Gp-604.pptx

Assignment presentation
on
Translocation, B-A chromosomal translocation and
gene location in various crops
(GP-604)
SPEA KER
Suchitra
Reg. no. 1010120026
Ph.D. (Ag.) Sem 3rd
Dept. Of Genetics and Plant Breeding
COA, JAU, Junagadh.
2
Dr. Praveen kona
Agricultural Research Scientist
Directorate of Groundnut Research
Junagadh
Submitted to

 In 1914, Belling reported 50% pollen abortion and 50% seed set in crosses of Florida
velvet bean which he termed as semi-sterility. Later in 1924, Belling and Blakeslee,
working with Datura stramonium, concluded that non-homologous chromosomes
could exchange segments.
 The breeding behaviour of semi-sterility in Stizolobium deeringianum was explained
in 1925 by Belling on the basis of “segmental interchange between non-
homologues”.
 In maize plant, semi-sterility was reported by Brink in 1927. In 1930, Burnham
reported a ring of 4 chromosomes in the semi-sterile plant of maize. In the same
year, McClintock showed that translocation heterozygotes produced a “cross-
shaped configuration” at pachytene.
 In Drosophila, the first translocation where a piece of X chromosome was attached
to the Y chromosome was reported by Stern in 1926.
 Certain genes have been reported to induce chromosome breaks leading to the
production of translocations. Genetically controlled systems of chromosome
breakage have been observed in some cases. In maize, chromosome breaks occurred
at AI of meiosis due to stickiness of chromosomes aberrations.
 The DS-AC system in maize first described by McClintock in 1950 also causes
structural changes by inducing chromosome breaks.
History
3
Prasad, G. (2018)

Translocations can originate in the following different ways:
(i) Translocations may originate spontaneously.
(ii) They may be induced by mutagens, viz., ionizing radiations and
many chemical mutagens, since they induce chromosome breakage.
(iii) Translocations may be induced by growing plants in calcium-
deficient media, as reported by Nilan and Phillips in 1957.
(iv) Translocations may be induced by oxygen applied at a high
atmospheric pressure, as reported by Kronstad et al., in 1959 and
Moutschen-Dahmen et al., in 1959.
(v) Translocations can be recovered from certain interspecific crosses
since the concerned species differ for chromosomal rearrangements,
including translocation, which become observable in their
interspecific hybrids.
(vi) Genetically controlled breakage in the chromosomes may also
produce translocations, such as, sticky gene (st) and DS-AC system
in maize.
Origin of Translocation
4
Prasad, G. (2018)

Translocation may be classified on the basis of the translocated segment
being present in the same, homologous or non-homologous chromosome,
and the number of breaks involved in the translocation.
A. Classification on the basis of involvement of the same or different
chromosomes:
1. Intra-chromosomal (internal) translocation or shift:
A segment of a chromosome is shifted from its original position to
some other position within the same chromosome. It is of two types:
(a) Intra-Radial: The shift occurs in the same arm.
(b) Extra-Radial: The shift occurs from one arm to the other arm.
2. Inter-Chromosomal translocation:
A chromosomal segment is transferred from one chromosome to
another one. It may be either fraternal or external.
(a) Fraternal:The chromosome segment is trans-located into the
homologous (Fig.1).
Types of Translocation
5
Prasad, G. (2018)

Fig.1 Diagrammatic representation of the origin of translocations involving the
same and homologous chromosomes ( = break position). (i) Intraradial
shift . (ii) Extraradial shift. (iii,iv) Fraternal translocations
6
Prasad, G. (2018)

(b) External: The chromosome segment is translocated into a non-homologous chromosome.
The inter-chromosomal translocation may be divided into the following three groups:-
I. Transposition: Transfer of a chromosome segment from one chromosome to another
chromosome is called transposition. It may be of the following types.
(i) Intercalation or insertion or insertional translocation: The transposition occurs in an
intercalary position.
(ii) Terminal transposition: The segment is attached to the chromosomal end. However,
terminal translocation is not possible so long as the telomere of the chromosome
remains intact. Therefore, terminal translocation can occur only when the chromosome
end is deleted or trans-located.
II. Reciprocal translocation or interchange: Exchange of segments between two or more
non-homologous chromosomes is called reciprocal translocation or interchange. It is of two
types: asymmetrical or aneucentric and symmetrical or eucentric.
(i) Asymmetrical or aneucentric translocation: After breakage, the broken acentric
segments fuse to form a trans-located acentric chromosome, while the two chromosomes
with centromeres fuse to produce a trans-located chromosome with two centromeres
(dicentric). The dicentric chromosome will produce bridge at anaphase if the two
centromeres move to opposite poles (Fig.2).
(ii) Symmetrical or eucentric translocation: Broken segments are exchanged between the
two non-homologous chromosomes so that both the chromosomes involved in
translocation possess only one centromere each (mono-centric) (Fig.2).
7
Prasad, G. (2018)

