Transfer of pest resistance from wild Triticum and Aegilops species into cultivated wheat species.
Harjit Singh, H.S. Dhaliwal, Khem Singh Gill, Jaswinder Kaur, and Tajinder Singh.
Under a recently concluded US-India Fund sponsored
project, `Cataloguing and Prebreeding of Wheat Genetic Resources',
efforts were made to transfer the new variability identified for
leaf rust, stripe rust, powdery mildew, Karnal bunt, and cereal
cyst nematode resistance into the background of the cultivated
species T. durum and T. aestivum. Successful transfer
of the desired variability was made in many interspecific crosses.
In others, the material is in advanced generations.
Leaf rust resistance was transferred successfully
from six different accessions of T. araraticum (AG) into
rust-susceptible T. durum lines. The seedling reactions
of the six different individual pathotypes of leaf rust indicated
their diversity with respect to the gene(s) for resistance. Two
of the resistant derivatives are expected to have received adult
plant resistance gene(s) from the donor parent. The other alien
disease-resistance genes transferred to susceptible T. durum
include stripe rust resistance and powdery mildew resistance from
T. araraticum (two accessions each), leaf rust resistance
from T. urartu, and stripe rust resistance from T. dicoccoides.
Stripe rust resistance also has been transferred from T.
dicoccoides into the susceptible T. aestivum.
Since the U- and C-genome Aegilops species
have been found to be sources of multiple disease resistance,
T. durum-Aegilops species amphiploids have been
developed to transfer leaf rust, stripe rust, powdery mildew,
and cereal cyst nematode resistances from Ae. umbellulata
(U) and leaf rust, stripe rust, and cereal cyst nematode resistances
from Ae. caudata (C) into susceptible lines of T. durum.
Two T. durum-Ae. squarrosa amphiploids also
were synthesized to transfer leaf rust and Karnal bunt resistance
from resistant accessions of Ae. squarrosa into
susceptilble backgrounds of T. durum. The work to transfer
disease resistance from these amphiploids into susceptible T.
aestivum cultivars is in progress.
Alien substitution lines carryinq leaf rust and stripe
rust resistance from Ae. ovata (UM) and Ae. triuncialis
into the background of susceptible, but widely adapted, Indian
spring bread wheat cultivar WL 711 have been developed. Testing
of BC2/BC3 progenies of the crosses of Ae. ovata and Ae.
triuncialis with WL 711 has indicated that these progenies
carry resistance to the Punjab population of cereal cyst nematode.
The materials in advanced generations and the interspecific
derivatives could be useful for the molecular tagging of desirable
traits, facilitating their further transfer and pyramiding.
Prebreeding of T. aestivum cultivars WL 711 and HD 2329.
H.S. Dhaliwal, Harjit Singh, and Tajinder Singh.
In a backcrossing program, useful variability for
16 traits was transferred from 22 different genetic stocks into
the background of two agronomically superior and widely adapted
Indian spring wheat cultivars, WL 711 and HD 2329. The characters
transferred included yield components and other useful morphological
characters; non-necrotic genes (ne1 and ne2); quality
traits like high protein content; the high-molecular-weight glutenin
subunits associated with high breadmaking quality; and genes for
resistance to leaf rust, stripe rust, Karnal bunt, and powdery
mildew. These backcross derivatives now are being utilized to
combine resistance to more than one disease with other desirable
genes transferred to these two cultivars. Isogenic lines for various
traits, developed in the background of these two cultivars, also
will be useful for the molecular tagging of agronomic, quality,
and disease resistance genes. These will be particularly useful
for characteristics like protein content, seed weight, sprouting
tolerance, and resistance to Karnal bunt.
MARATHWADA AGRICULTURAL UNIVERSITY
Wheat and Maize Research Unit, Parbhani - 431 402, Maharashtra,
India.
K.A. Nayeem and C.B. Latpate.
The major problem limiting yields in the warmer regions
is high temperatures coinciding with the critical stages of the
crop and a short winter season (about 14 days to 2 months). To
overcome the problem of high temperatures, efforts are underway
at Marathwada Agricultural University, Parbhani, to breed high
temperature-tolerant varieties with the use of wild species and
land races of T. durum and T. dicoccum species.
