Plant Cell Reports最新文献

Key message: Embryo abortion at the heart-shaped stage is the main reason for the failure of interspecific hybridization of hydrangea, and salicylic acid plays a key role during embryo abortion. Difficulties in obtaining seeds from interspecific hybridization between Hydrangea macrophylla and H. arborescens had severely restricted the process of breeding new hydrangea varieties. To clarify the cause of reproductive barriers, an interspecific hybridization was made between H. macrophylla 'Endless Summer' (female parent) and H. arborescens 'Annabelle' (male parent). The results showed that both parents' floral organs developed normally, 'Annabelle' had high pollen viability (84.83% at 8 h after incubation), and the pollen tube could enter into the ovule of 'Endless Summer' at 72 h after pollination. Therefore, the pre-fertilization barrier was not the main reason for the failure of interspecific hybridization. However, observation of the embryo development by paraffin sections showed that the embryo was aborted at the heart-shaped stage. In addition, salicylic acid (SA) content was significantly higher (fourfold, P < 0.01) at 21 days after pollination (DAP) as compared to that of 17 DAP, which means SA may be closely correlated with embryo development. A total of 957 metabolites were detected, among which 78 were significantly different. During the embryo abortion, phenylpropanoids and polyketides were significantly down-regulated, while organic oxygen compounds were significantly up-regulated. Further analysis indicated that the metabolic pathway was enriched in the shikimic acid biosynthesis pathway, which suggests that more SA was synthesized. Taken together, it can be reasonably speculated that SA plays a key role leading to embryo abortion underlying the interspecific hybridization between Hydrangea macrophylla and H. arborescens. The result is helpful to direct the breeding of hydrangea through distant hybridization.

Key message: High-throughput next-generation sequencing of 161 olive germplas. 33 samples were selected as core olive germplasm and Fingerprints were constructed. After GWAS analysis of olive leaf shape, 14 candidate genes were localized. Olive (Olea europaea L.) has been introduced to China since the 1960s. After a prolonged period of variation and domestication, there is a lack of comprehensive research on its genetics. The olive oil directly extracted from Olea europaea L. is recognized as 'liquid gold', nevertheless, people constantly overlook the valuable wealth of olive leaves. High-throughput next-generation sequencing was performed on 161 olive germplasm to analyze the kinship, genetic structure and diversity of olives, and the core germplasm of olives were selected and fingerprints were constructed. Meanwhile, Genome-wide association analysis (GWAS) was performed to locate the gene for regulating olive leaf shape. Herein, the results parsed that most of the Chinese olive germplasm was more closely related to the Italian germplasm. A wealth of hybridized germplasm possessed high genetic diversity and had the potential to be used as superior parental material for olive germplasm. A total of 33 samples were selected and characterized as core germplasm of olive and Fingerprints were also constructed. A total of 14 candidate genes were localized after GWAS analysis of four olive leaf shape phenotypes, including leaf shape, leaf curvature shape, leaf tip and leaf base shape. Collectively, this study revealed the genetic basis of olives in China and also succeeded in constructing the core germplasm that stands for the genetic diversity of olives, which can contribute to the scientific and effective collection and preservation of olive germplasm resources, and provide a scientific basis for the in-depth excavation and utilization of genes regulating olive leaf shape.

Key message: The barley mutant xan-h.chli-1 shows phenotypic features, such as reduced leaf chlorophyll content and daily transpiration rate, typical of wild barley accessions and landraces adapted to arid climatic conditions. The pale green trait, i.e. reduced chlorophyll content, has been shown to increase the efficiency of photosynthesis and biomass accumulation when photosynthetic microorganisms and tobacco plants are cultivated at high densities. Here, we assess the effects of reducing leaf chlorophyll content in barley by altering the chlorophyll biosynthesis pathway (CBP). To this end, we have isolated and characterised the pale green barley mutant xan-h.chli-1, which carries a missense mutation in the Xan-h gene for subunit I of Mg-chelatase (HvCHLI), the first enzyme in the CBP. Intriguingly, xan-h.chli-1 is the only known viable homozygous mutant at the Xan-h locus in barley. The Arg298Lys amino-acid substitution in the ATP-binding cleft causes a slight decrease in HvCHLI protein abundance and a marked reduction in Mg-chelatase activity. Under controlled growth conditions, mutant plants display reduced accumulation of antenna and photosystem core subunits, together with reduced photosystem II yield relative to wild-type under moderate illumination, and consistently higher than wild-type levels at high light intensities. Moreover, the reduced content of leaf chlorophyll is associated with a stable reduction in daily transpiration rate, and slight decreases in total biomass accumulation and water-use efficiency, reminiscent of phenotypic features of wild barley accessions and landraces that thrive under arid climatic conditions.

Key message: Here, we systematically analyzed the potential fusion and fission events of neighboring genes in Arabidopsis genome and analyzed the influence on the protein targeting.

Key message: The study established split-root system (SRS) in foxtail millet, and identified the molecular regulatory mechanisms and metabolic pathways related to systemic nitrogen signaling based on this system and transcriptome analysis. The growth of crops is primarily constrained by the availability of nitrogen (N), an essential nutrient. Foxtail millet (Setaria italica L.) is a significant orphan crop known for its strong tolerance to barren conditions. Despite this, the signaling pathway of nitrogen in foxtail millet remains largely unexplored. Identifying the candidate genes responsible for nitrogen response in foxtail millet is crucial for enhancing its agricultural productivity. This study utilized the split-root system (SRS) in foxtail millet to uncover genes associated with Systemic Nitrogen Signaling (SNS). Transcriptome analysis of the SRS revealed 2158 differentially expressed genes (DEGs) implicated in SNS, including those involved in cytokinin synthesis, transcription factors, E3 ubiquitin ligase, and ROS metabolism. Silencing of SiIPT5 and SiATL31 genes through RNAi in transgenic plants resulted in reduced SNS response, indicating their role in the nitrogen signaling pathway of foxtail millet. Furthermore, the induction of ROS metabolism-related genes in response to KNO₃ of the split-root System (Sp.KNO₃) suggests a potential involvement of ROS signaling in the SNS of foxtail millet. Overall, this study sheds light on the molecular regulatory mechanisms and metabolic pathways of foxtail millet in relation to SNS.