III. Whole-Arm translocations or whole-arm transfers: These are the
special types of translocations where almost the entire chromosome
arms are transposed or interchanged.
Such translocations are of three types:
(i) Centric fusion or Robertsonian translocation: The long arms of two
acrocentric chromosomes may fuse due to translocation to produce a
metacentric chromosome, while their short arms fuse to form a very
small chromosome.
(ii) Dissociation: Two metacentric chromosomes, one with long arms and
other with short arms may produce two acrocentric chromosomes
through translocation.
(iii) Tandem fusion: Such type of interchange is produced when the
break in one chromosome occurs near the centromere and in the other
chromosome, it occurs near the end. The result of such breakage and
reunion may be a large acrocentric chromosome and a small
metacentric chromosome, if both the chromosomes were originally
acrocentric. If one chromosome is a metacentric, the result o the
interchange will be two acrocentric chromosomes, one being small and
the other being large.
8
Prasad, G. (2018)

Fig.2 Diagrammatic representation of the origin of translocations involving the nonhomologous
chromosomes ( = break position). (i) Intrachromosomal translocation, (ii) Asymmetrical
interchange, (iii) Symmetrical interchange, (iv) Centirc fusion or robertsonian translocation, (v)
Dissociation, (vi, vii) Tandem fusion
9
Prasad, G. (2018)

B. Classification on the basis of the number of breaks involved:
According to this system Schulz-Schaeffer in 1980 divided the translocations
into four classes:
(1) Simple (one break),
(2) Reciprocal (two breaks),
(3) Shift (three breaks), and
(4) Complex (more than three breaks) translocations.
1. Simple translocation: In such a translocation, a segment of a chromosome
becomes attached to the end of a non-homologous chromosome. In 1929, Painter
and Muller reported such type of translocations in Drosophila. In view of the
stability of telomere, intact chromosomal end cannot fuse with a chromosomal
segment. Therefore, cases of simple translocations are either reciprocal
translocation in which a very small telomeric segment of one chromosome
(apparently devoid of a detectable gene) is involved in a reciprocal translocation,
or the telomeric region of the concerned chromosome gets deleted during the
translocation.
2. Reciprocal translocation or Interchange: In this type of translocation, segments
are exchanged between two non-homologous chromosomes, therefore, it involves
one break in each of the involved chromosomes (Fig.2). Most of the
translocations are reciprocal translocations. Such translocations have been
extensively studied in various plant and animal species.
10
Prasad, G. (2018)

3. Shift type of translocation or Transposition:
It involves three breaks, and the broken segment is shifted
(transposed) in the intercalary position (Fig.1). According to
whether same or different chromosomes involved, shift is of two
types:
(a) Intra-chromosomal shift: Shift is confined to the same
chromosome; the broken segment gets inserted either (i) within
the same arm, or (ii) in the other arm of the chromosome.
(b) Inter-chromosomal shift: A broken piece of a chromosome
is inserted into an intercalary position of a non-homologous
chromosome (Fig.2).
4. Complex Translocations:
In such translocations, more than three breaks are involved.
Mostly, such translocations are naturally occurring.
11
Prasad, G. (2018)

 We may define B chromosomes as dispensable supernumeraries which do not
recombine with any members of the basic A chromosome set and which have
irregular and non-Mendelian modes of inheritance.
 The term B chromosome was first used by Randolph (1928).
 Their actual discovery can probably be credited to Stevens (1908), who
described the presence of small additional supernumeraries appearing in
variable numbers in about 50% of random collections of the coleopteran
insects Diabrotica soror and Diabrotica punctata.
 Wilson (1906) had earlier used the same term to describe extra
chromosomes in the insect Metapodius, but had not sampled populations. In
plants much of the early work on Bs was undertaken in maize, beginning with
Kuwada in 1915, but it was Longley (1927), and later Randolph (1941) who
first distinguished these extras in maize as being supernumerary and who
presented the first detailed study in plants on their behaviour and
characteristics.
 Different names have been used, such as supernumerary, accessory and extra
fragment, but the term B chromosome, or just B, is now the standard and
certainly the most convenient form.
 B chromosomes are now known in at least 1372 flowering plants, of which 12
are conifers and 1360 are angiosperms.
About B chromosome……..
13
Jones, R. N. (1995)

