Chromosomes and Compatibility in the Aloinae

Meiosis and Pollen Mitosis in <i>Aloe barbadensis</i> Mill. (<i>A. perfoliata</i> var. <i>vera</i> L., <i>A. vera Auth</i>. non Mill.)

“…26). Secondary constrictions or satellites have not been recorded in this species, supporting Marshak (1934), though their presence has been noted in other species of Aloe; A. arborescens (Taylor 1925, Heitz 1931, A. saponaria (Taylor 1925) and A. spuria (Sato 1937(Sato , 1942. The writer finds that pollen mitotic studies reveal chromosome morphology so well (Fig.…”

“…The origin of bimodal karyotype of the Aloinae is explained (Stebbins 1971) by increasing asymmetry and heterogeneity plus the addition of a chromosome to the complement through fixation of a centric fragment. Marshak (1934) scanning of a large number of clear metaphase plates in the first division of micro spore nucleus showed bimodal nature of the karyotype and an average of seven well-spread metaphasic complements revealed four long and three short chromo somes (Fig. 26).…”

Karyotype of Aloe barbadensis Mill.: A reinvestigation.

“…Also, one of the small chromosomes is shown by him to be metacentric. As is clear from Marshak (1934) and Vig (1968), who have studied root tip cells, and Sapre (1975), who has studied pollen-mitosis, have not recorded any satellite in this species. However, repeated observations and staining in Feulgen revealed satellites on the long arms of two long chromosomes, the L1 and the L4.…”

“…L4 is the shortest overall, while L3 is slightly longer in its shorter arm compared to L4. The four long chromosomes vary only slightly in their total length and do not warrant any classification as 3 large and one inter mediate as has been done by either Marshak (1934) or Vig (1968).…”

“…However, employing Adhikary's method (1974) for precise determination of cen tromere, it is observed that the L1 is nearly submedian (L/S ratio=2.6), L2, L3 and L4 are nearly subterminal ((L/S ratios=4.5, 4.3 and 5.2, repectively), S1 is nearly submedian (L/S ratio=1.7) and S2 and S3 are nearly median (L/S ratio=l.5, both). Marshak (1934) puts a genome of this plant as an exception to other Aloe species in having three long, one intermediate and three short chromosomes, and reasons this to be the cause for its wider geographical distribution.…”