Developmental cues are encoded by the combinatorial phosphorylation of Arabidopsis RETINOBLASTOMA-RELATED protein RBR1.

RETINOBLASTOMA-RELATED (RBR) proteins orchestrate cell division, differentiation, and survival in response to environmental and developmental cues through protein-protein interactions that are governed by multisite phosphorylation. Here we explore, using a large collection of transgenic RBR phosphovariants to complement protein function in Arabidopsis thaliana, whether differences in the number and position of RBR phosphorylation events cause a diversification of the protein's function. While the number of point mutations influence phenotypic strength, phosphosites contribute differentially to distinct phenotypes.

The miRNA822 loaded by ARGONAUTE9 modulates the monosporic female gametogenesis in Arabidopsis thaliana.

The miR822 together with of AGO9 protein, modulates monosporic development in Arabidopsis thaliana through the regulation of target genes encoding Cysteine/Histidine-Rich C1 domain proteins, revealing a new role of miRNAs in the control of megaspore formation in flowering plants. 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 (Arabidopsis) undergoes a monosporic type of gametogenesis as three meiotically derived cells degenerate, and a single one-the functional megaspore (FM), divides mitotically to form the female gametophyte.

Domestication and lowland adaptation of coastal preceramic maize from Paredones, Peru.

Archaeological cobs from Paredones and Huaca Prieta (Peru) represent some of the oldest maize known to date, yet they present relevant phenotypic traits corresponding to domesticated maize. This contrasts with the earliest Mexican macro-specimens from Guila Naquitz and San Marcos, which are phenotypically intermediate for these traits, even though they date more recently in time. To gain insights into the origins of ancient Peruvian maize, we sequenced DNA from three Paredones specimens dating ~6700-5000 calibrated years before present (BP), conducting comparative analyses with two teosinte subspecies ( ssp.

Genomic methylation patterns in pre-meiotic gynoecia of wild-type and RdDM mutants of Arabidopsis.

Introduction: Although DNA methylation patterns are generally considered to be faithfully inherited in Arabidopsis thaliana (Arabidopsis), there is evidence of reprogramming during both male and female gametogenesis. The gynoecium is the floral reproductive organ from which the ovules develop and generate meiotically derived cells that give rise to the female gametophyte. It is not known whether the gynoecium can condition genomic methylation in the ovule or the developing female gametophyte.

The Arabidopsis TETRATRICOPEPTIDE-REPEAT THIOREDOXIN-LIKE (TTL) family members are involved in root system formation via their interaction with cytoskeleton and cell wall remodeling.

Lateral roots (LR) are essential components of the plant edaphic interface; contributing to water and nutrient uptake, biotic and abiotic interactions, stress survival, and plant anchorage. We have identified the TETRATRICOPEPTIDE-REPEAT THIOREDOXIN-LIKE 3 (TTL3) gene as being related to LR emergence and later development. Loss of function of TTL3 leads to a reduced number of emerged LR due to delayed development of lateral root primordia (LRP).

Isolation of Boechera stricta Developing Embryos for Hi-C.

The possibility of analyzing chromatin topology in developing plant embryos is hampered by inaccessibility of the embryo sac, deeply embedded in the maternal seed tissue, following double fertilization. Here we describe a protocol to isolate, purify, and prepare developing Boechera stricta embryos for chromosome conformation capture-based methods as in situ Hi-C experiments. Early globular embryos can be isolated by air-pressure microaspiration, and subsequently washed to eliminate residual cells from the endosperm and maternal seed coat, allowing for pure sampling of selected stages of embryogenesis.

Gradual domestication of root traits in the earliest maize from Tehuacán.

Efforts to understand the phenotypic transition that gave rise to maize from teosinte have mainly focused on the analysis of aerial organs, with little insights into possible domestication traits affecting the root system. Archeological excavations in San Marcos cave (Tehuacán, Mexico) yielded two well-preserved 5,300 to 4,970 calibrated y B.P.

Developing a rapid and highly efficient cowpea regeneration, transformation and genome editing system using embryonic axis explants.

Cowpea (Vigna unguiculata (L.) Walp.) is one of the most important legume crops planted worldwide, but despite decades of effort, cowpea transformation is still challenging due to inefficient Agrobacterium-mediated transfer DNA delivery, transgenic selection and in vitro shoot regeneration.

Unequal contribution of two paralogous CENH3 variants in cowpea centromere function.

In most diploids the centromere-specific histone H3 (CENH3), the assembly site of active centromeres, is encoded by a single copy gene. Persistance of two CENH3 paralogs in diploids species raises the possibility of subfunctionalization. Here we analysed both CENH3 genes of the  diploid dryland crop cowpea.

A detached leaf assay for testing transient gene expression and gene editing in cowpea ( [L.] Walp.).

Background: The legume cowpea ( L.) is extensively grown in sub-Saharan Africa. Cowpea, like many legumes has proved recalcitrant to plant transformation.

Whole-Mount Immunolocalization Procedure for Plant Female Meiocytes.

Here we present an optimized protocol for immunolocalization of meiotic proteins during female meiosis in whole mount tissues. It ensures ovule morphology integrity and homogeneous reagent penetration. The method relies on paraformaldehyde tissue fixation, polyacrylamide embedding, tissue permeabilization, antibody incubation, counterstaining, and confocal microscopy analysis.