• It goes without saying that the Bs originate from the As, and that there
are endless opportunities as errors in crossing over and in spindle
malfunction for fragments of As to be generated. Transient chromosome
fragments arising as by-products of meiotic infidelities are well known
to chromosome watchers, and many a cytologist has seen them come
and go.
• This is probably what happened in rye, where all Bs in all populations
are virtually identical at the cytological level, and which must have had
a once-and-for-all monophyletic origin.
• Isolating mechanisms which can prevent newly arising fragments from
pairing with their homologous parts are known, as in barley where a
fragment from a tertiary trisomic progressively shortens over cycles of
nuclear division and loses its capacity to recombine with its parent parts
(Wiebe, Ramage & Eslick, 1974).
ORIGIN OF B CHROMOSOMES
14
Jones, R. N. (1995)

Fig.3 Diagram of the B chromosome in maize (Jones and Ruban, 2019).
Fig.4 Production of a B-A translocation by breakage of a normal (A) chromosome and a B
chromosome at the sites indicated by arrows, followed by rejoining of broken ends as
illustrated, giving an AB chromosome and a BA chromosome (Beckett, 1978).
15

Fig.5 Development of a pollen grain with nondisjunction of the BA chromosome at the
second division of the microspore (modified from Roman I').
16
Beckett, J. B. (1978)

Fig.6 Alternative results of pollinating colorless (rr) with a pollen grain bearing gametes of
the constitution 10BB10RB10R and 10B, respectively. Male and female contributions to
embryo and endosperm are indicated. Presence of anthocyanin color is indicated by
stippling.
17

Locating recessive genes
 The procedure for locating a recessive gene to chromosome arm involves crossing
plants carrying the mutant with pollen from plants carrying B-A translocations.
 A recessive factor affecting either an endosperm or plant trait will be expressed in a
portion of the immediate F1 individuals of the critical cross (i.e., the cross with a B-A
translocation that generates a deficiency for the arm segment on which the factor is
located).
 In practice, recessive factors are located by crossing homozygous or heterozygous
plants with pollen from the basic set of B-A translocations. Most of these loci can be
located by self-pollinating or testcrossing hypoploids (AAB). Such crosses will give
normal 3:1 or 1:1 ratios, respectively, unless a hypoploid for the critical chromosome
is involved.
 This is because gametes receiving the AB chromosome will be grossly deficient and
will not function; from critical hypoploids the only mutant-free gametes to function
will be those that are derived through crossing over between the locus and the
breakpoint as follows.
18

Difficulties to locate recessive genes
• First, nonhypoploid plants usually need to be removed from the
row to allow the weaker hypoploids to develop properly and,
although some hypoploids can be recognized without difficulty,
others must be identified by the 50 percent aborted pollen.
• Second, some of the translocations produce hypoploids that are
nearly male sterile, or functionally male sterile, because the
apical pores of the small anthers fail to open.
• Third, hypoploid ears are often small and set no more than 50
percent of the ovules, so it may be difficult to get large
progenies to test. This difficulty is overcome if pollen from
hypoploids can be obtained to make testcrosses.
19

Locating dominant factors
 Dominant genes with altered or extreme expression in the hemizygous state
can be located to chromosome arm in the F1 as described above for recessives.
 Dominant genes without such altered expression in the hemizygote and
dominant genes situated between B-A translocations and the centromeres, or
even in the opposite chromosome arms, can be located by testing hypoploids.
 If the critical hypoploid is self-pollinated or outcrossed to normal, a high
proportion of the progeny will usually exhibit the dominant phenotype if
penetrance is complete.
 If a dominant gene is proximal to the breakpoint (middle figure) but very close
to it, there may be no crossovers, making it difficult to determine whether the
locus is proximal or distal to the breakpoint.
20

B-A translocations
are often maintained
in the heterozygous
condition by
crossing as female
by normal.
Approximately one-
third of the progeny
are again
heterozygous for the
translocation.
Fig.7 Gametes and
progeny obtained by
crossing a plant
heterozygous for a
B-A translocation
by a normal male.
21

Table 1. Review papers, and papers with major review sections, on B chromosomes
22
Jones, R. N. (1995)

Table 1. Review papers, and papers with major review sections, on B chromosomes
23
Jones and Ruban, 2019

Table 2. Genes located on B chromosomes in plants, excluding meiotic pairing genes
24
Jones, R. N. (1995)

