Abstract
Reduced height
(
Rht
)-
1
and
Photoperiod
(
Ppd
) have major effects on the adaptability of bread wheat (
Triticum aestivum
) to specific environments.
Ppd
–
D1a
is a photoperiod insensitive allele that reduces time to flowering. The gibberellin (GA) insensitive alleles
Rht
–
B1b
and
Rht
–
D1b
shorten plant stature and were important components of the ‘green revolution’. Two additional
Rht
–
B1
alleles were recently identified that contain a 160 or 197 bp insertion upstream of the coding region and may affect plant height or GA sensitivity Wilhelm et al. (Theor Appl Gen doi:
10.1007/s00122-013-2088-7
,
2013b
). We determined the frequency of the five alleles in a worldwide core collection of 372 wheat accessions (372CC) and estimated their effects on height, days to heading, and GA sensitivity when the collection was grown in pots outdoors or in the glasshouse. This revealed that each allele was widespread geographically with frequencies ranging from 0.12 to 0.25.
Ppd
-
D1a
was associated with significant (
p
≤ 0.05) reductions in days to heading and height relative to photoperiod sensitive
Ppd
-
D1b
. Relative to wild type,
Rht
-
B1b
and
Rht
-
D1b
each resulted in significant reductions in height (approximately 30 %) and GA sensitivity. The 160 and 197 bp alleles were associated with significant height reductions of 18 and 12 %, respectively, and with non-significant reductions in GA sensitivity relative to wild type. Two statistical methods were developed and used to estimate GA sensitivity of the 372CC accessions, but novel GA insensitive alleles were not identified. Further characterization of the
Rht
-
B1
insertion alleles is required, but our results suggest these may enable fine adjustments in plant height.