0000000000335410
AUTHOR
Maria-jesus Cornejo
Microsatellite marker-based genetic variability in Spanish rice cultivars and landraces
The genetic relationships among japonica rice cultivars and landraces were studied. Most of them are of Spanish origin, and were developed and cultivated for varying time periods over more than a century. To uncover genetic diversity within each cultivar, we analysed 30 plants per cultivar or accession using 10 fluorescently labelled primer pairs for SSR markers. Six cultivars were included in the study, with accessions from four different regions of Spain of the traditional cultivar Bomba. A total of 37 alleles were detected with a mean of 3.7 alleles per locus. Polymorphism information content (PIC) ranged from 0 to 0.78 with an average of 0.51 per locus. Genetic diversity for cvs. Albufe…
Morpho-physiological variations in response to NaCl stress during vegetative and reproductive development of rice
The complex nature of plant resistance to adverse environmental conditions, such as salinity and drought requires a better understanding of the stress-induced changes that may be involved in tolerance mechanisms. Here we investigate stress-related morpho-physiological effects during vegetative and reproductive growth in two Japonica rice cultivars (Bomba and Bahia) exposed to a range of NaCl concentrations from the seedling stage. The stress-related detrimental effects were observed either earlier or to a higher extent in cv. Bomba than in Bahia. Damages to the photosynthetic apparatus were related to loss of chlorophyll (Chl) and to a decrease of the maximum potential efficiency of PSII (F…
Uptake of an Endocytic Marker by Rice Cells: Variations Related to Osmotic and Saline Stress
Saline and osmotic stress are the main abiotic factors limiting the productivity of rice and other crop plants. Although both coincide in generating water deficit and affect many aspects of plant growth and development similarly, some effects of salinity are distinctively related to the ionic component of salt stress. At the cellular level, dessication tolerance is largely dependent on the cell's ability for osmotic adjustment. Here, we have studied the effects of saline and osmotic stress on endocytosis by rice cells, to investigate the common and distinctive effects of saline-generated stress and osmotically generated stress, and the possible involvement of endocytosis in tolerance mechan…
A relationship between tolerance to dehydration of rice cell lines and ability for ABA synthesis under stress
Plant dehydration is commonly caused by some adverse environmental conditions such as salinity, drought and freezing. As the plant hormone abscisic acid (ABA) is involved in responses to water stress, we studied its putative relationship with the degree of tolerance to these abiotic stresses. For this purpose we used cell lines that had been established from mature embryos of rice (Oryza sativa L, cvs. Bahia and Bomba), and selected by their high (L-T) or low (L-S) levels of tolerance to each type of stress. Tolerance of rice calli to either osmotic, saline, or freezing stress was generally improved by a previous treatment with ABA. This ABA effect was evident in those callus lines with low…
Uptake of endocytic markers by rice cells: variations related to the growth phase.
Endocytosis is now considered a basic cellular process common to plant cells. Although both non-specific and receptor-mediated endocytosis appear to take place in plant cells, the physiological role of the latter remains unclear. We have investigated the endocytic process in rice cell suspensions using two biotinylated proteins, peroxidase and bovine serum albumin (bHRP and bBSA), as markers. First, we show that markers are internalized by rice cells and appear in intracellular membranes. The uptake of the two markers is temperature dependent, saturable with time and markers dose and it is competed by free biotin. Thus, it shows the properties of a receptor-mediated process. We also show th…
Rice protoplasts isolated directly from mature-embryo-derived calli
Mature-embryo-derived calli of japonica rice (Oryza sativa L) Taipei 309 were used for replicated protoplast isolation experiments. Six out of nine callus lines produced protoplasts with satisfactory yield of 5.20×106–8.96×106 protoplasts/g FW (fresh weight). The remaining three callus lines initiated from seeds of cryopreserved-callus-derived plants had rooty calli, resulting in low yield of protoplasts and a large number of isolated banana-shape intact cells. Viability of protoplasts ranged 87.46%–94.15%. The average size of protoplasts was 207.49–379.04 μm2 in different callus lines. Comparitive experiments were also carried out using both calli and suspension culture cells for protoplas…
The Effect of Secretion on Lipids and their Distribution in Barley Aleurone Protoplasts
Barley aleurone protoplasts, when exposed to Ga3 and Ca2+ synthesize and secrete the hydrolytic enzyme α -amylase (Bush et al., 1986). At the same time, protoplasts undergo important structural changes which reflect the elaboration of the membrane system involved in protein synthesis and secretion. The mobilization of lipid reserves may be a preliminar step which would provide energy as well as several components for the synthesis of membrane lipids.
Gibberellic acid stimulates lipid metabolism in barley aleurone protoplasts
Abstract Changes in the lipid composition of barley aleurone protoplasts following incubation in the presence or absence of gibberellic acid (GA) were studied and correlated with cell development. Analysis of neutral lipids in protoplast extracts and purified lipid bodies provide evidence for the strong effect of GA on the mobilization of storage lipids. In vivo protoplast staining with the membrane marker N -phenyl-l-naphthylamine (NPN) and phospholipid determinations of protoplast extracts show an increase in membrane lipids during protoplast incubation. GA stimulates phospholipid metabolism by increasing the synthesis of phosphatidyl ethanolamine and phosphatidyl choline, the major phosp…
Differential salinity-induced variations in the activity of H+-pumps and Na+/H+ antiporters that are involved in cytoplasm ion homeostasis as a function of genotype and tolerance level in rice cell lines
The characterisation of cellular responses to salinity in staple crops is necessary for the reliable identification of physiological markers of salinity tolerance. Under saline conditions, variations in proton gradients that are generated by membrane-bound H⁺ pumps are crucial for maintaining cytoplasm homeostasis. We examined short (15 h) and longer term effects (4 days) of NaCl stress on the H⁺ pumping activities that are associated with the plasma membrane (P-ATPase) and the tonoplast (V-ATPase and V-PPase) in rice (Oryza sativa L.) callus lines that displayed different levels of NaCl tolerance and were established from two japonica rice cultivars. The applied stress conditions were base…