ABSTRACT
Desiccation-tolerance (DT) is the ability to lose virtually all free intracellular water and then recover normalphysiological functions. The phenomenon of DT is present in higher plants as well as few Pteridophytes whichwithstand drying up to 10%–20% of their dry weight and still resume metabolism following rehydration.The present investigation was carried to understand the biochemical adaptations against desiccation andalso subsequent rehydration in Adiantum raddianum (AR), an omnipresent fern in the Devarayanadurgaforest region of Tumakuru district of Karnataka, India. Detached fronds from healthy AR fern were fullyhydrated, subsequently desiccated, and rehydrated under in vitro conditions. During the desiccation process,the relative water content (RWC) of detached fronds decreased to as low as 16% after 4 hours with intenseinward curving. Upon rehydration, the RWC of the desiccated fronds regained 85% of the initial water contentwithin 4 hours. The rehydrated fronds almost showed the original morphology. Furthermore, physiologicalactivities of antioxidant enzymes such as superoxide dismutase, peroxidase, catalase, glutathione reductase,lipid peroxidation, and proline increased during desiccation but sucrose and starch content showed differentialresponse. The result obtained in this study reveals that AR has desiccation-tolerant properties.
ABSTRACT
In this research the cell membrane stability (CMS), relative water content (RWC) and effect of different water interval on Cymbopogon citratus (lemon grass) was assessed. The cell membrane stability and relative water content of the plant shows the physiological activity of the plant. The plant sample was subjected to three different watering regimes viz: one, two- and three-days intervals with a control sample irrigated daily for a period of twelve months. Uniform stalk of lemon grass plants were planted into a depth of 7.5 cm composted soil, each treatment was made in triplicate. The evaluated growth parameters where height of the plant, number of leaves and tillers, which were taken weekly for period of twelve months (year). The height shows a significant difference from first to twelfth month after planting. The height of the plant increases simultaneous with the age of the plant. First month after planting show significant difference in height of sample watered daily and treated samples. The results shows that the RWC (07.14%) and CMS (52.58%) was low in samples under water stress respectively when compared to well-watered samples (55.41%). No significant difference was observed between samples under one, two and three days interval. The number of leaves differs significantly in the first MAP except in the samples watered daily and three days interval. Maximum number of leaves was achieved at twelfth MAP under one day interval (137.33) followed by samples watered daily (126) and two days interval, while three days interval has the least number of leaves (leaf number). The number of tillers shows significant differences between the means at fifth and sixth MAP, (fifth MAP = 73.33 and sixth MAP = 126) and the treatments under one day intervals (fifth MAP = 18.33 and sixth MAP = 35.67). In the research, samples watered daily and under one day intervals shows high productivity when compared to the remaining treatment.
ABSTRACT
In plants, basic region/leucine zipper motif (bZIP) transcription factors regulate several developmental processes and activate genes in response to biotic and abiotic stresses. Role of stress responsive bZIP transcription factors was studied in paddy in relation to different stages of development and water deficit stress (WDS) in a drought tolerant cultivar N22 and susceptible IR 64. Further, relative water content (RWC), membrane stability index (MSI) and abscisic acid (ABA) content were measured as indices of WDS at different stages of development and levels of stress. Expression of stress responsive bZIP transcription factors was directly correlated to developmental stage and WDS and indirectly to RWC, MSI and ABA content.