农学最新文献

Genome editing has the potential to enhance yield and quality traits of crops. However, standard genetic transformation methods are not always applicable to modern germplasm. To tackle this challenge in the widely cultivated variety Ligena of the oilseed crop camelina (Camelina sativa (L.) Crantz), an only recently established principle of adventitious shoot formation from immature zygotic embryos was employed to further improve its fatty acid profile. In this approach, the three subgenomic homeologs of the FATTY ACID ELONGASE 1 (FAE1) gene were subjected to targeted mutagenesis. To pre-validate the Cas9-interacting, target motif-specific guide (g)RNAs, a robust protoplast-based DNA transfection method was established. This assay demonstrated that the preselected gRNAs were capable of eliciting mutations across all three camelina FAE1 homeologs. Likewise, targeted mutagenesis was successful at the whole-plant level. Triple-homozygous fae1 knockout mutants were identified amongst a segregating generation M₃ family. Gas chromatography of lipid extracts from M₄ seeds revealed a significant increase in all unsaturated C18 fatty acids including the particularly valuable α-linolenic acid. This was accompanied by a near elimination of the C20 and C22 very long-chain fatty acids including the nutritionally problematic erucic acid. Altogether, we have developed camelina elite lines with two significantly improved properties of high relevance for a health-promoting human nutrition.

The jasmonate signaling pathway coordinates plant defenses and growth, thereby enhancing fitness in changing conditions. Jasmonate-mediated responses are triggered by the recognition of external signals via pattern recognition receptors (PRRs) located on the cell membrane. Following signal perception, cells rapidly activate jasmonic acid (JA) biosynthesis, resulting in the accumulation of the bioactive jasmonate, jasmonoyl-isoleucine (JA-Ile). In the nucleus, the coronatine insensitive 1–jasmonate-ZIM-domain (COI1–JAZ) complex recognizes JA-Ile and triggers JAZ ubiquitination and proteasomal degradation. Consequently, transcription factors (e.g., MYC2) bound by JAZ are released, enabling the activation and amplification of JA responses. In parallel to this activation, feedback regulation orchestrated by transcription factors terminates transcription, preventing overcommitment to JA signaling. In this review, we summarize recent advances in understanding JA signaling, emphasizing the connection between PRR activation and JA biosynthesis, and the feedback regulatory mechanisms that ensure precision and robustness of the JA signaling pathway. Finally, we discuss how these mechanistic insights can be leveraged to optimize JA signaling for crop genetic improvement.

GABA, a non-proteinogenic amino acid with anti-hypertensive properties, holds health-beneficial potential when enriched in crops. Previous studies have established that targeted disruption of the calmodulin-binding domain (CaMBD) of the tomato glutamate decarboxylase 3 (SlGAD3) enhances GABA biosynthesis. In this study, we used CRISPR/Cas9-mediated gene editing to precisely modify the CaMBD coding sequence of SlGAD3 in three elite tomato varieties (SFT1, SFT2, and SFT3). Under our experimental conditions, targeted editing of SlGAD3 led to substantial accumulation of GABA in all three varieties without compromising key agronomic traits such as fruit size and number. Although flowering was delayed in SFT2 and SFT3 mutants, SFT1 mutants had higher GABA levels but also maintained a wild-type flowering time. This result highlights the critical importance of selecting specific varieties, such as SFT1, to minimize pleiotropic effects. By identifying varieties that can accumulate high levels of GABA without major reductions in growth and yield potential, this work bridges a critical gap between plant metabolic-engineering research and practical applications in commercial crop-improvement programs.

Symbiotic nitrogen fixation (SNF) between legumes and rhizobia contributes to sustainable agriculture. In root nodules, infected cells (ICs) are the primary sites of rhizobial colonization and nitrogen fixation. However, the function of the neighboring uninfected cells (UCs) has received little attention and is poorly understood. In this study, we employed a symplastic tracing approach to elucidate the role of UCs in nutrient storage and transport within root nodules. We uncovered an extensive network of plasmodesmata connecting ICs and UCs, while direct IC–IC connections were absent. By artificially inducing callose deposition at plasmodesmata, we demonstrate that plasmodesmata permeability between ICs and UCs regulates nutrient import into ICs, thereby influencing nutrient homeostasis and the SNF ability of nodules. Furthermore, high nitrogen levels triggered callose deposition at plasmodesmata, restricting nutrient transport, which may represent one mechanism by which excessive nitrogen inhibits SNF. These findings provide insights into the regulatory mechanisms of SNF and underscore the crucial role of UCs in optimizing nitrogen fixation efficiency.