PubMed · 13713325
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F HENKES. 1961. Drying up the towel problem.. https://doi.org/10.1176/ps.12.7.42
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With the objective to develop a practical and effective method of screening potato for drought tolerance, shoot and root growth in microtuber-derived plantlets was studied in vitro in three genotypes with known root mass production under field conditions. Different levels of water-stress were induced using five concentrations of either sorbitol or polyethylene glycol (PEG) in MS medium. Water potential of various media ranged from -0.80 MPa to -2.05 MPa. Water-stress in culture adversely affected plantlet growth, and genotypes differed for their responses. Genotype IWA-1 was less affected than IWA-3 and IWA-5. At the same level of water potential, sorbitol had lower adverse effect than PEG; the latter being sticky. Genotype x sorbitol and genotype x PEG interactions were significant. At 0.2 M sorbitol and 0.003 M PEG, IWA-1 had significantly more roots with higher total root length, root volume, as well as root-dry weight than those of IWA-3 and IWA-5, whereas the latter two genotypes were at par for all these characters. This pattern was similar to the reported pattern of these genotypes for root-dry weight under field conditions. It is concluded that in vitro screening of potato under specific and limited water-stress conditions may provide a system for effectively differentiating the genotypes for their expected root mass production under field conditions.
A microarray including 1654 cDNAs, mainly derived from dehydration-shocked barley leaf tissues, was utilized to monitor expression changes in leaves of barley plants subjected to slow drying conditions (7 d and 11 d: 7d-WS and 11d-WS) in soil and after rehydration. The results were compared with those obtained under shock-like conditions imposed with a 6 h dehydration treatment. A total number of 173 transcripts (approximately 10% of all transcripts profiled) were declared up- or down-regulated in at least one of the conditions tested. The majority of the transcripts were regulated by only one of the drought treatments, with 57% of the differentially expressed transcripts exclusively affected in the dehydration shock treatment, 6% at 7d-WS, 14% at 11d-WS, and 6% after rehydration. Irrespective of the low percentage of transcripts (10%) with similar expression changes between shock and slow stress treatments, a sizeable portion of these transcripts shared a common expression trend under the different drought treatment conditions, as evidenced by low but significant correlations between the fast occurring and the 7d-WS and 11d-WS treatments (r=0.32 and 0.41, P=0.001, respectively). These results are discussed with respect to the merit of different dehydration treatments in the investigation of the changes in transcript profiling.
The spatial heterogeneity of stomatal closure in response to rapid desiccation of excised well-watered Tradescantia virginiana leaves grown at moderate (55%) or high (90%) relative air humidity (RH) was studied using a chlorophyll fluorescence imaging system under non-photorespiratory conditions. Following rapid desiccation, excised leaves grown at high RH had both a greater heterogeneity and a higher average value of PSII efficiency (Phi(PSII)) compared with leaves grown at moderate RH. Larger decreases in relative water content resulted in smaller decreases in water potential and Phi(PSII) of high RH-grown leaves compared with moderate RH-grown leaves. Moreover, the Phi(PSII) of excised high RH-grown leaves decreased less with decreasing water potential, implying that the stomata of high RH-grown leaves are less sensitive to decreases in leaf water potential compared with moderate RH-grown leaves. After desiccation, some non-closing stomata were distributed around the main vein in high RH-grown leaves. Direct measurements of stomatal aperture showed 77% stomatal closure in the margins after 2 h desiccation compared with 40% closure of stomata in the main-vein areas in high RH-grown leaves. Faster closure of stomata in leaf margins compared with main-vein areas of leaves grown at high RH was related to substantially lower relative water content in these areas of the leaves.