Case study 1
26
Aung and Thomas, 1978
Wales, UK

Fig.18 The structure of the translocated chromosome in Av 1516 as revealed in mitotic and meiotic cells of
plants heterozygous for the translocation and in hybrids with cytological markers . (a) Somatic cell of
heterozygote translocation - only one ST21 (arrowed) . (b) Meiosis in heterozygote translocation with
heteromorphic bivalent . (c) Meiosis in the hybrid homozygous translocation x ditelocentric for long
arm of ST21 . Note extreme heteromorphic bivalent. (d) Meiosis in homozygous translocation x
ditelocentric addition for the short arm of the barbata chromosome. (e) Meiosis in homozygous
translocation x tetrasomic for ST 21 - pan handle trivalent . (f) Homozygous translocation x barbata
disomic addition line - pan handle trivalent
27
Wales, UK Aung and Thomas, 1978

Table 11. Segregation for mildew resistance in F2 from backcross hybrids
28

Table 12. Segregation for mildew resistance in backcross hybrids
Table 13. Morphological characters of nullisomic and substitution lines (mean values)
29

Case study 2
30
Taludar, 2010
West Bengal, India

Translocation line RT-1 RT-2 RT-3 RT-4 Total
Total number of plants studied 300 315 250 215 1080
Number of plants
Normal plants (N/N) 92 90 52 61 295
Translocation heterozygote (N/T) 126 151 138 113 528
Translocation homozygote (T/T) 80 70 53 36 239
Trisomics 02 04 07 05 18
Percentage of N/N plants 30.67 28.57 20.80 28.37 27.31
Percentage of N/T plants 42.00 47.94 55.20 52.56 48.89
Percentage of T/T plants 26.67 22.22 21.20 16.74 22.96
Percentage of trisomics 0.70 1.30 2.80 2.30 1.67
Table 14. Frequency of 4 types of offsprings obtained from the selfed generation of 4
reciprocal Translocation lines (RT-1, RT-2, RT-3, and RT-4) in grass pea (Lathyrus
sativus L.)
Data pooled over several generations.
31
West Bengal, India Taludar, 2010

Fig.19 (A) 7II in normal fertile
plants at diakinesis. (B) 1IV
(8 shaped) þ 5II at diakinesis
in N/T plants. (C) 1IV (ring
shaped) þ 5II at metaphase I
in N/T plants. (D) A chain of
6 chromosomes (1VI) þ 4II at
metaphase I in double
heterozygote plants. (E) Ring
of 6 chromosomes attached
with nucleolus at diakinesis in
double heterozygote plants.
(F) Eight-shaped hexavelent
associated with nucleolus þ
4II at diakinesis in double
heterozygote plants. (G)
Diakinesis showing 1 ring-
shaped and other 8-shaped
quadrivalent in 2IVþ3II
association. (H) Two ring-
shaped quadrivalents; one of
which associated with
nucleolus at diakinesis in
2IVþ3II association in double
heterozygote plants.
32
West Bengal, India
Taludar, 2010

Character RT-1 RT-2 RT-3 RT-4 Total
No. of PMCs
scored
550 600 500 500 2150
Eight shaped 221 357 341 310 1229
Ring shaped 297 198 138 161 794
Pollen sterility (mean±SE)
N/N 1.53 ± 1.2 1.49 ± 1.2 1.76 ± 2.0 1.60 ± 3.0 1.55 ± 5.0
N/T 59.11 ± 3.3 40.60 ± 4.0 34.88 ± 2.0 38.00 ± 1.9 45.37 ± 5.8
T/T 2.5 ± 5.0 2.0 ± 4.6 1.99 ± 7.0 3.0 ± 6.5 2.5 ± 6.1
Trisomics 59.00 61.95 61.11 62.00 60.47 ± 1.11
Seed yield/plant (gm)
N/N 16.60 ± 2.5 15.56 ± 3.9 13.36 ± 4.7 17.77 ± 5.8 15.75 ± 8.9
N/T 5.17 ± 2.0 8.45 ± 3.0 9.11 ± 3.5 8.79 ± 5.0 7.38 ± 7.0
T/T 7.06 ± 6.0 7.78 ± 6.7 10.55 ± 3.2 10.47 ± 2.9 8.33 ± 5.5
Trisomics 6.50 ± 0.00 7.50 ± 0.02 4.88 ± 0.05 5.90 ± 0.04 6.25 ± 0.10
Table15. Frequency of different quadrivalents, percentage of pollen sterility, and seed yield
per plant (gm) in selfed generation of 4 reciprocal translocation lines (RT-1, RT-2,
RT-3, and RT-4) in grass pea (Lathyrus sativus L.)
Data pooled over several generations.
33

