Showing papers by "Sowbiya Muneer published in 2012"

Mycorrhizal colonisation and P-supplement effects on N uptake and N assimilation in perennial ryegrass under well-watered and drought-stressed conditions

Abstract: To compare the effect of arbuscular mycorrhiza (AM) and P-supplement on N uptake and N assimilation under well-watered or drought-stressed conditions, Glomus intraradices-colonised, P-supplemented non-mycorrhizal (P) and non-mycorrhizal (control) plants of Lolium perenne were exposed to 12 days of water treatment. Leaf water potential (Ψ w), photosynthetic ability, and N and P nutritional status were measured at the beginning (day 0) and end (day 12) of water treatment. N absorption, amino acid and protein synthesis were quantified using the isotopic tracer 15N at day 12. Under well-watered conditions, growth response and physiological parameters were similar in AM and P plants, as compared to controls. Drought (10% water) significantly decreased these parameters in all three treatments. As compared to control plants, the negative impact of water deficit on the Ψ w, photosynthesis, biomass, and N and P content was highly alleviated in AM plants, while only slightly improved or remained the same level in P plants. The effect of AM symbiosis on N absorption and N assimilation was greater than that of the P supplement under well-watered and drought-stressed conditions, and this effect was highly enhanced under drought-stressed conditions. At terminal drought stress on day 12, the effect of AM colonisation on de novo synthesis of amino acids and proteins was 4.4- and 4.8-fold higher than that of the P supplement. These results indicate that the AM symbiosis plays an integrative role in N nutrition by alleviating the negative impacts of drought on N or P uptake and N assimilation, whereas the efficiency of a direct P supplement is very limited under drought-stressed conditions.

Mycorrhizal colonization alleviates drought-induced oxidative damage and lignification in the leaves of drought-stressed perennial ryegrass (Lolium perenne).

Abstract: To investigate the effects of arbuscular mycorrhizal (AM) fungus Glomus intraradices on antioxidative activity and lignification under drought-stressed (DS) conditions, the enzyme activities, growth, lignin contents and some stress symptomatic parameters as affected by drought treatment were compared in AM colonized or non-colonized (non-AM) perennial ryegrass plants for 28 days. Drought significantly decreased leaf water potential (Ψ(w) ), photosynthesis rate and biomass. The negative impact of drought on these parameters was much highly relived in AM plants compared to non-AM ones. Drought increased H₂O₂, lipid peroxidation, phenol and lignin levels, with significantly higher in non-AM relative to AM plants at day 28 after drought treatment. The enhanced activation of guaiacol peroxidase (GPOX), coniferyl alcohol peroxidase (CPOX), syringaldazine peroxidase (SPOX) and polyphenol oxidase (PPO) was closely related with the decrease in Ψ(w) in both AM and non-AM plants. GPOX, CPOX, SPOX and PPO highly activated with a concomitant increase in lipid peroxidation and lignin as the Ψ(w) decreased below -2.11 MPa in non-AM plants, while much less activated by maintaining Ψ(w) ≥-1.15 MPa in AM ones. These results indicate that AM symbiosis plays an integrative role in drought stress tolerance by alleviating oxidative damage and lignification, which in turn mitigate the reduction of forage growth and digestibility under DS conditions.

Fe modulates Cd-induced oxidative stress and the expression of stress responsive proteins in the nodules of Vigna radiata

Abstract: The aim of this study was to investigate the protective role of Fe in providing tolerance against Cd-stress in root nodules of Vigna radiata, because Cd may be more deleterious in the absence of Fe. Biochemical, histological and proteomic responses to Cd-exposure (50 μM CdCl2) were examined under Fe-sufficient (+Fe/+Cd) or Fe-deficient (−Fe/+Cd) soils by comparing non −Cd exposed control (+Fe/−Cd) plants with additional control of Fe-deficient and non-exposed Cd plants (−Fe/−Cd). Cd-exposure negatively affected on growth and some physiological parameters of host plant and nodules, and also induced oxidative stress with the decline of antioxidative enzyme activities. The negative effects of Cd-exposure in +Fe/+Cd plants were much less than those in −Fe/+Cd and −Fe/−Cd ones. When compared with −Fe/Cd and −Fe/−Cd plants, a marked improvement of bacteriod development and cell division was observed and deformation of cell wall remarkably alleviated in the nodules of (+Fe/Cd) plants. Proteomic study revealed that 20 proteins were differentially expressed by Fe/Cd combined treatment. Eleven proteins of interest were identified and classified as precursor for RNA metabolism, storage of seeds, hypothetical proteins, and unknown proteins. These results indicate that Fe plays a pivotal role in alleviating Cd-stress, as evidence by reduction in oxidative damage and protection of cell wall and bacteriods in nodules.

