Xiangzheng Liao

Leymus chinensis is a typical clonal plant and dominant species in alkalized grasslands of northern China. It has been verified that clonal integration mediates alkali stress tolerance of this species via supporting mother ramets to daughter ramets, but the mechanisms remain poorly understood. In this study, we investigated physiological and transcriptomic responses of mother ramets and daughter ramets (integration and cutting) of L. chinensis under alkali stress, with a focus on the role of clonal integration in enhancing stress tolerance in daughter ramets. Physiological analyses revealed that under alkali stress, compared with cutting treatments, clonal integration enhanced photosynthetic capacity, reduced Na ⁺ accumulation, and maintained K ⁺ homeostasis in daughter ramets. In contrast, integrated mother ramets exhibited enhanced Na ⁺ toxicity, decreased photosynthesis, and increased oxidative damage, suggesting a resource reallocation strategy prioritizing daughter ramet survival. In addition, transcriptomic analyses elucidated the underlying molecular basis. Compared with control groups, alkali stress strongly enhanced the upregulation of 57 sugar metabolism and 19 glycolysis genes, 15 ion homeostasis genes, 100 ROS-scavenging-related genes (including 4CL , PAL , and POD ), and 26 ethylene signaling genes in integrated daughter ramets. Crucially, compared with their respective controls, these key genes remained unchanged or downregulated in cutting daughter ramets under alkali stress. This integration-driven activation systematically supported energy assimilation, stable Na ⁺ /K ⁺ balance, antioxidant defense, and stress alleviation. Collectively, these findings demonstrated that clonal integration in L. chinensis functions as a protective mechanism for daughter ramets under alkali stress through coordinated regulation of photosynthetic maintenance, ion homeostasis, antioxidant defense, and hormone signaling.

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), threatens global wheat production. Breeding resistant varieties is a key to disease control. In this study, 198 modern wheat varieties were phenotyped with the prevalent Pst races CYR33 and CYR34 at the seedling stage and with mixed Pst races at the adult-plant stage. Seven stable resistance varieties with infection type (IT) ≤ 2 and disease severity (DS) ≤ 20% were found, including five Chinese accessions (Zhengpinmai8, Zhengmai1860, Zhoumai36, Lantian36, and Chuanmai32), one USA accession (GA081628-13E16), and one Pakistani accession (Pa12). The genotyping applied a 55K wheat single-nucleotide polymorphism (SNP) array. A genome-wide association study (GWAS) identified 14 QTL using a significance threshold of p ≤ 0.001, which distributed on chromosomes 1B (4), 1D (2), 2B (4), 6B, 6D, 7B, and 7D (4 for CYR33, 7 for CYR34, 3 for mixed Pst races), explaining 6.04% to 18.32% of the phenotypic variance. Nine of these QTL were potentially novel, as they did not overlap with the previously reported Yr or QTL loci within a ±5.0 Mb interval (consistent with genome-wide LD decay). The haplotypes and resistance effects were evaluated to identify the favorable haplotype for each QTL. Candidate genes within the QTL regions were inferred based on their transcription levels following the stripe rust inoculation. These resistant varieties, QTL haplotypes, and favorable alleles will aid in wheat breeding for stripe rust resistance.

Climate change threatens major global crops including wheat of subtropical regions, especially during critical developmental stages. To address this concern, researchers try to identify exotic genetic diversity with pronounced stress tolerance or avoidance or find improved genotypes with optimal sowing time. Current research evaluated seven exotic Chinese wheat genotypes (MY4094, MY1617, MY1416, MY2914, MY1501, MY1419, and MY902) for yield and associated characters along with a local check variety (PS-15) under optimal (1st November), moderate (16th November), and late sowing times (1st December) during both years. The result revealed that delayed sowing reduced yield and yield components of the tested genotypes, including the local check. Genotype MY1617 performed best under optimal sowing in terms of grain yield and yield attributes, with a 5% increase over the local check. MY902 had the highest seed yield among late-sown genotypes. Correlation analysis showed that grain yield was positively correlated with grains per spike, days to anthesis, booting, and heading. The current study provides important information for wheat breeders to exploit exotic genetic materials under a diverse sowing window and develop genotypes with improved traits that may boost wheat growers’ production.

Temperature-sensitive genic male sterile (TGMS) line Beijing Sterility 366 (BS366) has been utilized in hybrid breeding for a long time, but the molecular mechanism underlying male sterility remains unclear. Expression arrays, small RNA, and degradome sequencing were used in this study to explore the potential role of miRNA in the cold-induced male sterility of BS366. Microspore observation showed defective cell plates in dyads and tetrads and shrunken microspores at the vacuolated stage. Differential regulation of Golgi vesicle transport, phragmoplast formation, sporopollenin biosynthesis, pollen exine formation, and lipid metabolism were observed between cold and control conditions. Pollen development was significantly represented in the 352 antagonistic miRNA-target pairs in the integrated analysis of miRNA and mRNA profiles. The specific cleavage of ARF17 and TIR1 by miR160 and miR393 were found in the cold-treated BS366 degradome, respectively. Thus, the cold-mediated miRNAs impaired cell plate formation through repression of Golgi vesicle transport and phragmoplast formation. The repressed expression of ARF17 and TIR1 impaired pollen exine formation. The results of this study will contribute to our understanding of the roles of miRNAs in male sterility in wheat.

The pollen fertility of photoperiod/temperature sensitive genic male sterile (P/TGMS) wheat is controlled by light and/or temperature. Circular RNA (circRNA) and long non-coding RNA (lncRNA) are known to participate in the development of anthers in plants, but their impact on male sterility in the P/TGMS line is not well understood. In this study, we carried out high-throughput sequencing to investigate the differential expression of lncRNAs and circRNAs and their biological functions in anthers of photo-thermosensitive genic male sterile (PTGMS) wheat line BS366-42L during the transition phase of male fertility under four different photoperiod and temperature treatments. Eight lncRNAs, 40 mRNAs and three circRNAs were screened out and thought as essential candidates that closely related to male sterility. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to predict the potential functions of differentially expressed RNAs. The results indicated that carbohydrate-related metabolism was important for male sterility in the wheat PTGMS line BS366-42L. lncRNA/circRNA-mRNA-miRNA (ceRNA) integrate networks were constructed to reflect their complex inner association with male sterility. Our study provides a systematic perspective on the potential function of RNAs in male fertility in PTGMS lines of wheat.