Karyotypic Studies of <i>Commelina benghalensis</i> variety <i>benghalensis</i> and <i>C. forskalaei</i> (Commelinaceae) from Nigeria

Abstract

The study investigated the mitotic chromosomes of two variants of C. benghalensis var. benghalensis and C. forskalaei from Nigeria using classical cytogenetic techniques. The two variants of C. benghalensis var. benghalensis have the same diploid chromosome number of 2n=22 and the same karyotype formula of (8 m+10 sm+4 st) chromosomes. The two variants of C. forskalaei have the same diploid chromosome number of 2n=30 and the same karyotype formula of (14 m+ 6 sm+10 st) chromosomes. Terminal satellites were observed on the short arms of sub-terminal chromosome pair number 13 of C. forskalaei cf 1 and the short arms of sub-terminal chromosome pair number 7 of C. forskalaei cf 2. No satellites were observed in the chromosomes of the two variants of C. benghalensis. The chromosomes of the two variants of C. benghalensis var. benghalensis are mainly medium sized (1.00-1.43 µm) while the chromosomes of C. forskalaei are mainly small sized (0.47-0.97 µm). Results indicate interspecific variation in chromosome numbers and forms in the two Commelina species investigated.

Karyo-Morphology and Nucleoli Analysis of Commelina L. (Commelinaceae) from Ethiopia

“…C. benghalensis of the current study falls within 2B Stebbins category. This is in disagreement with the diploid material from Nigeria [30]. This might be associated with genetic difference that associated with difference in agro-ecology.…”

“…According to somatic chromosome analysis of the root tips, this species possesses 2n=6x=66 ( Figure 1C and Table 1). The karyotpe constructed based on calculated arm ratio and chromosome size revealed the presence of eighteen metacentric chromosome pairs (pair numbers 1,3,4,5,8,11,14,15,16,18,22,24,25,29,30,31,32,33), twelve sub-metacentrics (pair numbers 6,7,9,10,12,17,19,20,21,23,27,28) and 3 sub-telocentric pairs (pairs 2, 13, 26 ) ( Figure 1D). The karyotype formula was, therefore, 36m + 24sm + 6st.…”

“…The variant of C. diffusa collected from Ginchi possessed 2n= 66 (Table 1 and Figure 1E). Based on centromeric ratio and chromosome length measurements , the karyotype (Figure 1F) consisted of fourteen metacentric pairs (pair numbers 1,4,6,15,16,20,21,23,25,26,30,31,32,33), thirteen sub-metacentrics (pairs 2, 3, 5, 7, 8, 9, 10, 13, 17, 19, 24, 27, 28) and six sub-telocentrics (pairs 11, 12, 14, 18, 22, 29) with a formula of 28m + 26sm + 12st. The asymmetry index is 65.56 and belongs to 2B type of Stebbins karyotype classi cation (Table 1).…”

Karyotype analysis in <i>Machaerium lunatum</i> (Linn. f.) Ducke

“…The high percentage of metacentric chromosomes in plant is an indication of symmetric karyotype which is primitive in nature (Stebbins 1950 Zheng et al (1991) in Phaseolus vulgaris and Tabur et al (2009) in Vicia, Coronilla, Trifolium and Spatium. The presence of subtelometacentric chromosomes suggests that M. lunatum is highly advanced (Oziegbe and Eludini 2013). Finally, it is also important to note that a symmetric karyotype does not necessarily implies primitivity as assumed by earlier students (Lorenzo and Halil 2013) and is evident in M. lunatum due to the presence of metacentric and submetacentric chromosomes.…”

Chromosome and nucleoli diversity in some species of Commelina L. (Commelinaceae) from Ethiopia

“…1C and Table 1). The karyotpe constructed based on calculated arm ratio and chromosome size revealed the presence of eighteen metacentric chromosome pairs (pair numbers 1,3,4,5,8,11,14,15,16,18,22,24,25,29,30,31,32,33), twelve sub-metacentrics (pair numbers 6, 7,9,10,12,17,19,20,21,23,27,28) and 3 sub-telocentric pairs (pairs 2, 13, 26 ) (Fig. 1D).…”