activity in the inflorescence meristem (IM), coupled with a separable developmental arrest in all unopened floral primordia (floral arrest); these events occur well before the visible arrest of the inflorescence. We show that global removal of inflorescences can delay both IM arrest and floral arrest, but that local fruit removal only delays floral arrest, emphasising the separability of these processes. We test a role for cytokinin in regulating inflorescence arrest, and find that cytokinin treatment can delay arrest. We further show that gain-of-function cytokinin receptor hypersensitive mutants can delay floral arrest, and also IM arrest, depending on the expression pattern of the receptor; conversely, loss-of-function mutants prevent extension of flowering in response to inflorescence removal. Collectively, our data suggest that the dilution of cytokinin among an increasing number of sink organs leads to end-of-flowering in Arabidopsis by triggering IM and floral arrest, conversely meaning that a lack of reproductive success can homeostatically extend flowering in compensation.

scholarly journals SHAGGY-like kinase 12 regulates flowering through mediating CONSTANS stability in Arabidopsis

2020 ◽  
Vol 6 (24) ◽  
pp. eaaw0413 ◽  
Author(s):  
Ying Chen ◽  
Shiyong Song ◽  
Yinbo Gan ◽  
Lixi Jiang ◽  
Hao Yu ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Glycogen Synthase ◽  
Floral Induction ◽  
Reproductive Development ◽  
Flowering Plants ◽  
Floral Transition ◽  
Glycogen Synthase Kinase 3 ◽  
Loss Of Function ◽  
Site Specific ◽  
Precocious Flowering

Photoperiod is a major environmental cue that determines the floral transition from vegetative to reproductive development in flowering plants. Arabidopsis thaliana responds to photoperiodic signals mainly through a central regulator CONSTANS (CO). Although it has been suggested that phosphorylation of CO contributes to its role in photoperiodic control of flowering, how this is regulated so far remains unknown. Here, we report that a glycogen synthase kinase-3 member, SHAGGY-like kinase 12 (SK12), plays an important role in preventing precocious flowering through phosphorylating CO. Loss of function of SK12 causes early flowering. SK12 expression in seedlings is decreased during the floral transition, and its expression in vascular tissues is required for repressing flowering. SK12 interacts with and phosphorylates CO at threonine 119, thus facilitating CO degradation. Our findings suggest that site-specific phosphorylation of CO by SK12 is critical for modulating the photoperiodic output for the floral induction in Arabidopsis.

scholarly journals MIR822 modulates monosporic female gametogenesis through an ARGONAUTE9-dependent pathway in Arabidopsis thaliana

2021 ◽  
Author(s):  
ANDREA TOVAR AGUILAR ◽  
Daniel GRIMANELLI ◽  
Gerardo Acosta Garcia ◽  
Jean Philippe Vielle Calzada ◽  
Jesus Agustin Badillo-Corona ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Flowering Plants ◽  
Loss Of Function ◽  
Genes Encoding ◽  
Functional Megaspore ◽  
Dependent Pathway ◽  
Female Gametogenesis

In the ovule of flowering plants, the establishment of the haploid generation occurs when a somatic cell differentiates into a Megaspore Mother Cell (MMC) and initiates meiosis. As most flowering plants, Arabidopsis thaliana undergoes a monosporic type of gametogenesis; three meiotically derived cells degenerate without further division, and a single one, the functional megaspore (FM), divides mitotically to form the female gametophyte. In Arabidopsis, the ARGONAUTE4 clade proteins are involved in the control of megasporogenesis. In particular, mutations in ARGONAUTE9 (AGO9) lead to the ectopic differentiation of gametic precursors that can give rise female gametophytes. However, the genetic basis and molecular mechanisms that control monosporic gametogenesis remain largely unknown. Here, we show that Arabidopsis plants carrying loss-of-function mutations in the AGO9-interacting miR822a give rise to extranumerary surviving megaspores that acquire a FM identity and divide without giving rise to differentiated female gametophytes. The overexpression of three miR822a target genes encoding Cysteine/Histidine-Rich C1 domain proteins (DC1) phenocopy mir822a plants. The miR822a targets are overexpressed in ago9 mutant ovules, confirming that miR822a acts through an AGO9-dependent pathway to negatively regulate DC1 domain proteins. Our results identify a new role of miRNAs in the most prevalent form of female gametogenesis in flowering plants

scholarly journals A super-pangenome framework of the genus Glycine unveils polyploid evolution and life-strategy transition

