scholarly journals Genomic insights into the recent chromosome reduction and polyploidization of complex autopolyploid sugarcane S. spontaneum

2021 ◽  
Author(s):  
Jisen Zhang ◽  
Qing Zhang ◽  
Yiying Qi ◽  
Haoran Pan ◽  
Gang Wang ◽  
...  
Keyword(s):  
Adaptive Evolution ◽  
Chromatin Structure ◽  
Stress Resistance ◽  
Chromosome Numbers ◽  
Genetic Background ◽  
North India ◽  
Homologous Chromosomes ◽  
Basic Chromosome ◽  
Ancestral Form ◽  
New Directions

Abstract S. spontaneum is a founding Saccharum species that contributes stress resistance to the genetic background of modern sugarcane cultivars. Here, we have assembled the autopolyploid S. spontaneum Np-X genome with ancestral form into 40 pseudo-chromosomes in 10 homologous groups, revealing the recent chromosome reduction and polyploidization that occurred in Saccharum. The paleo-duplicated chromosomal pairs exhibit functional redundancy in Saccharum and underwent fission followed by fusion accompanied by centromeric spreading around 0.80 million years ago (Mya) before evolving into their current forms with basic chromosome numbers x = 9 and x = 8 in S. spontaneum, likely in a stepwise manner. WGDs occurred independently in Saccharum species around 1.5 Mya. Highly diverse chromatin structures exist among homologous chromosomes despite their high collinearity, and the re-structuring of NpChr5 and NpChr8 might have suppressed switching of chromatin structure from inactive to active. Resequencing of 116 sugarcane accessions elucidated that the S. spontaneum originated from North India and that the basic chromosome numbers x = 8, x = 9, and x = 10 originated independently, indicating that recent chromosome reduction rather than polyploidization has driven the adaptive evolution of Saccharum. Our study provides genomic resources and suggests new directions for accelerating sugarcane improvement and advances our knowledge of the evolution of auto-polyploids.

Basic Chromosome Numbers in Silene and Saponaria

Nature ◽  
1960 ◽  
Vol 186 (4722) ◽  
pp. 412-413 ◽  
Author(s):  
T. N. KHOSHOO
Keyword(s):  
Chromosome Numbers ◽  
Basic Chromosome

scholarly journals Inbreeding effects in Drosophila congenic strains: the influence of genetic background of different origin

2021 ◽  
Vol 28 ◽  
pp. 19-23
Author(s):  
O. V. Gorenskaya ◽  
V. V. Navrotskaya ◽  
N. Ye. Volkova ◽  
N. S. Filiponenko
Keyword(s):  
Life Span ◽  
Natural Population ◽  
Stress Resistance ◽  
Genetic Background ◽  
Wing Vein ◽  
Congenic Strains ◽  
Lethal Mutations ◽  
Dominant Lethal ◽  
Dominant Lethal Mutations ◽  
Reproductive Indices

Aim. To compare reproductive indices and stress resistance of Drosophila at outbreeding and inbreeding. Methods. Drosophila melanogaster congenic strains with incomplete development of the radial wing vein – radius incompletus – were used: the laboratory one and the strain, in which the mutation was placed into the genetic background of wild type strain, which originates from the natural population from radiation contaminated territory. Before the experiment strains have passed 65 generations of inbreeding. Viability (number of individuals, pupa stage mortality), dominant lethal mutations frequency and life span of imago at starvation were analysed. Results. After inbreeding, there was a decrease in the frequency of dominant lethal mutations and an increase in viability of the strain, which originates from the natural population, and a decrease of mortality at the pupal stage in both strains. Decreased life span of imago at starvation has been shown only for the inbred strain, which originates from the natural population. Conclusions. Inbreeding for 65 generations has no significant negative effect on reproductive indices; reduction of stress resistance during inbreeding has been shown only for the strain, which originates from the radiation contaminated territory. Keywords: Drosophila, viability, dominant lethal mutations, life span of imago at starvation, inbreeding.

