Transcription factor CaNAC1 regulates low-temperature-induced phospholipid degradation in green bell pepper.

Phospholipids constitute the main component of biomembranes. During low-temperature storage and transportation of harvested bell peppers (Capsicum annuum), chilling injury participates in their decay. A primary cause of this chilling injury is phospholipid degradation. In this study, three genes encoding phospholipase D (PLD) were identified from bell peppers and their activities were examined under cold stress. Low temperature (4 °C) induced strong accumulation of the CaPLDα4 transcript, suggesting that it is associated with the phenomenon of phospholipid degradation and destruction of cell membranes. Low temperature also significantly induced increased amounts of NAM-ATAF1/2-CUC2 (NAC) domain transcription factors. CaNAC1 was found to interact with the promoter of CaPLD4 in a yeast one-hybrid screen. Electrophoretic mobility shift and ß-glucuronidase reporter assays demonstrated that CaNAC1 binds to the CTGCAG motif in the CaPLDα4 promoter, thereby activating its transcription and controlling phospholipid degradation. The ubiquitination sites of the CaNAC1 protein were characterized by liquid chromatography-tandem mass spectrometry. We conclude that CaNAC1 is a transcriptional activator of CaPLDα4 and suggested that it participates in the degradation of membrane lipids in bell peppers when they are stored at low temperature.

Complementary Transcriptomic and Proteomic Analysis Reveals a Complex Network Regulating Pollen Abortion in GMS (msc-1) Pepper (Capsicum annuum L.).

Pepper (Capsicum annuum L.) is a globally important horticultural crop. Use of the genic male-sterile (GMS) line enables efficient commercial hybrid pepper seed production. However, the mechanisms of pepper GMS functioning remain unclear. In this study, we used proteomic and transcriptomic analysis to identify proteins and genes related to genic male sterility. A total of 764 differentially expressed proteins (DEPs) and 1069 differentially expressed genes (DEGs) were identified in the proteomic and transcriptomic level respectively, and 52 genes (hereafter "cor-DEGs-DEPs" genes) were detected at both levels. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified 13 DEPs and 14 DEGs involved in tapetum and pollen development. Among the 13 DEPs identified, eight were involved in pollen exine formation, and they were all up-regulated in the fertile line 16C1369B. For the 14 DEGs identified, ABORTED MICROSPORES (AMS) and DEFECTIVE IN TAPETAL DEVELOPMENT AND FUNCTION1 (TDF1) were involved in tapetum development, and both are possibly regulated by Msc-1. All of these genes were detected and confirmed by qRT-PCR. The presence of these genes suggests their possible role in tapetum and pollen exine formation in GMS pepper. Most key genes and transcription factors involved in these processes were down-regulated in the sterile line 16C1369A. This study provides a better understanding of GMS (msc-1) molecular functioning in pepper.

Surface charging by the cold plasma discharge of lentil and pepper seeds in comparison with polymers.

Cold plasma treatment charges organic surfaces. Surface density of the electrical charge supplied by cold radiofrequency plasma to the pepper and lentil seeds and various polymers: polyethylene, polystyrene, polycarbonate and poly(methyl methacrylate) was established experimentally. The surface charge density for all of studied interfaces, with one exception of polycarbonate was estimated as σ≈0.75-3.7µC/m2; for the polycarbonate it was almost an order of magnitude larger, namely σ≈7-9µC/m2. The kinetics of the surface charge leakage was studied. The characteristic time of temporal change in the surface density of the electrical charge gained by the seeds is markedly larger than that of synthetic polymers.

Effects of high-humidity hot air impingement blanching (HHAIB) pretreatment on the change of antioxidant capacity, the degradation kinetics of red pigment, ascorbic acid in dehydrated red peppers during storage.

Effect of high-humidity hot air impingement blanching on photochemical degradation kinetics (red pigments and ascorbic acid) and antioxidant capacity changes (2,2-diphenyl-1-picrylhydracyl, DPPH and total antioxidant capacity) of red pepper during 6-month storage at ambient temperature in dark was investigated. Ultrastructure of raw and blanched samples was also observed using a transmission electron microscope (TEM). Blanching followed by drying resulted in 63-85% and 33-59% reduction in red pigment and ascorbic acid content, respectively. The antioxidant capacity of samples was found to increase after drying. After 6-month storage, further breakdown of red pigment and ascorbic acid was observed. The red pigment degradation followed the first-order reaction kinetics; untreated samples displayed the most red pigment loss, while the Weibull model described well the ascorbic acid degradation kinetics. Ultrastructure observations explained why over-blanching can cause serious phytochemical degradation. The current findings indicate proper blanching pretreatment prevents phytochemicals degradation of dried pepper during storage.

