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1

Root-favoured biomass allocation improves growth and yield of field-grown rice (Oryza sativa L.) plants only when the shoot sink is expandable

100%
Nada R. M., Abogadallah G. M.
Acta Physiologiae Plantarum
|
2018
|
tom 40
|
nr 06
2

Physiological aspects of tolerance in Atriplex halimus L. to NaCl and drought

71%
Nemat Alla M. M., Khedr A.-H. A., Serag M. M., Abu-Almaga A. Z., Nada R. M.
Acta Physiologiae Plantarum
|
2011
|
tom 33
|
nr 2
Forty-day-old seedlings of Atriplex halimus were treated either with NaCl (50, 300 and 550 mM) for the subsequent 30 days or with 15% PEG for the subsequent 10 days. As much as 50 mM of NaCl significantly increased shoot fresh and dry weight and height; nevertheless, 300 or 550 mM NaCl seemed to have no effect. On the other hand, these growth parameters were not affected by drought after 3 or 6 days, but were reduced after 10 days. The gas exchange parameters (photosynthetic rate, stomatal conductance and transpiration rate) were increased by 50 mM NaCl, but decreased by 300 and 550 mM. These parameters were decreased in response to drought only after 10 days of withholding water. In contrast to Na⁺, K⁺ was significantly decreased by NaCl but not by drought. The time course effect revealed that phosphoenol pyruvate carboxylase (PEPC) protein was doubled in response to NaCl after 1 and 5 h and continued thereafter, higher than control, while drought had no significant effect. Rubisco seemed unchanged by NaCl or drought. It could be concluded that the decrease in fresh weight might be attributed to the decrease in water content. Moreover, the decrease in photosynthesis could result from a decrease in stomatal conductance, a protective mechanism against water loss to improve water use efficiency. These findings indicate that Atriplex halimus tolerates NaCl and drought through decreasing growth, reducing gas exchange parameters to improve water use efficiency, uptake Na⁺ and saving, if any, the photosynthetic enzyme particularly PEPC.
3

Supplementary CaCl2 ameliorates wheat tolerance to NaCl

71%
Nemat Alla M. M., Abogadallah G. M., Badran E. G., Nada R. M., Hassan N. M.
Acta Physiologiae Plantarum
|
2014
|
tom 36
|
nr 08
Nine-day-old seedlings of two wheat cultivars (Misr1 and Sakha93) were treated with NaCl at 75, 150 and 225 mM for 15 days with or without the presence of 10 mM CaCl₂. All concentrations of NaCl led to significant decreases in fresh and dry weights of only Sakha93; however, Misr1 seemed to be affected only at the highest concentration. Nonetheless, growth parameters of both cultivars under normal conditions were most likely similar. On the other hand, lipid peroxides (as MDA) and H₂O₂ were greatly accumulated particularly in Sakha93; significant increases were detected in Misr1 treated only at 225 mM. Also, all concentrations of NaCl decreased GSH content in Sakha93; nevertheless, there were no great differences among both cultivars under normal conditions. On the other hand, the activities of the enzymatic antioxidants, GR, GST, CAT and POD were unaffected in Misr1 by all concentrations but inhibited in Sakha93. AOX responded differently to NaCl, there were decreases in Misr1 by 75 and 225 mM and in Sakha93 by 75 and 150 mM. However, the application of CaCl₂ alleviated the impacts of NaCl; there was a retraction in growth reduction in Misr1 to reach most likely those of the control. In addition, the accumulated MDA and H₂O₂ were greatly counterbalanced. On the contrary, the decreased GSH contents seemed unrecovered in Sakha93 in spite of the alleviations in magnitudes. Moreover, there were recoveries in the activities of GR and POD in Sakha93; nevertheless, GST and CAT activities remained significantly inhibited. These findings suggest that Misr1 is a more tolerant cultivar to NaCl than Sakha93. Moreover, the results reveal that ROS scavenging is efficient and became more inducible in the less susceptible than in the more susceptible cultivar. The response of AOX appeared to coincide with antioxidants so that the damage which was inflicted by NaCl can be ameliorated by overexpression of antioxidants especially with the presence of CaCl₂.
4

Growth stimulation and inhibition by salt in relation to Na+ manipulating genes in xero-halophyte Atriplex halimus L.

61%
Khedr A. H. A., Serag M. S., Nemat-Alla M. M., El-Naga A. Z. A., Nada R. M., Quick W. P., Abogadallah G. M.
Acta Physiologiae Plantarum
|
2011
|
tom 33
|
nr 5
In the present study, Na⁺ manipulating genes could contribute not only to ion homeostasis but also to growth stimulation with exposing the halophyte Atriplex halimus L. to moderate NaCl concentration. The stimulation of growth was attributed to Na⁺ accumulation inside the vacuole leading to increase leaf cell size as well as accelerate leaf cell division. Increasing the assimilatory surface could result in enhancing the photosynthetic rate. The reduction of A. halimus growth compared to optimum growth at 50 and 200 mM NaCl could be attributed to osmotic effect rather than the ionic one of salt stress. The inhibition of photosynthesis seemed to be resulted from limitation of CO₂ due to the osmotic effect on stomatal conductance rather than the activity loss of photosynthetic machinery. The depletion of starch content along with the increase in sucrose content could imply that photosynthesis may be a limiting for A. halimus growth. The fast coordinate induction of Na⁺ manipulating genes could reveal that the tolerance of A. halimus to high concentrations evolved from its ability to regulate and control Na⁺ influx and efflux. V-H⁺-PPase may play a vital role in A. halimus tolerance to osmotic and/or ionic stress due to its kinetics of induction. It seemed that H⁺-ATPase plays a pivotal role in A. halimus tolerance to stress due to the increase in its protein level was detected with all NaCl concentrations as well as with PEG treatments. Both of these genes might be useful in improving stress tolerance in transgenic crops.
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