Stem Apical Meristem Research Articles

What is going on with the flower bud differentiation and metabolites control of scape elongation on Clivia miniata Regel?

Clivia miniata Regel, a globally renowned ornamental plant, is used in China to celebrate Lunar New Year (the Chinese Spring Festival). However, its anthesis in greenhouses often misses the timing of this festival. Understanding the mechanism of flower bud differentiation and scape elongation is critical for the accurate and stable regulation of anthesis. Currently, little is known about the molecular mechanism of anthesis regulation in C. miniata. In this study, a hypothetical model for its growth and the flowering mechanism was verified by systematic observation over a whole year. Once ripe-to-flower a C. miniata plant followed an autonomous, sympodial, and modular growth system in which the stem apical meristem produced four leaves before terminating in an inflorescence. Paraffin section observation revealed six stages of flower bud differentiation. Moreover, a metabolomic profile of a young leaf adjacent to the scape, at each of four stages of scape development, enabled us to identify metabolites involved in various pathways that correlated with regulation of anthesis. A total of 510 metabolites were identified as present across the different development stages of scapes. Of them, 159 metabolites were differentially expressed, and were enriched in the pathways of amino acid, sugar, glycerophospholipid, and glutathione. Amino acids, sugars, glycerophospholipids, and hormones were suggested to participate in development to anthesis by regulating the molecular network involved in scape elongation. The rate of scape appearance was highest (100 %) following spray application of 50 mg/L GA3. While all treatments could advance anthesis, a spray treatment at 200 mg/L GA3 advanced anthesis by 42 days.

Genome-Wide Identification, Classification and Expression Analyses of MADS-Box Genes Reveal Their Role in Stem Gall Formation and Expansion of Zizania latifolia

MADS-box genes are important transcription factors in eukaryotes that are involved in regulating the growth and development of many plants. Jiaobai is a special aquatic vegetable formed through the stem expansion of Zizania latifolia infected by Ustilago esculenta and is wildly cultivated in Southeast Asia. To date, the biological function of MADS-box genes in Z. latifolia remains largely unknown. In this study, a genome-wide search for MADS-box genes in Z. latifolia was performed, and 87 MADS-box genes were identified. According to the phylogenetic analysis, there were 27 type I genes and 60 type II genes. The type I genes were mainly distributed in the Mα, Mβ and Mγ subfamilies, and the type II genes were divided into 14 subfamilies and unevenly distributed across 17 chromosomes. The encoded protein sequences ranged from 91 to 433 amino acids, the number of exons was 1~14, and most type I genes did not contain introns. The promoter region contained a large number of functional domains related to light response, plant hormones, stress and the meristem. An analysis of the expression patterns showed that there were massive differences in the expression of the MADS-box genes in different tissues, with six genes highly expressed in leaves and eight genes highly expressed in the stem apical meristem. Photoperiod and temperature were found to regulate the formation of the stem gall (SG) of Z. latifolia, and short-day (SD) conditions had an obvious promoting effect. ZlMADS57 and ZlMADS85 were significantly increased in SG under SD. Further analysis of the expression levels of MADS-box genes during the developmental stages of Z. latifolia found that the ZlMADS45, ZlMADS57, ZlMADS81 and ZlMADS85 were highly expressed 10 days before the SG formation, and ZlMADS66 reached its highest value on the day when the SG began forming. ZlMADS14, ZlMADS15, ZlMADS32, ZlMADS36, ZlMADS59 and ZlMADS71 were highly expressed after SG expansion, indicating that the MADS-box gene may play an important role in regulating SG formation and the subsequent expansion of Jiaobai. This study provides a reference for the functional identification of the MADS-box gene family and establishes a foundation for regulating the maturity of Z. latifolia.

Morphogenesis Changes in Protocorm Development during Symbiotic Seed Germination of Dendrobium chrysotoxum (Orchidaceae) with Its Mycobiont, Tulasnella sp.