2021 ◽  
Author(s):  
Yongbin Zhuang ◽  
Xutong Wang ◽  
Xianchong Li ◽  
Junmei Hu ◽  
Lichuan Fan ◽  
...  
Keyword(s):  
Phase Transition ◽  
Adaptive Evolution ◽  
Genome Stability ◽  
Gene Clusters ◽  
Flowering Plants ◽  
Life Strategy ◽  
Perennial Species ◽  
Polyploid Evolution ◽  
Genetic Potential ◽  
Polyploid Genome

Abstract Polyploidy and life strategy transitions between annuality and perenniality often occur in flowering plants. However, the evolutionary propensities of polyploids and genetic bases of such transitions remain elusive. We assembled plantum genomes of representative perennial species across the genus Glycine including five diploids and a young allopolyploid, and constructed a Glycine super-pangenome framework by integrating 26 annual soybean genomes. The perennials exhibited greater genome stability than the annuals, with few centromere repeats abundant in the latter. Biased subgenome fractionation has occurred in the allopolyploid, primarily by accumulation of small deletions in gene clusters through illegitimate recombination, which was associated with preexisting local genomic differentiation. A gene annotated to modulate vegetative to reproductive phase transition was identified to have undergone adaptive evolution underlying the perenniality-annuality transition. Our study provides mechanistic insights into polyploid genome evolution and lays a foundation for unleashing genetic potential from the perennial gene pool for soybean improvement.

par-4, a gene required for cytoplasmic localization and determination of specific cell types in Caenorhabditis elegans embryogenesis.

Genetics ◽  
1992 ◽  
Vol 130 (4) ◽  
pp. 771-790 ◽  
Author(s):  
D G Morton ◽  
J M Roos ◽  
K J Kemphues
Keyword(s):  
Caenorhabditis Elegans ◽  
Cell Types ◽  
Intestinal Cells ◽  
Specific Cell ◽  
Cytoplasmic Localization ◽  
Loss Of Function ◽  
Embryo Viability ◽  
Cell Stage ◽  
Maternal Genome

Abstract Specification of some cell fates in the early Caenorhabditis elegans embryo is mediated by cytoplasmic localization under control of the maternal genome. Using nine newly isolated mutations, and two existing mutations, we have analyzed the role of the maternally expressed gene par-4 in cytoplasmic localization. We recovered seven new par-4 alleles in screens for maternal effect lethal mutations that result in failure to differentiate intestinal cells. Two additional par-4 mutations were identified in noncomplementation screens using strains with a high frequency of transposon mobility. All 11 mutations cause defects early in development of embryos produced by homozygous mutant mothers. Analysis with a deficiency in the region indicates that it33 is a strong loss-of-function mutation. par-4(it33) terminal stage embryos contain many cells, but show no morphogenesis, and are lacking intestinal cells. Temperature shifts with the it57ts allele suggest that the critical period for both intestinal differentiation and embryo viability begins during oogenesis, about 1.5 hr before fertilization, and ends before the four-cell stage. We propose that the primary function of the par-4 gene is to act as part of a maternally encoded system for cytoplasmic localization in the first cell cycle, with par-4 playing a particularly important role in the determination of intestine. Analysis of a par-4; par-2 double mutant suggests that par-4 and par-2 gene products interact in this system.

scholarly journals Brassinosteroids repress the seed maturation program during the seed-to-seedling transition

2021 ◽  
Author(s):  
Jiuxiao Ruan ◽  
Huhui Chen ◽  
Tao Zhu ◽  
Yaoguang Yu ◽  
Yawen Lei ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Transcription Factor ◽  
Abscisic Acid ◽  
Plant Hormone ◽  
Flowering Plants ◽  
Seed Maturation ◽  
Domain Protein ◽  
Abscisic Acid Insensitive3 ◽  
Underlying Mechanisms ◽  
Embryonic Structure