Cross Metaphase I chromosome association in the
offspring
Pollen
sterility
ina double
heterozygote
Total plants
7II 11V+5II 1VI+4II 21V+3II
RT-1 × cultivar 48 40 — — — 88b
RT-2 × cultivar 59 51 — — — 110b
RT-3 × cultivar 42 37 — — — 79b
RT-4 × cultivar 37 29 — — — 66b
RT-1 × RT-2 200 122 58 — 61 380
RT-1 × RT-3 216 90 — 44 77 350
RT-1 × RT-4 213 91 61 — 63 365
RT-2 × RT-3 126 87 47 — 66 260
RT-2 × RT-4 162 83 45 — 60 290
RT-3 × RT-4 215 139 — 51 73.90 405
Total (RT × RT) 1132 612 211 95 67.54 2050
Table 16. Metaphase I chromosome configuration of F1 plants derived from RT × normal
cultivar and intercrosses between 4 RT lines in grass pea (2n=14)
Pooled data of several years of intercrosses presented.
a In percentage.
b Segregation consistent with the expected 1:1 ratio at 5% level of significance with c2 value (1 df) 0.73
in RT-1 × cultivar, 0.58 in RT-2 × cultivar, 0.32 in RT-3 × cultivar, and 0.97 in RT-4 × cultivar.
34

Case study 3
35
Ma et al., 2016
Stadt Seeland, Germany

Fig. 8 The distribution of active
and inactive RNA polymerase II
(RNAPII) in rye and wheat
nuclei with two B chromosomes
(Bs) was identified by
structured illumination
microscopy (SIM). Immuno-
staining of RNAPIISer2ph
(active) and fluorescence in situ
hybridization (FISH) with the B
specific repeat D1100 or
Revolver to identify rye B
chromatin show the presence of
active RNAPII at rye B
chromatin (Merge 1). Inactive
RNAPII also co-localizes with
B chromatin and, in rye, it is
even amplified (Merge 2). The
right panels show the regions of
interest (rectangle) magnified.
(a) Interphase nuclei of rye
possessing two Bs. (b)
Interphase nuclei of a wheat–rye
two B addition line.
36
Ma et al., 2016

Fig.9 Differential expression
between 0B and 4B rye
plants and gene ontology
(GO) enrichment of B-
located transcripts. (a) The
volcano plots reveal
differences in gene
expression between rye 0B
and 4B in the vegetative
(root and leaves) and
generative (anther)
samples. (b) The bar chart
highlights significantly
enriched GO categories of
the still transcribed portion
of B-located gene
candidates identified in
anthers (orange) and
root/leaves (green) in
comparison with a
combined reference set of
all rye A and B genes for
the respective tissues
37
Ma et al., 2016

Fig.10 Chromosomal locations of ScKIF4A,
ScSHOC1 and ScAGO4B by fluorescence
in situ hybridization (FISH). Mitotic
metaphase or meiotic metaphase I cells of
rye with B chromosomes (Bs) after FISH
with labeled ScKIF4A (a), ScSHOC1 (b)
and ScAGO4B (c) (in red). FISH with the
B specific D1100 repeat (in green) allowed
the identification of Bs. Chromosomes are
stained by 40 ,6-diamidino-2-phenylindole
(DAPI) (in blue). Arrowheads, signals from
Bs; arrows, A-localized FISH signals
38
Ma et al., 2016

Fig.11 Quantitative analysis of
ScKIF4A, ScAGO4B and
ScSHOC1 transcripts in the
presence and absence of B
chromosomes (Bs). The total
transcription of ScKIF4A
(a), ScSHOC1 (c) and
ScAGO4B (e) was measured
by quantitative reverse
transcription-polymerase
chain reaction (RTPCR) in
rye anther cDNA containing
different numbers of Bs. The
contribution of B-derived
ScKIF4A (b), ScSHOC1 (d)
and ScAGO4B (f) transcripts
from rye anther cDNA with
different numbers of Bs was
measured by colony PCR,
followed by cleaved
amplified polymorphic
sequences (CAPS) analysis
or nested PCR
39
Ma et al., 2016

Fig.12 Rye A- and B-
derived AGO4B-
like proteins show
similar slicer
activity. The
mRNAs encoding
the A- and B-
derived ScAGO4B-
like proteins were
translated in
Nicotiana tabacum
BY-2 lysate (BYL)
in the absence or
presence of an
exogenous, 24-
nucleotide small
interfering RNA
(siRNA) targeting
the mRNA of green
fluorescent protein
(GFP)
40
Ma et al., 2016

Case study 4
41
Huang et al., 2016
Beijing, China

Fig.20 FISH identification of B
chromosome number. The red
signal is digoxingenin-labeled
ZmBs. The B chromosome number
was confirmed by counting ZmBs
signals and total chromosome
number. (a) B73 + 0B, (b) B73 +
1B, (c) B73 + 6Bs. Arrows indicate
the B chromosome
42
Beijing, China Huang et al., 2016