Correlations of carotenoid content and transcript abundances for fibrillin and carotenogenic enzymes in Capsicum annum fruit pericarp.

The fruits of Capsicum spp. are especially rich sites for carotenoid synthesis and accumulation, with cultivar-specific carotenoid accumulation profiles. Differences in chromoplast structure as well as carotenoid biosynthesis are correlated with distinct carotenoid accumulations and fruit color. In the present study, the inheritance of chromoplast shape, carotenoid accumulation profiles, and transcript levels of four genes were measured. Comparisons of these traits were conducted using fruit from contrasting variants, Costeño Amarillo versus Costeño Red, and from F1 hybrids; crosses between parental lines with novel versions of these traits. Intermediate chromoplast shapes were observed in the F1, but no association between specific carotenoid accumulation and chromoplast shape was detected. Increased total carotenoid content was associated with increased ß-carotene and violaxanthin content. Transcript levels for phytoene synthase (Psy) and ß-carotene hydroxylase (CrtZ-2) were positively correlated with increased levels of specific carotenoids. No correlation was detected between transcript levels of capsanthin/capsorubin synthase (Ccs) and carotenoid composition or chromoplast shape. Transcript levels of fibrillin, were differentially correlated with specific carotenoids, negatively correlated with accumulation of capsanthin, and positively correlated with violaxanthin. The regulation of carotenoid accumulation in chromoplasts in Capsicum fruit continues to be a complex process with multiple steps for control.

Plant cell piercing by a predatory mite: evidence and implications.

Omnivorous arthropods can play an important role as beneficial natural enemies because they can sustain their populations on plants when prey is scarce, thereby providing prophylactic protection against an array of herbivores. Although some omnivorous mite species of the family Phytoseiidae consume plant cell-sap, the feeding mechanism and its influence on the plant are not known. Using scanning electron microscopy we demonstrated that the omnivorous predatory mite Euseius scutalis penetrates epidermal cells of pepper foliage and wax membranes. Penetration holes were teardrop shape to oval, of 2-5 µm diameter. The similarities between penetration holes in pollen grains and in epidermal cells implied that the same penetration mechanism is used for pollen feeding and plant cell-sap uptake. Variation in shape and size of penetration holes in leaves and a wax membrane were attributed to different mite life stages, depth of penetration or the number of chelicerae puncturing (one or both). Punctured stomata, epidermal and vein cells appeared flat and lacking turgor. When the mite penetrated and damaged a single cell, neighboring cells were most often intact. In a growth chamber experiment very large numbers of E. scutalis negatively affected the growth of young pepper plants. Consequently caution should be taken when applying cell-piercing predators to young plants. Further studies are needed to take advantage of the potential sustainability of plant cell-sap feeding predators.

Tissue microstructure, physicochemical properties, and bioactive compound locations in different sweet pepper types.

This article focuses on the location and content of some bioactive compounds in three different California sweet pepper types (red, green and yellow). The location was studied using different microscopic techniques, such as scanning electron microscopy at low temperatures (cryo-SEM) and light microscopy. Several physicochemical properties of the samples (carotenoid content, total soluble phenol content, antioxidant activity, dietary fibre content, total soluble solids content, pH and textural properties) were also examined. The degree of compaction and structuring of the cell wall was found to be indirectly related to solute transport at the cellular level and directly related to total dietary fibre content. The three types of pepper displayed formation and accumulation of phenolic aggregates and an active circulation of solutes. Yellow pepper tissue had the most labile cell walls and the highest transport of solutes. Red peppers could be suitable for obtaining extracts rich in carotenoid compounds, yellow peppers for obtaining phenolic compounds with a high antioxidant activity and green peppers for extracts with high dietary fibre content.

Capsicum annuum S (CaS) promotes reproductive transition and is required for flower formation in pepper (Capsicum annuum).

