Allelic diversity of genes regulating growth habit and photoperiod response in
temperate cereals maintained at the VIR germplasm collection
N.I. Vavilov Research Institute of Plant Industry (VIR)
Elena Potokina*, Nikolai Dzjubenko
* [email protected]
Among the key traits that have been involved in wheat and barley domestication was the adaptation of flowering time to different
areas. Migration of the cereal crops to regions outside its place of origin was accelerated through mutations in genes regulating
growth habit (Vrn genes) and photoperiod response (Ppd genes). Allelic diversity of the genes is a valuable source for breeders to
develop new cultivars with improved adaptive properties to address the issue of climate change.
Several Vrn and Ppd genes have been recently cloned in wheat and barley genomes:
A genome (wheat)
B genome (wheat)
D genome (wheat)
Vrn-B3
Vrn-D1
Vrn-H3
Ppd-H1
Ppd-D1
Vrn-B1
Vrn-A1
Ppd-H2
Vrn-H2
Vrn-H1
Barley genome
For the cloned Ppd and Vrn genes the gene-specific (functional) markers are available (also known as perfect or diagnostic markers).
These markers provide a unique opportunity to screen large collections of wheat and barley germplasm for allelic diversity
at the Ppd and Vrn genes, as in the example below:
Wheat Ppd-D1
(dominant / recessive allele) PCR assay
Wheat Vrn-D1
(dominant / recessive allele) PCR assay
R D
Barley Ppd-H1
(dominant / recessive allele) PCR assay
D R
D R
339
276+269
1671
997
414
288
70
The combination of Ppd and Vrn alleles has significant influence on the development pattern of wheat cultivars. Below we compared
heading date of 57 wheat varieties carrying different allele combinations of the genes under long (18 h) and short (12 h) photoperiod
conditions: D-RDD means dominant/recessive allele combination for genes: (Ppd-D1)-(vrn-A1)-(Vrn-B1)-(Vrn-D1)
48
85
Mean
±SE
±SD
Mean
±SE
±SD
80
46
Heading date (12h photoperiod)
Heading date (18h photoperiod)
75
44
42
40
38
70
65
60
55
50
Ppd-D1a(Dom)
3%
45
36
40
34
D-RDD
D-RRD
D-RDR
R-DDR
D-RRR
35
R-RDR
R-RDD
R-RRD
D-RDD
D-RRD
D-RDR
R-DDR
D-RRR
R-RDR
R-RDD
R-RRD
Gene-specific markers currently available for Ppd and Vrn genes in wheat
and barley allow breeders to manipulate consciously the original material
and to select the allele combinations that would be optimal for specific
conditions of cultivation.
Ppd-D1a(Dom)
Ppd-D1b(Rec)
Wheat genotypes carrying dominant Ppd-D1a allele
are the «champions» in heading date under short day
conditions. However, only 3% out of 160 Russian
spring wheat varieties carry the Ppd-D1a allele
58
Mean
±SE
±SD
56
Allele combinations of Ppd-H1, Ppd-H2 and Vrn-H1, Vrn-H2, Vrn-H3 genes
(DD-DDD) were investigated among 91 cultivars and breeding lines of Russian
barley germplasm using gene-specific primers. Significant association between
the allele combinations and heading date of the lines was detected. Barley
varieties that carry the dominant allele of Ppd-H1 transit to flowering much faster
comparing to other genotypes under long day conditions. Donors of the dominant
Ppd-H1 allele are valuable source for breeding of ultra-early barley varieties for
the Northern areas of Russia.
Heading date (days)
54
52
50
48
46
44
42
40
RD-DRR
RD-DDR
RD-DRD
Resume:
Molecular marker assay was employed to assess the
vernalization and photoperiod response of wheat and
barley cultivars included in Recommended List
Varieties for Russia.
DD-DRD
2%
DD-DRR
6%
RR-DRD
RD-DDD
DD-DRR
DD-DRD
RD-DRR
RD-DRD
RD-DDR
Restricted allelic variation was detected in wheat
and barley varieties currently recommended for
commercial propagation in Russia.
RD-DDD
The severe deficiency of dominant alleles of Vrn
and Ppd genes in the domestic cereal germplasm could
be replenished by involving in breeding programs new
donors of the beneficial alleles of the adaptationresponsive genes.
DD-DRD
RR-DRD
RD-DRR
DD-DRR
The dominant Ppd-H1 allele was detected only for 8% of
cultivars included in Recommended List Varieties for Russia