Flowering in Pisum: A Fifth Locus, Veg

In addition to the known loci, If, e, sn and hr, a fifth locus,veg, is shown to control flowering in peas. Regardless of thegenotype for the other flowering genes, plants homozygous forthe gene veg did not initiate flower buds under a wide rangeof photoperiod and temperature regimes, including those normallyhighly promotory in peas. Treatment with various plant growthsubstances and grafting to stocks known to promote floweringalso failed to cause initiation. Gene veg prevented expressionof allelic differences at the If locus but segregation for allelesat the sn and hr loci was clearly visible by examination ofseveral vegetative characteristics. For example, sn hr veg andSn hr veg plants showed an opening of the apical bud, productionof lateral branches, and a reduction in growth rate, leafletsize, internode length and stem thickness at approx the sametime as sn hr Veg and Sn hr Veg plants carrying the Lf allelecommenced fruit production, respectively. The graft-transmissibleinhibitor controlled by gene Sn is therefore not specific forthe transition from vegetative to reproductive growth. Geneveg allows the processes leading to apical and foliar senescenceto be examined independently of any effect of flowering andfruiting. We found that gene Sn influenced the total numberof leaves expanded in veg plants but not the time of shoot senescence,which, in plants without flowers and fruits appeared to resultfrom failure of the root system. Pisum sativum L., garden pea, flowering, senescence, genetics