Plant surface immune receptors are tightly controlled to maintain homeostasis and prevent overactivation. However, the mechanisms coordinating the balance remain largely unknown. The monocot-specific receptor-like kinase SDS2 regulates cell death and immunity in rice. Here, we identify Thr671, a conserved phospho-switch in RD-type Ser/Thr kinases across kingdoms, as the central node that orchestrates both immune activation and turnover of SDS2. Autophosphorylation of Thr671 initiates signaling but also primes SDS2 for ubiquitination and degradation by the E3 ligase SPL11. This degradation is antagonized by the phosphatase SIPP1, which stabilizes SDS2 through Thr671 dephosphorylation to promote immunity. Strikingly, a second phosphatase, SIPP2, displaces SIPP1 from SDS2 via competitive binding, thereby enabling SPL11-dependent SDS2 degradation and ensuring timely immune attenuation. Thus, the SIPP1-SPL11-SIPP2 module establishes a dynamic equilibrium essential for SDS2 homeostasis, providing new insights into the sophisticated regulation of surface receptors.
Pseudotaxus chienii
, the only species in the genus
Pseudotaxus
, is closely related to
Taxus
genus. Whether
P. chienii
can produce paclitaxel has long remained controversial. Here, we present a chromosome-level, haplotype-resolved genome of
P. chienii
, with each haplotype ( ~ 15.4 Gb) exhibiting high continuity and completeness. We identify a structurally conserved yet physically dispersed genomic region, termed the Taxane Biosynthetic Archipelago (TBA), containing three biosynthetic gene clusters and collinear core genes essential for taxane biosynthesis. Integrative transcriptomic, metabolite, and heterologous enzymatic analyses reveal that while
P. chienii
retains a largely conserved genomic architecture associated with paclitaxel biosynthesis, its terminal pathway shows severe functional degradation and may have largely lost the functional capacity for paclitaxel production. Concurrently, it exhibits significant accumulation of taxinine J. This study provides an evolutionary framework for interpreting the long-standing debate on paclitaxel production beyond
Taxus
, and understanding the evolutionary decay of complex specialized pathways.
Huan Wang, Hai-Dong Chen, Ya-Ping Sun et al.· Nature Communications· 0 citations
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