Key message: Overexpression of ZmNAC19, a NAC transcription factor gene from maize, improves embryo development in transgenic Arabidopsis. NAC proteins are plant-specific transcription factors that are involved in multiple aspects of plant growth, development and stress response. Although functions of many NAC transcription factors have been elucidated, little is known about their roles in seed development. In this study, we report the function of a maize NAC transcription factor ZmNAC19 in seed development. ZmNAC19 is highly expressed in embryos of developing maize seeds. ZmNAC19 localizes to nucleus and exhibits transactivation activity in yeast cells. Overexpression of ZmNAC19 in Arabidopsis significantly increases seed size and seed yield. During 3 to 7 days after flowering, embryos of ZmNAC19-overexpression Arabidopsis lines developed faster compared to Col-0, while no visible differences were detected for their endosperms. Furthermore, overexpression of ZmNAC19 in Arabidopsis leads to increased transcription levels of two embryo development-related genes YUC1 and RGE1, and several elements proven to be binding sites of NAC transcription factors were observed in promoters of these two genes. Taken together, these results suggest that ZmNAC19 acts as a positive regulator in plant embryo development.

Key message: Two plant U-box E3 ligases, PUB5 and PUB44, antagonistically regulate the NLR receptor SUMM2-mediated autoimmunity in Arabidopsis, indicating a new regulatory mechanism for fine-tuning plant immunity.

Key message: Assembly of PUFA-attached TAGs is intimately correlated to turnover of newly formed membrane lipids in starch-deficient Chlamydomonas exposed to high light and nitrogen stress under air-aerated mixotrophic conditions. Triacylglycerols (TAGs) rich in polyunsaturated fatty acids (PUFAs) in microalgae have attracted extensive attention due to its promising application in nutraceuticals and other high-value compounds. Previous studies revealed that PUFAs accumulated in TAG primarily derived from the dominant membrane lipids, monogalactosyldiacylglycerolipid, digalactosyldiacylglycerol and diacylglycerol-N,N,N-trimethylhomoserine (DGTS), in the model alga Chlamydomonas reinhardtii. However, their respective contribution to PUFA-attached TAG integration has not been clearly deciphered, particularly in starchless Chlamydomonas that hyper-accumulates TAG. In this study, the starchless C. reinhardtii BAFJ5 was mixotrophically cultivated in photobioreactors aerated with air (0.04% CO₂), and we monitored the dynamic changes in growth, cellular carbon and nitrogen content, photosynthetic activity, biochemical compositions, and glycerolipid remodeling under high light and nitrogen starvation conditions. The results indicated that multiple PUFAs continually accumulated in total lipids and TAG, and the primary distributors of these PUFAs gradually shifted from membrane lipids to TAG in stress-induced BAFJ5. The stoichiometry analyses showed that the PUFA-attached TAG assembly attributed to turnover of not only the major glycerolipids, but also the phospholipids, phosphatidylethanolamine (PE) and phosphatidylglycerol. Specifically, the augmented C16:3n3 and C18:3n3 in TAG mainly originated from de novo-synthesized galactolipids, while the cumulative C18:3n6 and C18:4n3 in TAG were intimately correlated with conversion of the newly formed DGTS and PE. These findings emphasized significance of PUFA-attached TAG formation dependent on turnover of de novo assembled membrane lipids in starch-deficient Chlamydomonas, beneficial for enhanced production of value-added lipids in microalgae.

Key message: Enhanced recombinant protein expression was achieved in Salinas lettuce and commercial lettuce by designing a unique RNAi that knockdown the gene-silencing mechanism in transient assays. Improved yields of recombinant proteins (RP) are necessary for protein-production efficiency and ease of purification. Achieving high yield in non-tobacco plants will enable diverse plants to be used as hosts in transient protein-expression systems. With improved protein yield, lettuce (Lactuca sativa) could take the lead as a plant host for RP production. Therefore, this study aimed to improve RP production in lettuce var. Salinas by designing a single RNA interference (RNAi) construct targeting LsRDR1 and LsRDR6 using the Tsukuba system vector. Two RNAi constructs, RNAi-1 and RNAi-2, targeting common regions of LsRDR1 and LsRDR6 with 75% and 76% similarity, respectively, were employed to evaluate simultaneous gene silencing. Quantitative transcription analysis demonstrated that both RNAi constructs effectively knocked down LsRDR6 and LsRDR1, but not LsRDR2, at both 3 and 5 days post-infiltration (dpi), with RNAi-1 exhibited slightly higher efficiency. Based on the protein yield, co-expression of RNAi-1 with enhanced green fluorescent protein (EGFP) increased EGFP expression by approximately 4.9-fold and 3.7-fold at 3 dpi and 5 dpi, respectively, compared to control. A similar but slightly lower increase (2.4-fold and 2.33-fold) was observed in commercial lettuce at 3 and 5 dpi, respectively. To confirm these results, co-infiltration with Bet v 1, a major allergen from birch pollen, resulted in a 2.5-fold increase in expression in Salinas lettuce at 5 dpi. This study marks a significant advancement in enhancing transient protein production in lettuce, elevating its potential as a host for recombinant protein production.