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[Objective] The desert plant Karelinia caspia has a broad-spectrum of stress resistance, including salt/alkali tolerance and high temperature tolerance, which is a precious natural plant germplasm native to Xinjiang. It has been noted that mining the genes involved in extreme temperature and salt tolerance of K . caspia as well as analyzing their expression under stress is critical for using these genes to enhance crop stress resistance, increase yield, and promote the exploration and utilization of the genetic resources of the desert plants. [Methods] Potted K . caspia seedlings were subjected to different durations of high temperature (45 ℃), low temperature (4 ℃), and high salt (400 mmol/L Na+ ) stress. Root, stem, and leaf tissues were collected to analyze the expression of the HTR gene family (KcHTRs) by using RT-PCR and other techniques, and analyze their stress resistance and optimal induction conditions for protein expression by a prokaryotic expression system. [Results] (1) Seven of the KcHTR gene family members were screened and cloned from the transcriptomic data obtained from high temperature treatments of K . caspia. By constructing prokaryotic expression vectors and inducing expression, cDNA lengths of the KCHTR gene family were determined to be between 708 and 789 bp, and the molecular weights of the expressed protein was between 27 and 29 kD. (2) It was found that the optimal expression system of E. coli BL21 was 0.8 at OD600, IPTG concentration 0.5 mmol/L, and induction time 8-10 h at the optimum temperature of 37 ℃. (3) Recombinant E. coli was treated with simulated high temperature, low temperature and salt stress, and the results showed that KcHTRs enhanced the host tolerance to the stresses to certain extent. [Conclusion] The results showed that KcHTRs has broad-spectrum of stress resistance, mainly extreme temperature, and actively responds to stress conditions.

The halophyte Karelinia caspia has not only fodder and medical value but also can remediate saline-alkali soils. Our previous study showed that salt-secreting by salt glands is one of main adaptive strategies of K. caspia under high salinity. However, ROS scavenging, ion homeostasis, and photosynthetic characteristics responses to high salinity remain unclear in K. caspia. Here, physio-biochemical responses and gene expression associated with ROS scavenging and ions transport were tested in K. caspia subjected to 100-400mM NaCl for 7 days. Results showed that both antioxidant enzymes (SOD, APX) activities and nonenzymatic antioxidants (chlorogenic acid, α-tocopherol, flavonoids, polyamines) contents were significantly enhanced, accompanied by up-regulating the related enzyme and non-enzymatic antioxidant synthesis gene (KcCu/Zn-SOD, KcAPX6, KcHCT, KcHPT1, Kcγ-TMT, KcF3H, KcSAMS and KcSMS) expression with increasing concentrations of NaCl. These responses are beneficial for removing excess ROS to maintain a stable level of H2O2 and O2- without lipid peroxidation in the K. caspia response to high salt. Meanwhile, up-regulating expression of KcSOS1/2/3, KcNHX1, and KcAVP was linked to Na+ compartmentalization into vacuoles or excretion through salt glands in K. caspia. Notably, salt can improve the function of PSII that facilitate net photosynthetic rates, which is helpful to growing normally in high saline. Overall, the findings suggested that ROS scavenging systems and Na+/K+ transport synergistically contributed to redox equilibrium, ion homeostasis, and the enhancement of PSII function, thereby conferring high salt tolerance. [ABSTRACT FROM AUTHOR]

It was established, that Harmala and Karelinia caspia possess ability increase immune response to sheep erythrocytes and titer antierythrocytes antibodies in peripheral blood, stimulated proliferation cells in central (thymus, bone morrow) and peripheral (lymph nodes) organs of immunity of mice radiation sickness. [ABSTRACT FROM AUTHOR]

Sunflower broomrape (Orobanche cumana Wallr.) is a holoparasitic plant species which mainly parasitizes a few species of the Asteraceae in the wild and is exclusively found growing on sunflower in agricultural fields (Fernández-Martínez et al. 2015). O. cumana is a serious threat to sunflower production in Xinjiang and Inner Mongolia (Shi et al. 2015). Karelinia caspia (Pall.) Less. (Asteraceae) is an ecologically important plant species occurring across the desert ecosystems of Russia, Central Asia, and northwest China. It plays an important role in reducing wind erosion and desertification (Xu et al. 2018). During the 2018 and 2019 growing seasons, sunflower broomrape was observed parasitizing K. caspia in non-cultivated areas adjacent to sunflower fields near Beitun city (87°51'E, 47°15'N) in Xinjiang, China. Sunflower broomrape plants were identified morphologically as O. cumana according to Pujadas-Salvà and Velasco (2000). The host plants were identified morphologically as K. caspia according to Lin et al (1979). The ribosomal DNA internal transcribed spacer (ITS) and the trnL-F region of the parasite were amplified by PCR using primer pairs ITS1/ITS4 and trnL-FF/trnL-FR, respectively (Taberlet et al. 1991; Anderson et al. 2004). The ITS sequence of the parasite (Accession No. MT795725.1) showed 100% identity (675bp out of 689bp) to that of O. cernua var. cumana (KC811228.1). The trnl-F sequence of the parasite (Accession No. ON843707) showed 98% identity (675 of 689 bp) to O.cernua var. cumana (KT387722.1). Multi-locus phylogenetic analysis of the two sequences showed clustering with sunflower broomrape. The ITS region of the parasite and host was were amplified by PCR using the primer pair ITS1F/ITS4R (Taberlet et al.1991), and the ITS sequences of the host (Accession No. MT791995.1) showed 99.86% identity (728bp of 802bp) to that of K. caspia (LN607483.1). Rhizotron and pot experiments were carried out to assess the parasitic relationship between O. cumana and K. caspia. In the rhizotron experiment, 2-week-old seedlings of K. caspia were inoculated with sterilized 400 O. cumana seeds in a 15-cm petri dish filled with a sponge overlaid with glass fiber filter paper. The parasitic state of O. cumana was observed 9 days after inoculation. In another trial, seeds of K. caspia were sowed in 2-L and 4-L pots containing sand-vermiculite-compost (1:1:1 v:v:v). These pots were artificially inoculated with 50 mg of O. cumana seeds per 1 kg of substrate. After 20 and 70 days, corresponding to the early parasitic and flowering stages, respectively, of O. cumana, K. caspia plants were uprooted from the media and washed carefully. The parasitic relationship was confirmed by the attachment position of the broomrape to the K. caspia root. To our knowledge, this is the first report of O. cumana parasitizing K. caspia in Xinjiang, China. This phenomenon means that sunflower broomrape can raise up seed on a newly recognized host. Weed eradication in and near sunflower fields is a key measure to control sunflower broomrape.