The endangered epiphytic orchid, Dendrobium chrysotoxum, is known for its ornamental and medicinal uses. However, knowledge of this orchid’s symbiotic seed germination, protocorm anatomy, and developmental morphology is completely unknown. In this study, we investigated the process of protocorm development of D. chrysotoxum during symbiotic germination using anatomical technologies and scanning electron microscopy. There are six development stages that were morphologically and anatomically defined during symbiotic seed germination. The embryo transformed into a protocorm at stage two, and a protrusion developed from the top of the protocorm at stage three and elongated to form the cotyledon at stage four. The stem apical meristem (SAM) was initiated at stage three and well developed at stage four. The first leaf and the root appeared at stages five and six, respectively. The hyphae entered through the micropylar end of the seed at stage one and then invaded the protocorm through rhizoids when rhizoids formed. Invading fungal hyphae colonized the inner cortex at the base of protocorms, formed pelotons, and were digested by host cells later. We conclude that protocorm development is programmed by the embryo, which determines the structure and function of the protocorm. The two developmental zones in a polarized D. chrysotoxum embryo include the smaller cells zone, which forms the cotyledon and a shoot apical meristem at the apical end, and the larger cells zone, which forms the mycorrhiza to house the symbiont at the basal end. These results will provide important insights for further research on the mechanisms underlying orchid-fungi symbiosis and enhance the understanding of orchid evolution.

An LTR retrotransposon insertion inside CsERECTA for an LRR receptor-like serine/threonine-protein kinase results in compact (cp) plant architecture in cucumber.

The compact (cp) phenotype in cucumber (Cucumis sativus L.) is an important plant architecture-related trait with a great potential for cucumber improvement. In this study, we conducted map-based cloning of the cp locus, identified and functionally characterized the candidate gene. Comparative microscopic analysis suggested that the short internode in the cp mutant is due to fewer cell numbers. Fine genetic mapping delimited cp into an 8.8-kb region on chromosome 4 harboring only one gene, CsERECTA (CsER) that encodes a leucine-rich repeat receptor-like kinase. A 5.5-kb insertion of a long terminal repeat retrotransposon in the 22nd exon resulted in loss-of-function of CsER in the cp plant. Spatiotemporal expression analysis in cucumber and CsER promoter-driven GUS assays in Arabidopsis indicated that CsER was highly expressed in the stem apical meristem and young organs, but the expression level was similar in the wild type and mutant cucumber plants. However, CsER protein accumulation was reduced in the mutant as revealed by western hybridization. The mutation in cp also did not seem to affect self-association of CsER for formation of dimers. Ectopic expression of CsER in Arabidopsis was able to rescue the plant height of the loss-of-function AtERECTA mutant, whereas the compact inflorescence and small rosette leaves of the mutant could be partially recovered. Transcriptome profiling in the mutant and wild type cucumber plants revealed hormone biosynthesis/signaling, and photosynthesis pathways associated with CsER-dependent regulatory network. Our work provides new insights for the use of cp in cucumber breeding.

Genome-Wide Identification and Expression Pattern Analysis of KNOX Gene Family in Orchidaceae.

The establishment of lateral organs and subsequent plant architecture involves factors intrinsic to the stem apical meristem (SAM) from which they are derived. KNOTTED1-LIKE HOMEOBOX (KNOX) genes are a family of plant-specific homeobox transcription factors that especially act in determining stem cell fate in SAM. Although KNOXs have been studied in many land plants for decades, there is a dearth of knowledge on KNOX’s role in Orchidaceae, the largest and most diverse lineage of flowering plants. In this study, a total of 32 putative KNOX genes were identified in the genomes of five orchid species and further designated into two classes (Class I and Class II) based on phylogenetic relationships. Sequence analysis showed that most orchid KNOX proteins retain four conserved domains (KNOX1, KNOX2, ELK, and Homeobox_KN). Comparative analysis of gene structure showed that the exon–intron structure is conserved in the same clade but most orchids exhibited longer intron, which may be a unique feature of Orchidaceae. Cis-elements identified in the promoter region of orchid KNOXs were found mostly enriched in a function of light responsiveness, followed by MeJA and ABA responsiveness, indicative of their roles in modulating light and phytohormones. Collinear analysis unraveled a one-to-one correspondence among KNOXs in orchids, and all KNOX genes experienced strong purifying selection, indicating the conservation of this gene family has been reinforced across the Orchidaceae lineage. Expression profiles based on transcriptomic data and real-time reverse transcription–quantitative PCR (RT-qPCR) revealed a stem-specific expression of KNOX Class I genes and a broader expression pattern of Class II genes. Taken together, our results provided a comprehensive analysis to uncover the underlying function of KNOX genes in Orchidaceae.

