Development and Characterization of a Hexaploid <i>Pennisetum orientale</i> (2<i>n</i>=6<i>x</i>=54) Cytotype Recovered through B_III Hybridization

Abstract

Summary Pennisetum orientale is an important perennial species having high ecological and forage value. It is largely tetraploid (2n=4x=36) and obligate apomictic in mode of reproduction. A new hexaploid (2n=6x=54) derivate of P. orientale is reported here, recovered in a population derived from self-pollination of a tetraploid genotype. The origin of the 6x cytotype from a 4x cytotype is demonstrated through fertilization of an unreduced egg cell with a reduced male gamete (B III hybridization), yielding experimental evidence of uncoupling of apomixis components in P. orientale. This 6x cytotype was compared for its morphological, cytological and reproductive traits vis-à-vis parental 4x cytotype, and also for potential of gene transfer in otherwise apomictic P. orientale.

Multiporate Pollen of Poaceae as Bioindicator of Environmental Stress: First Archaeobotanical Evidence from the Early–Middle Holocene Site of Takarkori in the Central Sahara

“…Since the occurrence of multiporate pollen in normally monoporate species is related to hybridization causing changes in reproductive biology [3,9], we argue that most Takarkori's Poaceae were polyploids probably also equipped with apomixis. Actually, the tribes Andropogoneae and Paniceae, largely in the form of spikelets and caryopses in the archaeobotanical record of this rockshelter [23] and abundant in other sites of the area (e.g., [30,31]), are known to include polyploids and also some obligately apomictic species (e.g., [32,33]).…”

Partitioning Apomixis Components to Understand and Utilize Gametophytic Apomixis

“…Variability has been successfully generated through addition of genomes utilizing B III hybridization in otherwise apomictic species, such as Brachiaria decumbens , Panicum maximum , Poa pratensis , E. curvula , C. ciliaris , Pennisetum orientale etc. ( Bashaw and Hignight, 1990 ; Nogler, 1994 ; Naumova et al, 1999 ; Matzk et al, 2005 ; Kaushal et al, 2015a , 2018 ). In fact, B III hybrids are formed directly, without intermediary of sexual relatives, and thus give rise to new apomictic biotypes, thereby further increasing the polymorphism of the agamic species complex ( Nogler, 1994 ).…”

“…Such systems, when duly coupled with polyploidy, offer advantages for precise understanding of the various mechanisms, leading to interaction effects between apomixis components as well as their interface with genetic, epigenetic and environmental factors ( Matzk et al, 2001 , 2005 ; Aliyu et al, 2010 ; Hojsgaard, 2018 ). Additionally, it also serves as a stable system to generate newer cytotypes, through B III , M 1 or HAPA ( Kaushal et al, 2009 , 2015a ).…”