Likepeople,plantsexperiencestress.Andalso,likepeople,theresponsetothatstresscandeterminesuccess.Badenvironmentalconditions,suchasdrought,flood,heatandotherstresses,affectyields(产量)morethancroppestsan
Likepeople,plantsexperiencestress.Andalso,likepeople,theresponsetothatstresscandeterminesuccess.
Badenvironmentalconditions,suchasdrought,flood,heatandotherstresses,affectyields(产量) morethancroppestsanddiseases.Wearetryingtofindawaytoequipplantswiththeabilitytotolerateenvironmentalstressandmaintainhighyields,saidStephenHowell,aprofessorofgeneticsandcellbiology.
Plantcellsproduceproteins (蛋白质) andshipthemtodifferentpartsofthecell.Undernormalconditions,theseproteinsarefoldedintotheirnormal,healthystructuresastheyareproduced.Whenaplantisunderstress,itscellsproducepoorlyfoldedorunfoldedproteins.Thenabuilt-insystemsensesthisand"setsoffanalarminthecell,"saidHowell.
Inresponsetothealarm,anotherprotein (IRE1)startsworkingandcreatesadifferentprocesswhichactivates (激活) thestressresponsegeneswhoseproductsbringaboutdefensivemeasuresthathelptheplantsurvive.
"Asitturnsout,responsesthatareactivatedunderstressconditionsactually inhibit thegrowthofplants,"saidHowell."Thisallowsthemtopreservetheirenergytosurvivethestressconditions."
Forplantsinthewild,thisresponseisahelpforsurvival,hesaid.Inproductionofagriculturecrops,however,thisresponsereducesyields.
"Youdon'twantcropplantstostopgrowing,"Howellsaid."Youwantthemtocontinuetogrowandproduceeventhoughtheyareunderstress."
Withthenewunderstandingofthisstressresponse,thenextstepmaybetosilencethealarmsystem,saidHowell."Whatmaybeimportantistodisablesomeofthesestressresponses.Thatmaymaketheplantmoreproductiveunderstressconditions."
28.Accordingtothetext,analarmintheplantcellsiscausedby___.
A.thefoldedproteins
B.thechangedproteins
C.thedefensivemeasures
D.thestressresponsegenes
29.Theenergypreservedintheplantsunderstressconditions___.
A.helpstheplantstosurvive
B.helpstomaintainhighyields
C.keepstheplantsgrowing
D.helpstoproducep