Cai He

Drought stress caused by continuous global warming poses a severe challenge to the growth and development of Nitraria tangutorum. Abscisic acid has an important regulatory function in the process of plants responding to drought stress. This study took the N. tangutorum seedlings of Zhangye provenance 2-17-16 genealogy as the research object to explore the physiological mechanism of how different concentrations of exogenous ABA alleviate drought damage in N. tangutorum. The results showed that exogenous ABA could promote the growth and increase the leaf relative water content of N. tangutorum seedlings under drought stress. It alleviates the photosynthetic inhibition phenomenon of N. tangutorum seedlings under drought stress by regulating the photoprotective mechanism and energy distribution efficiency of photosystem II. It also alleviates the drought damage of N. tangutorum by increasing the content of osmotic-adjustment substance contents such as soluble sugar, soluble protein, proline, and starch, as well as enhancing the activity of antioxidant enzymes such as POD, SOD, and CAT. The comprehensive analysis showed that 20 μM and 30 μM ABA have the best alleviating effects on the drought damage of N. tangutorum seedlings. This study provides a theoretical basis for the restoration, propagation, and protection of N. tangutorum, and it is of great significance for maintaining the balance and stability of desert ecosystems.

Understanding the relationships between diversity and functional traits in plant communities is essential for elucidating ecosystem functions, forecasting community succession, and informing ecological restoration efforts in arid regions. Although the current research on plant functional traits and diversity has improved our ability to predict ecological functions, there are still many problems, such as how environmental changes affect the relationship between species diversity and plant functional traits, and how these interactions affect plant community functions. We examined the relationships among leaf and fine root functional traits, species diversity, and functional diversity at the community level, along with their environmental interpretations, in a plant community within the desert–oasis transition zone of the Hexi Corridor, where habitats are undergoing significant small-scale changes. During dune succession, plant community composition and diversity exhibited significant variation. Plants are adapted to environmental changes through synergistic combinations of above-ground and below-ground traits. Specifically, plants in fixed dunes adopted a “slow investment” strategy, while those in semi-fixed and mobile dunes employed a “fast investment” approach to resource acquisition. A strong coupling was observed between plant community functional traits and species diversity. Soil phosphorus content and compactness emerged as primary factors influencing differences in plant community functional traits and composition. These soil factors indirectly regulated fine root functional traits and diversity by affecting species diversity, thereby driving community succession. Our study elucidates the “soil—diversity—community functional trait” linkage mechanisms in the successional process of desert plants. This research provides scientific support for the restoring and reconstruction of degraded ecosystems in arid zones.

Pear (Pyrus spp.) is a globally important fruit crop, with China leading in the production and cultivation area. Pear dry blight, a destructive fungal disease, has emerged as a significant threat to pear orchards in Wuwei, Gansu Province, China. This study aimed to identify the causal pathogen, evaluate its pathogenicity, and assess the efficacy of commonly used fungicides. A total of 276 fungal isolates were obtained from symptomatic Pyrus bretschneideri stems and characterised through morphological and molecular analyses. Diaporthe fukushii was identified as the causal pathogen. Pathogenicity assays on Zaosu pear branches and Huangguan pear fruits resulted in 82% and 100% disease incidence, respectively, fulfilling Koch’s postulates. In vitro fungicide evaluations demonstrated that thiophanate-methyl and difenoconazole + propiconazole exhibited the strongest inhibitory effects, followed by mancozeb, metalaxyl-mancozeb, and carbendazim, whereas chloroisobromine cyanuric acid and dimethomorph were the least effective. These findings are critical for developing effective management strategies to mitigate the impact of pear dry blight on pear production.

The variation and correlation among desert plant traits are helpful to understanding the adaptation strategies of plants to the environment and the mechanism of community assembly. However, the diversity and covariation among fine root traits of desert plants and their phylogenetic relationships remain unclear. Principal component analysis, Pearson’s correlations, phylogenetic independent comparison, mixed linear model, and variance decomposition were used to investigate the variation and correlation among 10 fine root traits of 25 common desert plants in arid areas. The results are as follows: (1) We found that all fine root traits varied more among interspecific variation, with the coefficient of variation ranging from 21.83% to 105.79%. Most traits were predominantly shaped by interspecific variation, whereas root phosphorus content (RPC) and intraspecific variation in root carbon/nitrogen ratio (RCN) were more important. (2) Root traits were correlated with four axes of variation. Root nitrogen content (RNC) correlated positively with root diameter (AD) and tissue density (RTD) but negatively with specific root length (SRL), which was inconsistent with the inference of the root economics spectrum (RES). (3) Covariance and trade-off strategies of fine root traits in different life forms of plants were different. Herb RNC was negatively correlated with SRL and positively correlated with AD, while this relationship did not exist in shrubs. Moreover, shrub AD was negatively correlated with RTD, but herbs showed no significant correlation. (4) Influenced by phylogenetic factors, fine root traits exhibited a covariant or trade-off pattern. Taken together, fine root traits were predominantly shaped by interspecific variation, but intraspecific variation also played a significant role. Concurrently, distinct patterns in fine root covariation and trade-off strategies among different life forms of plants were also observed. Future studies should explore the variation and correlation among traits at different scales within and between species from the perspective of life form.

