Flowering in Pisum: A Sixth Locus, Dne

A sixth major flowering gene, dne, is identified in the gardenpea (Pisum salivum L.). Linkage tests show dne is located onchromosome 3 near locus st. The ability to respond to photoperioddepends on the joint presence of the dominant genes Sn and Dnewhich together confer a long day habit. Genotypes Sn dne, snDne and sn dne are all essentially day-neutral although by examiningseveral flowering criteria under strictly controlled conditionssome small responses could be demonstrated. Like sn, dne reducedthe response to vernalization when substituted into genotypeSn Dne. It is suggested genes Sn and Dne both control steps in a biosyntheticpathway which leads to the production of a graft-transmissibleinhibitor of flowering and apical senescence. Stocks of genotypeSn dne and sn Dne promoted flowering in Sn Dne scions whileSn Dne stocks delayed flowering in Sn dne (and sn Dne) scions.However, reciprocal grafting between genotypes Sn dne and snDne gave no evidence of physiological complementarity correspondingto the genetic complementarity ofSn and Dne. Initial resultssuggest dne may be less effective than sn at blocking inhibitorproduction but this requires confirmation.