In a set of 14 dMt F₁'s, the six A-genome F₁'s (except dMt 4A) were of two types; type-1 had PMC's with 13''+t1t''' and type-2 had PMC's with 13''+t1t''' as well as 11"+1^IV+t1t''' (Table 1). Eight 6A dMt F₁'s were examined; five had 13''+t1t''' , two had 11''+111t^IV+t'' and one had 11''+t(1''')t^V. In contrast, each of the seven B- genome dMt F₁'s were of only type-1 having PMC's with 13''+t1t''' and no type 2 plants (Table 1). These results indicate that (a) the A-genome dMt F₁'s had a multivalent configuration that was absent in the B-genome dMt F₁'s, and (b) chromosome 6A was involved in a translocation that produced the quadrivalent configuration including telocentrics. Perhaps, (vent) durum plants used in crosses with the dDt's of the B-genome chromosomes did not have a 2A. 6A translocation chromosome and, therefore, did not produce a multivalent in the PMC's of F₁ plants. Five dMt 7B F₁'s were examined; four had 13"+t1t''' and one had 13''+t1t'''+tS' in which the short arm telo (tS) remained unpaired.

Of the 14 dMt F₁'s crossed to normal durum, 13 produced disomics (2n=28; 14'' or 12''+1^IV) and dMts (13''+t1t'''), while 1 (dMt2B) produced 21 plants having PMCs with 14'', 12''+1^IV, 13''+t1''+1', or 13''+1'+tS' but no dMt (Table 2), indicating that the female gametes having maternal chromosome 2B were transmitted. Thus, the scs^spt gene is located on chromosome 2B and female gametes without scs^spt did not function. However, one exceptional plant had a maternal telocentic 2BS (tS) that remained unpaired (in all 11 PMC's examined) with the paternal chromosome 2B from normal durum, indicating that tS was homoeologous to the short-arm of chromosome 2B of durum and did not pair with it. Therefore, chromosome 2B in (vent) durum consists of the long arm of chromosome 2B of durum and short-arm (tS) of 2B from Ae. speltoides. Additionally, the presence of two plants with 12''+t1t''', one from a cross with dMt 2A and one from a cross with dMt 6A, indicate that the (vent) durum line has a 2A.6A translocation chromosome (Table 2).

Of the 79 plants from a cross of dMt 1A F₁ to normal durum, 19 had 14'', 58 had 13''+t1t''' , one had 13''+t1t'' and 1 had 12''+1'''+t1t''', indicating that the 15-chromosome female gametes having telocentrics 1AL+1AS and 13 normal chromosomes had a functional advantage over those having 14 maternal chromosomes of normal durum (Table 2). Our explanation is that the telocentrics 1AL and 1AS in the (vent) dMt F₁ have certain gene(s) from the Chinese Spring double-ditelosomic 1A (CS-dDt 1A) that are not present in chromosome 1A of normal durum. The CS-dDt 1A is the progenitor of Langdon-dDt 1A (Joppa 1988). The residual CS gene(s) in Langdon dDt 1A may have improved nucleocytoplasmic compatibility and provided functional advantage to gametes carrying telocentic 1AL+ 1AS, because CS is fully compatible with (vent) cytoplasm (Maan 1975). However, of 41 plants from a cross* of dMt 2A to normal durum, 15 had 14'' or 12''+1^IV, 22 had 13''+t1t''' or 13''+t1'' indicating that the female gametes of dMt 2A F₁ carrying 14 normal chromosomes of durum functioned nearly as well as those with 13 normal durum chromosomes and 2AL+2AS telocentrics (Table 2).

The dMt 2A progeny included additional seven plants; one each with 13''+1'(from 13-chromosome female gamete) or 13''+1''' (showing a 6A.2A/2A.6A translocation configuration), or 9''+6'''+t1''+4' (from a 28- chromosome unreduced female gamete), respectively, fertilized by the 14-chromosome male gametes, and 14' or 12''+2t'' (a. haploid and diploid produced by apomixis, respectively), and 10"+2^IV, or 11''+2^IV (having 4 chromosomes in each translocation configuration) (Table 2). Similarly, dMt 1B produced two additional plants; one had PMC's with 12''+ 2t1'' (Table 2), indicating that an additional translocation involved chromosome 1B and another chromosome, and one having PMC's with 4''+t1''+18' (with reduced meiotic pairing), indicating that this plant had a deletion of the asynaptic gene in chromosome 3A. The gametocidal (Gc^spt) gene in the T2BL.2S may have produced plants with unexpected chromosome numbers and meiotic. configurations that resulted from chromosomal breakage and deletions, because scs^spt was hemizygous in the male-sterile plants with a T2A.6A. Also, certain genes producing apomixis and meiotic non-reduction may have been occasionally expressed in certain florets of (vent) scs^spt;- durum (Table 2).