Apomixis and Tetraploidy in Pennisetum orientate Rich.¹

Abstract

Five accessions of Pennisetum orientate Rich were tetraploid with 2N = 36. Pairing at diakinesis and metaphase I was generally normal, as was anaphase I disjunction. Quadrivalent frequency per cell ranged from zero to eight, but was usually three to five. Pollen sterility was about 28% and due, in part, to laggards, rare unequal disjunction, and univalent misdivision. Embryo development was aposporous. Development of nucellar embryo sacs was accompanied by degeneration of sexual tissue. multiple embryos were not found.

Karyotype diversity analysis and nuclear genome size estimation for Pennisetum Rich. (Poaceae) ornamental grasses reveal genetic relationship and chromosomal evolution

“…In the present study, the basic and total chromosome numbers of the four wild Pennisetum species and one artificial hybrid were consistent with previous studies (Narayan, 1951;Ono and Tateoka, 1953;Pantulu, 1967;Chatterji and Timothy, 1969;Simpson and Bashaw, 1969;Rangasamy, 1972;Vardhan and Lakshmi, 1983;Kaur et al, 2014). The ploidies of the four cultivars were reported for the first time.…”

“…Among the nine Pennisetum taxa used as ornamental grass mentioned above, the chromosome characters of the following five taxa have been reported: P. orientale (Narayan, 1951;Chatterji and Timothy, 1969;Rangasamy, 1972;Vardhan and Lakshmi 1983;Techio et al, 2002Techio et al, , 2010, P. alopecuroides (Ono and Tateoka, 1953), P. villosum (Rangasamy, 1972), P. setaceum (Simpson and Bashaw, 1969), and P. glaucum × P. purpureum (Techio et al, 2002;Barbosa et al, 2003). These early studies, however, focused primarily on overall counts of chromosomes, rather than their individual morphology or genetic implications among species as revealed by karyotype parameters.…”

Cytotaxonomy and evolution in Pennisetum section Brevivalvula (Gramineae) in tropical Africa

“…The high frequency of agamospermy among polyploid plants (Gustafsson, 1946(Gustafsson, -1947 and specifically within panicoid grasses (Brown 8c Emery, 1958) has been recognized for many years. In the genus Pennisetum, apomixis has been reported in several species in section Cenchropsis (Narayan, 1955;Chatterji & Timothy, 1969a;1969b). Although embryological data are not available, fertility data in Table 4 strongly suggest the presence of agamospermy in the section Breuivaluula.…”

Morphological, cytological and reproductive characterization of tri-species hybrids (GOS) between Pennisetum glaucum, P. orientale and P. squamulatum

“…However, in P. orientale the genetic regulation of apomixis/apospory seems different. Diploids are sexual, while polyploids are apomictic in this species (Patil et al 1962;Chatterji and Timothy 1969;Jauhar 1981). Truly apomictic hybrids (i.e.…”