Anatomy of the main stem of soybean plants submitted to the removal of the stem apical meristem

Some plant species allow the cutting of the apical meristem in order to assist activities of genetic improvement programs, among them is the soybean. The objective was to verify if the removal of the apical meristem of soybean plants induces any alteration in the stem anatomy, since it was verified that the removal of the apical meristem reduces the need for tutoring of the plants cultivated under greenhouse conditions. The experiment was conducted with plants of the BRSMG 752S cultivar and the treatments consisted of sections of the hypocotyl region of plants that had undergone apical meristem removal at the V2 development stage and of plants without apical meristem removal. The permanent slides were processed following the usual methodologies in plant anatomy. Descriptions and measurements of anatomical tissues were made for comparison between treatments. Plants with removal presented epidermis as a covering tissue until 20 days after the V2 development stage, while plants without removal of the apical meristem presented it until 30 days after V2. Periderm was observed only in plants with removal, and this feature was not evident in plants without removal until 30 days after V2. There was formation of secondary vascular tissues in the collections 30 days after removal (V2 stage). Thus, we conclude that the removal of the apical meristem accelerates the secondary development in hypocotyls of soybean plants grown under greenhouse conditions.

TPR domain coding gene ST2 may be involved in regulating tillering and fertility in rice

A decrease in the tiller number and male sterility will lead to a decline in the rice yield. Therefore, it is significant to study the molecular mechanism of controlling the tiller number and regulating the male reproductive development. The mutant st2 (single tiller 2) was induced by ethyl methane sulfonate (EMS) in the indica maintainer line Xinong 1B and showed single tillering and male sterility. I<sub>2</sub>-KI staining showed that the st2 pollen was aborted. The scanning electron microscope (SEM) observation underlined that the anther of st2 became smaller, the wax of the epidermis reduced, the inner wall shrank and the Ubisch body decreased, the pollen collapsed, and the germination pore developed abnormally. The genetic analysis discovered that the trait was controlled by a single recessive nuclear gene located on chromosome 3. LOC_Os03g05540 encoding a tetratricopeptide repeat (TPR) domain was identified as the candidate gene by sequencing. The quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that ST2 was highly expressed in the stem apical meristem (SAM) and the initial stage of meiosis during the anther development. The subcellular localisation indicated that ST2 is a nuclear and plasmic localisation protein. The homology analysis demonstrated that ST2 was evolutionarily conserved. These results laid a foundation for further study of the ST2 function.

The short but useful life of Prepusa montana Mart. (Gentianaceae Juss.) leaf colleters-anatomical, micromorphological, and ultrastructural aspects.

Colleters are secretory structures involved in the protection of young and developing plant organs. Although the presence of colleters in Gentianales is described as a synapomorphy, studies on the morphofunctionality of colleters and the mechanisms underlying the synthesis and release of colleter secretion in Gentianaceae are scarce. Here, we described the ontogeny and the morphological and functional aspects of colleters of Prepusa montana, revealed the nature of the key compounds present in the secretion, and explored the cellular aspects of the synthesis and release of secretion and senescence of colleters. Samples of the stem apical meristem with leaf primordium and young leaves; adult and senescent leaves were observed using light and electron microscopy. The colleters, located in the axil of the leaf, have a protodermal origin and develop asynchronously. They are digitiform, possessing a short peduncle and a secretory head containing homogeneous cells with dense cytoplasm and abundant endoplasmic reticulum and Golgi bodies. The secretion, composed of polysaccharides and proteins, is accumulated in schizogenous spaces and released through the separation of peripheral secretory cells and loosening of the external periclinal wall. Presumably, senescence is caused by programmed cell death. The morphoanatomical characterization of P. montana leaf colleters described here is the first record for the genus and the peculiar accumulation of colleter secretion in schizogenous spaces expanding our knowledge on the diversity of these secretory structures. Our results also provide insights into programmed cell death as an eminent topic related to secretory structures.