Two New Basic Chromosome Numbers in the Genus Pennisetum

Nature ◽  
1956 ◽  
Vol 178 (4544) ◽  
pp. 1241-1242 ◽  
Author(s):  
M. S. SWAMINATHAN ◽  
JOGINDER NATH
Keyword(s):  
Chromosome Numbers ◽  
Basic Chromosome

Chromosome studies on African plants. 9. Chromosome numbers in Ehrharta (Poaceae: Ehrharteae)

Bothalia ◽  
1989 ◽  
Vol 19 (1) ◽  
pp. 125-132 ◽  
Author(s):  
J. J. Spies ◽  
E. J. L. Saayman ◽  
S. P. Voges ◽  
G. Davidse
Keyword(s):  
Chromosome Number ◽  
Ploidy Level ◽  
Chromosome Numbers ◽  
Basic Chromosome Number ◽  
B Chromosomes ◽  
Basic Chromosome ◽  
Cytogenetic Studies ◽  
African Plants ◽  
First Time

Cytogenetic studies of 53 specimens of 14 species of the genus  Ehrharta Thunb. confirmed a basic chromosome number of 12 for the genus. Chromosome numbers for 13 species are described for the first time. The highest ploidy level yet observed in the genus (2n = lOx = 120) is reported for E. villosa var.  villosa. B chromosomes were observed in several specimens of four different species.

Basic chromosome numbers and polyploid levels in some South African and Australian grasses (Poaceae)

Bothalia ◽  
1991 ◽  
Vol 21 (2) ◽  
pp. 163-170 ◽  
Author(s):  
J. J. Spies ◽  
E. Van der Merwe ◽  
H. Du Plessis ◽  
E. J. L. Saayman
Keyword(s):  
South Africa ◽  
South African ◽  
Chromosome Numbers ◽  
B Chromosomes ◽  
Basic Chromosome ◽  
First Time ◽  
Chromosomal Behaviour

Chromosome numbers of 46 specimens of grasses, involving 24 taxa from South Africa and Australia, have been determined during the present study. For the first time chromosome numbers are given for Eragrostis sarmentosa (Thunb.) Trin. (n = 20). Panicum aequinerve Nees (n = 18),  Digitaria argyrograpta (Nees) Stapf (n = 9) and D. maitlandii Stapf C.E. Hubb. (n = 9). Additional polyploid levels are described for Diplachne fusca (L.) Beauv. ex Roem. Schult. (n = 10) and Digitaria diagonalis (Nees) Stapf var.  diagonalis (n = 9).B-chromosomes were observed in several different specimens. The presence of B-chromosomes often results in abnormal chromosomal behaviour during meiosis.

A SYNOPSIS OF CYTOLOGICAL STUDIES IN GESNERIACEAE

2003 ◽  
Vol 60 (3) ◽  
pp. 425-447 ◽  
Author(s):  
M. MÖLLER ◽  
M. KIEHN
Keyword(s):  
Chromosome Numbers ◽  
New World ◽  
Web Search ◽  
Current Knowledge ◽  
Molecular Data ◽  
Generic Level ◽  
Old World ◽  
Basic Chromosome ◽  
Cytological Data ◽  
The Family

Our knowledge of cytological data published on members of the family Gesneriaceae is summarized and critically evaluated in the light of current taxonomic treatments and phylogenetic hypotheses. There are about 1000 published chromosome counts, covering 56% of the genera but only 18% of the species. In particular the New World tribes Beslerieae and Napeantheae and the Old World tribe Didymocarpeae are underexplored at generic level. In Gesneriaceae chromosome data are a valuable source of taxonomic characters. From our current knowledge of the phylogenetic relationships in the family we know that basic chromosome numbers in the New World subfamily Gesnerioideae appear to be rather conserved, but that a more complex pattern of genome evolution seems to be present among the Old World tribes. Both polyploidy and dysploid changes have played a significant role in the evolution of the family. However, the number of species for which both cytological and molecular data are available is at present too low to reach firm conclusions on ancestral basic chromosome numbers, particularly for the Old World group. To facilitate wider access to cytological data on the Gesneriaceae, a website has been developed (http://www.rbge.org.uk/rbge/web/search/index.jsp), which is introduced in this paper.

Chromosome numbers in some species of Trifolium

1969 ◽  
Vol 20 (5) ◽  
pp. 883 ◽  
Author(s):  
AJ Pritchard
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Basic Chromosome Number ◽  
Basic Chromosome ◽  
First Time

The chromosome numbers of 31 species of Trifolium are reported, 18 for the first time. A reduction in basic chromosome number has occurred only in the three most highly specialized subgenera, and polyploids occur mainly in one of the more primitive subgenera.

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