Stem Apical Meristem Research Articles

Comparative study of the effect of culture media and hormonal treatment on callus formation and regeneration of some native Sistan grapes

Grapevins have Bronze ages archive in Sistan area of Iran.a comparative study on the effect of different culture media ( MS, MS/2 , Chee and Pool, WPM ) and 3 levels of BAP ( 0, 1,2 mg/l) on callus production of 2 native cultivars tissue was carried out. Explants from shoot and leaf tissue were transferred onto different culture media. results showed MS culture medium had maximum effect on callus production in stem apical meristem tissue and effective hormone treatment was 2 mg/l BAP and 4-6 weeks in darkness. 0.5 mg of callus transferred to culture media with NAA 10 m and BAP 5 m. shoot proliferation was obtained by subculturing the micro cutting on same media as used for shoot formation. Maximum rooting occurred on ½ MS culture medium without hormone.

Effect of cadmium on fatty acid composition of lipids in the shoots of Karelian birch cultured in vitro

The effects of cadmium (10−6, 10−5, 10−4, and 10−3 M) on the growth and development of stem apical meristem and fatty acid (FA) composition of particular lipid fractions (neutral lipids, glyco-, and phospholipids) were investigated in the shoots of Karelian birch (Betula pendula var. carelica (Mercklin) Hamet-Ahti) produced in vitro. Low cadmium concentration (10−6 M) slightly stimulated shoot morphogenesis. However, at the concentration of 10−4 M, shoot growth and development was terminated, and the concentration of 10−3 M turned out to be critical (the meristem died within the first 5 days). The presence of Cd in the medium considerably affected FA composition in the shoots. The most pronounced changes occurred in the fraction of glycolipids, and the extent of adverse influence significantly depended on metal concentration in the medium. At the Cd concentration of 10−4 M, the content of di-and trienoic FAs decreased by 3–4 times, whereas the level of monoenoic FAs rose by 5 times. The revealed differences in the FA composition of lipids in birch were considered as an indicator of adverse effect of cadmium on the structure and functions of chloroplasts and therefore on photosynthesis.

Genetic control of fasciation in pea (Pisum sativum L.)

The inheritance and manifestation of fasciation character in three fasciated lines of common pea Pisum sativum L. were investigated. All studied forms are characterized by abnormal enlargement of stem apical meristem leading to distortions in shoot structure. It was estimated that fasciation in mutant Shtambovyi is connected with recessive mutation in gene FAS, which was localized in linkage group III using morphological and molecular markers. It was demonstrated that fasciation in cultivar Rosacrone and line Lupinoid is caused by recessive mutation of the same gene (FA). The peculiar architecture of inflorescence in the Lupinoid line is a result of interaction of two recessive mutations (det fa). Investigation of interaction of mutations fa and fas revealed that genes FA and FAS control consequential stages of apical meristem specialization. Data on incomplete penetrance and varying expressivity were confirmed for the mutant allele fa studied.

Determination of the Photoperiod-Sensitive Inductive Phase in Maize with Leaf Numbers and Morphologies of Stem Apical Meristem

It is vital to determine the effective photoperiods of maize for making full use of tropical germplasm, which is the foundation for determining the effect of latitude and planting date on the development of photoperiod-sensitive maize cultivars. The objective of this study is to determine the photoperiod-sensitive inductive phase using reciprocal transfer between long-day (LD) (15 h d -1) and short-day conditions (SD) (9 h d -1). For Huangzao 4 and CML288, days to tassel and pollen shedding were recorded, and stem apical meristems (SAM) were observed by a laser scanning confocal microscope. The results show that the seedlings are insensitive to photoperiod when they are very young (juvenile). However, after this period, LD delays flowering and increases the leaf numbers below the inflorescence, and the length of the interval of the photoperiod-sensitive inductive phase is longer under LD conditions than under SD conditions. Transferred from SD to LD, plants show a sudden decrease in leaf numbers once sufficient SD has been received for flower commitment. While transferred from LD to SD, plants have a continuous increase in leaf numbers during the photoperiod sensitive inductive phase under LD conditions. At the same time, when plants are competent to flowers, the obvious morphology is the elongation of maize SAM. There is an obvious variance of the photoperiod sensitive phase under LD and SD conditions in different maize.

Statistical recognition of random and regular phyllotactic patterns.

A statistical method used in ecology is adapted to characterize the degree of order in phyllotactic systems. The test consists of subdividing a planar projection of the stem apical meristem into 16 sectors and counting the number of primordia appearing in each. By dividing the sum of squared deviations by the mean number of primordia per sector the chi-square (chi2) is obtained. When there are a total number of 20 primordia, if the chi2 is less than 6.26, the phyllotaxis is spiral; if it is between 6.26 and 27.5 the phyllotaxis is random; and if it is greater than 27.5, the phyllotaxis is distichous or whorled (level of significance alpha = 5 %). It is also possible to remove one or more sectors. If there are k sectors, the two critical values delimiting the random zone will be found in a chi2 table for k - 1 degrees of freedom. The method is applied to the analysis of sho mutants described by Itoh et al. in 2000 (Plant Cell 12: 2161-2174). The results obtained are in agreement with the theoretical analysis showing that a whorled or spiral phyllotactic system may contain a certain number of randomly distributed elements without losing its regular global structure.