The development of anastomosed laticifers in the stem apical meristem and vascular cambium of Hancornia speciosa (Apocynaceae) is related to climatic seasonality

The development of anastomosed laticifers in the stem apical meristem and vascular cambium of Hancornia speciosa (Apocynaceae) is related to climatic seasonality

Selenium nanoparticles induced variations in growth, morphology, anatomy, biochemistry, gene expression, and epigenetic DNA methylation in Capsicum annuum; an in vitro study

This study aimed to explore whether supplementation of the culture medium with selenium nanoparticles (nSe) can influence growth, biochemistry, expression of transcription factors, and epigenetic DNA methylation in Capsicum annuum. The seeds were grown in hormone-free MS culture medium supplemented with nSe (0, 0.5, 1, 10, and 30 mgL−1) or corresponding doses of bulk type selenate (BSe). Incorporation of nSe into the medium caused variations in morphology and growth in a manner dependent on the dose and Se type. The low doses of nSe displayed growth-promoting effects, whereas nSe at 10 and 30 mgL−1 were associated with severe toxicity and abnormality in leaf and root development. MSAP analysis confirmed the substantial variation in cytosine DNA methylation in response to the toxic dose of nSe exhibiting epigenetic modification. The nSe toxicity was associated with DNA hyper-methylations. The nSe treatments transcriptionally upregulated the bZIP1 transcription factor by an average of 3.5 folds. With a similar trend, the upregulation (mean = 9.8 folds) in the expression of the WRKY1 transcription factor resulted from the nSe application. The nSe0.5 or nSe1 treatments resulted in a significant induction (mean = 48%) in nitrate reductase activity. A high dose of nSe led to an increase in proline concentration. The nSe treatments were also associated with modifications in activities of peroxidase and catalase enzymes. Besides, the nSe utilization increased the activity of phenylalanine ammonia-lyase enzyme (mean = 76%) and concentrations of soluble phenols (mean = 51%). The toxic dose of nSe also caused abnormalities in the structure of the stem apical meristem. The nSe toxicity was also associated with inhibition in the differentiation of xylem tissues. These findings provide novel insights into the nSe-associated molecular variations in conferring the modified growth, anatomy, and metabolism.

Phyllotaxis Turns Over a New Leaf-A New Hypothesis.

Phyllotaxis describes the periodic arrangement of plant organs most conspicuously floral. Oscillators generally underlie periodic phenomena. A hypothetical algorithm generates phyllotaxis regulated by the Hechtian growth oscillator of the stem apical meristem (SAM) protoderm. The oscillator integrates biochemical and mechanical force that regulate morphogenetic gradients of three ionic species, auxin, protons and Ca2+. Hechtian adhesion between cell wall and plasma membrane transduces wall stress that opens Ca2+ channels and reorients auxin efflux “PIN” proteins; they control the auxin-activated proton pump that dissociates Ca2+ bound by periplasmic arabinogalactan proteins (AGP-Ca2+) hence the source of cytosolic Ca2+ waves that activate exocytosis of wall precursors, AGPs and PIN proteins essential for morphogenesis. This novel approach identifies the critical determinants of an algorithm that generates phyllotaxis spiral and Fibonaccian symmetry: these determinants in order of their relative contribution are: (1) size of the apical meristem and the AGP-Ca2+ capacitor; (2) proton pump activity; (3) auxin efflux proteins; (4) Ca2+ channel activity; (5) Hechtian adhesion that mediates the cell wall stress vector. Arguably, AGPs and the AGP-Ca2+ capacitor plays a decisive role in phyllotaxis periodicity and its evolutionary origins.

