Molecular Plant最新文献

Cold stress is one of the major abiotic stress factors affecting rice growth and development, leading to significant yield loss in the context of global climate change. Exploring natural variants that confer cold resistance and the underlying molecular mechanism responsible for this is the major strategy to breed cold tolerant rice varieties. Here, we show that the natural variations of a SIMILAR to RCD ONE (SRO) gene, OsSRO1c, confer cold tolerance in rice at both seedling and booting stages. OsSRO1c possesses intrinsic liquid-liquid phase separation ability in vivo and in vitro and recruits an AP2/ERF transcription factor and positive cold stress regulator, OsDREB2B, into its biomolecular condensates in the nucleus, resulting in elevated transcriptional activity of OsDREB2B. The OsSRO1c-OsDREB2B complex directly responds to low temperature through dynamic phase transitions and regulates key cold response genes, including COLD1. Furthermore, introgression of an elite haplotype of OsSRO1c into a cold susceptible indica rice significantly increases its cold resistance. Collectively, our work reveals a novel cold tolerance regulatory module in rice and provides promising genetic targets for molecular breeding of cold-tolerant rice varieties.

The optimal plant height is crucial in modern agriculture, influencing lodging resistance and facilitating mechanized crop production. Upland cotton (Gossypium hirsutum) is the most crucial fiber crop globally, but the knowledge of the genetic basis underlying plant height still needs to be discovered. Here we conducted a genome-wide association study (GWAS) to identify the major locus controlling plant height (PH1) in upland cotton. The locus encodes gibberellin 2-oxidase 1A (GhPH1), with a 1,133 bp-length structural variation (PAV^PH1) located approximately 16 kb upstream of it. The presence or absence of PAV^PH1 confers a differential expression of GhPH1, consequently leading to changes in plant height. Further analysis revealed that a gibberellin-regulating transcription factor (GhGARF) recognizes a specific 'CATTTG' motif on the GhPH1 promoter and PAV^PH1. This binding event down-regulates GhPH1, indicating that PAV^PH1 functions as a distant upstream silencer. Intriguingly, we found that the critical repressor of the strigolactone (SL) signaling pathway, DWARF53 (D53), directly interacts with GhGARF and inhibits its binding to targets. Moreover, our study uncovers a previously unrecognized GA-SL crosstalk mechanism mediated by the GhD53-GhGARF-GhPH1/PAV^PH1 module, crucial in regulating the plant height of upland cotton. These findings shed light on the genetic basis and gene interaction network underlying plant height and provide valuable insights for developing semi-dwarf cotton varieties through precise modulation of GhPH1 expression.

Root-knot nematodes (RKNs) are plant pests that infect the roots of host plants. Bacillus thuringiensis (Bt) nematicidal proteins exhibited toxicity to nematodes. However, the application of nematicidal proteins for plant protection is hampered by the lack of effective delivery systems in transgenic plants. In this study, we discovered the accumulation of leucoplasts (root plastids) in galls and RKN-induced giant cells. RKN infection causes the degradation of leucoplasts into small vesicle-like structures, which are responsible for delivering proteins to RKNs, as observed through confocal microscopy and immunoelectron microscopy. We showed that different-sized proteins from leucoplasts could be taken up by Meloidogyne incognita female. To further explore the potential applications of leucoplasts, we introduced the Bt crystal protein Cry5Ba2 into tobacco and tomato leucoplasts by fusing it with a transit peptide. The transgenic plants showed significant resistance to RKNs. Intriguingly, RKN females preferentially took up Cry5Ba2 protein when delivered through plastids rather than the cytosol. The decrease in progeny was positively correlated with the delivery efficiency of the nematicidal protein. In conclusion, this study offers new insights into the feeding behavior of RKNs and their ability to ingest leucoplast proteins, and demonstrates that root leucoplasts can be used for delivering nematicidal proteins, thereby offering a promising approach for nematode control.

Xenia, the phenomenon in which the pollen genotype directly affects the phenotypic characteristics of maternal tissues (i.e., fruit ripening), has applications in crop production and breeding. However, the underlying molecular mechanism has yet to be elucidated. Here, we investigated whether mobile mRNAs from the pollen affect the ripening and quality-related characteristics of the fruit using cross-pollination between distinct Malus domestica (apple) cultivars. We demonstrated that hundreds of mobile mRNAs originating from the seeds are delivered to the fruit. We found that the movement of one of these mRNAs, ACC oxidase 3 (MdACO3), is coordinated with fruit ripening. Salicylic acid treatment, which can cause plasmodesmal closure, blocks MdACO3 movement, indicating that MdACO3 transcripts may move through the plasmodesmata. To assess the role of mobile MdACO3 transcripts in apple fruit, we created MdACO3-GFP-expressing apple seeds using MdACO3-GFP-overexpressing pollen for pollination and showed that MdACO3 transcripts in the transgenic seeds move to the flesh, where they promote fruit ripening. Furthermore, we demonstrated that MdACO3 can be transported from the seeds to fruit in the fleshy-fruited species tomato and strawberry. These results underscore the potential of mobile mRNAs from seeds to influence fruit characteristics, providing an explanation for the xenia phenomenon. Notably, our findings highlight the feasibility of leveraging diverse pollen genomic resources, without resorting to genome editing, to improve fruit quality.

Steroidal glycoalkaloids (SGAs) are specialized metabolites produced by hundreds of Solanum species, including important vegetable crops such as tomato, potato, and eggplant. Although it has been known that SGAs play important roles in defense in plants and "anti-nutritional" effects (e.g., toxicity and bitterness) to humans, many of these molecules have documented anti-cancer, anti-microbial, anti-inflammatory, anti-viral, and anti-pyretic activities. Among these, α-solasonine and α-solamargine isolated from black nightshade (Solanum nigrum) are reported to have potent anti-tumor, anti-proliferative, and anti-inflammatory activities. Notably, α-solasonine and α-solamargine, along with the core steroidal aglycone solasodine, are the most widespread SGAs produced among the Solanum plants. However, it is still unknown how plants synthesize these bioactive steroidal molecules. Through comparative metabolomic-transcriptome-guided approach, biosynthetic logic, combinatorial expression in Nicotiana benthamiana, and functional recombinant enzyme assays, here we report the discovery of 12 enzymes from S. nigrum that converts the starting cholesterol precursor to solasodine aglycone, and the downstream α-solasonine, α-solamargine, and malonyl-solamargine SGA products. We further identified six enzymes from cultivated eggplant that catalyze the production of α-solasonine, α-solamargine, and malonyl-solamargine SGAs from solasodine aglycone via glycosylation and atypical malonylation decorations. Our work provides the gene tool box and platform for engineering the production of high-value, steroidal bioactive molecules in heterologous hosts using synthetic biology.