Fig.21 Differential gene expression in the presence/absence of B chromosome. (a) Up-
regulated genes in both groups. (b) Down-regulated genes in both groups. (c) qRT-PCR
validation of differentially expressed genes
43
Huang et al., 2016

Fig.22 Differential gene expression in the presence/absence of B chromosome.
(d) Gene Ontology annotation of up-regulated genes by Singular
Enrichment Analysis (SEA)
44

Table 17. Significant GO terms of up-regulated genes
45

Table 18. Sequence analysis of four B-located genes
46

Fig.23 A-homologous genes located
on B chromosome. (a to d)
Fluorescence in situ hybridization
of B-located genes, pachytene
stage chromosomes were probed
with plasmids of B-located gene
(red) and ZmBs (green). The
signals of GRMZM2G013761B
appeared on the DH2
heterochromatic region of B
chromosome (a); the
GRMZM2G054938B was located
on the proximal euchromatic (PE)
region near DH1 side (b);
AF466202.2_FG007B had two
foci on PE region (c); and
GRMZM2G356653B was close to
centromeric knob (d). The relative
location of these four B
chromosome genes were
illustrated in (e). Arrowheads
indicate the ZmBs signals, and
arrows indicate the signals of B-
located genes
47
Huang et al., 2016

Fig.24 Alignment of 3 B
chromosome located sequences.
(a) Alignment of the assembled
sequence
comp75688_c6_seq20, the
1900 bp fragment of
comp75688, and the full-length
comp75688 from B73 + B and
Starter + B. Sequence in black
box was the newly discovered
B-specific sequence. (b)
Alignment between the de novo
assembled sequence and 1.6 kb
B-located sequence. (c)
Comparison of the assembled
comp30393_c0_seq1, the B-
located sequences
comp30393_Starter_B and
comp30393_B73_B, and the
transcribed sequence; these four
sequences showed 100 %
identity to one another but were
significantly different from
their A-genome homologues.
Arrowheads indicate the SNPs
between sequences
48
Huang et al., 2016

Table 19. RepeatMasker analysis of the three B-located fragments
49

Fig.25 Expression and chromosome location of B-specific fragment comp75688. (a) qRT-
PCR detected the expression of comp75688 with two SCARs, and comp75688 was
expressed in a B-dosage dependent manner. (b) FISH detection of the location of
comp75688, the 3.2 kb comp75688 was digoxigenin-labeled (red) and the ZmBs was
biotin-labeled (green). More condense comp75688 signal was detected on the long arm
of the B chromosome. Arrowheads indicate the ZmBs signals
50

Case study 5
51
Roupakias et al., 1980
North Carolina, USA

Table 3. The CAT-1, CAT-2 and CAT-3 isozy mes carried by each of the B-A translocation
strains used
52
North Carolina, USA Roupakias et al., 1980

Fig.13a and b. Behavior of B A
chromosomes during meiosis and pollen
development. B A chromosomes may
undergo nondisjunction at the second
microspore mitotic division resulting in a
hyperploid sperm nucleus (1)and a
hypoploid sperm nucleus (2). If a diploid
female homozygous for CAT-1 F is
crossed to the critical B-A translocation
(the translocation where Cat1 is located)
carrying CAT-1VM, different phenotypes
will be observed in the scutellum and in
the endosperm. In case (a) the endosperm
will be FFVV while the scutellum and
embryo will be F. In case (b) the
endosperm will be FF, while the scutellum
and embryo will be FVV. G.N., generative
nucleus; T.N., Tube nucleus, END.,
endosperm; EMB., embryo; A, normal
chromosome; A B, A chromosome-B
chromosome translocation with A
centromere; B A, B chromosome-A
chromosome translocation with B
centromere; M, V, F are the respective
catalase isozymes specified by the allelic
genes CatlM, Cat1 V and CatlF
53

Cross
Cat-1 variants of the
male plants used
The cat-1 phenotypes observed in scutellum
female male FM FV FF Total
W59 X Tb-lSb M 20 20
Wl0 X Tb-lSb M 14 14
W59 X Tb-lLa V 24 24
Wl0 X Tb-lLa M 10 10
W59 X Tb-3La-2S6270 M 21 21
W59 x Tb-1Sb-2L4464 M 28 28
R6-45 X Tb-3Sb M 21 21
W59 X Tb-3La MV 9 12 21
W39 X Tb-3La V 22 22
Wl0 X Tb-4Sa V 21 21
W59 X Tb-9Sb-4L65 04 M 21 21
W59 x Tb-1La-558041 MV 11 l7 6 34
W10 X Tb-1La-5 S8041 MV 2 10 2 14
R6-48 X Tb-1La-5 S8041 V 4 2 6
W59 X Tb-5La M 21 21
h’10 x Tb-6Lc MV 12 9 21
W59 x Tb-7Lb M 21 21
W59 x Tb-8Lb M 20 20
W59 X Tb-9La V 20 20
W59 X Tb-10Sc V 20 20
Oh51Aa X Tb-10La F 14 14
Table 4. The CAT-1 phenotypes observed in F1 progeny of crosses made between B-A translocations
carrying the M,V or MV CAT-1 isozymes, as males, and inbred strains homozygous for the
fast CAT-1 variant (FF), as females
aOh51A is homozygous for the V variant of Carl isozymes. F, M and V are allelic forms of CAT-1 54

