Development Of Endosperm Cells Research Articles

Split application of phosphorus fertilizer increased wheat grain weight under post-anthesis drought stress by delaying programmed cell death of endosperm

Drought is one of the important factors affecting wheat yield. However, the effect of split application of phosphorus fertilizer on the programmed cell death (PCD) of wheat endosperm cells under different post-anthesis water treatments is still unclear. In this study, three phosphorus fertilization methods (P1, all phosphorus fertilizer was applied at the spring green-up stage; P2, 50 % and 50 % of phosphorus fertilizer were applied at the spring green-up stage and jointing stage, respectively; P3, 40 %, 30 %, and 30 % of phosphorus fertilizer were applied at the spring green-up, jointing, and grain filling stages, respectively) were designed. Besides, two post-anthesis water treatments were designed: WT, full irrigation treatment; DT, drought stress treatment. Then, the effects of P1, P2, and P3 treatments on the endosperm cell development, nuclear number, nuclease activity, DNA fragmentation, DNA content, grain weight, and phosphorus content of winter wheat variety “Xindong 23” under WT and DT conditions were determined at different stages after anthesis. The results showed that under WT and DT conditions, the degree of nuclear deformation and nuclear membrane depression in P3 treatment was milder than that in P1 and P2 treatments. The ACPase amount in P3 treatment was more than that in P1 and P2 treatments. The number of endosperm nuclei in P3 treatment was higher than that in P1 and P2 treatments. Under DT condition, the endosperm DNA content of wheat grains collected 14–35 days post anthesis (DPA) in P3 treatment increased, and the peak time of genomic DNA fragmentation in P3 treatment was later, compared with those in P1 treatment. Under DT condition, the grain weight and grouting rate in P3 treatment were higher than those of P1 treatment at 7–28 DPA, and the 1000-grain weight of P3 was the highest under both WT and DT conditions, reaching 47.03 and 40.57 g, respectively. Under WT and DT conditions, compared with P1 treatment, the protein content change rate (3.16 % and 5.59 %, respectively) and the total phosphorus content change rate (34.36 % and 35.08 %, respectively) of wheat grains in P3 treatment were the highest. In summary, under the DT condition, split application of phosphorus fertilizer (P3, spring green-up stage stage: jointing stage: filling stage = 4: 3: 3) could increase the phosphorus uptake and utilization of wheat plants and grains, suppress the DNA fragmentation of endosperm cells, and delay the deformation and disintegration of nuclei, which ultimately delayed the PCD in endosperm and realized high grain weight and protein content.

Endosperm and amyloplast development in waxy wheat cultivars.

The endosperm is an essential part of wheat grains, and the accumulation of amyloplasts in endosperm determines the quality of wheat. Because waxy wheat has a special starch quality, there is a need to understand differences in endosperm and starch morphologies among waxy wheat cultivars. This study investigated differences in the endosperm and amyloplasts of two near-isogenic lines (Shimai19-P and Shimai19-N) and the wheat cultivar Shimai19 during various growth stages using light microscopy and scanning electron microscopy. At 8days after pollination (DAP), with endosperm development, the amyloplast distributions in the different endosperm regions of the three wheat varieties were in the following order: center of ventral endosperm > subaleurone of ventral endosperm > center of dorsal endosperm > modified aleurone > subaleurone of dorsal endosperm. At 16 DAP, small amyloplasts appeared in the endosperm cells in all three wheat cultivars; subsequently, endosperm cell development until maturity was more rapid in Shimai19-N than in the other varieties. This study revealed variations in amyloplast accumulation among endosperm regions and waxy wheat varieties during wheat grain development, which improved the understanding of nutrient accumulation and nutrient transfer of wheat grains.

Control of ovule development in Vitis vinifera by VvMADS28 and interacting genes.

