Biology subjects

Begcy, K.

Publications and source records attributed to Begcy, K..

6 recordsLinked to original sources

bioRxiv2024

Genome-Wide Transcriptome Dynamics in Auxin Homeostasis During Fruit Development in Strawberry (F. x ananassa)

The plant hormone auxin plays a crucial role in regulating important functions in strawberry fruit development. Although a few studies have described the complex auxin biosynthetic and signaling pathway in wild diploid strawberry (Fragaria vesca), the molecular mechanisms underlying auxin biosynthesis and crosstalk in octoploid strawberry fruit development are not fully characterized. To address this knowledge gap, comprehensive transcriptomic analyses were conducted at different stages of fruit development and compared between the achene and receptacle to identify developmentally regulated auxin biosynthetic genes and transcription factors during the fruit ripening process. Similar to wild diploid strawberry, octoploid strawberry accumulates high levels of auxin in achene compared to receptacle. Consistently, genes functionating in auxin biosynthesis and conjugation, such as TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS (TAAs), YUCCA (YUCs), and GRETCHEN HAGEN 3 (GH3s) were found to be primarily expressed in the achene, with low expression in the receptacle. Interestingly, several genes involved in auxin transport and signaling like PIN-FORMED (PINs), AUXIN/INDOLE-3-ACETIC ACID proteins (Aux/IAAs), TRANSPORT INHIBITOR RESPONSE 1 / AUXIN-SIGNALING F-BOX (TIR/AFBs) and AUXIN RESPONSE FACTOR (ARFs) were more abundantly expressed in the receptacle. Moreover, by examining DEGs and their transcriptional profiles across all six developmental stages, we identified key auxin-related genes co-clustered with transcription factors from the NAM-ATAF1,2-CUC2/ WRKYGQK motif (NAC/WYKY), BASIC REGION/ LEUCINE ZIPPER motif (bZIP), and APETALA2/Ethylene Responsive Factor (AP2/ERF) groups. These results elucidate the complex regulatory network of auxin biosynthesis and its intricate crosstalk within the achene and receptacle, enriching our understanding of fruit development in octoploid strawberries.

developmental biology↗

bioRxiv2024

Maize stigmas react differently to self-/cross-pollination and fungal invasion

During sexual reproduction in flowering plants, rapid tip-growing pollen tubes travel from the stigma inside the maternal tissues of the pistil towards ovules. In maize, the stigma is highly elongated forming thread-like strands known as silks. Only compatible pollen tubes are supported to penetrate and to grow successfully through the transmitting tract of the silk to reach the ovules. Like pollen, fungal spores germinate at the surface of silks and generate tube-like structures (hyphae) penetrating silk tissue. To elucidate commonalities and differences between silk responses to various invaders, we compared growth behavior of the various invaders as well as the silk transcriptome after self-pollination, cross-pollination and infection using two different fungi. We report that self-pollination triggers especially senescence genes, while incompatible pollination using Tripsacum dactyloides leads to downregulation of rehydration genes, microtubule and modulation of cell wall-related genes explaining slower pollen tube growth and their arrest. Invasion by the ascomycete Fusarium graminearum triggers numerous defense responses including the activation of monolignol biosynthesis and NAC as well as WRKY transcription factor genes, while responses to the basidiomycete Ustilago maydis are generally much weaker. Cell wall and phytoalexin biosynthesis pathways were selected as examples to demonstrate usability of the data sets provided. One sentence summaryData sets are provided and analyzed to elucidate how maize stigmas (silks) respond to different biotic invaders including own and alien pollen tubes as well as hyphae of two different fungi.

plant biology↗

bioRxiv2024

Cell Size Controls Photosynthetic Capacity in a Mesoamerican and an Andean Genotype of Phaseolus vulgaris L.

The efficiency of CO2 flux in the leaf is hindered by a several structural and biochemical barriers which affect the overall net photosynthesis. However, the dearth of information about the genetic control of these features is limiting our ability for genetic manipulation. We performed a comparative analysis between a Mesoamerican and an Andean cultivar of Phaseolus vulgaris at variable light and CO2 levels. The Mesoamerican bean had higher photosynthetic rate, maximum rate of rubisco carboxylase activity and maximum rate of photosynthetic electron transport at light saturation conditions than its Andean counterpart. Leaf anatomy comparison between genotypes showed that the Mesoamerican bean had smaller cell sizes than the Andean bean. Smaller epidermal cells in the Mesoamerican bean resulted in higher stomata density and consequently higher stomatal conductance for water vapor and CO2 than in the Andean bean. Likewise, smaller palisade and spongy mesophyll cells in the Mesoamerican than in the Andean bean increased the cell surface area per unit of volume and consequently increased mesophyll conductance. Finally, smaller cells in the Mesoamerican also increased chlorophyll and protein concentration per unit of leaf area. In summary, we show that differential cell size controls the overall net photosynthesis and could be used as a target for genetic manipulation to improve photosynthesis. HighlightPhotosyntheUc performance comparison between a Mesoamerican and an Andean bean genotype showed higher rate at increased light and CO2 levels. Differences could be explained by variaUon in cell size.

