ITEMS FROM THE RUSSIAN FEDERATION
ALL-RUSSIAN INSTITUTE OF AGRICULTURAL BIOTECHNOLOGY -ARRIAB
Timiryazevskaya ul. 42, Moscow, 127550, Russia.
The problem of female fertility and some possibilities to improve Triticum aestivum L. x T. timopheevii Zhuk. hybrids at the first backcross.
V.F. Kozlovskaya and M.M. Starostenkova.
Introgressive hybrids are known to be characterized
by a self-sterile first generation, and progeny usually is obtained
by backcrossing. This undoubtedly important stage is the least
studied step in the introgression of alien genetic material into
cultivated wheat, because of parental incompatibility and low
F1 hybrid production. In our experiments, we have overcome the
incompatibility between T. aestivum and T. timopheevii.
The main objectives of this study were to analyze variation in
the first backcross, determine factors to correct them, and ascertain
the reasons for infertility in F1 `T. aestivum x T.
timopheevii' hybrids using cytoembryological techniques.
Six bread wheat cultivars, derived from different
ecological areas, were used as maternal and recurrent parents.
Triticum timopheevii var. viticulosum, K-47793,
was used as a pollinator. Backcrosses were by conventional methods
(a one-time pollination at the beginning of flowering) and also
using an optimum pollinating regime. The optimum pollinating time
was determined by comparing the BC1 effectiveness after twofold
pollinating (on the first (I) and third (III) days and on the
second (II) and fourth (IV) days from the hybrids' anthesis)
concurrent with daily pollinating (IV) in experimental conditions.
The same set of hybrids was backcrossed using conventional (4
seasons) and optimum pollinating (3 seasons) regimes during 4
and 3 seasons, respectively. An analysis of variance was made
on the experimental data.
After conventional backcrossing, an analysis of variation
showed that the prevalent contribution to phenotypic variability
belonged to environmental factors. The average proportion of the
environmental contribution exceeded that of `genotype'
and `genotype x environment' interaction by 3.7 times.
Consequently, an increase in BC1F1 seed set after conventional
backcrossing was due to positive modifications. We hypothesize
that the environment affected the results through anthesis dynamics.
Optimizing a pollinating regime according to flowering dynamics
could lead to a reduction in environmental effects and to an increase
in seed set. Based on the high seed set, labor, time, and material
consumption, we established that pollinating regime I, III was
optimum. This regime ensured a 1.8-times increase (from 3.3 to
6.0 %) of the results on average of the whole hybrid seed set.
This suitable pollination regime was used when six F1 hybrids
were backcrossed for three seasons. A 3.7-times increase of `genotype'
contribution and more than a 5-times (from 37.0 to 7 0 %) reduction
of the `environmental' component were found through
statistical analysis. Hence, anthesis dynamics appeared to be
environmentally dependent and impeded the reliable estimation
of the genotype's role in variation of the studied trait.
A cytoembryological analysis of six F1 `T.
aestivum x T. timopheevii' hybrids indicated
that the specific disturbance was the lack of an embryo sac. The
hybrid frequency was about 79.9 and varied from 70.4 to 97.5,
according to genotype. This abnormality in hybrid genotypes could
be due to the incapability of the megaspore egg-cell to differentiate
or to cell lysis or breaking mechanisms prior to meiosis. In any
case, these irregularities took place at the sporophyte stage,
and sterility is of a diplontic nature. However, we did not notice
this type of abnormality during a mass analysis of PMCs in meiosis
of the present hybrids. Probably, this is evidence of independent
genetic control of male and female generative sphere development.
Available embryo sacs underwent destructive changes to different
extents (5.5 % of embryo sacs) and ranged from slightly to extremely
visible: nuclei appeared as dark, formless spots on a structureless
cytoplasm background. Furthermore, 5.9 % of the embryo sacs lacked
antipodes and were referred to as structural failures. Normal
female gametophytes were observed with an average frequency of
4.8 % with a limit of variation of 0.8-11.7 %, depending
on genotype.
Consequently, the efficiency of introgression at
the most difficult stageóthe first backcrossócould
be increased greatly by obtaining a set of hybrids to indirectly
estimate the level of female fertility, (based on the results
of the optimum (I, III) regime of pollination) or directly according
to the frequency of embryo sac occurrence in the ovule. The result
will be to provide the greatest numbers of F1 seeds for breeding
and research with the use of the most suitable genotypes.
Personnel.
This year Dr. Sci. (Biol.) Vera Kozlovskaya continued
the research on introgressive hybridization of wheat species.
Marina Starostencova is a second year postgraduate student.
