▁domain ▁T A LE s ▁ ▁also ▁possess ▁a ▁number ▁of ▁conser ved ▁features ▁in ▁the ▁domains ▁fl ank ing ▁the ▁repe ats . ▁These ▁include ▁domains ▁for ▁type - III - secret ion , ▁nuclear ▁local ization ▁and ▁trans cription al ▁activation . ▁This ▁allows ▁T A LE s ▁to ▁carry ▁out ▁their ▁bi ological ▁role ▁as ▁effect or ▁prote ins ▁secret ed ▁into ▁host ▁plant ▁cells ▁to ▁activ ate ▁expression ▁of ▁specific ▁host ▁gen es . ▁ ▁D iversity ▁and ▁evolution ▁ ▁Wh ilst ▁the ▁R VD ▁positions ▁are ▁commonly ▁the ▁only ▁variable ▁positions ▁within ▁a ▁single ▁T A LE ▁repeat ▁array , ▁there ▁are ▁more ▁differences ▁when ▁comparing ▁repeat ▁arrays ▁of ▁different ▁T A LE s . ▁The ▁divers ity ▁of ▁T A LE s ▁across ▁the ▁X anth omon as ▁genus ▁is ▁considerable , ▁but ▁a ▁particularly ▁striking ▁finding ▁is ▁that ▁the ▁evolution ary ▁history ▁one ▁arriv es ▁at ▁by ▁comparing ▁repeat ▁compos itions ▁diff ers ▁from ▁that ▁found ▁when ▁comparing ▁non - repeat ▁sequences . ▁Re peat ▁arrays ▁of ▁T A LE s ▁are ▁thought ▁to ▁evol ve ▁rapidly , ▁with ▁a ▁number ▁of ▁recom bin atorial ▁processes ▁suggested ▁to ▁shape ▁repeat ▁array ▁evolution . ▁Re com bin ation ▁of ▁T A LE ▁repeat ▁arrays ▁has ▁been ▁demonstrated ▁in ▁a ▁forced - selection ▁experiment . ▁This ▁evolution ary ▁dynam ism ▁is ▁thought ▁to ▁be ▁made ▁possible ▁by ▁the ▁very ▁high ▁sequence ▁identity ▁of ▁T A LE ▁repe ats , ▁which ▁is ▁a ▁unique ▁feature ▁of ▁T A LE