Review article Proteomics of nitrogen fixing nodules under various environmental stresses

Abstract: Proteomics is an ideal tool to study the interaction of root nodules and their symbiotic bacteria as it provides a broad overview of proteins produced by both partners during their constant signal exchange and allows the signal transduction path ways following photophosphorylation. Iron containing proteins play a key role in symbiotic nitrogen fixation that occurs in a nodule-a specialized structure present on roots. Several proteins like those related to SNF (symbiotic nitrogen fixation), predominantly components of nitrogenase complexes, such as nif D, nif H, nif K, nitrogen regulatory protein II (GlnB) and PIIA (PtsN), and urease accessory protein (UreE) have been found to be affected by abiotic stress. Nodules are better equipped with all kinds of antioxidant systems (i.e., ascorbate-glutathione pathway or Superoxide dismutase) which have been formed to show a decline under stress conditions. The present review article aims to investigate the nodule physiology, the effect of different abiotic stress on nodule proteins comprehensive account of these stress-responsive proteins and their role in combating stress in legume nodules. This will help to elucidate which specific key proteins are affected by abiotic stress. As such, it will greatly facilitate understanding resistance or stress tolerance mechanism and hence improvement in crop resistance.

Proteomics of nitrogen fixing nodules under various environmental stresses.

Abstract: Proteomics is an ideal tool to study the interaction of root nodules and their symbiotic bacteria as it provides a broad overview of proteins produced by both partners during their constant signal exchange and allows the signal transduction path ways following photophosphorylation. Iron containing proteins play a key role in symbiotic nitrogen fixation that occurs in a nodule-a specialized structure present on roots. Several proteins like those related to SNF (symbiotic nitrogen fixation), predominantly components of nitrogenase complexes, such as 'nifD', 'nifH', 'nifK', nitrogen regulatory protein II (GlnB) and PIIA (PtsN), and urease accessory protein (UreE) have been found to be affected by abiotic stress. Nodules are better equipped with all kinds of antioxidant systems (i.e., ascorbate-glutathione pathway or Superoxide dismutase) which have been formed to show a decline under stress conditions. The present review article aims to investigate the nodule physiology, the effect of different abiotic stress on nodule proteins comprehensive account of these stress-responsive proteins and their role in combating stress in legume nodules. This will help to elucidate which specific key proteins are affected by abiotic stress. As such, it will greatly facilitate understanding resistance or stress tolerance mechanism and hence improvement in crop resistance.

Effect of Sulfate Supply Level on Sulfate Assimilation in Different Oilseed Rape Cultivars

Abstract: 유채 품종에서 황 공급수준이 황산염 흡수 및 동화에 미치는 영향을 구명하고자 어린 잎과 성엽조직에서 ATP sulfurylase (ATPs), SO₄²? 흡수, 글루타치온 함량을 분석하였다. 본 실험에서 10가지 유채 품종들 (Mosa, Capitol, Saturnin, Akela, Pollen, Mokpo, Youngsan, Tamra Colosse 그리고 Naehan)은 황 공급수준에 따라 몇 가지 황산염 흡수와 동화 능력이 다르게 나타났다. 황 결핍 조건에서 모든 품종의 ATP sulfurylase (ATPs) 활력은 늙은 잎에 비해 어린 잎에서 높게 나타났으며, 글루타치온 함량은 황 공급수준이 감소함에 따라 어린 잎에서 많이 증가하였다. 이러한 결과들은 유채 품종별 황 결핍조건에서 황을 이용하는 능력이 다르다는 것을 잘 보여주었다.