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[en] Salinity is one of the major constraints that impair plant growth and ultimately limits crop productivity. Growing salt-tolerant crops is thought to be an efficient strategy to make use of the saline land. Pumpkin (Cucurbita moschata) is an economically important and worldwide cultivated vegetable. EMS (ethyl methanesulfonate), as a mutagenic agent, has been widely used to increase genetic variability in crop breeding. In this study, we designed a screen of NaCl-tolerant mutants induced by EMS in Cucurbita moschata. Two NaCl-tolerant mutants were screened under NaCl stress and further identified using physiological and biochemical parameters. As the result of genetic analysis, we deduced that the NaCl-tolerant mutant phenotype was controlled by QTLs. This research provides the protocol of mutant screening and new sources for salt-tolerant cultivar breeding in pumpkin. The mutants can also be used to better understand the salt-tolerance mechanism in plants. (author)
[en] The recA and the recX genes of Herbaspirillum seropedicae were sequenced. The recX is located 359 bp downstream from recA. Sequence analysis indicated the presence of a putative operator site overlapping a probable σ70-dependent promoter upstream of recA and a transcription terminator downstream from recX, with no apparent promoter sequence in the intergenic region. Transcriptional analysis using lacZ promoter fusions indicated that recA expression increased three- to fourfold in the presence of methyl methanesulfonate (MMS). The roles of recA and recX genes in the SOS response were determined from studies of chromosomal mutants. The recA mutant showed the highest sensitivity to MMS and UV, and the recX mutant had an intermediate sensitivity, compared with the wild type (SMR1), confirming the essential role of the RecA protein in cell viability in the presence of mutagenic agents and also indicating a role for RecX in the SOS response. (author)
[en] A wide range of morphological mutants were identified in two varieties of mungbean. These mutants involved traits effecting plant height, growth habit, seed and pod. The frequency of morphological mutants differed in different mutagenic treatments and also between the varieties. The highest mutation frequency was noticed in the EMS treated population whereas the lowest frequency was observed SA treatments, HZ treatments being the intermediate. Variety NM-1 gave the broader spectrum and frequency of morphological mutations than the var. PDM-11. Of all the mutant types, maximum occurrence of mutation was observed for plant height. (author)
[en] Magnetic reconnection has been suggested to play an important role in the dynamics and energetics of plasma turbulence by spacecraft observations, simulations, and theory over the past two decades, and recently, by magnetosheath observations of MMS. A new method based on magnetic flux transport (MFT) has been developed to identify reconnection activity in turbulent plasmas. This method is applied to a gyrokinetic simulation of two-dimensional (2D) plasma turbulence. Results on the identification of three active reconnection X-points are reported. The first two X-points have developed bidirectional electron outflow jets. Beyond the category of electron-only reconnection, the third X-point does not have bidirectional electron outflow jets because the flow is modified by turbulence. In all cases, this method successfully identifies active reconnection through clear inward and outward flux transport around the X-points. This transport pattern defines reconnection and produces a new quadrupolar structure in the divergence of MFT. This method is expected to be applicable to spacecraft missions such as MMS, Parker Solar Probe, and Solar Orbiter.