The genetic control of the transition to flowering has mainly been studied in model species, while few data are available in crop species such as pepper (Capsicum spp.). To elucidate the genetic control of the transition to flowering in pepper, mutants that lack flowers were isolated and characterized. Genetic mapping and sequencing allowed the identification of the gene disrupted in the mutants. Double mutants and expression analyses were used to characterize the relationships between the mutated gene and other genes controlling the transition to flowering and flower differentiation. The mutants were characterized by a delay in the initiation of sympodial growth, a delay in the termination of sympodial meristems and complete inhibition of flower formation. Capsicum annuum S (CaS), the pepper (Capsicum annuum) ortholog of tomato (Solanum lycopersicum) COMPOUND INFLORESCENCE and petunia (Petunia hybrida) EVERGREEN, was found to govern the mutant phenotype. CaS is required for the activity of the flower meristem identity gene Ca-ANANTHA and does not affect the expression of CaLEAFY. CaS is epistatic over other genes controlling the transition to flowering with respect to flower formation. Comparative homologous mutants in the Solanaceae indicate that CaS has uniquely evolved to have a critical role in flower formation, while its role in meristem maturation is conserved in pepper, tomato and petunia.

Subcellular distribution and chemical forms of cadmium in two hot pepper cultivars differing in cadmium accumulation.

A greenhouse experiment was conducted to compare the subcellular distribution and chemical forms of cadmium (Cd) in roots, stems, leaves, and fruits between a low-Cd cultivar (Yeshengchaotianjiao, YCT) and a high-Cd cultivar (Jinfuzaohuangjiao, JFZ) of hot pepper (Capsicum annuum L.). The Cd concentrations in the root's subcellular fractions, and in all chemical forms in roots, were 1.85-4.88- and 1.84-4.90-fold higher, respectively, in YCT than in JFZ. Compared with JFZ, YCT had significantly lower Cd concentrations in the subcellular fractions (1.10-2.42-fold) of stems and leaves and in almost all chemical forms (1.17-2.97-fold) in the stems and leaves. Also, in fruits, the concentrations of Cd in the cell wall and soluble fractions were 1.18-2.24-fold significantly lower in YCT than in JFZ, and there were lower Cd concentrations (1.36-2.08-fold) in the chemical forms in YCT than in JFZ.

Multiple microscopic approaches demonstrate linkage between chromoplast architecture and carotenoid composition in diverse Capsicum annuum fruit.

Increased accumulation of specific carotenoids in plastids through plant breeding or genetic engineering requires an understanding of the limitations that storage sites for these compounds may impose on that accumulation. Here, using Capsicum annuum L. fruit, we demonstrate directly the unique sub-organellar accumulation sites of specific carotenoids using live cell hyperspectral confocal Raman microscopy. Further, we show that chromoplasts from specific cultivars vary in shape and size, and these structural variations are associated with carotenoid compositional differences. Live-cell imaging utilizing laser scanning confocal (LSCM) and confocal Raman microscopy, as well as fixed tissue imaging by scanning and transmission electron microscopy (SEM and TEM), all demonstrated morphological differences with high concordance for the measurements across the multiple imaging modalities. These results reveal additional opportunities for genetic controls on fruit color and carotenoid-based phenotypes.

Ultrastructural study on dynamics of lipid bodies and plastids during ripening of chili pepper fruits.

Dynamics of lipid bodies and plastids in chili pepper fruits during ripening were investigated by means of transmission electron microscopy. Mesocarp of chili pepper fruits consists of collenchyma, normal parenchyma, and huge celled parenchyma. In mature green fruits, plastids contain numerous thylakoids that are well organized into grana in collenchyma, a strikingly huge amount of starch and irregularly organized thylakoids in normal parenchyma, and simple tubes rather than thylakoids in huge celled parenchyma. These morphological features suggest that plastids are chloroplasts in collenchyma, chloroamyloplasts in normal parenchyma, proplastids in huge celled parenchyma. As fruits ripen to red, plastids in all cell types convert to chromoplasts and, concomitantly, lipid bodies accumulate in both cytoplasm and chromoplasts. Cytosolic lipid bodies are lined up in a regular layer adjacent to plasma membrane. The cytosolic lipid body consists of a core surrounded by a membrane. The core is comprised of a more electron-dense central part enclosed by a slightly less electron-dense peripheral layer. Plastidial lipid bodies in collenchyma, normal parenchyma, and endodermis initiate as plastoglobuli, which in turn convert to rod-like structures. Therefore, plastidial lipid bodies are more dynamic than cytosolic lipid bodies. Both cytosolic and plastidial lipid bodies contain rich unsaturated lipids.