Fig.14a-c. a Root tip spread of a 22
chromosome seedling which
exhibited the FVV CAT1
phenotype in the scutellum; b root
tip spread of a 22 chromosome
plant exhibiting CAT-2PZZ; from
the cross R6-49 X Tb-1Sb. c root
tip spread of a 22 chromosome
plant exhibiting CAT-3AAB from
the cross W59 X Tb-1La
55

Fig.15a and b.
Zymograms of
catalase phenotypes
observed in plants
derived from the
cross W10 X Tb-1
La-5S8041. a plant
no. 2: b plant no. 7,
8 and 9. CAT-l
genotype of each
plant sample is
indicated. S =
scutellum and
embryo; E =
endosperm; C =
control; 0 = origin;
migration is anodal
56
North Carolina, USA
Roupakias et al., 1980

Table 5. Analysis of progeny of self-pollinated plants heterozygous for the marker
gene, brittle endosperm (bt ) and for two CAT-1 isozymes +F /bt, V
Type of
endosperm
Genotype of
scutellar tissue
The CAT-1 phenotypes
observed in scutella tissue
FF FV VV Total
Normal (+-) 118 253 24 395
Brittle bt1bt1 1 13 73 87
Total 119 266 97 482
57

Cross CAT-2 variants of the plants used
Female x Male Female Male
R6-45 x Tb-lSb PP ZZ
R6-49 x Tb-lSb PP ZZ
W59 x Tb-lLa PP ZZ
W59 x Tb-2S-3L627(1 PP ZZ
W10 x Tb-15b-2L4464 ZZ PP
W59 x Tb-15b-2L4464 PP ZZ
R6-45 x Tb-35b PP ZZ
W59 x Tb-3La PP ZZ
W59 x Tb-95b-4L6504 PP ZZ
SD10 x Tb-4Sa PP ZZ
W59 x Tb-1La-3S8041 PP ZZ
W59 x Tb-5La PP ZZ
SD10 x Tb-65a PP ZZ
W10 x Tb-6Lc ZZ PZ
SD10 x Tb-6Lc PP PZ
W59 x Tb-7Lb PP ZZ
W59 x Tb-8Lb PP ZZ
W59 x Tb-9La PP ZZ
W59 x Tb-10Sc PP PZ
Oh51A x Tb-10Sc ZZ PZ
W59 x Tb-10La PP PZ
Oh51A x Tb-10La ZZ PZ
W64A x Tb-10La CZ PP
Table 6. CAT-2 variants of the inbred strains and B-A translocations used
59

Cross
CAT-1 variants observed in scutellum of F, and backcross
progeny
Female male ZZ PZ PZZ PP Total
R6-45 Tb-lSb 36 7 9 52
R6-49 Tb-lSb 46 8 17 71
W5 9 Tb-lLa 21 21
V5 9 Tb-2S-3L6270 24 24
W10 Tb-1Sb-2L4464 50 50
W5 9 Tb-15b-2L4464 21 21
R6-45 Tb-35b 21 21
W5 9 Tb-3La 50 50
W5 9 Tb-95b-4L6504 21 21
SD10 Tb4 Sa 16 16
W5 9 Tb-1La-55804 1 21 21
W59 Tb-5 La 28 28
SD1 0 Tb-6Sa 21 21
W10 Tb-6Lc 9 12 21
SD10 Tbfi Le 12 10 22
W5 9 Tb-7 Lb 21 21
W5 9 Tb-8Lb 20 20
W5 9 Tb-9La 20 fi0
W5 9 Tb-1 0Sc 18 22 40
Oh5 1A Tb-10Sc 38 36 74
W5 9 Tb-10La 50 45 95
Oh51A Tb-1 0La 71 108 179
W64A Tb-10La 17 17
Table 7. The CAT-2 phenotypes observed in F1 progeny of crosses made between B-A
translocations, as males, and inbred strains as females
60

t ;Z 3 4 5 6 7 8
9 10 11 12 13 14
Fig.16a-c. a Schematic drawing
of 1) CAT-2Z, 2) CAT-2P, 3)
CAT2PZ and 4) CAT-2ZZP. b
Progeny from the cross R6-49
X Tb-lSb (CAT-2PP X CAT-
2ZZ) showing the
nondisjunction phenotypes
expected. No. 6 CAT-2Z
control, 7 CAT-2P control, 1
and 10 are CAT-2ZZP, 4 and
15 are CAT-2P, 2, 3, 5, 8, 9,
11, 12, 13 and 14 are CAT-
2ZP. c Nondisjunction
phenotypes CAT-2P and
CAT2ZZP observed in the
cross R6-49 X TblSb. CAT-2P
control, CAT-2ZP, CAT-2ZZP,
CAT-2P, CAT-2Z control
58