Orthologs of the Arabidopsis CLAVATA1 Gene in the Cultivated Brassicaceae Plants

In Arabidopsis thaliana, the CLAVATA1 (CLV1) gene is involved in maintaining the balance between the stem cells in the central zone of the stem apical meristem and the determined cells at its periphery. However, CLV1 has not been previously characterized in other Brassicaceae. Using the direct amplification of genomic DNA, we obtained a full-length CLV1 ortholog from canola plants (Brassica napus), and also three CLV1 fragments from rape (B. rapa), canola (B. napus), and false flax (Camelina sativa), which corresponded to the transmembrane domain and a part of the kinase domain of the CLAVATA1 protein. The nucleotide and deduced amino acid sequences of the full-size CLV1 ortholog from B. napus were similar by 81 and 87% to the prototype gene from arabidopsis; in the case of shorter gene fragments, the similarity was as high as 91–93 and 98%, respectively. By their primary structure, the CLV1 genes in the Brassicaceae considerably differ from their putative structural homologs beyond this family.

Minimizing phenol pollution in sugarcane stem apical meristem culture

The stem apical meristem expiants of sugarcane were pretreated with sterile water for 30 minutes and inoculated on MS medium with 6 BA 2.0 mg.L-1 + NAA 0.1 mg.L-1. The best result of minimizing phenol pollution was obtained when 0.02% (not higher than 0.05%) active carbon (AC) was directly added into the media. The phenol pollution could also be minimized when antioxidant PVP (Polyvinylpyrrolidone) was added into the media, or the explants were transferred onto fresh medium when they began getting brown.

Relations of endogenous and applied gibberellins to growth and accumulation of essential elements in oregano plants grown in copper rich soils

Oregano plants were grown in soils containing various levels of copper [0.3 (control), 13.0, 17.0, 19.0, 22.0 and 24.5 pM Cu/g of soil]. Treated plants showed a reduction in height which was concentration dependent. In spite of this effect, the levels of gibberellin-like substances in the stem apices and leaves of the treated plants were higher than those of the control. Application of 30 pM, gibberellic acid (GA 3 ) (drops put on the stem apical meristem) resulted in a significant increase of the height of the controls. GA 3 -treated plants grown in copper rich soil also exhibited a not statistically significant increase in height. The uptake and distribution of essential elements in the organs of the oregano plants were also studied. Differences among the elements concerning their accumulation in the plant organs were observed. Their levels became modified when gibberellic acid was added on the stem apex. With some exceptions, application of GA 3 decreased the levels of Cu and other metals in the plant organs compared to non-treated plants. The negative effect of copper on the growth of oregano plants is considered not to be due to the level of GAs, but probably to other parameters (toxicity, etc.).

Uptake and localization of lead in corn (Zea mays L.) seedlings, a study by histochemical and electron microscopy

A detailed microscopic analyses of the mode of lead uptake and localization in root, stem and leaf initials of corn seedlings grown in cultural solution is reported. Lead, as other minerals, was passively absorbed into the root tip region and transported by the active apical growth force. The entrance of lead was mainly from the thin epidermal cell walls at the meristematic region. Only limited amounts of lead entered into protoplasts, primarily during the early stage of cell development. However, accumulation of lead within cell walls increased as cells matured. Both local and long distance transport of lead were apoplastic. Once the vascular stele differentiated from the ground meristem, lead entered into the central conducting systems. Lead was also absorbed from the water absorbing zone but this lead mainly remained in the cortex. The Casparin strip was an effective barrier limiting the movement of lead. However, transport through passage cells was observed. The direction of lead movement was also mainly towards high growth rate areas as seen at meristematic root initials, the leaf primordia and the transaction zone at the stem apical meristem. Damaged plasmalemmae allowed lead to enter cells from cell walls. Lead deposition in the cytoplast was observed.

Definition of constitutive gene expression in plants: the translation initiation factor 4A gene as a model

The NeIF-4A10 gene belongs to a family of at least ten genes, all of which encode closely related isoforms of translation initiation factor 4A. The promoter region of NeIF-4A10 was sequenced, and four mRNA 5' ends were determined. Deletions containing 2750, 689 and 188 bp of untranscribed upstream DNA were fused to the GUS reporter gene and introduced into transgenic tobacco. The three constructs mediated GUS expression in all cells of the leaf, stem and shoot apical meristem. Control experiments using in situ hybridization and tissue printing indicated that the observed GUS expression matches the expression patterns of NeIF-4A mRNA and protein. This detailed analysis at the level of mRNA, protein and reporter gene expression shows that NeIF-4A10 is an ideal constitutively expressed control gene. We argue that inclusion of such a control gene in experiments dealing with specifically expressed genes is in many cases essential for the correct interpretation of observed expression patterns.