Combined full-length transcriptomic and metabolomic analysis reveals the regulatory mechanisms of adaptation to salt stress in asparagus.

Soil salinity is a very serious abiotic stressor that affects plant growth and threatens crop yield. Thus, it is important to explore the mechanisms of salt tolerance of plant and then to stabilize and improve crop yield. Asparagus is an important cash crop, but its salt tolerance mechanisms are largely unknown. Full-length transcriptomic and metabolomic analyses were performed on two asparagus genotypes: 'jx1502' (a salt-tolerant genotype) and 'gold crown' (a salt-sensitive genotype). Compared with the distilled water treatment (control), 877 and 1610 differentially expressed genes (DEGs) were identified in 'jx1502' and 'gold crown' under salt stress treatment, respectively, and 135 and 73 differentially accumulated metabolites (DAMs) were identified in 'jx1502' and 'gold crown' under salt stress treatment, respectively. DEGs related to ion transport, plant hormone response, and cell division and growth presented differential expression profiles between 'jx1502' and 'gold crown.' In 'jx1502,' 11 ion transport-related DEGs, 8 plant hormone response-related DEGs, and 12 cell division and growth-related DEGs were upregulated, while 7 ion transport-related DEGs, 4 plant hormone response-related DEGs, and 2 cell division and growth-related DEGs were downregulated. Interestingly, in 'gold crown,' 14 ion transport-related DEGs, 2 plant hormone response-related DEGs, and 6 cell division and growth-related DEGs were upregulated, while 45 ion transport-related DEGs, 13 plant hormone response-related DEGs, and 16 cell division and growth-related DEGs were downregulated. Genotype 'jx1502' can modulate K+/Na+ and water homeostasis and maintain a more constant transport system for nutrient uptake and distribution than 'gold crown' under salt stress. Genotype 'jx1502' strengthened the response to auxin (IAA), as well as cell division and growth for root remodeling and thus salt tolerance. Therefore, the integration analysis of transcriptomic and metabolomic indicated that 'jx1502' enhanced sugar and amino acid metabolism for energy supply and osmotic regulatory substance accumulation to meet the demands of protective mechanisms against salt stress. This work contributed to reveal the underlying salt tolerance mechanism of asparagus at transcription and metabolism level and proposed new directions for asparagus variety improvement.

Comparative transcriptome analysis of the garden asparagus (Asparagus officinalis L.) reveals the molecular mechanism for growth with arbuscular mycorrhizal fungi under salinity stress.

Soil salinity is one of the most abiotic stress factors that severely affects the growth and development of many plants, which can ultimately threaten crop yield. Arbuscular mycorrhiza fungi (AMF) has been proven to be effective in mitigating salinity stress by symbiosis in many crops. Asparagus officinalis are perennial plants grown in saline-alkaline soil, however, limited information on their molecular mechanisms has restricted efficient application of AMF to garden asparagus under salinity stress. In this study, we conducted a transcriptome analysis on the leaves of garden asparagus to identify gene expression under salinity stress. Seedlings were grown in 4 treatments, including non-inoculated AMF using distilled water (NI), inoculated AMF using distilled water (AMF), non-inoculated with salinity stress (NI + S), and inoculated with salinity stress (AMF + S). A total of 6019 novel genes were obtained based on the reference-guided assembly of the garden asparagus transcriptome. Results revealed that 455 differentially expressed genes (DEGs) were identified when comparing NI + S to AMF + S. However, among the up-regulated DEGs, 41 DEGs were down-regulated, while 242 DEGs had no differences in their expression levels when comparing NI to NI + S. These DEGs' expression patterns may be key induced by AMF under salinity stress. Additionally, the GO and KEGG enrichment analyses of 455 DEGs revealed that these genes mainly participate in the improvement of the internal environment in plant cells, nitrogen metabolic-related processes, and possible photoprotection mechanisms. These findings provide insight into enhanced salinity stress adaptation by AMF inoculation, as well as salt-tolerant candidate genes for further functional analyses.

[Toxicological effects of omethoate on leaf photosystem II of cole].

After spraying different concentrations of two brands pesticide omethoate on cole (Brassica campestris L.) leaves, the leaf chlorophyll a fluorescence transients were measured by a Plant Efficiency Analyzer (PEA), and the toxicological effects and rudimental dynamic courses of omethoate on the leaf photosystem II (PS II) were investigated by JIP-test. The results showed that after spraying omethoate except at the concentration of 0.50% , the maximal efficiency of photochemistry (F(v)/F(m)) did not have a remarkable change. However, with increasing omethoate concentration, the minimal fluorescence F(o), maximal fluorescence F(m), relative variable fluorescence at the J-step (V(J)), and electron transport flux perreactive center in PS II (ET(o)/RC) increased remarkably, but psi(o), the efficiency that a trapped exciton in PS ]I moved an electron into the electron transport chain beyond Q(A)-, decreased remarkably. The test two brands of pesticide omethoate had almost alike effects on the PS II of cole, and the residual effect of the pesticide was the strongest at the third day after spraying and petered out from the ninth to twelfth day. The main targets of omethoate on the PS II of cole could be listed as promoting the reduction from Q(A) to Q(A) (-) (increasing of V(J)) and the electron transmission from Q(A) (-) to Q(B) (increasing of ET(o)/RC).