Immunolocalization to Study ARGONAUTE Proteins in Developing Ovules of the Brassicaceae.

Determining the in situ pattern of protein expression is crucial to accurately establish regulatory function and mode of action of any plant developmental program. Here, we describe two immunolocalization procedures that are consistently used to determine subcellular localization of ARGONAUTE proteins in the ovule of the Brassicaceae. The first is performed in resin-embedded semi-thin sections of developing ovules that can be observed under bright-field microscopy.

Apomixis in flowering plants: Developmental and evolutionary considerations.

Apomixis refers to a set of reproductive mechanisms that invariably rely on avoiding meiotic reduction and fertilization of the egg cell to generate clonal seeds. After having long been considered a strictly asexual oddity leading to extinction, the integration of more than 100 years of embryological, genetic, molecular, and ecological research has revealed apomixis as a widely spread component of the dynamic processes that shape flowering plant evolution. Apomixis involves several flexible and versatile developmental pathways that can be combined within the ovule to produce offspring.

Asymmetric paternal effect on offspring size linked to parent-of-origin expression of an insulin-like growth factor.

Sexual reproduction brings together reproductive partners whose long-term interests often differ, raising the possibility of conflict over their reproductive investment. Males that enhance maternal investment in their offspring gain fitness benefits, even if this compromises future reproductive investment by iteroparous females. When the conflict occurs at a genomic level, it may be uncovered by crossing divergent populations, as a mismatch in the coevolved patterns of paternal manipulation and maternal resistance may generate asymmetric embryonic growth.

Organellar Genomes from a ∼5,000-Year-Old Archaeological Maize Sample Are Closely Related to NB Genotype.

The story of how preColumbian civilizations developed goes hand-in-hand with the process of plant domestication by Mesoamerican inhabitants. Here, we present the almost complete sequence of a mitochondrial genome and a partial chloroplast genome from an archaeological maize sample collected at the Valley of Tehuacán, México. Accelerator mass spectrometry dated the maize sample to be 5,040-5,300 years before present (95% probability).

The earliest maize from San Marcos Tehuacán is a partial domesticate with genomic evidence of inbreeding.

Pioneering archaeological expeditions lead by Richard MacNeish in the 1960s identified the valley of Tehuacán as an important center of early Mesoamerican agriculture, providing by far the widest collection of ancient crop remains, including maize. In 2012, a new exploration of San Marcos cave (Tehuacán, Mexico) yielded nonmanipulated maize specimens dating at a similar age of 5,300-4,970 calibrated y B.P.

A Primary Sequence Analysis of the ARGONAUTE Protein Family in Plants.

Small RNA (sRNA)-mediated gene silencing represents a conserved regulatory mechanism controlling a wide diversity of developmental processes through interactions of sRNAs with proteins of the ARGONAUTE (AGO) family. On the basis of a large phylogenetic analysis that includes 206 AGO genes belonging to 23 plant species, AGO genes group into four clades corresponding to the phylogenetic distribution proposed for the ten family members of Arabidopsis thaliana. A primary analysis of the corresponding protein sequences resulted in 50 sequences of amino acids (blocks) conserved across their linear length.

A Multigenic Network of ARGONAUTE4 Clade Members Controls Early Megaspore Formation in Arabidopsis.

The development of gametophytes relies on the establishment of a haploid gametophytic generation that initiates with the specification of gametophytic precursors. The majority of flowering plants differentiate a single gametophytic precursor in the ovule: the megaspore mother cell. Here we show that, in addition to argonaute9 (ago9), mutations in other ARGONAUTE (AGO) genes such as ago4, ago6, and ago8, also show abnormal configurations containing supernumerary gametophytic precursors in Arabidopsis thaliana Double homozygous ago4 ago9 individuals showed a suppressive effect on the frequency of ovules with multiple gametophytic precursors across three consecutive generations, indicating that genetic interactions result in compensatory mechanisms.

New observations on gametogenic development and reproductive experimental tools to support seed yield improvement in cowpea [Vigna unguiculata (L.) Walp].

Cowpea reproductive tools. Vigna unguiculata L. Walp.

Whole-mount immunolocalization to study female meiosis in Arabidopsis.

Here we describe a whole-mount immunolocalization protocol to follow the subcellular localization of proteins during female meiosis in Arabidopsis thaliana, a model species that is used to study sexual reproduction in flowering plants. By using confocal microscopy, the procedure allows one to follow megasporogenesis at all stages before differentiation of the functional megaspore. This in particular includes stages that occur during prophase I, such as the installation of the axial and central elements of the synaptonemal complex along the meiotic chromosomes.

Functional analysis of the Arabidopsis thaliana CHLOROPLAST BIOGENESIS 19 pentatricopeptide repeat editing protein.

The Arabidopsis thaliana pentatricopeptide repeat (PPR) family of proteins contains several degenerate 35-aa motifs named PPR repeats. These proteins control diverse post-transcriptional regulatory mechanisms, including RNA editing. CLB19 belongs to the PLS subfamily of PPR proteins and is essential for the editing and functionality of the subunit A of plastid-encoded RNA polymerase (RpoA) and the catalytic subunit of the Clp protease (ClpP1).