Genome-Wide Analysis of Dynamin Gene Family in cassava (Manihot esculenta Crantz) and Transcriptional Regulation of Family Members ARC5 in Hormonal Treatments.

The Dynamin gene family play a significance role in many physiological processes, especially ARC5 (Accumulation and replication of chloroplasts 5) in the process of plastid division. We performed a genome-wide analysis of the cassava Dynamin family based on the published cassava genome sequence and identified ARC5. 23 cassava Dynamins (MeDynamins) were identified and renamed. 23 MeDynamins were further divided into five major groups based on their structural and phylogenetic characteristics. The segmental duplication events have a significant impact on the expansion of MeDynamins. ARC5 expression analysis showed that there were differences between leaves and roots of cassava at different developmental stages. The tissue-specific expression analysis of the MeDynamins showed that most of MeDynamins were expressed in stem apical meristem and embryogenesis, whereas ARC5 was mainly expressed in leaves. The processing of IAA (Indole-3-acetic Acid) and MeJA (Methyl Jasmonate) verified the prediction results of cis-elements, and ACR5 was closely related to plant growth and positively correlated. It also indicated that high concentrations of MeJA treatment caused the cassava defense mechanism to function in advance. In conclusion, these findings provide basic insights for functional validation of the ARC5 genes in exogenous hormonal treatments.

Evidence for the Regulation of Gynoecium Morphogenesis by ETTIN via Cell Wall Dynamics.

ETTIN (ETT) is an atypical member of the AUXIN RESPONSE FACTOR family of transcription factors that plays a crucial role in tissue patterning in the Arabidopsis (Arabidopsis thaliana) gynoecium. Though recent insights have provided valuable information on ETT's interactions with other components of auxin signaling, the biophysical mechanisms linking ETT to its ultimate effects on gynoecium morphology were until now unknown. Here, using techniques to assess cell-wall dynamics during gynoecium growth and development, we provide a coherent body of evidence to support a model in which ETT controls the elongation of the valve tissues of the gynoecium through the positive regulation of pectin methylesterase (PME) activity in the cell wall. This increase in PME activity results in an increase in the level of demethylesterified pectins and a consequent reduction in cell wall stiffness, leading to elongation of the valves. Though similar biophysical mechanisms have been shown to act in the stem apical meristem, leading to the expansion of organ primordia, our findings demonstrate that regulation of cell wall stiffness through the covalent modification of pectin also contributes to tissue patterning within a developing plant organ.

Co-ordination between primordium formation and leaf appearance in soybean (Glycine max) as influenced by temperature

Soybean (Glycine max) production is expanding into cooler and warmer environments. Temperature influence on nodal leaf appearance rate and, especially, nodal primordium formation rate – two critical parameters that determine potential leaf area, light absorption, and crop growth and yield – is poorly understood. This study was designed to determine the influence of temperature on primordium formation and leaf appearance and to investigate how the co-ordination between these two processes is affected by contrasting temperature regimes. The experiments were conducted in field and greenhouse settings using indeterminate cultivars differing in maturity group. Soil and air temperature was measured at 30-min intervals in all experiments, starting at sowing and ending at physiological maturity. Plants were dissected every 4–7d to determine the number of primordia at the stem apical meristem and to estimate primordium formation rate. The number of nodal leaves at main stem was assessed periodically during the entire growing season to estimate rate of leaf appearance. Primordium formation ended near the beginning of pod setting, while leaf appearance ceased at the beginning of seed filling. The end-season final number of primordia was greater than the final leaf number, revealing a surplus of primordia that did not advance beyond primordial stage. Across experiments, mean temperature during the phases of primordium formation and leaf appearance ranged from 15 to 26°C. Both primordium formation and leaf appearance were temperature-dependent, but primordium formation was faster than leaf appearance. The plastochron was 36°Cd, whereas the phyllochron was biphasic, decreasing from 83°Cd to 58°Cd during ontogeny. A strong relationship was found between the number of primordia and the number of leaves, which was stable across experiments, temperature treatments, and cultivars. This study has established that both primordium formation and leaf appearance in soybean are influenced by temperature, with a co-ordination between these two processes. The co-ordination model presented here can be used for robust prediction of seasonal nodal leaf dynamics in soybean.

