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IntroductionSoil salinity–alkalinity has emerged as a global problem affecting many ecosystems, including grassland. Plants evolve into different ecotypes to adapt to various environments. Leymus chinensis widely distributed in the eastern Eurasian steppe, has evolved into two main ecotypes: yellow–green(YG) and gray–green (GG). Studies on the adaption mechanisms of both ecotypes in response to saline–alkaline stress are limited.MethodsIn this study, the growth and physiological traits of ecotypes YG and GG in soils with different salinity–alkalinity levels—severe saline–alkaline soil (SS), moderate saline–alkaline soil (MS), and light saline–alkaline soil (LS)—were studied. After exposure to saline–alkaline stress for 15 months, the L. chinensis ecotypes exhibited significant differences in the growth characteristics.ResultsThe specific leaf area, individual tiller biomass, net photosynthetic rate, and potassium content of the two ecotypes under MS conditions were significantly higher than or similar to those under LS conditions. This indicates that L. chinensis showed a certain degree of tolerance to saline–alkaline environments under MS conditions. Saline–alkaline stress increased the tillers by 56% in GG and reduced them by 26% in YG, and did not alter the SLA and the number of individual tiller leaves of GG but reduced that of YG. Moreover, with increasing levels of saline–alkaline stress, ecotype GG exhibited an increase in net photosynthetic rate (Pn), while ecotype YG showed insignificant changes. Under SS, GG exhibited higher Pn and chlorophyll content than YG. Additionally, with the increase in the saline–alkaline stress level, the Na+ content increased, but GG exhibited a significantly lower Na+ content than YG. Conversely, the K+ and Ca2+ contents and the K+/Na+ and Ca2+/Na+ ratios decreased, but GG exhibited higher values than YG.DiscussionGG reduced Na+ by absorption by increasing tillers. Additionally, GG absorbed more K+ and Ca2+ ions, thereby maintaining higher K+/Na+ and Ca2+/Na+ ratios than YG under saline–alkaline stress. These adaptive strategies enable ecotype GG to grow and maintain normal physiological functions under high saline–alkaline stress. The findings of this study hold practical significance for enhancing the economic and ecological value of saline–alkaline grasslands.

Soil salinity is important abiotic stress affecting various ecosystems worldwide such as grassland. Distinct ecotypes often evolve within species by natural selection to facilitate adaptation to different types of environmental stress. Leymus chinensis is a perennial rhizomatous grass that is widely distributed in the eastern Eurasian steppe; it has two main ecotypes, namely, yellow-green (YG) and gray-green (GG), which differ in their strategy for coping with salinity stress. Few studies have examined the seed germination of the two ecotypes under salinity stress. In this study, the seed germination and seedling growth of two ecotypes of L. chinensis in response to different levels of salinity (NaCl) stress [0 (control), 20, 50, 100, and 200 mM] were examined. Then, ungerminated seeds were placed under normal conditions to evaluate seedling growth following exposure to salt stress (i.e., regermination). The germination percentage was significantly higher, and the mean germination time was significantly shorter in the GG ecotype than in the YG ecotype at all NaCl concentrations. As the salinity level increased, the radicle length of the two ecotypes decreased; however, GG had longer radicles and a higher number of radicles, even at 200 mM NaCl when no radicle protruding from the seed coat was detected in YG. The shoot length of GG was significantly longer than that of YG at all NaCl levels. After salinity stress was removed, the seed germination percentage increased as the original concentration of NaCl applied increased, but the total germination percentage did not significantly differ among NaCl concentrations. The total seed germination percentage of GG was approximately 80%, whereas that of the YG was approximately 20%. The seedling length of regerminated seeds for both GG and YG was similar. The thousand-grain weight of GG was significantly higher than that of YG. GG was more salt-tolerant than YG and might be better capable of surviving in harsher environments, suggesting that GG might be particularly useful for saline grassland restoration.

The reproductive characteristics of plants are likely affected by climate change e.g., changes in precipitation patterns and nitrogen deposition, but few studies have examined the effects of these ecological agents of selection on the seed yield and germination characteristics of perennial grasses. Here, we conducted a multiple-year pot experiment with Leymus chinensis, a common perennial grass in the eastern region of the Eurasian steppe zone, which was grown under three water treatments with and without nitrogen addition. The seed yield of L. chinensis increased with precipitation and was highest (7.0 g/pot) under 747 mm of precipitation with nitrogen addition (10.5 g/m2). Seed yield was positively correlated with heading number, tiller number, and grain number per spike, and the heading number was a critical factor affecting seed yield. Seed germination percentage and the time to obtain 50% germination were affected by environmental cues experienced by the mother plants.

BackgroundIt is well known that the clivus is composed of abundant cancellous bone and is often invaded by pituitary adenoma (PA), but the range of these cancellous bone corridors is unknown. In addition, we found that PA with clivus invasion is sometimes accompanied by petrous apex invasion, so we speculated that the petrous apex tumor originated from the clivus cancellous bone corridor. The aim of this study was to test this hypothesis by investigating the bony anatomy associated with PA with clival invasion and its clinical significance.MethodsTwenty-two cadaveric heads were used in the anatomical study to research the bony architecture of the clivus and petrous apex, including six injected specimens for microsurgical dissection and sixteen cadavers for epoxy sheet plastination. The surgical videos and outcomes of PA with clival invasion in our single center were also retrospectively reviewed.ResultsThe hypoglossal canal and internal acoustic meatus are composed of bone canals surrounded by cortical bone. The cancellous corridor within clivus starts from the sellar or sphenoid sinus floor and extends downward, bypassing the hypoglossal canal and finally reaching the occipital condyle and the medial edge of the jugular foramen. Interestingly, we found that the cancellous bone of the clivus was connected with that of the petrous apex through petroclival fissure extending to the medial margin of the internal acoustic meatus instead of a separating cortical bone between them as it should be. It is satisfactory that the anatomical outcomes of the cancellous corridor and the path of PA with clival invasion observed intraoperatively are completely consistent. In the retrospective cohort of 49 PA patients, the clival component was completely resected in 44 (89.8%), and only five (10.2%) patients in the early-stage had partial residual cases in the inferior clivus.ConclusionThe petrous apex invasion of PA is caused by the tumor invading the clivus and crossing the petroclival fissure along the cancellous bone corridor. PA invade the clivus along the cancellous bone corridor and can also cross the hypoglossal canal to the occipital condyle. This clival invasion pattern presented here deepens our understanding of the invasive characteristics of PA.