The physiological parameters, i.e., cell membrane thermostability,
total chlorophyll stability, stomatal aperture index, stomatal
frequency, and leaf temperature differential, were studied (Anonymous
1990). The quick method of counting stomatal frequency and size,
described by Nayeem and Dalvi (1989), provided a simple technique
for screening the wheat varieties against high temperature conditions.
Leaf temperature differential also was found to be a cheap and
convenient method for screening high temperature-tolerant cultivars
or lines of wheat and is presented here.
The wheats were from a series of lines that were
selected from crosses involving T. durum with T. dicoccum,
T. timophevii, T. carthilicum, and Parbhani T. dicoccum
mutants from land races of T. dicoccum exposed to a 40
Kr dose of gamma rays. All these were grown in a trial consisting
of 36 genotypes with three replications in a balanced lattice
design. The leaf temperature (3rd from the top, excluding the
flag leaf) after flowering was recorded with the help of a digital
thermometer processing probe. The mean temperature differential
(MTD) refers to the difference between the ambient temperature
and the leaf canopy temperature in degrees celcius (Table 1).
Table 1. Mean leaf temperature differentials (_C) among wheat crosses.
_______________________________________________________________
No.of Group
Crosses lines I II III
_______________________________________________________________
T. durum x T. durum 10 Nil 6 4
T. durum x T. timophevii l0 1 5 4
T. carthilicum x T. durum l0 1 2 7
T. timophevii x T. durum 10 1 5 4
T. dicoccum x T. durum 12 6 2 4
T. dicoccum land race 1 1 ó ó
T. dicoccum mutants 2 2 ó ó
T. aestivum (checks) 5
ó ó 5
TOTAL 58 12 20 28
_______________________________________________________________
The analysis of variance and the estimate of heritability
values were worked out as per the procedure outlined by Hensen
et al. (1956).
Results indicated three genotype groups as follows:
I. Low (minus C and less than 1.5_C temperature differential),
II. Medium (1.5 to 5.0_C temperature differential), and
III. High (greater than a 5_C temperature differential).
The distribution, mean, and range of each group are
presented in Table 2, and the results of an analysis of variance
are in Table 3.
Table 2. Distribution of wheat derivatives for leaf temperature differential.
_________________________________________________________________
Group No.of lines Mean temperature differential
in degrees C
____________________________________
Range Mean
_________________________________________________________________
I (Low) 12 -2.51-0.62 -1.05 ± (0.02)
II (Medium) 20 1.5l-4.81 2.16 ± (0.89)
III (High) 28 5.62-14.16 8.65 ± (2.12)
_________________________________________________________________
Table 3. Analysis of variance for interspecific groups of wheat for leaf temperature differential.
_____________________________________________________________________________
Group Source d.f. MSS F Heritabity
(%)
_____________________________________________________________________________
I (Low) Replication 2 2.67 21.25
Lines 11 7.06 8.57**
Error 22 0.82
II (Medium) Replication 2 0.90
Lines 19 6.12 6.00** 71.61
Error 38 1.02
III (High) Replication 2 0.085
Lines 27 11.43 8.34** 62.51
Error 54 1.37
_____________________________________________________________________________
Out of the three groups studied for mean temperature
differential, five lines of group I exhibited a mean temperature
differential of -l.05 ± 0.02 and range between -2.51 to 0.62_C.
We infer that T. dicoccum possesses heat-tolerant genes,
because the leaf temperature is much less than the ambient temperature.
Nonadditive gene action for group I and additive gene action for
groups II and III were noticed, as indicated by heritability estimates.
The two new Khapli mutants possess the desirable traits of heat-tolerant
genes and grain color, with easy threshability or brittle rachis.
References.
Anonymous. 1990. Final Report of ad hoc scheme on
ìBreeding of Wheat Varieties Tolerant to High Temperature
Conditions of Jayakwadi and Purna Command Areaî. Submitted
to ICAR CI 87/32 APH 30 (1987-1990).
Hanson CH, Robinson HR, and Comstock R.E. 1956. Biometrical
studies in yield in segregating population of Korean Lespedae.
Agron J 48:268-329.
Nayeem KA and Dalvi DG. 1989. A rapid technique for
stomatal print by `Fevicol'. Curr Sci 58(11):640-641.