Seedless grapes are increasingly popular throughout the world, and the development of seedless varieties is a major breeding goal. In this study, we demonstrate an essential role for the grapevine MADS-box gene VvMADS28 in morphogenesis of the ovule. We found that VvMADS28 mRNA accumulated in the ovules of a seeded cultivar, 'Red Globe', throughout the course of ovule and seed development, especially within the integument/seed coat. In contrast, in the seedless cultivar 'Thompson Seedless', VvMADS28 was expressed only weakly in ovules, and this was associated with increased levels of histone H3 lysine 27 trimethylation (H3K27me3) within the VvMADS28 promoter region. RNAi-mediated transient suppression of VvMADS28 expression in 'Red Globe' led to reduced seed size associated with inhibition of episperm and endosperm cell development. Heterologous overexpression of VvMADS28 in transgenic tomatoes interfered with sepal development and resulted in smaller fruit but did not obviously affect seed size. Assays in yeast cells showed that VvMADS28 is subject to regulation by the transcription factor VvERF98, and that VvMADS28 could interact with the Type I/ Mβ MADS-domain protein VvMADS5. Moreover, through DNA-affinity purification-sequencing (DAP-seq), we found that VvMADS28 protein specifically binds to the promoter of the grapevine WUSCHEL (VvWUS) gene, suggesting that maintenance of the VvMADS28-VvMADS5 dimer and VvWUS expression homeostasis influences seed development. Taken together, our results provide insight into regulatory mechanisms of ovule and seed development associated with VvMADS28.

An image processing method for investigating the morphology of cereal endosperm cells

ABSTRACTIn cereal seeds, the number, morphology and development of endosperm cells are closely related to grain quality, weight and yield. Endosperm cells differ morphologically in different regions of the seed. Nevertheless, it is important to be able to analyze the morphology of cereal endosperm cells. We established an image processing method to enhance the outlines of endosperm cells. The endosperm cell wall was traced precisely using the “pen tool” in Photoshop software (PS). The tracing was defined as the “work path” and was highlighted using the PS “brush tool.” Images of mature rice, maize and wheat endosperm sections stained with different methods were analyzed using this method. Combined with the whole sections of mature and developing cereal kernels, the processed image exhibited clearly the morphology of endosperm cells in any region of endosperm and at any stage of endosperm development. The processed image was more accurate and efficient for analyzing morphological characteristics than the unprocessed image.

Returning the Rice Residue Affects Accumulation and Physicochemical Properties of Wheat Starch

Core Ideas Returning residue increased wheat production per plant, increased total starch, and decreased amylose content. Residue return sped up endosperm cell development, increasing B‐type starch granules at 17 and 27 d after anthesis. Residue return increased the proportion of small B‐type starch granules. Morphology of B‐type starch did not differ between groups of rice straw returned to the field vs. the residue return treatments. Residue return decreased relative crystallinity and increased the ratio of amorphous to ordered carbohydrates. Removing rice (Oryza sativa) straw has the potential to impact nutrient cycling and wheat quality. The objective of this study was to determine the impact of rice straw removal on wheat production and quality. The experiment contained three rice residue rates: none, rice residue mixed into the surface 5‐cm depth, and rice residue mixed into the 15‐cm soil depth. Returning the rice residue increased the wheat production per plant, total starch content, and decreased amylose content. Incorporating rice straw into the surface 5 cm or the 15 cm of soil depth accelerated endosperm development and increased the amounts of B‐type starch granules at 17 and 27 d after anthesis, and the proportion of small B‐type starch granules. Incorporating rice straw into the surface 5 cm or the 15 cm soil depth decreased the relative degree of crystallinity and increased the ratio of amorphous structure to ordered carbohydrate structure in the external region of the granules. Pasting parameters including peak, breakdown, final, and setback viscosities increased, whereas pasting time and temperature decreased in the returning the rice residue group. Returning the rice residue at 5 and 15 cm exhibited similar effects on the granule development and physicochemical properties of wheat starch. The impact of returning the rice residues to the soil on wheat production and wheat kernel quality was attributed to enhanced soil fertility. This study may contribute to knowledge on crop cultivation, crop physiology, and food science.

The release of cytochrome c and the regulation of the programmed cell death progress in the endosperm of winter wheat (Triticum aestivum L.) under waterlogging.

