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Triticeae Genomics and Genetics 2011, Vol.2, No.1, 1
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grains have become one of the ideal ways in high-yield
breeding of wheat, of which has made encouraging
progress so far (Rajaram, 2002; Yen et al., 1995;
Swaminathan et al., 1966; Koric, 1973; 1980).
Multiple spikelet traits can be divided into three types,
including branch type multiple spikelet, complex
spike type multiple spikelet and straight-spike type
multiple spikelet (no branch) (Millet, 1987; Li, and
Zhao, 2000). Tibetan triple spikelet wheat (
Triticum
aestivum
L. Concv.
Tripletum
, 2n=42, AABBDD),
belonging to the straight-spike type multiple spikelet,
was a unique landrace collected in 1990’s in the Tibet
of China, with the traits of three spikes bearing on
each rachis of ear (Figure 1), while common wheat
(
Triticum aestivum
L., 2n=42, AABBDD) has only
one spike on each rachis of panicle (Figure 1) (Yan
and Yang, 1999; Yang et al., 2004). The characteristics
of triple spikelet in Tibetan triple spikelet wheat have
genetic stability, similar to the triple spikelet of the
six-rowed barley. Although the ear length of Tibetan
triple spikelet wheat is quite similar with the ordinary
ear length, the plant can bear more than 60 spikes each
ear with more than 170 spikelets as well as has the
normal tillering and full filling seed, of which the
numbers of spikes and spikelets reach 2 or 3 times
than that of common wheat (Yang et al., 2004). So far
Tibetan triple spikelet wheat is the only one of triple
spikelet wheat found in the world, which will provide
a new valuable gene resource to mine new favorable
genes as well as to develop high yield variety of wheat.
Currently, most of studies showed that the trait if
multiple spikelet (supernumerary spikelet) would be a
recessive trait, governed by one or two genes (Yang et
al., 2005; Martinek and Bednar, 2001; Peng et al.,
1998a; Millet, 1986; Pennell and Halloran 1983;
Sharman, 1967). Some of studies found that the
multiple spikelet might be dominant or partially
dominant trait inheritance controlled by one or two
genes (Sun et al., 2009; Sun et al., 2000; Chapman
and McNeal, 1971; Dencic, 1988). Also some studies
found that multiple spikelet traits could be quantitative
inheritance, usually jointly controlled by a major gene
and several minor genes (Zheng, 1994a; 1994b;
Klindworth et al., 1990a; 1990b; Millet, 1987). Previous
studies on chromosome analysis by using monomer
and nullisome of Chinese Spring had some multiple
spikelet gene mapped on the chromosomes of 2A, 4A,
5A, 7A, 2B, 4B, 2D, 3D and 6D (Peng et al., 1998a;
1998b; Zheng et al., 1994b; Yen et al., 1995), of which
there was a strong genetic effect on the chromosome
2D (Peng et al., 1998a). It has reported that the second
homology group of wheat chromosome might carry
the genes controlling trait of multiple spikelet by
studies on multiple spikelet characteristics of the
tetraploid and hexaploid wheat (Peng et al., 1998a;
Laykova et al., 2005; Klindworth et al., 1997;). Sears
(1954) found that the deletions in the chromosome 2A
or 2D of hexaploid wheat might generate LSS trait of
which the gene inhibiting this trait located on
chromosome 2DS and 2AL.
Figure 1 Phenotypes of the triple-spikelet ear and the normal
spikelet ear (Yang et al., 2005)
Note: A: An ear of TTSW; B: A triple-spikelet; C: Normal
spikelet; D: A normal ear
Previous studies of our group have shown that (Yang
et al., 2005; Yang et al., 2004) the triple spikelet trait
was no any association with the undesirable traits of
Tibetan triple spikelet having low kilo-grain weight
and low seed setting rate and so on. We obtained
excellent triple spikelet individual from the progenies
derived the triple spikelet germplasm, which possessed
multiple spikelet with more flowers and more grains
as well as high weight of 1000 grain weight and single
panicle. It has confirmed that it would be feasible to
improve the yield of wheat by the use of triple spikelet
trait, as well as found that Tibetan triple spikelet trait
was controlled by two independent recessive genes
based on genetic analysis (Yang et al., 2005; Yang et
al., 2004). However, there is no any study on mapping
on the the triple spikelet trait so far. In this study, we
employed the advanced line TTSW
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spikelet trait derived from the progenies of the cross