Drought-induced plant mortality, resulting from either hydraulic failure or carbon starvation, is hypothesized to be modulated by the drought intensity. However, there is a paucity of research investigating the response strategies in desert shrubs under drought stress with different intensities. We transplanted potted Reaumuria soongorica (Pall.) Maxim. and Salsola passerina Bunge seedlings in the rain-out shelter, and implemented three water treatments: a control (well-watered, CK), a chronic drought (gradually less watered, CD), and a flash drought (not watered, FD). We then quantified plant physiological traits associated with water use and carbon assimilation. Both R. soongorica and S. passerina showed similar changes in water use and carbon characteristics under different drought treatments. Water use efficiency was not significantly changed, but embolism resistance was significantly lower in CD, and leaf specific conductivity and embolism resistance were significantly lower in FD compared to CK. Under the drought treatment, both shrubs had significantly lower hydraulic safety margins than CK, with FD being significantly lower than CD. Notably, FD had lower carbon assimilation and a lower leaf non-structural carbon concentration, but higher stem non-structural carbon concentration. The results of a principal component analysis showed that net photosynthetic rate, sapwood specific conductivity, embolism resistance, midday water potential, and leaf and stem soluble sugar concentration were the main axes of variation for R. soongorica traits. CK had the highest water use efficiency, net photosynthetic rate, and gas exchange rate, while FD had the lowest embolism resistance and highest osmoregulation. Midday water potential, leaf and stem soluble sugar concentration were the main axes of variation for S. passerina traits, and individual distribution under three water treatments was associated with drought tolerance traits. The findings suggest that species exhibit different response strategies for resistance to drought stress, with R. soongorica being drought-avoidant and S. passerina being drought-tolerant. These findings highlight the adaptive capacity of desert shrubs to water deficit and provide insights for assessing hydraulic failure and carbon starvation in desert shrubs.

High temperature and drought are common environmental stresses that desert plants must withstand to grow and reproduce. In order to understand the resistance mechanisms of the desert plant Atraphaxis bracteata (A. Los) responding to natural high temperature and drought conditions, we combined physiological characteristics, transcriptome, and metabolome analysis to explore its responses in three different plant ages and CK. The results showed that most physiological indicators of A. bracteata increased with the age, except for SOD activity. There were 4 698, 7 594, and 8 485 differentially expressed genes (DEGs) and 119, 124, 188 differential expressed metabolites (DAMs) in the 3‐age‐old (T1), 5‐age‐old (T2) and 15‐age‐old (T3) plants compared to the CK, respectively. These DEGs were mainly enriched in plant hormone signal transduction, phenylpropanoid biosynthesis, AMPK signalling pathway, flavonoid biosynthesis, circadian rhythm‐plant pathways, glycine, serine, and threonine metabolism pathways. At the same time, the enriched DAMs were mainly involved in the aminoacyl‐tRNA biosynthesis pathway, arginine and proline metabolism pathway, flavonoid biosynthesis, and others. In addition, most DEGs involved in flavonoid biosynthesis, photosynthesis and plant hormones closely associated with abiotic stress were down‐regulated, and which numbers increased with age. Moreover, a higher number of DEGs and DAMs accumulated with age, which may be the key factor for the age‐dependent resistance of A. bracteata to abiotic stress. Therefore, these results could provide a way to better understand the stress resistance mechanism and provide a reference for further exploitation and utilization of A. bracteata.

Hydraulic traits are essential functional characteristics of plants related to water absorption, transport, and loss, serving as indicators of a plant’s adaptability to prevailing environmental water conditions. However, the hydraulic traits of shrub, particularly desert plants in arid and semi-arid regions, have been underexplored. In this study, we conducted a pot experiment using Caroxylon passerinum (Bunge) Akhani and Roalson as the subject. Three treatment groups were established: adequate water supply, mild drought, and severe drought. After subjecting the shrub to drought and subsequent rehydration, we measured hydraulic conductivity, net photosynthetic rate, and stomatal conductance. We found that leaf water potential decreased and stomatal conductance and net photosynthesis decreased with increasing drought intensity. We found that leaf water potential and stomatal conductance decreased with increasing drought intensity. Although there was no significant change in hydraulic conductivity in the two drought groups, the values were greater in the drought group than in the control, and greater in the mild drought group than in the severe drought group. Meanwhile, the embolism resistance decreased with increasing drought intensity. After rehydration, hydraulic conductivity did not return to control levels in the severe drought group, as did embolism resistance in the two drought groups, and leaf water potential did not recover significantly. The results showed that drought stress increased the hydraulic conductivity of C. passerinum, and this effect was more pronounced under mild drought stress. After the stress was lifted, C. passerinum continued to maintain a lower leaf water potential to promote water uptake. This result provides a reference for us to study water use of desert shrubs under different drought stresses.