Shoot

About: Shoot is a research topic. Over the lifetime, 32188 publications have been published within this topic receiving 693348 citations.

The PGPR Stenotrophomonas maltophilia SBP-9 Augments Resistance against Biotic and Abiotic Stress in Wheat Plants.

Abstract: Certain plant growth promoting bacteria has ability to ameliorate abiotic and/or biotic stressors which can be exploited to enhance plant growth and productivity of the plants under stress conditions. Therefore, the present study aimed to examine the role of a rhizospheric bacterial isolate SBP-9 isolated from Sorghum bicolor (i) in promoting the wheat plant growth under salinity stress, and (ii) in enhancing the defense response in wheat against fungal pathogen ‘Fusarium graminearum’. The test isolate possessed plant growth promoting (PGP) traits including ACC deaminase (ACCD), gibberellic acid, indole acetic acid (IAA), siderophore, and inorganic phosphate solubilization. Under salt (NaCl) stress, inoculation of this isolate to wheat plant significantly increased plant growth in terms of various growth parameters such as shoot length/root length (20 to 39%), fresh weight/dry weight (28 to 42%), and chlorophyll content (24 to 56%) following inoculation of test isolate SBP-9. Bacterial inoculation decreased the level of proline, and malondialdehyde, whereas elevated the antioxidative enzymatic activities of superoxide-dismutase (SOD; 28 to 41%), catalase (CAT; 24 to 56%), and peroxidase (POX; 26 to 44%). Furthermore, it also significantly decreased the Na+ accumulation in both shoot and roots in the range of 25 to 32%, and increased the K+ uptake by 20 to 28%, thereby favoring the K+/Na+ ratio. On the other hand, the test isolate also enhanced the level of defense enzymes like β-1, 3 glucanase, phenylalanine ammonia lyase (PAL), peroxidae (PO), and polyphenol oxidase (PPO), which can protect plants from the infection of pathogens. The result of colonization test showed an ability of the test isolate to successfully colonize the wheat plants. These results indicate that Stenotrophomonas maltophilia SBP-9 has potential to promote the wheat growth under biotic and abiotic (salt) stressors directly or indirectly and can be further tested at field level for further exploitation as bioinoculant.

Direct and indirect effects of VA mycorrhizal fungi and rhizosphere microorganisms on acquisition of mineral nutrients by maize (Zea mays L.) in a calcareous soil

Abstract: SUMMARY Maize (Zea mays L.) was grown in a fertilized calcareous soil in pots which were separated by 30 μm nylon nets into three compartments, a central one for root growth and two outer ones for hyphal growth. The treatments comprised of sterilised soil, either inoculated with rhizosphere microorganisms together with Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe, with rhizosphere microorganisms alone, or non-inoculated (sterile control). In the mycorrhizal treatment concentrations of P and Zn were increased in shoot and roots, as was uptake of P and Zn per unit root dry weight or per unit root length. Copper concentration in roots of mycorrhizal plants, and total uptake and uptake per unit root dry weight or per unit root length of Cu was also increased. The higher acquisition of P, Zn and Cu in the mycorrhizal plants is ascribed to VA mycorrhiza per se (hyphal uptake and translocation to the host). Besides these direct effects, VA mycorrhizal fungi and rhizosphere microorganisms affected the acquisition of other nutrients mostly through alteration of root morphology. In both mycorrhizal and sterile treatments, the decreased concentrations of Ca and Si in the shoot but increased concentrations in the roots seem to be related to restricted apoplasmic solute transport across the endodermal barrier due to decreased number of lateral roots. The concentration of K in both shoot and roots, and Fe in shoot were lower in mycorrhizal plants due to reduced root length. Manganese concentration was also distinctly lower in both shoot and roots in mycorrhizal and sterile treatments, an effect which is attributed to the decrease in Mn reduction in the rhizosphere. Irrespective of nutrient, the uptake per unit root length was higher in mycorrhizal plants, probably due to hyphal contribution and increased supply of nutrients to the root surface by mass flow. Soil analysis indicates hyphal translocation of K but not Mg. The results demonstrate that effects of VA mycorrhizal infection on root morphology and rhizosphere microorganisms have to be considered in interpretations of mycorrhizal effects on mineral nutrient acquisition.