Reverse Genetic Analysis of Transcription Factor OsHox9, a Member of Homeobox Family, in Rice

Homeobox transcription factors participate in the growth and development of plants by regulating cell differentiation, morphogenesis and environmental signal response. To reveal the functions of these transcription factors in rice, we constructed the RNAi vectors of OsHox9, a member of homeobox family, and analyzed the function of OsHox9 using reverse genetics. The plant height and tillering number of RNAi transgenic plants decreased compared with those of wild-type plants. Reverse transcription-polymerase chain reaction analysis showed that OsHox9 expression reduced in the transgenic plants with phenotypic variance, whereas that in the transgenic plants without phenotypic variance was similar to that in the wild-type plants. This result suggests that the phenotypes of the transgenic plants were caused by RNAi effects. The tissue-specificity of OsHox9 expression indicated that it was expressed in different organs, with high expression in stem apical meristem and young panicles. Subcellular location of OsHox9 demonstrated that it was localized on the cell membrane.

Genetic variation in four maturity genes affects photoperiod insensitivity and PHYA-regulated post-flowering responses of soybean

BackgroundAbsence of or low sensitivity to photoperiod is necessary for short-day crops, such as rice and soybean, to adapt to high latitudes. Photoperiod insensitivity in soybeans is controlled by two genetic systems and involves three important maturity genes: E1, a repressor for two soybean orthologs of Arabidopsis FLOWERING LOCUS T (GmFT2a and GmFT5a), and E3 and E4, which are phytochrome A genes. To elucidate the diverse mechanisms underlying photoperiod insensitivity in soybean, we assessed the genotypes of four maturity genes (E1 through E4) in early-flowering photoperiod-insensitive cultivars and their association with post-flowering responses.ResultsWe found two novel dysfunctional alleles in accessions originally considered to have a dominant E3 allele according to known DNA markers. The E3 locus, together with E1 and E4, contained multiple dysfunctional alleles. We identified 15 multi-locus genotypes, which we subdivided into 6 genotypic groups by classifying their alleles by function. Of these, the e1-as/e3/E4 genotypic group required an additional novel gene (different from E1, E3, and E4) to condition photoperiod insensitivity. Despite their common pre-flowering photoperiod insensitivity, accessions with different multi-locus genotypes responded differently to the post-flowering photoperiod. Cultivars carrying E3 or E4 were sensitive to photoperiod for post-flowering characteristics, such as reproductive period and stem growth after flowering. The phytochrome A–regulated expression of the determinate growth habit gene Dt1, an ortholog of Arabidopsis TERMINAL FLOWER1, was involved in the persistence of the vegetative activity at the stem apical meristem of flower-induced plants under long-day conditions.ConclusionsDiverse genetic mechanisms underlie photoperiod insensitivity in soybean. At least three multi-locus genotypes consisting of various allelic combinations at E1, E3, and E4 conferred pre-flowering photoperiod insensitivity to soybean cultivars but led to different responses to photoperiod during post-flowering vegetative and reproductive development. The phyA genes E3 and E4 are major controllers underlying not only pre-flowering but also post-flowering photoperiod responses. The current findings improve our understanding of genetic diversity in pre-flowering photoperiod insensitivity and mechanisms of post-flowering photoperiod responses in soybean.

