CF-9 (Q40235) curation notes

Solanum pimpinellifolium Cf-9 (Hcr9-9C), receptor-like protein recognising the
Fulvia fulva (Cladosporium fulvum) effector AVR9 (partner of genes/FULFL/AVR9).

Sources used

• UniProt Q40235, GOA (10 rows), CF-9-deep-research-falcon.md, cached PMIDs.
• Newly cached: PMID:10758503, 11226184, 26765243, 15131698 (retracted), 31310343 (retraction notice).

Key findings

• Gene identity and resistance: PMID:7973631
• Plasma membrane, glycosylated: PMID:10758503
• Specificity in central LRRs: PMID:11226184
• Ectodomain structure-function (66 mutants): PMID:15722474
• Cytosolic tail: PMID:26315781
• Co-receptor: PMID:26765243 SOBIR1 association data (PMID:23716655) were mainly shown for Cf-4/Ve1; not asserted for Cf-9 here.
• Direct binding unresolved: PMID:12239406
• Natural variation: PMID:11517316

CITRX caution

The IPI protein-binding row (CITRX, Q9LKW0; PMID:26315781, Y2H) traces back to
PMID:15131698, retracted 2019: PMID:31310343.
The falcon deep-research file still presents CITRX as a negative regulator; disregarded.

Decisions

• protein binding (IPI) -> REMOVE (uninformative; partner chloroplastic).
• defense response to fungus x7 -> ACCEPT (Cf-9 is the receptor initiating the defence; participation, not just necessity).
• plasma membrane IEA -> ACCEPT. response to molecule of fungal origin IEP -> KEEP_AS_NON_CORE.
• NEW: GO:0140376 innate immune receptor activity and GO:0002768 immune response-regulating
  cell surface receptor signaling pathway. Comparator: Cf-4 (O50025) carries both in GOA (EXP).
  GO:0140376 chosen over pattern recognition receptor activity / binding terms because
  AVR9 is a race-specific effector, not a PAMP, and direct binding is unproven.

Project curation question 3 (necessity vs participation)

Unlike MLO/PEN-type genes, Cf-9's defence-to-fungus rows are justified: the protein
performs the perception step. The mechanistic term (cell-surface receptor signalling)
was added as NEW and placed in core_functions.