Understanding the mechanisms of chilling injury in bell pepper fruits using the proteomic approach.

In order to advance in the understanding of CI in pepper fruits, the cell ultrastructure alterations induced by CI and the physiological and metabolic changes have been studied along with the proteomic study. When stored at low temperatures bell pepper (Capsicum annuum) fruits exhibited visual CI symptoms and important alterations within the cell ultrastructure, since peroxisomes and starch grains were not detected and the structure of the chloroplast was seriously damaged in chilled tissues. Physiological and metabolic disorders were also observed in chilled fruits, such as higher ethylene production, increased MDA content, changes in sugar and organic acids and enzymatic activities. The comparative proteomic analysis between control and chilled fruits reveals that the main alterations induced by CI in bell pepper fruits are linked to redox homeostasis and carbohydrate metabolism. Thus, protein abundance in the ascorbate-glutathione cycle is altered and catalase is down-regulated. Key proteins from glycolysis, Calvin cycle and Krebs cycle are also inhibited in chilled fruits. Enolase and GAPDH are revealed as proteins that may play a key role in the development of chilling injury. This study also provides the first evidence at the protein level that cytosolic MDH is involved in abiotic stress.

Cytopathological potato virus Y structures during Solanaceous plants infection.

The ultrastructural analysis of tobacco, potato and pepper tissues during infection with necrotic strains and the ordinary Potato virus Y strain of revealed the presence of virus inclusions not only in the epidermis and mesophyll but also in the vascular tissues. For the first time cytoplasmic inclusions were documented in companion cells and phloem parenchyma as well as in xylem tracheary elements. The ultrastructural features studied in this work consisted of mostly laminated inclusions (in the traverse and longitudinal section), which were frequently connected with enlarged cisternae of endoplasmic reticulum (ER) located in the direct vicinity of the cell wall attached to virus particles opposite to plasmodesmata. It was noticed that ER participates in synthesis and condensation of the PVY inclusions. During compatible interaction of tobacco and potato plants with PVY, amorphous and nuclear inclusions were observed. Such forms were not found in pepper tissues and potato revealing the hypersensitivity reaction to the infection with PVY necrotic strains. It was stated that the forms of cytoplasmic inclusions cannot serve as a cytological criterion to distinguish the potato virus Y strains and do not depend on host resistance level. Only in compatible interaction in Solanaceous plants tissues cytoplasmic inclusions were observed from the moment the morphological symptoms appeared. In the reaction of hypersensitivity, the inclusions were found on the 24th day following the infection with the PVY necrotic strains, whereas the symptoms were observed 3 days after the PVY infection.

Activity and expression of polygalacturonase vary at different fruit ripening stages of sweet pepper cultivars.

Activity and expression of polygalacturonase (PG), a hydrolytic enzyme involved in ultrastructural changes in the pericarp of sweet pepper (Capsicum annaum), were investigated at different ripening stages of the pepper cultivars Mandi and Talanduo. Molecular cloning of CaPG was carried out by constructing a cDNA library from three stages of fruit ripening. Morphological determination, PG assay, RT-PCR, and ultrastructural studies were used to quantify changes in CaPG gene expression in the pericarp from green, color change and fully ripened stages. We found that CaPG gene expression, PG activity and striking changes in the structure of the cell wall occurred with the transition of ripening stages. CaPG gene expression was high (obvious PCR products) in mature and ripened stages of both cultivars; however, the CaPG gene was not expressed in preclimacteric fruits or vegetative tissues. We conclude that developmental regulation of CaPG gene expression is instrumental for sweet pepper fruit ripening; its expression during development leads to dissolution of middle lamella and eventually disruption of the fully ripened cell wall.

CaMF2, an anther-specific lipid transfer protein (LTP) gene, affects pollen development in Capsicum annuum L.