GUS activity for miR165a/166b, REV, and WUS/CLV3 in in vitro direct Arabidopsis thaliana shoot regeneration

In Arabidopsis thaliana, the process of shoot regeneration in vitro requires the presence of specific miRNAs. We describe here the β-glucuronidase (GUS) expression domains for miR165a/166b, REV, and WUS/CLV3 during direct shoot regeneration. Increased GUS activity of miR166b and REV were first detected within the shoot apical meristem of explants, while no pmiR165a::GUS activity appeared there. The zone of pWUS::GUS activity covered the inner sides of developing protuberances, while that of pCLV3::GUS was more restricted. Once the primary shoot had emerged from the protuberance, pREV::GUS activity was turned on throughout the protuberance. pmiR165a::GUS activity was detected in a small number of protuberance surface cells, while pWUS::GUS activity was restricted to within a few cells beneath the protuberance surface. After the differentiation of leaf-like structures, GUS activity for miR165a and miR166b appeared largely on their abaxial surface, while pWUS::GUS activity was concentrated at the apex of the primary shoot, and no pCLV3::GUS activity was detectable. Following the formation of secondary shoots, pmiR165a::GUS activity was detected on their abaxial surface. GUS activity for miR166b, REV, and WUS/CLV3 were concentrated in the stem apical meristem. The observations suggested that each member of this set of genes might play a distinct role in both primary and secondary shoot regeneration.

Critical level of radiation damage of root apical meristem and mechanisms for its recovery in Pisum sativum L.

The dose dependencies of growth and cytogenetical values have been built to determine the critical level of root apical meristem damage induced by cute irradiation in the range from 2 to 20 Gr. We have analyzed the frequencies of aberrant anaphases and the aberration distribution per cell, on the one hand, and the growth of biomass, the survival and regeneration of the root meristem, on the other hand. The critical level of damage to the stem apical meristem and root of seedlings was defined as 44-48% of aberrant anaphase. Exceeding of this level leads to the launch of suicidal program through induction of multiaberrant damages and interphase cell death. It appears that competition of clones of non-aberrant cells, the cells bearing 1 and 2 damages and multiaberrant cells plays the primary role in the mechanisms of recovery. The regeneration provides full or partial restoration of the main root apical meristem. However these local processes are insufficient to restore morphogenesis and survival of seedlings in excess of the critical level damage.

On the role of genes determinate, late flowering and fasciata in the morphogenesis of pea inflorescence

The effects of mutations determinate (det), late flowering (lf), fasciata (fa, fas), and nodulation4 (nod4) on development of inflorescence in pea were characterized. All listed mutations distort functions of stem apical meristem and influence development of axillary flower-bearing axis (short paracladium) leading to formation of terminal flower and bracts. Structure of flower terminating short paracladium was analyzed and hypothesis on origin of its structure was proposed. Scheme of genetic network in control of inflorescence development in pea was designed.

OsCD1 encodes a putative member of the cellulose synthase‐like D sub‐family and is essential for rice plant architecture and growth

The cell wall plays important roles in plant architecture and morphogenesis. The cellulose synthase-like super-families were reported to contain glycosyltransferases motif and are required for the biosynthesis of cell wall polysaccharides. Here, we describe a curled leaf and dwarf mutant, cd1, in rice, which exhibits multiple phenotypic traits such as the reduction of plant height and leaf width, curled leaf morphology and a decrease in the number of grains and in the panicle length. Map-based cloning indicates that a member of the cellulose synthase-like D (CSLD) group is a candidate for OsCD1. RNAi transgenic plants with the candidate CSLD gene display a similar phenotype to the cd1 mutant, suggesting that OsCD1 is a member of the CSLD sub-family. Furthermore, sequence analysis indicates that OsCD1 contains the common D,D,D,QXXRW motif, which is a feature of the cellulose synthase-like super-family. Analysis of OsCD1 promoter with GUS fusion expression shows that OsCD1 exhibits higher expression in young meristem tissues such as fresh roots, young panicle and stem apical meristem. Cell wall composition analysis reveals that cellulose content and the level of xylose are significantly reduced in mature culm owing to loss of OsCD1 function. Take together, the work presented here is useful for expanding the understanding of cell wall biosynthesis.