Abstract In flowering plants, repression of the seed maturation program is essential for the transition from the seed to the vegetative phase, but the underlying mechanisms remain poorly understood. The B3-domain protein VIVIPAROUS1/ABSCISIC ACID-INSENSITIVE3-LIKE 1 (VAL1) is involved in repressing the seed maturation program. Here we uncovered a molecular network triggered by the plant hormone brassinosteroid (BR) that inhibits the seed maturation program during the seed-to-seedling transition in Arabidopsis (Arabidopsis thaliana). val1-2 mutant seedlings treated with a BR biosynthesis inhibitor form embryonic structures, whereas BR signaling gain-of-function mutations rescue the embryonic structure trait. Furthermore, the BR-activated transcription factors BRI1-EMS-SUPPRESSOR 1 and BRASSINAZOLE-RESISTANT 1 bind directly to the promoter of AGAMOUS-LIKE15 (AGL15), which encodes a transcription factor involved in activating the seed maturation program, and suppress its expression. Genetic analysis indicated that BR signaling is epistatic to AGL15 and represses the seed maturation program by downregulating AGL15. Finally, we showed that the BR-mediated pathway functions synergistically with the VAL1/2-mediated pathway to ensure the full repression of the seed maturation program. Together, our work uncovered a mechanism underlying the suppression of the seed maturation program, shedding light on how BR promotes seedling growth.

scholarly journals Orchid Bsister gene PeMADS28 displays conserved function in ovule integument development

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ching-Yu Shen ◽  
You-Yi Chen ◽  
Ke-Wei Liu ◽  
Hsiang-Chia Lu ◽  
Song-Bin Chang ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Protein Interaction ◽  
Ectopic Expression ◽  
Flowering Plants ◽  
Complementation Test ◽  
Ovule Development ◽  
Mads Box ◽  
Temporal Expression ◽  
Protein Protein Interaction ◽  
Silique Length

AbstractThe ovules and egg cells are well developed to be fertilized at anthesis in many flowering plants. However, ovule development is triggered by pollination in most orchids. In this study, we characterized the function of a Bsister gene, named PeMADS28, isolated from Phalaenopsis equestris, the genome-sequenced orchid. Spatial and temporal expression analysis showed PeMADS28 predominantly expressed in ovules between 32 and 48 days after pollination, which synchronizes with integument development. Subcellular localization and protein–protein interaction analyses revealed that PeMADS28 could form a homodimer as well as heterodimers with D-class and E-class MADS-box proteins. In addition, ectopic expression of PeMADS28 in Arabidopsis thaliana induced small curled rosette leaves, short silique length and few seeds, similar to that with overexpression of other species’ Bsister genes in Arabidopsis. Furthermore, complementation test revealed that PeMADS28 could rescue the phenotype of the ABS/TT16 mutant. Together, these results indicate the conserved function of BsisterPeMADS28 associated with ovule integument development in orchid.

scholarly journals The efficacy of CRISPR-mediated cytosine base editing with the RPS5a promoter in Arabidopsis thaliana

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Minkyung Choi ◽  
Jae-Young Yun ◽  
Jun-Hyuk Kim ◽  
Jin-Soo Kim ◽  
Sang-Tae Kim
Keyword(s):  
Arabidopsis Thaliana ◽  
Cytidine Deaminase ◽  
Biological Research ◽  
Loss Of Function ◽  
Nucleotide Substitutions ◽  
Viral Origin ◽  
Nonsense Mutations ◽  
Base Editing ◽  
Low Efficiency ◽  
Viable System

AbstractCRISPR/Cas9-mediated genome editing is an important and versatile technology in modern biological research. Recent advancements include base-editing CRISPR tools that enable targeted nucleotide substitutions using a fusion protein comprising a nickase variant of Cas9 and a base deaminase. Improvements in base editing efficiencies and inheritable of edited loci need to be made to make CRISPR a viable system in plants. Here, we report efficiency of cytosine base editors (CBEs) in Arabidopsis thaliana by applying the strong endogenous RPS5a promoter to drive the expression of nickase Cas9 and either rAPOBEC1 from rat (BE3) or the PmCDA1 activation-induced cytidine deaminase from sea lamprey (AIDv2). Compared with the strong heterologous CaMV35S promoter of viral origin, the RPS5a promoter improved CBE efficiency by 32% points with the number of T1 plants showing over 50% conversion ratio when the LFY gene was targeted. CBE induced nonsense mutations in LFY via C-to-T conversion, which resulted in loss-of-function lfy phenotypes; defects in LFY function were associated with the targeted base substitutions. Our data suggest that optimal promoter choice for CBE expression may affect base-editing efficiencies in plants. The results provide a strategy to optimize low-efficiency base editors and demonstrate their applicability for functional assays and trait development in crop research.

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