Based on the gene differential expression analysis performed by cDNA-amplified fragment length polymorphism (cDNA-AFLP) in the genic male sterile-fertile line 114AB of Capsicum annuum L., a variety of differentially expressed cDNA fragments were detected in fertile or sterile lines. A transcript-derived fragment (TDF) specifically accumulated in the flower buds of fertile line was isolated, and the corresponding full-length cDNA and DNA were subsequently amplified. Bioinformatical analyses of this gene named CaMF2 showed that it encodes a lipid transfer protein with 94 amino acids. Spatial and temporal expression patterns analysis indicated that CaMF2 was an anther-specific gene and the expression of CaMF2 was detected only in flower buds at stage 3-7 of male fertile line with a peak expression at stage 4, but not detected in the roots, tender stems, fresh leaves, flower buds, open flowers, sepals, petals, anthers or pistils of male sterile line. Further, inhibition of the CaMF2 by virus-induced gene silencing (VIGS) method resulted in the low pollen germination ability and shriveled pollen grains. All these evidence showed that CaMF2 had a vital role in pollen development of C. annuum.

Characterisation, immunolocalisation and antifungal activity of a lipid transfer protein from chili pepper (Capsicum annuum) seeds with novel α-amylase inhibitory properties.

Lipid transfer proteins (LTPs) were thus named because they facilitate the transfer of lipids between membranes in vitro. This study was triggered by the characterization of a 9-kDa LTP from Capsicum annuum seeds that we call Ca-LTP(1) . Ca-LTP(1) was repurified, and in the last chromatographic purification step, propanol was used as the solvent in place of acetonitrile to maintain the protein's biological activity. Bidimensional electrophoresis of the 9-kDa band, which corresponds to the purified Ca-LTP(1) , showed the presence of three isoforms with isoelectric points (pIs) of 6.0, 8.5 and 9.5. Circular dichroism (CD) analysis suggested a predominance of α-helices, as expected for the structure of an LTP family member. LTPs immunorelated to Ca-LTP(1) from C. annuum were also detected by western blotting in exudates released from C. annuum seeds and also in other Capsicum species. The tissue and subcellular localization of Ca-LTP(1) indicated that it was mainly localized within dense vesicles. In addition, isolated Ca-LTP(1) exhibited antifungal activity against Colletotrichum lindemunthianum, and especially against Candida tropicalis, causing several morphological changes to the cells including the formation of pseudohyphae. Ca-LTP(1) also caused the yeast plasma membrane to be permeable to the dye SYTOX green, as verified by fluorescence microscopy. We also found that Ca-LTP(1) is able to inhibit mammalian α-amylase activity in vitro.

Characterization and genetic analysis of a low-temperature-sensitive mutant, sy-2, in Capsicum chinense.

A temperature-sensitive mutant of Capsicum chinense, sy-2, shows a normal developmental phenotype when grown above 24°C. However, when grown at 20°C, sy-2 exhibits developmental defects, such as chlorophyll deficiency and shrunken leaves. To understand the underlying mechanism of this temperature-dependent response, phenotypic characterization and genetic analysis were performed. The results revealed abnormal chloroplast structures and cell collapse in leaves of the sy-2 plants grown at 20°C. Moreover, an excessive accumulation of reactive oxygen species (ROS) resulting in cell death was detected in the chlorophyll-deficient sectors of the leaves. However, the expression profile of the ROS scavenging genes did not alter in sy-2 plants grown at 20°C. A further analysis of fatty acid content in the leaves showed the impaired pathway of linoleic acid (18:2) to linolenic acid (18:3). Additionally, the Cafad7 gene was downregulated in sy-2 plants. This change may lead to dramatic physiological disorder and alteration of leaf morphology in sy-2 plants by losing low-temperature tolerance. Genetic analysis of an F(2) population from a cross between C. chinense 'sy-2' and wild-type C. chinense 'No. 3341' showed that the sy-2 phenotype is controlled by a single recessive gene. Molecular mapping revealed that the sy-2 gene is located at a genomic region of the pepper linkage group 1, corresponding to the 300 kb region of the Ch1_scaffold 00106 in tomato chromosome 1. Candidate genes in this region will reveal the identity of sy-2 and the underlying mechanism of the temperature-dependent plant response.

[Histological and cytological study on the ontogeny of embryoid in pepper anther culture].

