EVIDENCE FROM A MAIZE DESYNAPTIC MUTANT POINTS TO A PROBABLE ROLE OF SYNAPTONEMAL COMPLEX CENTRAL REGION COMPONENTS IN PROVISION FOR SUBSEQUENT CHIASMA MAINTENANCE
Mp. Maguire et al., EVIDENCE FROM A MAIZE DESYNAPTIC MUTANT POINTS TO A PROBABLE ROLE OF SYNAPTONEMAL COMPLEX CENTRAL REGION COMPONENTS IN PROVISION FOR SUBSEQUENT CHIASMA MAINTENANCE, Genome, 36(5), 1993, pp. 797-807
Homozygotes for the dsy1 desynaptic mutant of maize show massive failu
re of chiasma maintenance during diplotene and diakinesis. Although so
me chiasmata persist until anaphase I in most microsporocytes expressi
ng this mutant, homozygotes are completely or nearly, completely steri
le, owing apparently to disjunctive irregularities. Pachytene synaptic
errors and some synaptic failure also are found, but recombination no
dules are common in homologously synapsed regions, and equational sepa
ration of a heterozygous knob into univalents or open arms at diakines
is clearly demonstrates that chiasma failure occurs following crossing
-over. A wider than normal synaptonemal complex central region and uni
form apparent weakness of central region cross connections to spreadin
g procedures strongly suggest the presence of a genetic lesion in a sy
naptonemal complex central region component. The dsy1 mutant may provi
de an especially important source of material for molecular studies on
the nature of chiasma maintenance mechanism.