Chromosome number and meiosis in populations ofSennaspecies (Caesalpinioideae – Fabaceae) from Southeast Brazil

Abstract

Senna Mill. is one of the most representative genera of Caesalpinioideae, with wide geographical distribution. Some species have been cytogenetically characterized, but there is no information on population level. Therefore, the present work had the objective of characterizing and comparing chromosomal number and meiotic behavior of 39 accessions belonging to 11 species of Senna Mill. from southern Minas Gerais state, Brazil. Meiotic preparations were obtained by cell suspension technique and stained with 10% Giemsa solution. All meiotic phases were analyzed and the meiotic index was obtained. The species showed different chromosome numbers (n = 12, 13, 14, and 28). Meiotic behavior of four species is described for the first time. The chromosomal numbers reported for most species coincide with those described for populations from either Southern Brazil or from state of Pará. Intraspecific variation for chromosome number was observed in S. rugosa (G. Don) H. S. Irwin & Barneby (n = 14 and n = 28). This variation along with multivalent occurrence suggests polyploidization as an important event in the evolution of this species, as described for many others, mainly in Caesalpinioideae. Most of the analyzed species showed regular meiotic behavior, despite the occurrence of some irregularities.

Intra- and interspecific karyotypic variations of the genus Senna Mill. (Fabaceae, Caesalpinioideae)

“…The chromosome numbers recorded here for species of the genus Senna confirmed previous counts reported in the literature (Biondo et al 2005a;Resende et al 2013;Souza & Benko-Iseppon 2004), with new records for S. georgica (2n = 26) and S. rizzinii (2n = 26).…”

“…Although 2n = 28 predominated (68.9 % of the species), there are significant numbers of records of 2n = 26 (14.8 %) and 2n = 24 (13.5 %) among its species (Goldblatt 1981;Souza & Benko-Iseppon 2004;Biondo et al 2005a;Matos et al 2011;Resende et al 2013;Rice et al 2015). Interspecific variations were observed in the present work, with five species showing 2n = 28 but four species showing 2n = 26.…”

“…In those cases, intraspecific variations could be related to factors such as distance or geographic isolation, together with hybridization in natural populations. Intraspecific variations were also observed in Senna spectabilis, with records of 2n = 26 and 28 (Resende et al 2013;Rice et al 2015), although those variations appear to be distinct at the variety level, as S. spectabilis var. excelsa shows 2n = 28 in all of its karyotypic descriptions (including the present work), while S. spectabilis var.…”

“…Chromosome counts are available for approximately 20 % of the species of Senna, with a predominance of 2n = 28, although there are also records of 2n = 22, 24 and 26 (Goldblatt 1981;Souza & Benko-Iseppon 2004;Biondo et al 2005a;Matos et al 2011;Resende et al 2013;Rice et al 2015); records of polyploidy, such as 2n = 42, 56 and 112 in Senna rugosa (Resende et al 2014), 2n = 56 in S. aversifl ora, and 2n = 52 and 104 in S. gardneri (Matos et al 2011) have also been cited. The consistent record of 2n = 28 for most species demonstrates that the basic number may be x = 14, while the other numbers (x = 11, 12 and 13) apparently reflect disploidy events (Goldblatt 1981).…”

An overview of chromosome and basic numbers diversity in cytologically investigated polypetalous genera from the Western Himalayas (India)

“…Likewise, there have been major contributions to the cytology of polypetalous plants. Important contributors from outside India include Zhou et al (2002), Lihová et al (2003), Ghaffari (2004), Yan-Jun et al (2006), Wang et al (2008), Sheng et al (2010), Gholipour and Sheidai (2010), Gömürgen et al (2011), Ranjbar et al (2012), Chung et al (2013), and de Resende et al (2013). Major contributions over the past few decades from India include Sarkar (1967-1968), Sharma (1970), Roy and Sharma (1971), Chatterjee and Sharma (1972), Sanjappa (1979), Hore (1971Hore ( , 1980, Panigrahi and Purohit (1984), Subramanian (1985), Govindarajan and Subramanian (1986) and Vaidya and Joshi (2003).…”