▁the ▁D ▁ring ▁is ▁quite ▁constant ▁across ▁the ▁different ▁species , ▁which ▁led ▁research ers ▁to ▁suspect ▁that ▁the ▁bi ological ▁activity ▁re lies ▁on ▁this ▁part ▁of ▁the ▁mole c ule . ▁D ifferent ▁studies ▁have ▁demonstrated ▁that ▁the ▁activity ▁of ▁the ▁mole cules ▁is ▁lost ▁when ▁the ▁C - D ▁section ▁of ▁the ▁mole cules ▁is ▁modified . ▁ ▁Since ▁str ig ol act ones ▁are ▁involved ▁in ▁the ▁signal ing ▁path way ▁required ▁for ▁germ ination ▁of ▁par as it ic ▁species ▁( such ▁as ▁Str iga ▁sp .), ▁they ▁have ▁been ▁a ▁proposed ▁target ▁to ▁control ▁p ests ▁and ▁over g row th ▁of ▁these ▁par as it ic ▁organ ism . ▁Using ▁a ▁mole c ule ▁similar ▁to ▁str ig ol act ones ▁could ▁be ▁the ▁key ▁to ▁design ing ▁a ▁chemical ▁and ▁bi ological ▁mechanism ▁to ▁stop ▁the ▁colon ization ▁of ▁av plant ' s ▁root ▁by ▁par as it ic ▁plants . ▁ ▁Disc overy ▁ ▁Germ ination ▁of ▁par as it ic ▁plant ▁▁ ▁Str ig ol act ones ▁were ▁first ▁isolated ▁in ▁ 1 9 6 6 ▁from ▁cot ton ▁plants , ▁specifically ▁from ▁the ▁roots . ▁However ▁its ▁role ▁in ▁germ ination ▁of ▁other ▁organ isms ▁was ▁not ▁determined ▁until ▁later . ▁Pre vious ▁studies ▁with ▁Str iga ▁l ute a ▁had ▁already ▁shown ▁that ▁root ▁extract s ▁from ▁the ▁host ▁plants ▁were ▁necessary ▁for ▁the ▁par as it ic ▁seed ▁to ▁start ▁germ in ating , ▁which ▁made ▁obvious ▁that ▁a ▁subst