THE MOSCOW PEOPLE'S FRIENDSHIP UNIVERSITY
Ul. Efremova, I8, kv. 7, Moscow, 119048, Russia.
Reaction of wheat to light and length of the vegetation period.
Alexander Federov.
The adaptation of plants to environmental conditions,
resistance to pathogens and pests, and the amount and quality
of harvest are determined to a great extent by the length of the
vegetative period. What causes different lengths of the vegetation
period are not yet fully known. Although the so-called theory
of the stage development of plants (Lysenko, 1936) has been invalidated,
publications still appear where authors support this theory.
According to the theory of stage development of plants,
the type of development (winter or spring) and length of the vegetation
period (early or late ripening) are determined by vernalization,
particularly by its duration and conditions (Lysenko, 1936). This
corresponds, to a certain extent, to data from the 1930s and 1950s,
when it was discovered that winter wheat planted in the spring
from vernalized seeds (germinated seeds kept at 0-3_C for
40-60 days) yielded like a spring-planted spring wheat.
There are experimental data on the vernalization of spring wheat,
but it was believed to be of short duration (5-15 days/year)
and required higher temperatures (5-15_C) (Lysenko, 1936).
The basis of this theory disagrees with the published
data:
1. No reaction to vernalization occurs under normal
growing conditions in many spring cereals (Gypalo and Skripchinsky
1971).
2. Winter varieties will flower without vernalization
when grown under continual, intensive light (Fedorov, 1976, 1989)
or when grown first under short days for a certain period followed
by growth in long days (Rasunov 1961; Fedorov 1996).
3. A vernalization requirement is lacking under field
conditions in cereals and, in many forage grasses, all types of
plant development are lacking during the spring-summer period.
Spring and alternative plants flower and bear fruits normally
without vernalization. Winter-sown alternative and winter plants
vernalize in autumn, but do not react to vernalization in spring
and summer.
4. The alternative and winter wheats (originating
from the same geographical region) as a rule, have identical vernalization
requirements (length and conditions). In the field, their vernalization
begins and ends at approximately the same time (Fedorov 1976,
1989).
The aims of this work were to define the parameters
that influence ontogenesis and to determine the type of plant
development and the length of the vegetation period. Wheat varieties
(predominantly regionalized) differing in type of development
(winter, alternative, and spring) were crossed. The hybrids and
parental varieties were planted as nonvernalized and vernalized
seeds in the field and in the greenhouse under controlled conditions
at various day lengths: natural, 12-hour, and continuous illumination.
In the greenhouse, lights equipped with DRI 2000-6 metal-halogen
lamps and reflecting mirrors were used at the different light
regimes. Besides the standard phenological observations, differentiation
of the shoot apex was monitored.
Our results indicate that the length of the period
from germination to ear formation in F1 hybrids (winter wheat
`Lutescens 329' x spring wheat `Lutescens 62')
at a natural day length was 6 days shorter than that of the parental
spring variety. Under short-day conditions, the difference was
30 days. The reaction of F1 hybrids to vernalization was more
pronounced than that of the parental spring variety, especially
under short-day conditions. Vernalization accelerated the development
of the spring variety by 9 days at a 12-hour illumination, compared
to the natural day length, and that of the F1 plants by 20 days.
The following winter wheat cultivars were used: Lutescens
329, with the highest level of winter- and frost-hardiness;
Mironovskya 808, of medium winter hardiness; Bankuti 1201, the
least winter- and frost-hardy. The alternative wheats used were
Czech, with the highest reaction to photoperiod and of medium
winterhardiness; Surkhak 5688, a central Asian cultivar; and a
Bulgarian cultivar, 109, with the least photoperiodic response
and low frost hardiness. The spring wheat Lutescens 62, with a
low photoperiodic reaction and poor frost hardiness, was used.
The data of Table 1 suggest that hybrid F1 plants
resulting from crossing varieties of different developmental types
(spring, winter, and alternatives) are distinguished from each
other, and from the parental forms, by their reaction to light
and their response to vernalization.
In particular, the early generations from crosses
between the alternative and spring cultivars and the winter and
spring cultivars under short-day conditions significantly lag
behind the spring varieties in development. First generation hybrids
from crosses of a winter cultivar with an alternative have a greater
lag in development under short days than the hybrid plants of
the aforementioned combinations.
