L-Theanine is a health-beneficial tea-specific amino acid. This amino acid is synthesized through the catalytic action of L-theanine synthase or its isoenzymes, utilizing ethylamine and L-glutamic acid as primary substrates. As the rate-limiting substance, traditional ethylamine synthesis relies on tea root metabolism, and exploring new synthetic pathways can boost L-theanine production and explore environmental application values. Self-developed Tongji_Software was used to predict a potential pathway for ethylamine synthesis. A cell-free protein synthesis (CFPS) system was adopted for verification, and genome engineering was performed to construct a recombinant strain. According to the software predictions, atrazine chlorohydrolase (AtzA) and hydroxyatrazine deethylaminase (AtzB) could convert the herbicide atrazine into ethylamine. CFPS based on Pseudomonas knackmussii (P. knackmussii) produced 88.5 μM L-theanine within a 24-h period, while the engineered strain P. knackmussii-AtzAB yielded 445.7 μM with the conversion rate of 44.6% over 84 h of fermentation. In summary, we revealed a novel pathway for ethylamine synthesis, which can promote L-theanine accumulation in tea trees and degrade environmental pollutants.
S. Yu, J. Feng, G. Zhou et al.· Plant biology· 0 citations
Sugarcane (Saccharum spp.) is an important crop for food and energy security. Identifying SNPs and genes associated with sugarcane yield and related traits is crucial for developing high - yielding sugarcane cultivars through molecular breeding. Here, we measured nine phenotypic traits across 160 sugarcane genotypes and employed multiple statistical models (namely MLM, CMLM, MLMM, FarmCPU and SUPER) in GWAS to identify stable and pleiotropic loci. A total of 200 SNPs corresponding to 137 QTLs were detected to be significantly associated with nine traits using multiple statistical models, among which 18 QTLs were consistently identified by two or more models. Notably, the SNP S9A_47793177 on chromosome 9A showed the strongest association with phenotypic variation in aboveground biomass, with a phenotypic explanation rate of 70.54%. Additionally, several QTLs significantly associated with tillering - related traits were identified, suggesting that these QTLs may play crucial roles in the regulation of tillering. The QTLs and SNPs identified in this study provide a significant foundation for molecular marker - assisted breeding in sugarcane. This advancement can significantly enhance the efficiency of genetic improvement for sugarcane yield and tillering - related traits.
L. Zhang, C. Xu, J. Li et al.· Plant biology· 0 citations
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