The characteristics of histology and cytology of embryogenesis in pepper anther culture were examined with fluorescence microscopy, scanning microscopy, and electron microscopy. Pepper was characterized by a strong asynchrony of pollen development within a single anther. With the change of culture period, the proportion of dead pollen increased drastically from 2 day after culture. Microspores that were cultured at the late-uninucleate stage followed one of two developmental pathways. In the more common route, the first sporophytic division was asymmetric and produced what appeared to be typical bicellular pollen. Embryogenic pollen was formed by repeated divisions of the vegetative nuclei. An exine with its specific pattern had already been formed, when microspores were released from tetrads. During subsequent pollen development, microspores increased in size and continued to strengthen the exine. After 24 h in culture, the microspores had increased in size. Thereafter, embryogenesis was indicated in some microspores by two different morphological changes. One featured an expansion in volume of the cell cluster around the germination aperture, the other showed cell cluster volume expansion over the entire microspore surface. Morphogenesis of microspore-derived embryos has been analyzed, at both light and electron microscopical levels. The changes in cell organization after embryogenesis induction, and the characterization of the time sequence of a set of structural events, had been also explained. These changes mainly affected the plastids, the vacuolar compartment, the cell wall and the nucleus. Further differentiation processes mimicked that of the zygotic development.

Use of cross-flow membrane filtration in a recirculating hydroponic system to suppress root disease in pepper caused by Pythium myriotylum.

Zoosporic pathogens in the genera Pythium and Phytophthora cause extensive root disease epiphytotics in recirculating hydroponic vegetable-production greenhouses. Zoospore cysts of Pythium myriotylum Drechsler were used to evaluate the effectiveness of cross-flow membrane filters to control pythiaceous pathogens in recirculating hydroponic systems. Four membrane filter brands (Honeycomb, Polypure, Polymate, and Absolife) were tested alone or in combination to determine which filters would effectively remove infective propagules of P. myriotylum from solutions and reduce disease incidence and severity. Zoospore cysts of P. myriotylum generally measured 8 to 10 microm, and it was hypothesized that filters with pore-sizes<5 microm would be effective at removing 100% of the infective propagules and protect pepper plants from root infection. Single-filter assays with Honeycomb and Polypure brands removed 85 to 95% of zoospore cysts when pore sizes were rated at 1, 5, 10, 20, or 30 microm. Single-filter assays of Polymate and Absolife brands were more effective, exhibiting apparently 100% removal of zoospore cysts from nutrient solutions on filters rated at 1 to 10 microm. However, plant bioassays with Honeycomb and Polymate single filters failed to give long-term protection of pepper plants. Double-filter assays with 1- and 0.5-microm Polymate filters significantly increased the protection of pepper plants grown in nutrient film technique systems but, eventually, root disease and plant wilt could be observed. Insect transmissions by shore flies were not factors in disease development. Scanning electron microscopy images of zoospore cysts entrapped on Polymate filters revealed zoospore cysts that were either fully encysted, partially encysted, or of unusually small size (3 microm in diameter). It was concluded that either the atypically small or pliable pleomorphic zoospore cysts were able to penetrate filter membranes that theoretically should have captured them.

[Cytological observation of anther abortion and starch distribution of a cytoplasm male sterile pepper (Capsicum annum L.)].

A cytoplasm male sterile pepper (Capsicum annum L.) was examined using cytochemical method to study its pollen abortion. Thick sections of both anthers of male sterility line 8214A and its maintainer 8214B at different stages were stained using Periodic Acid-Schiff's (PAS) reaction to detect starch distribution. Anther structure and starch distribution in both anthers of male sterility and maintainer line were similar before the meiosis of microspore mother cells. After meiosis, the size of tapetal cells of fertile anthers of maintainer line increased and became high vacuolation. Abundant small starches appeared in the connective cells from tetrad stage to early stage of microspore development. At the late stage of microspore, the tapetal cells began to degenerate and the starches in the connective cells became large. Bi-cellular pollen synthesized starches after the large vacuole of vegetative cell disappeared, and abundant starches were stored in the mature pollen. In the anthers of male sterile line, meiosis of microspore mother could occurred and the tetrads could be formed in the locule, but the tetrads were extruded together because the locule could not enlarge its space. Finally, the tetrad microspores degenerated. The development of vascular tissue of the sterile anthers was normal and abundant starches were stored in the connective cells, which suggested that the function of plant transporting polysaccharide into anther was normal but tapetum could not transport the polysaccharide into locule. According to our result, the pollen abortion occurred in the tetrad stage and the abnormal development of tapetal cells might be the reason which induced tetrad microspore abortion in this male sterile pepper.