Dynamics of aquaporins and water relations during hypocotyl elongation in Ricinus communis L. seedlings

Abstract

The rate of water flow across biological membranes can be modulated by aquaporins which are expressed in many cells and tissues. The biological functions of these water channels in cellular processes have often been anticipated from the expression pattern, although the participation in the underlying process is not known in many cases. Ten putative aquaporin transcripts were identified in castor bean (Ricinus communis L.) seedlings and the water channel activity of three selected genes was analysed by heterologous expression in Xenopus oocytes, as well as the spatial and temporal expression by in situ hybridization/immunolocalization along the hypocotyl's axis. Water relations parameters were studied in elongating and non-elongating tissues using the cell pressure probe technique. These results indicate that (i) the amount of the RcPIP2-1 aquaporin correlated best with the elongation activity of the etiolated hypocotyl and (ii) the hydraulic conductivity of cortex cells is significantly higher in the elongating region of the hypocotyl compared with the nonelongating, mature region.

The mutual responses of higher plants to environment: Physiological and microbiological aspects

“…From the angle of individual plant development, Plant Growth Grand Periodicity curve can reflect and show the above trend [4-9,102-109,136-140]. Besides, plant responses to soil water deficits take a "slow-fast-slow" shaped curve in terms of main physio-biochemical indices change and this is in agreement with Plant Growth Grand Periodicity, which also illustrates this fact and the wide plasticity for plants [29,31,32,101,102]. Surely, concerted expression of corresponding genes in plant gene regulatory network system makes it possible that we can see the phenotype and phenotype change under given temporal-spatial condition [23,24,82,83,93,95].…”

“…For instance, by introducing betA gene derived from E. coli into tobacco and potato, betaine content in the transgenic plants increased to 5 mol/g (dry weight) and tolerance to salt and cold for the transgenic plants was improved greatly. The goal of recently established plant gene engineering strategy based on transcriptional elements is to improve plant comprehensiveresistance characters [15,16,29,30]. Compared with the previous traditional method of introducing or improving individual functional genes, the new strategy will play more important role in plant molecular breeding because modifying regulatory activities of a transcriptional element can influence functions of many genes, easily reaching the aim of improving plant comprehensive resistance (to drought, salinity, freezing, diseases, UV-B and others) [93,95,117].…”

“…Plants live in soil-plant-atmosphere continuum (SPAC) environment, and they have to coordinate the mechanisms of diverse types to respond to the above changing environment at any time for sustainable survival [4][5][6][7][8][9][21][22][23][24][25][26][27][28][29][47][48][49][50][51][52][53][54][55][56][57][58][59]. Plant production realization is obtained eventually through physiological pathways at least at the level of individual and community [102][103][104][105][106][107][108][109]120,[130][131][132][133][134][135][136][137][138][139][140].…”

“…Water deficits in soil environment also influence solute transport (ion and nutrient uptake of plants) to larger extent, which effects on photosynthetic reactions in plant chloroplasts in many ways [117,120,131,135,[139][140][141][142][143][144][145][146][147]. This is the reason that ion homeostasis and redox state have been brought to attention [4][5][6][7][21][22][23][24][25][26][27][28][29][111][112][113][114][115][116][117][118][119]. The series of the above reactions and processes occurring at different soil-root biointerfaces is regulated and controlled by plant gene regulatory network system spatially and temporally on the basis of responding to plant developmental cues, through which plants can elegantly respond to the changing environment [8][9][10][11][12][13][14][15][16][17]…”

Mammalian androgen stimulates photosynthesis in drought-stressed soybean

“…Water flow in the plant, together with the hydration of tissues and cells, is dependent on the presence and functioning of water channels -aquaporins. Aquaporins represent an important selective pathway for water to move across plant cellular membranes according to a water potential gradient [30,31]. There are many types of aquaporins and their functioning depends on gene expression or is regulated by physiological mechanisms (phosphorylation, pH, Ca +2 ) [31,32].…”