Maintenance of shoot growth by endogenous ABA: genetic assessment of the involvement of ethylene suppression

Abstract: Previous work demonstrated that normal levels of endogenous abscisic acid (ABA) are required to maintain shoot growth in well-watered tomato plants independently of effects of hormone status on plant water balance. The results suggested that the impairment of shoot growth in ABA-deficient mutants is at least partly attributable to increased ethylene production. To assess the extent to which ABA maintains shoot growth by ethylene suppression, the growth of ABA-deficient (aba2-1) and ethylene-insensitive (etr1-1) single- and double-mutants of Arabidopsis was examined. To ensure that the results were independent of effects of hormone status on plant water balance, differential relative humidity regimes were used to achieve similar leaf water potentials in all genotypes and treatments. In aba2-1, shoot growth was substantially inhibited and ethylene evolution was doubled compared with the wild type, consistent with the results for tomato. In the aba2-1 etr1-1 double mutant, in which ABA was equally as deficient as in aba2-1 and shoot growth was shown to be insensitive to ethylene, shoot growth was substantially, although incompletely, restored relative to etr1-1. Treatment with ABA resulted in the complete recovery of shoot growth in aba2-1 relative to the wild type, and also significantly increased the growth of aba2-1 etr1-1 such that total leaf area and shoot fresh weight were not significantly lower than in etr1-1. In addition, ABA treatment of aba2-1 etr1-1 restored the wider leaf morphology phenotype exhibited by etr1-1. The results demonstrate that normal levels of endogenous ABA maintain shoot development, particularly leaf expansion, in well-watered Arabidopsis plants, partly by suppressing ethylene synthesis and partly by another mechanism that is independent of ethylene.

Plant Tissue Culture Concepts and Laboratory Exercises

Abstract: (Note: Topic chapters appear below in bold upper and lower case letters Laboratory chapters appear below in nonbold upper and lower case letters.) PART I-INTRODUCTION Introduction of plant tissue and cell culture PART II-HISTORY OF PLANT TISSUE CULTURE History of plant tissue and cell culture PART III-SUPPORTING METHODOLOGIES Getting started with tissue culture-Media preparation, sterile technique and laboratory equipment Nutrition of callus cultures Histological techniques Microscopy and photography Statistical analysis of plant tissue culture data PART IV-PROPAGATION TECHNIQUES Propagation from preexisting meristems Micropropagation of Syngonium by shoot culture Micropropagation of Dieffenbachia Micropropagation of potato by node culture and microtuber production Micropropagation of lilac Micropropagation and in vitro flowering of rose Propagation from nonmeristematic tissues- organogenesis Direct shoot organogenesis from leaf explants of chrysanthemum Shoot organogenesis of watermelon Direct and indirect shoot organogenesis from leaves of Torenia fournieri Shoot organogenesis from petunia leaves Propagation from nonmeristematic tissues- Nonzygotic embryogenesis Embryogenic callus and suspension cultures from leaves of orchardgrass Somatic embryogenesis from seeds of melon Somatic embryogenesis from mature peanut seed Direct somatic embryogenesis from leaves and flower receptacles of cineraria Somatic embryogenesis from immature seeds of yellow poplar Introduction of somatic embryogenesis in conifers PART V-CROP IMPROVEMENT TECHNIQUES Use of protoplasts for plant improvement Isolation, culture and fusion of tobacco and potato protoplasts Isolation of protoplasts from leaves of chrysanthemum and orchardgrass Haploid cultures Production of haploid tobacco plants using another culture Transformation Transformation of tobacco and carrot using Agrobacterium tumefaciens and expression of the ss-glucuronidase (GUS) reporter gene Transformation of chrysanthemum leaf explants using Agrobacterium tumefaciens Construction and use of a simple gene gun for particle bombardment Germplasm preservation Vitrification as a method to cryopreserve shoot tips Secondary product expression in vitro Pigment production in Ajuga cell culture In vitro plant pathology PART VI-SPECIAL TOPICS Variation in culture Tissue culture of ferns Commercial laboratory production Indexing for plant pathogens Culture indexing for bacterial and fungal contaminants PART VII-APPENDIX I: LIST OF SUPPLIERS PART VIII-INDEX