Table 8. CAT-3 variants of the inbred strains and B-A translocations used
61

Cross
CAT-3 variants observed in coleoptile tissue of F, and
backcross progeny
Female Male AAB AA AB BB Total
W59 Tb-lLa 17 15 5 37
W59 Tb-1Sb-2L4464 21 21
W59 Tb-3La-256 270 21 21
W59 Tb-3La-2S6 270 10 13 23
W59 Tb-3La 21 21
W59 Tb-3La 39 34 73
W59 Tb-9Sb-4L6504 21 21
W59 Tb-1La-5 S8041 21 21
h'59 Tb-5La 21 21
W59 Tb-5 La 36 36
W59 Tb-7Lb 21 21
W59 Tb-8Lb 20 20
W59 Tb-9La 9 11 20
Oh51A Tb-10Sc 38 36 74
W59 Tb-10La 51 44 95
Oh51A Tb-10La 96 77 173
Table 9. The CAT-3 phenotypes observed in F1 progeny of crosses made between B-A
translocations, as males, and inbred strains homozygous for CAT-3, as females
62

Fig.17 Zymogram phenotypes observed in progeny of the cross W5 9 × Tb-1 La. The
phenotypes CAT-3B and CAT-3 AAB are phenotypes expected from non-
disjunction gametes
63

Case study 6
64
Cruz et al., 2016
Manhattan, KS
Manhattan, KS

Fig.26 Head blast reaction caused by isolate T-25 of Magnaporthe oryzae for 61
winter, 7 spring wheat cultivars (†), and 6 near isogenic lines (‡). All entries contain
the marker for the 2NS segment from Aegilops ventricosa. Entries are sorted by
disease reaction from lowest to highest. Mean reaction was 19.7%
65
Manhattan, KS Cruz et al., 2016

Fig.27 Head blast reaction caused by isolate T-25 of Magnaporthe oryzae for 169 winter
wheat lines that do not contain the marker for the 2NS segment from Aegilops ventricosa.
Mean was 39.7%
66

Fig.28 Head blast reaction caused by isolate T-25 of Magnaporthe oryzae for 175 spring
wheat lines that do not contain the marker for the 2NS segment from Aegilops ventricosa.
Six parents of isogenic lines and one susceptible check Glenn without the 2NS segment
are labeled with †. Mean reaction was 71.1%
67

Fig.29 Head blast reaction of selected winter wheat cultivars to two isolates (T-25 and B-71)
of the Triticum pathotype of Magnaporthe oryzae; cultivars followed by a plus sign (+)
contain the 2NS chromosome segment. Means with an asterisk (*) showed that B-71
caused significantly (p < 0.05) higher disease than T-25 on all cultivars except the
susceptible check Everest, which was already at 100%
68

Fig.30 Head blast
reaction of near-
isogenic spring
wheat lines with or
without the 2NS
chromosome
segment to
inoculation with
isolates T-25 (a), B-
2 (b), B-71 (c), and
P-3 (d) of
Magnaporthe oryzae
Triticum pathotype
under greenhouse
conditions. Means
with an asterisk (*)
on isolines with 2NS
are significantly (p <
0.05) different from
their corresponding
isogenic parent.
69

Fig.31 Foliar blast reaction of near-
isogenic spring wheat lines with or
without the 2NS chromosome
segment after inoculation with
isolates T-25 (a), B-2 (b), and B-71
(c) of Magnaporthe oryzae Triticum
pathotype under greenhouse
conditions. Means with an asterisk
(*) were significantly (p < 0.05)
different from their corresponding
isogenic parent
70

Fig.32 Field reaction of spring wheat lines with
or without the 2NS chromosome segment to
head blast in Bolivia during 2014 in two
locations at the Quirusillas municipality (a
and b), and 2015 in one location at
Quirusillas (c). South American (S) and
North American (N) cultivars with known
reaction to wheat head blast were included as
checks. Means with an asterisk (*) were
significantly (p < 0.05) different from their
corresponding isogenic parent
71

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