Generation of New Salt-Tolerant Wheat Lines and Transcriptomic Exploration of the Responsive Genes to Ethylene and Salt Stress

Abstract

Background: Wheat (Triticum aestivum L.) is a staple crop in the world, but is only moderately salt tolerant. However, salt stress affects one-fifth of irrigated agricultural land in the world, it is of great importance to cultivate salt-tolerant varieties to improve the global wheat production. Results: In this study, over 90,000 wheat seeds of cultivar ‘Luyuan502’ were mutated by EMS, and 2000 salt-tolerant lines were harvested from salinized field. By analysis of ethylene sensitivity, salt related physiological factors, and preliminary crop yield, 12 salt-tolerant wheat lines with high production were selected among the crop plants. Transcriptome analysis indicated that a large number of the transcripts levels were significantly altered, mainly based on antenna proteins involved in photosynthesis, biosynthesis of secondary metabolites, cyanoamino acid metabolism, carotenoid biosynthesis, thiamine metabolism, and cutin, suberine and wax biosynthesis pathways including CABs, PERs/PODs, BGLUs, CYP707s, and ZEPs. qRT-PCR analysis revealed that the expressions of salt-related genes in the wheat lines were mostly higher than the wild type, and salt stress can significantly increase the expression levels of the ethylene-related genes in the wheat lines. Based on transcriptomic data, nine novel wheat ERFs were identified and analyzed, and it is suggested that they may play important roles in mediation of ethylene response and salt tolerance.Conclusion: Salt-tolerant wheat mutant lines with ethylene insensitivity were obtained from screen of a wheat EMS-mutagenized pool. Transcriptome data showed that the mutant plants exhibit significant alterations in the antenna proteins involved in various biological processes. Expression analysis suggests that ERFs may mediate ethylene response and salt tolerance of the wheat lines.

Generation of the wheat mutants with high iron (Fe) and expression analysis of the responsive genes involved in iron accumulation and ethylene response

“…To generate stress-tolerant wheat plants, the bread wheat cultivar 'Luyuan502' was mutagenized by EMS as previously described (Ma, et al 2021). In brief, the EMS-mutagenized seeds were sown, grown and screened in a saline-alkali soil eld (0.3% -0.7% salinity).…”

“…Among them, the salt tolerant wheat lines were selected for further study mainly based on their increased yields by 20% -30% in the M 2 -M 5 generations (Ma et al 2021). Next, the iron contents of the salt tolerant wheat mutant lines were measured.…”

“…We examined the ethylene sensitivity of the wheat mutant seedlings with high iron. As previously described (Ma et al 2021), the wheat seeds were soaked and cultivated in the petri dish supplemented with the ethylene precursor ACC at different concentrations (0, 100, 200, 300, and 400 µM) for 48 h, and the longest seedling root lengths were measured. As shown in Figure 4, the seedling root lengths were decreased as ACC concentration increased.…”

“…Expression pro les of ethylene responsive genes in the wheat mutant lines with high iron Ethylene sensitivity alteration of the wheat mutant seedlings prompted us to investigate the change of transcript levels among the ethylene signaling-associated genes in the wheat mutant lines. The wheat ETHYLENE RESPONSE FACTOR (ERF) genes (TaERF1, 2, 3, 4 and 6) were chosen for examination of their transcript levels when treated with ACC as previously described (Ma et al 2021), and the results indicated that transcript levels of the TaERFs were rapidly increased and peaked at 6 h, after then they decreased at 12 h in the wild type (LY502) (Fig. 5).…”

“…Previously, we used EMS (ethylmethylsulfonate) mutagenesis to generate a mutant library from the popular wheat variety 'Luyuan 502' in China (Ma et al 2021). By screen of the mutant plants, a number of salt-tolerant lines with high crop yield were obtained from the study.…”