ABSTRACT
Abiotic stress causes abrupt increase in the expression of stress-associated proteins, which provide tolerance by modulating the defense mechanism of plants. Small heat shock proteins (sHSPs) and anti-oxidant enzymes are important for environmental stress tolerance of the plants. In this study, two full-length cDNAs encoding small heat shock protein (sHSP) and superoxide dismutase (SOD), designated as TasHSP and SODI were identified and characterized from C-306 (thermotolerant) and PBW343 (thermosusceptible) cultivars of wheat (Triticum aestivum L.). An alpha crystalline domain was observed in TasHSP and manganese/iron binding domain in case of SODI. Quantitative real-time PCR showed very high transcript level of TasHSP and SOD in C-306 compared to PBW343 at different stages of growth and against differential heat stress (HS). Under differential HS at milky-dough stage, the fold change in transcript of both TasHSP and SOD was observed maximum in C-306, compared to PBW343. Protein profiling and isoenzymes analysis showed the expression of several heat-stable proteins and prominent isoenzymes of SOD in C-306, compared to PBW343. Scanning electron microscopy (SEM) of starch granules showed globular, well-shaped and more numbers of endospermic cells in C-306, compared to defragmented, irregular shaped and shrunken granules in case of PBW343 under HS treatment (42°C for 2 h). Diurnal change in soluble starch synthase (SSS) activity showed an increase in the activity during afternoon (35°C), compared to morning (29°C) and evening (32°C) in both the cultivars. Under heat stress (42°C for 2 h), a drastic decrease in the SSS activity was observed, due to the thermal denaturation of the enzyme. Thermotolerance capacity analyzed using cell membrane stability (CMS) showed significantly higher CMS in case of C-306, compared to PBW343 at different stages of growth. Findings suggest that abundance of TasHSP and SODI during milky-dough stage plays a very important role in starch granule biosynthesis. The mechanism may be further exploited to develop tolerant wheat cultivar with high quality seeds.
Subject(s)
Amino Acid Sequence , Base Sequence , Cell Membrane/metabolism , Cloning, Molecular , DNA, Complementary/metabolism , Gene Expression Profiling , Gene Expression Regulation, Plant , Heat-Shock Proteins/metabolism , Hot Temperature , Isoenzymes/metabolism , Microscopy, Electron, Scanning , Models, Biological , Molecular Sequence Data , Phylogeny , Real-Time Polymerase Chain Reaction/methods , Sequence Homology, Amino Acid , Starch/metabolism , Starch Synthase/metabolism , Superoxide Dismutase/metabolism , Triticum/metabolismABSTRACT
Objective:To screen better excipient and better ratio of the excipients and to improve the formability of the compound Chinese medicine Changle (Saliva Miltiorrhiza) and resistant to moisture of the granules. Methods: Through measuring the distribution of the size and the absorption of moisture of the granule the formability was determined. Under high moisture for a moment, the amount of absorption of moisture and the flowability of the granule was measured and the appearance was observed as to determine the nature of resistant to moiture of the granules. Results: The better excipients was soluble starch and avicel. It was better that the combined excipients of starch: avicel in a ratio of 1∶1 was mixed with the extract powder in a ratio of 2∶3. Conclusion: When the combined excipients of starch: avicel in a rato of 1∶1 was used, the extract powder was easy to be formed and the granule made was moisture-resistant.