Timing of events in crown-gall tumor development on pinto bean leaves☆

[摘要] TumorsinitiatedonprimaryPintobeanleavesbyAgrobacteriumtumefaciensmaybecountedasearlyas48hoursafterinoculation.Thenumberoftumorsperleafincreaseslinearlyuntilday7or8andbyday9iscomplete.Tumorgrowth(logarithmofmeantumordiameter)showsanapproximateparallelrelationtotumorappearance,diminishingafterday8toone-fifththeoriginalgrowthrate.Tumorsappearingearlyorlateexhibitsimilargrowthcurves;thedecreaseingrowthrate,however,occursatsmallertumorsizes,thelaterthetumorisfirstobservedontheleaf.Thenumberofplantcellsinitiallyparticipatingintumorformationmaybeestimatedfromthesedatatobe9cellsfortheaveragetumor.Infectedleavesaremostsensitivetotheinhibitionoftumorformationbyelevatedtemperaturetreatmentswhenthetreatmentsareapplied9–10hoursafterinoculationandarecompletelyresistantafter42hours.Conversionofhalfthepotentialtumorsitestotumorsitesmaytakeplacewithin12hoursafterinoculation,andby42hoursallpotentialsitesareconverted.Aportionofthesetumorsmaybeinitiatedimmediatelyafterinoculation.ThenumberofviableA.tumefacienscellsrecoverablefrominoculatedleavesdecreasestolessthan1%oftheoriginalinoculumwithinthefirstdayfollowinginfection.Aminimumof104to105bacteriaperleafisreachedat4–6daysafterinoculation.Ontheaverage,thereareabout1500bacteriaatthisminimumpointpertumorinitiated.Thenumberofrecoverablebacteriaisnotobviouslyrelatedtotumorformation.

[学科分类] 生物科学（综合）