The halophyte Karelinia caspia has not only fodder and medical value but also can remediate saline-alkali soils. Our previous study showed that salt-secreting by salt glands is one of main adaptive strategies of K. caspia under high salinity. However, ROS scavenging, ion homeostasis, and photosynthetic characteristics responses to high salinity remain unclear in K. caspia . Here, physio-biochemical responses and gene expression associated with ROS scavenging and ions transport were tested in K. caspia subjected to 100-400 mM NaCl for 7 days. Results showed that both antioxidant enzymes (SOD, APX) activities and non-enzymatic antioxidants (chlorogenic acid, α-tocopherol, flavonoids, polyamines) contents were significantly enhanced, accompanied by up-regulating the related enzyme and non-enzymatic antioxidant synthesis gene ( KcCu/Zn-SOD , KcAPX6 , KcHCT, KcHPT1 , Kcγ-TMT, KcF3H , KcSAMS and KcSMS ) expression with increasing concentrations of NaCl. These responses are beneficial for removing excess ROS to maintain a stable level of H 2 O 2 and O 2 - without lipid peroxidation in the K. caspia response to high salt. Meanwhile, up-regulating expression of KcSOS1/2/3, KcNHX1, and KcAVP was linked to Na + compartmentalization into vacuoles or excretion through salt glands in K. caspia . Notably, salt can improve the function of PSII that facilitate net photosynthetic rates, which is helpful to growing normally in high saline. Overall, the findings suggested that ROS scavenging systems and Na + /K + transport synergistically contributed to redox equilibrium, ion homeostasis, and the enhancement of PSII function, thereby conferring high salt tolerance., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Li, Mur, Wang, Hou, Zhao, Chen, Wu and Guo.)

• Expression of KcSOS1 was induced and regulated by salt in the recretohalophyte Karelinia caspia. • KcSOS1 regulated Na+ transport to participate in salt secretion in K. caspia under salt stress. • KcSOS1 indirectly modulated K+ uptake/transport system in K. caspia exposed to salt stress. • These mechanisms maintain K+/Na+ homeostasis at the whole plant level in K. caspia. One of the most important adaptive strategies is the secretion by salt glands of excessive salt to the leaf surface to maintain K+/Na+ homeostasis in the recretohalophyte Karelinia caspia under high salt conditions. The plasma membrane Na+/H+ antiporter (SOS1) has been shown to be involved in Na+ transport and correlated with K+ nutrition in glycophytes. However, it remains unclear whether this adaptive strategy is associated with SOS1 in K. caspia. Here, we explored the possible role of KcSOS1. KcSOS1 was localized to the plasma membrane, and its expression was regulated and induced by salt. Expression of KcSOS1 in an Arabidopsis sos1 mutant restored its salt tolerance, indicating that KcSOS1 is a Na+ efflux protein. RNA interference was used to generate KcSOS1 -silenced-lines (KSLs) in K. caspia that the growth was severely affected by salt. Silencing KcSOS1 disrupted the Na+ transport system, resulting in decreased Na+ secretion rates in KSLs compared to that in wild-type in the presence of 200 mM NaCl. KSLs also displayed a decline in K+ accumulation resulting from low net K+ uptake into the root-xylem-sap. The expression of genes encoding proton pump, Na+ transporters or K+ channels linked to K+/Na+ homeostasis, including KcHKT1 , KcNHX1 and KcPHA , or KcAKT1 , KcAKT2 and KcSKOR , was downregulated in different tissues of KSLs. Overall, our findings suggest that KcSOS1 participates in the process of salt secretion by regulating the Na+ transport, and also indirectly modulates the K+ uptake/transport. These mechanisms maintain systemic K+/Na+ homeostasis to confer salt tolerance. [ABSTRACT FROM AUTHOR]