Revealing the genetic basis for stress-resistant traits in extremophile plants will yield important information for crop improvement. Zygophyllum xanthoxylum, an extant species of the ancient Mediterranean, is a succulent xerophyte that can maintain a favorable water status under desert habitats; however, the genetic basis of this adaptive trait is poorly understood. Furthermore, the phylogenetic position of Zygophyllales, to which Z. xanthoxylum belongs, remains controversial. In this study, we sequenced and assembled the chromosome-level genome of Z. xanthoxylum. Phylogenetic analysis showed that Zygophyllales and Myrtales form a separated taxon as a sister to the clade comprising fabids and malvids, clarifying the phylogenetic position of Zygophyllales at whole-genome scale. Analysis of genomic and transcriptomic data revealed multiple critical mechanisms underlying the efficient osmotic adjustment using Na⁺ and K⁺ as ‘cheap’ osmolytes that Z. xanthoxylum has evolved through the expansion and synchronized expression of genes encoding key transporters/channels and their regulators involved in Na⁺/K⁺ uptake, transport, and compartmentation. It is worth noting that ZxCNGC1; 1 (cyclic nucleotide-gated channels) and ZxCNGC1; 2 constituted a previously undiscovered energy-saving pathway for Na⁺ uptake. Meanwhile, the core genes involved in biosynthesis of cuticular wax also featured an expansion and up-regulated expression, contributing to the water retention capacity of Z. xanthoxylum under desert environments. Overall, these findings boost the understanding of evolutionary relationships of eudicots, illustrate the unique water retention mechanism in the succulent xerophyte that is distinct from glycophyte, and thus provide valuable genetic resources for the improvement of stress tolerance in crops and insights into the remediation of sodic lands.

Cultivated grasslands provide an important strategy for reducing pressure on degraded natural grasslands and increasing high-quality forage supply. However, how stand-age-related variation affects belowground–aboveground coordination and forage production in cultivated Leymus chinensis remains unclear. Here, we compared a natural L. chinensis stand (NL) with 3-, 4-, and 5-year-old cultivated ‘Zhongke No. 1’ stands by integrating plant trait measurements, biomass assessment, nutrient analysis, forage quality evaluation, correlation analysis, and structural equation modeling. (1) Compared with NL, cultivated stands generally showed greater vegetative growth and aboveground biomass, lower fiber concentrations, and higher soluble sugar concentration and relative feed value. (2) Root and aboveground traits exhibited distinct stand-age-related patterns, with the 3Y stand showing greater root exploration traits, the 4Y stand achieving the highest aboveground biomass (4.61 t/hm²), and the 5Y stand exhibiting greater root thickening and ramet density. (3) Carbon, nitrogen, and phosphorus concentrations varied among stand ages, indicating shifts in nutrient status during stand development. (4) Correlation analysis and PLS-SEM revealed that root architecture, nutrient status, and aboveground morphology were closely associated with forage yield and quality variation. These findings highlight the importance of stand-age-dependent belowground–aboveground coordination for optimizing the management and utilization of cultivated L. chinensis grasslands.

Low soil fertility caused by organic matter deficit severely restricts crop productivity in sandy lands. To investigate the effects of organic matter addition on plant yield and soil productivity in sandy areas, a two-factor randomized block field experiment was conducted using oat (Avena sativa) with five ratios (7:3, 3:2, 1:1, 2:3, 3:7; w:w) and five application rates (0, 5, 10, 15, and 20, t·ha⁻¹) of peat powder and fermented manure in the Horqin Sandy Land, which is a typical agro-pastoral ecotone in northern China. Application of combined peat powder and fermented manure significantly increased oat yield, and the fertilization rate exerted a stronger effect on oat yield than the mixing ratio of the two organic materials. Furthermore, organic fertilization significantly increased the relative abundances of microorganisms, improved soil C, N and P contents, and enhanced the activities of urease, invertase, and catalase. The combination of an application rate of 20 t·ha⁻¹ and a 3:2 peat-powder-to-fermented-manure ratio represents a promising fertilization regime among treatments tested for oat cultivation in this region, given its highest aboveground dry-matter yield. Collectively, these findings show that rational combined application of fermented manure and peat powder in sandy land can significantly increase soil enzyme activities and optimize soil nutrient stoichiometry, and is positively correlated with rhizosphere microbial community composition and oat yield.