Mild salinity stimulates a stress-induced morphogenic response in Arabidopsis thaliana roots

Abstract

Plant roots exhibit remarkable developmental plasticity in response to local soil conditions. It is shown here that mild salt stress stimulates a stress-induced morphogenic response (SIMR) in Arabidopsis thaliana roots characteristic of several other abiotic stresses: the proliferation of lateral roots (LRs) with a concomitant reduction in LR and primary root length. The LR proliferation component of the salt SIMR is dramatically enhanced by the transfer of seedlings from a low to a high NO3− medium, thereby compensating for the decreased LR length and maintaining overall LR surface area. Increased LR proliferation is specific to salt stress (osmotic stress alone has no stimulatory effect) and is due to the progression of more LR primordia from the pre-emergence to the emergence stage, in salt-stressed plants. In salt-stressed seedlings, greater numbers of LR primordia exhibit expression of a reporter gene driven by the auxin-sensitive DR5 promoter than in unstressed seedlings. Moreover, in the auxin transporter mutant aux1-7, the LR proliferation component of the salt SIMR is completely abrogated. The results suggest that salt stress promotes auxin accumulation in developing primordia thereby preventing their developmental arrest at the pre-emergence stage. Examination of ABA and ethylene mutants revealed that ABA synthesis and a factor involved in the ethylene signalling network also regulate the LR proliferation component of the salt SIMR.

Root system architecture: insights fromArabidopsisand cereal crops

“…Many plants adapted to drought, such as sorghum, have a naturally more vertically orientated root structure [109]. Soil salinity also has an effect on root architecture owing to the infliction of osmotic and ionic stress on the roots, but in contrast to drought stress, high soil salinity inhibits primary root elongation while promoting lateral root emergence in glycophytes such as Arabidopsis [110,111]. Drought is often associated with high temperatures; in this issue, Hund et al [112] discuss the effects of high soil temperature on root growth in maize.…”

Molecular basis of plant stress

“…Other examples are morphological changes of leaves such as leaf rolling or thickening wax layers, which are often observed in response to stresses such as drought, high light salt, temperature, heavy metals, UV radiation, or biotic challenges [3,4]. Modifications in root architecture occur in response to many unfavorable abiotic factors, particularly osmotic and nutrient stresses [1,5,6]. The morphological and physiological changes are determined by molecular responses that govern global transcriptome, proteome, and metabolome adjustments, eventually resulting in stress protection, altered growth and development, or death in the worst scenario.…”

Regulation of Root Length and Lateral Root Number in Trifoliate Orange Applied by Peroxide Hydrogen and Arbuscular Mycorrhizal Fungi

“…The H2O2 excess accumulation in plants could be used as ROS to induce oxidative burst in cells, thereby triggering cell death. On the other hand, H2O2 is also regarded as an important signal compound concerning the interaction of plants with pathogenic microorganisms (Apel and Hirt, 2004;Laloi et al, 2004), as well as many other processes referring to root biology, such as gravitropism, root elongation growth and root hair development (Zolla et al, 2010;Jiang et al, 2012). However, the interaction between AMF and H2O2 on RSM traits of the host plant is poorly known.…”