It has been shown in mammalian systems that the mitochondria can play a key role in the regulation of apoptosis by releasing intermembrane proteins (such as cytochrome c) into the cytosol. Cytochrome c released from the mitochondria to the cytoplasm activates proteolytic enzyme cascades, leading to specific nuclear DNA degradation and cell death. This pathway is considered to be one of the important regulatory mechanisms of apoptosis. Previous studies have shown that endosperm cell development in wheat undergoes specialized programmed cell death (PCD) and that waterlogging stress accelerates the PCD process; however, little is known regarding the associated molecular mechanism. In this study, changes in mitochondrial structure, the release of cytochrome c, and gene expression were studied in the endosperm cells of the wheat (Triticum aestivum L.) cultivar "huamai 8" during PCD under different waterlogging durations. The results showed that waterlogging aggravated the degradation of mitochondrial structure, increased the mitochondrial permeability transition (MPT), and decreased mitochondrial transmembrane potential (ΔΨm), resulting in the advancement of the endosperm PCD process. In situ localization and western blotting of cytochrome c indicated that with the development of the endosperm cell, cytochrome c was gradually released from the mitochondria to the cytoplasm, and waterlogging stress led to an advancement and increase in the release of cytochrome c. In addition, waterlogging stress resulted in the increased expression of the voltage-dependent anion channel (VDAC) and adenine nucleotide translocator (ANT), suggesting that the mitochondrial permeability transition pore (MPTP) may be involved in endosperm PCD under waterlogging stress. The MPTP inhibitor cyclosporine A effectively suppressed cell death and cytochrome c release during wheat endosperm PCD. Our results indicate that the mitochondria play important roles in the PCD of endosperm cells and that the increase in mitochondrial damage and corresponding release of cytochrome c may be one of the major causes of endosperm PCD advancement under waterlogging.

Lipid partitioning in maize (Zea mays L.) endosperm highlights relationships among starch lipids, amylose, and vitreousness.

Content and composition of maize endosperm lipids and their partition in the floury and vitreous regions were determined for a set of inbred lines. Neutral lipids, i.e., triglycerides and free fatty acids, accounted for more than 80% of endosperm lipids and are almost 2 times higher in the floury than in the vitreous regions. The composition of endosperm lipids, including their fatty acid unsaturation levels, as well as their distribution may be related to metabolic specificities of the floury and vitreous regions in carbon and nitrogen storage and to the management of stress responses during endosperm cell development. Remarkably, the highest contents of starch lipids were observed systematically within the vitreous endosperm. These high amounts of starch lipids were mainly due to lysophosphatidylcholine and were tightly linked to the highest amylose content. Consequently, the formation of amylose-lysophosphatidylcholine complexes has to be considered as an outstanding mechanism affecting endosperm vitreousness.

Herbaceous peony seed oil: A rich source of unsaturated fatty acids and γ‐tocopherol

Herbaceous peony (Paeonia lactiflora Pall.) seed oil (HPSO) was extracted from seeds by ultrasonic‐assisted extraction (UAE). Changes in the oil yield, fatty acid (FA) composition, retinol and tocopherol (α‐, γ‐, and δ‐tocopherol) contents of HPSO at the different developmental stages and in tested cultivars were examined, and the microscopic structure of HPSO droplets was also observed. The results showed that the HPSO yield increased with the seed development and reached its maximum level at the mature stage with values from 29.04 to 34.98% for different cultivars. The unsaturated fatty acid (UFA) contents were between 88.36 to 94.58%. Among the UFAs, the contents of oleic acid (27.19–45.06%), linoleic acid (20.59–37.59%), and α‐linolenic acid (13.59–30.87%) were relatively high. The average γ‐tocopherol content was 337.47 ± 57.42 µg/g, accounting for approximately 92.97% of the total tocopherol content. Transmission electron microscopy (TEM) observations of the HPSO microscopic structures indicated that the quantity and size of the oil bodies increased with the development of endosperm cells in P. lactiflora. This report was the first to study the HPSO, and the results will provide theoretical guidance for the exploitation and utilization of P. lactiflora resources.The content of UFA (A) was more than 90% in HPSO, and the content of γ‐tocopherol was 353.67 ± 0.22 µg/g, accounting for about 93% of total tocopherols content (B).

Development of endosperm cells and starch granules in common wheat

The objective of the present study was to understand the developmental regularity of wheat endosperm cells at different Days After Pollination (DAP) using microscopic and histochemical methods. Resin semi-thin sections of the endosperm and the enzymatically dissociated Starchy Endosperm Cells (SECs) were observed under a light microscope. The results showed that: (1) SECs were irregular-shaped and had two types of starch granules: large oval-shaped A-type starch granules and small spherical B-type starch granules. (2) The growth shape of SECs was referred to as S-curve and the fastest cell growth period was at 16–24 DAP. (3) The largest increase and growth of A-type starch granules were mainly at 4–16 DAP. B-type starch granules increased rapidly after 16 DAP and made up over 90% of the total starch granules in SEC during the late stage of endosperm development. (4) The nuclei of SEC deformed and degenerated during the middle and late stages of endosperm development and eventually disappeared. However, starch granules still increased and grew after the cell nuclei had degenerated. The investigations showed the development regularity of starch endosperm cells and starch granules, thereby improving the understanding of wheat endosperm development.