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Wheat Information
Service
Number 74: 22-24 (1992)
Hybrid
necrosis in bread wheat. III.
R. P. Singh, I. Singh and R. K. Chowdhury
Department of Plant Breeding Haryana Agricultural University,
Hisar-125004, India
Hybrid necrosis is the pre-mature gradual death of leaves and leaf
sheaths in certain crosses of wheat and is the major barrier in
combining desirable traits into hybrid combinations. Based on the
earlier studies, two complementary ganes, namely, Ne1 and
Ne2 when brought together in hybrid combination, either in
homo- or heterozygous form, cause necrosis (Hermsen 1963). The degree
of necrosis in F1 plants varies depending on the multiple
alleles (s, m and w) of these two genes (Ne1 and Ne2).
Hermsen (1963) has given 0-9 grades of necrosis in F1
hybrids depending on different combinations of the three alleles of
Ne1 and Ne2 genes as:
0-3 Weak necrosis (Hybrids produce normal seeds)
3-6 Moderate necrosis (Hybrids produce pre-mature seeds)
6-9 Severe (No seed obtained from hybrids)
Indian varieties have been reported to be generally having Ne1
gene, while Mexican varieties are supposed to have Ne2
gene (Gill et al 1969, Anand et al 1969, Chowdhury 1981, 1983).
Because of these reasons, many times it becomes cumbersome to combine
desirable traits of Indian varieties with that of Mexico, if the
genotypes in combination have Ne1 and Ne2 genes,
respectively. This problem has already been experienced in case of
variety C306, which is one of the top drought tolerant varieties and
has good quality grains. Since it carries
Ne1 gene many of the crosses to Mexican varieties with Ne2
gene fail, though some way-outs have been suggested to overcome
the necrosis in F1 generations of the crosses (Dhaliwal et
al. 1986).
While breeding of high yielding and drought and rust resistant
varieties, we at Haryana Agricultural University are attempting a
number of crosses in bread wheat every year and screening their
hybrid generations. We came across many of the crosses showing
necrotic behaviour in F1 generation. We have already
published two lists of such crosses (Chowdhury, 1981, 1983). Here we
have compiled the third list of bread wheat crosses showing necrosis.
Depending on the gene combination we have sorted out wheat genotypes
having Ne1 or
Ne2 genes.
Other varieties have also been listed which have given indication of
non-carrier of either Ne1 or Ne2 or both
(Table
1). The data on
morphological features like plant height and number of leaves (green
as well as dry) per tiller of some of the necrotic F1
hybrids have been given in Table
2.
The observations made on these necrotic F1 hybrids showed
that the yellowing of leaves started at 2-3 leaf stage and most of
the hybrids died at the 5-6 leaf stage without producing ear, showing
the characteristic of severe necrosis of grade 7 as described by
Hermsen (1963).
It is well established that Indian variety C306 carries Ne1
gene. Therefore, the varieties like IWP72, WH331, UP262, P488,
Raj 939, CBS289, cm 58803, cm 59376, cm 66675, CBS102, PC89, WL410,
Kalyansons, which have produced necrotic hybrids with C306, carry
Ne2 gene. Similarly, the variety GP104 which give normal
plants with C306 but showed necrosis with above listed varieties must
have Ne1
gene. Other varieties like GP106, WH157 and AP105 also gave
indication of having Ne1 gene in their genotypic background.
The crosses involving WH331 showed less necrosis, indicating that
this variety may be having m or w allele of Ne2 but it needs
further confirmation. There were varieties like WH157, IWP72 and
WL410 which were earlier reported to be non-carrier of necrotic
genes, have now been identified having Ne1 (WH157) and
Ne2 (WL410 and IWP72) genes. These information will be of
importance to be wheat breeders and geneticists in their
hybridization programme.
References
Anand SC, Gill BS
and jain FP (1969)
Necrosis in intervarietal crosses of wheat. Indian J Genet 29:
131-134.
Chowdhury RK (1981) Hybrid necrosis in wheat. Wheat Inf Serv 53:
40-42.
Chowdhury RK (1983) Hybrid necrosis in wheat. Wheat Inf Serv 57:
9-11.
Dhaliwal HS, Sharma SK and Randhawa AS (1986). How to overcome hybrid
necrosis in wheat. Wheat inf Serv 61/62: 27-28.
Gill KS, Vasudeva DR, Dhai BS
and Gupta ML (1969)
Necrosis in hybrids of Punjab variety C306 and Mexican varieties of
wheat. PAU J Res 6: 8-13.
Hermsen JG Th (1963) Hybrid necrosis as a problem for wheat breeder.
Euphytica 12: 1-16.
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