physiology↗

bioRxiv2023

Heat stress at the bicellular stage inhibits sperm cell development and their transport into pollen tubes

For a successful double fertilization process in flowering plants (angiosperms), pollen tubes each deliver two non-motile sperm cells towards female gametes (egg and central cell, respectively). Heatwaves especially during the reproduction period are threatening male gametophyte (pollen) development, which results in severe yield losses. By using maize as a crop and grass model system, we found strong seed set reduction when moderate heat stress was applied for two days during the uni- and bicellular stages of pollen development. We show that heat stress accelerates pollen development and impairs pollen germination capabilities, when applied at the unicellular stage. Heat stress at the bicellular stage impairs sperm cell development and their transport into pollen tubes. To understand the course of the latter defects, we used marker lines and analyzed the transcriptomes of isolated sperm cells. While heat stress also affects the expression of genes involved in transcription, RNA processing and translation, especially genes in DNA replication and the cell cycle were mis-regulated. This includes centromeric histone CENH3 and -tubulin. Most mis-regulated genes are involved in transition from metaphase to anaphase during pollen mitosis II (PM II). Heat stress activates spindle assembly check point and meta-to anaphase transition genes in sperm cells. In summary, mis-regulation of the identified genes during heat stress at the bicellular stage explains sperm cell development and transport defects ultimately leading to sterility.

plant biology↗

bioRxiv2023

Environmental conditions predetermine innate antioxidants pool in sea oat (Uniola 4 paniculata L.) seeds

Background and AimsSecondary metabolites such as antioxidants are critical components that protect seeds from stress damage during seed development, desiccation, and ex-situ storage. Antioxidants are essential determinants of seed quality, longevity, and persistence. Understanding the environmental factors that regulate the accumulation, content, and function of antioxidant pools in sea oat seeds is critical for gene banking and understanding the environmental impacts on seed quality. MethodsGermination, viability, and Trolox Equivalent Antioxidant Capacity (TEAC) were analyzed on seeds from 18 sea oat populations from the US Atlantic and Gulf of Mexico coasts. We first assessed baseline TEAC, followed by TEAC performed on imbibed seeds for 36 hours at 35/25 {degrees}C during the day and night, respectively. Then, we analyzed the relationship of the antioxidant pools from these 18 sea oat populations to sampling site environmental classifications. Key ResultsHigher baseline antioxidants were common in regions with extreme environmental conditions corresponding to sea oat populations growing at latitudinal extremes characterized by warmer and colder temperatures. Baseline antioxidants did not correlate with prevailing seed germination. However, higher concentrations of antioxidants following imbibition were associated with poor seed germination in warmer conditions. ConclusionsOur results indicate that climatic conditions and environmental components associated with temperatures and precipitation may largely influence the innate pool of antioxidants in sea oat seeds. Also, a high amount of antioxidants following sea oat seeds imbibition suggest seed damage or poor viability influenced by environmental stress conditions during seed development.

physiology↗

bioRxiv2021

Arabidopsis ABIG1 Functions in Laminar Growth and Polarity Formation through Regulation by REVOLUTA and KANADI

Leaf laminar growth and adaxial-abaxial boundary formation are fundamental outcomes of plant development. Boundary and laminar growth coordinate the further patterning and growth of the leaf, directing the differentiation of cell types within the top and bottom domains and promoting initiation of lateral organs along their adaxial/abaxial axis. Leaf adaxial-abaxial polarity specification and laminar out-growth are regulated by two transcription factors, REVOLUTA (REV) and KANADI (KAN). ABA INSENSITIVE TO GROWTH 1 (ABIG1) is a HOMEODOMAIN-LEUCINE ZIPPER (HD-ZIP) Class II transcription factor and is a direct target of the adaxial-abaxial regulators REV and KAN. To investigate the role of ABIG1 in the leaf development and establishment of polarity, we examined the phenotypes of both gain-of-function and loss-of-function mutants. Through genetic interaction analysis with REV and KAN mutants, we have determined that ABIG1 plays a role in leaf laminar-growth as well as in adaxial-abaxial polarity establishment. Genetic and physical interaction assays showed that ABIG1 interacts with the transcriptional corepressor TOPLESS (TPL). This study provides new evidence that another HD-ZIP II gene, ABIG1, facilitates growth through the corepressor TPL. HighlightABIG1, a HD-ZIP Class II transcription factor, promotes laminar growth and adaxial-abaxial polarity through the regulation of REV and KAN.

developmental biology↗