Plant Cell最新文献

Root rot, induced by Phytophthora medicaginis, causes devastating damage to perennial alfalfa (Medicago sativa). However, the mechanism by which P. medicaginis infects Medicago remains elusive. Here, we identified the VASCULAR HIGHWAY 1-INTERACTING KINASE (VIK)-ANKYRIN PROTEIN KINASE (APK)-ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1) pathway during P. medicaginis infection in Medicago truncatula. MtAPK is an autoimmune gene, and Mtapk-mediated autoimmunity depends on MtEDS1. P. medicaginis infection triggers MtVIK to phosphorylate Ser20 of MtAPK, enhancing the interaction between MtAPK and MtEDS1 in the cytoplasm and constraining the nuclear resistance of MtEDS1. Disease resistance could be enhanced not only by knocking out MtVIK but also by the Ser20Ala site mutation of MtAPK. Interestingly, we found that alfalfa germplasms with lower MsVIK expression after inoculation with P. medicaginis exhibited greater disease resistance. Furthermore, CRISPR/Cas9 editing of MsVIK mutants in alfalfa resulted in stronger disease resistance without growth or yield penalties. Taken together, VIK is a negative regulator of Medicago immunity and has significant potential for cultivating durable resistance in crops through genetic modification.

Maize (Zea mays L.) is the world's most productive grain crop and a cornerstone of global food supply. However, in temperate agricultural systems, maize exhibits 2 key anomalies. First, as a tropical species, maize cannot be planted in the cold conditions of early spring when light and natural soil nitrogen are available, resulting in a shorter growing season and creating a seasonal mismatch between nitrogen accessibility and demand. Second, maize kernel protein is a major nitrogen sink, driving fertilizer demand because of the scale of cultivation. This inefficient mismatch stems from modern maize's uses and the modest nutritional value of storage proteins. To address these anomalies, we established the Circular Economy that Reimagines Corn Agriculture initiative. Our vision requires advances in 3 research areas: (ⅰ) developing cold and frost tolerance during germination and early growth to enable the use of spring nitrogen and light resources; (ⅱ) reducing nitrogen allocation to grain by reducing low-quality storage proteins and developing alternative nitrogen sinks; and (ⅲ) stabilizing soil nitrogen by enhancing biological nitrification inhibition. We present blueprints for a nitrogen-efficient, cold-tolerant maize designed to utilize the full growing season, enabling farmers in temperate regions to fully leverage maize's C4 photosynthesis, reduce fertilizer inputs, increase yields, and minimize environmental impact.

Insulators are cis-regulatory elements that separate transcriptional units, whereas silencers are elements that repress transcription regardless of their position. In plants, these elements remain largely uncharacterized. Here, we use the massively parallel reporter assay Plant STARR-seq with short fragments of 8 large insulators to identify more than 100 fragments that block enhancer activity. The short fragments can be combined to generate more powerful insulators that abolish the capacity of the strong viral 35S enhancer to activate the 35S minimal promoter. Unexpectedly, when tested upstream of weak enhancers, these fragments act as silencers and repress transcription. Thus, these elements are capable of insulating or repressing transcription, depending on the regulatory context. We validate our findings in stable transgenic Arabidopsis thaliana, maize (Zea mays), and rice (Oryza sativa) plants. The short elements identified here should be useful building blocks for plant biotechnology.

In plants, embryo size is determined via interactions between metabolic and developmental signals. Maize (Zea mays) big embryo 6 (bige6) enhances embryo size while sharply reducing plant growth. Here, we show that BigE6 encodes a plastidial prephenate aminotransferase (PPA-AT), a key enzyme in the arogenate pathway for L-phenylalanine (Phe) and L-tyrosine (Tyr) biosynthesis. The maize BigE6 paralog, BigE6Like, encodes a cytosol-localized PPA-AT, revealing Phe and Tyr biosynthesis via cytosolic arogenate as a potential alternative to the known cytosolic phenylpyruvate pathway. Moreover, the single PPA-AT gene of Arabidopsis (Arabidopsis thaliana) encodes plastidial and cytosolic enzymes by alternative splicing. Transgenic rescue of a ppa-at mutant in Arabidopsis demonstrates that the plastidial PPA-AT is indispensable for seed formation due, in part, to its essential role in the female gametophyte. Leaves of bige6 maize maintained overall homeostasis for aromatic amino acids and downstream metabolites, revealing a resilience of mechanisms that scale growth to a limiting supply of Phe and Tyr. In bige6 seeds, broad perturbation of amino acid homeostasis is associated with transcriptomic upregulation of growth processes in the embryo and endosperm, implicating amino acid signaling in the regulation of embryo size. Our findings reveal the complexity and developmental dependence of growth responses to limiting amino acid biosynthesis.