The F1 from crosses between winter and alternative cultivars are delayed during short, and also long (natural summer), days. After spring sowing, the F1 hybrids of crosses between winter and alternative cultivars have a long tillering stage similar to that of a winter wheat. But quite unlike a winter wheat, these cultivars form ears at the end of summer, the date depending on both the alternative and the winter cultivars. When the same alternative cultivar (Czech alternative) was crossed with different winter wheats, the duration of the vegetative period and the expression of a photoperiodic response were greater when the degree of winterhardiness was greater, i.e., in those wheats from the farthest north. In particular, the F1 of crosses between the Czech alternative and Lutescens 329 formed ears later and lagged in development more with short days than the F1 of crosses with Bankuti 1201. The degree of the photoperiodic response (a greater lag of development with short days) in the F1 was higher than in the parent alternative wheat, because of the influence of the winter parent.
Table 1. The influence of day length and vernalization on the development of the F1 from crosses between
spring (S), winter (W), and alternative (A) wheat cultivars (sown 30 April).
_________________________________________________________________________________________
Time from
emergence to
Light differentiation Heading
Cross Seed sown treatment of shoot (days) date
_________________________________________________________________________________________
(W x S) F1 Lutescens 329 x Lutescens 62
unvernalized natural 13 30.06
vernalized natural 13 5.07
unvernalized 12 h 29 24.08
vernalized 12 h 18 4.08
(A x S) F1 Czech Alternative x Lutescens 62
unvernalized natural 16 30.06
vernalized natural 14 27.06
unvernalized 12 h 27 23.08
vernalized 12 h 18 5.08
(W x A) F1 Lutescens 329 x Czech Alternative
unvernalized natural 56 20.08
vernalized natural 18 13.07
unvernalized 12 h 86 did not head
vernalized 12 h 30 did not head
(W x A) F1 Bankuti 1201 x Czech Alternative
unvernalized natural 41 1.08
unvernalized 12 h 69 did not head
(W x A) F1 Lutescens 329 x Surkhak 5688
unvernalized natural 39 29.07
unvernalized 12 h 65 did not head
(A) Czech Alternative
unvernalized natural 25 12.07
vernalized natural 14 2.08
unvernalized 12 h 52 did not head
vernalized 12 h 23 16.08
(W) Lutescens 329*
unvernalized natural 119 20.08
vernalized natural 15 13.07
unvernalized 12 h ó did not head
vernalized 12 h 29 did not head
(S) Lutescens 62
unvernalized natural 12 24.06
vernalized natural 12 24.06
unvernalized 12 h 23 26.07
vernalized 12 h 18 20.07
_________________________________________________________________________________________
* Under intensive, continuous light conditions (50-70
klx) and headed on 22 August).
Therefore, an increase in the degree of response
to photoperiod in the F1 is due to the winter cultivar. This discovery
also is supported by the fact that, unlike the alternative variety,
this F1 lags behind in development under long-day conditions,
but not as much as the winter variety.
These data suggest that plants of different developmental
types, particularly alternative and winter wheats, are distinguished
by their reaction to light. The delayed development under short-day
conditions in alternative wheats and under both long- and short-day
conditions in winter wheats is basically the same phenomenon.
Both the reaction of unvernalized alternative wheats to photoperiod
(lag of development under short-day conditions) and the winterhardiness
of winter wheats (lag of development under long- and short-day
conditions) are adaptive properties resulting from the development
of winterhardiness in the autumn.
Plant response to vernalization is determined by
their reaction to light. The more cultivars and F1 hybrids react
to vernalization, the longer the delay in development under definite
light conditions. Under long-day conditions, the F1s of the crosses
between `spring and alternative' and `spring
and winter' wheats show very low, if any, delay in development,
with no response to vernalization. The F1s of crosses between
`winter and alternative' wheats show a considerably
longer delay of development under long-day conditions and, accordingly,
acceleration of development after vernalized seed are sown. Under
short-day conditions, plants of all hybrid combinations respond
to vernalization more effectively than under long days. The lag
of development under short days is longer. In their reaction to
light and vernalization, the F1s are intermediate between the
original parent lines, but closer to that parent with the least
degree of winter hardiness.
In the duration and pattern of vernalization, the
F1s of the crosses between a winter cultivar and an alternative
show almost no difference from the parent varieties. For example,
the F1s of crosses of the winter wheat Mironovskya 808 with the
Czech alternative has a 45-day vernalization, equal to that of
the parents. However, the F1s and parents differ markedly in development
type and vegetative period, mainly because of their different
reaction to light conditions related to response to, but not the
duration and temperature conditions of, vernalization. In our
studies conducted over many years, segregation in F2 hybrids from
`spring x winter', `alternative x winter',
and `alternative x spring' wheats was always complicated
in terms of the type of development, length of the vegetative
period, and winterhardiness. Among the hybrid plants, there usually
was a complete transition from one parental variety to another
(Table 2).
Hybrid F2 plants from the crosses `Lutescens
329 x Lutescens 62' and `Lutescens 329 x Czech alternative'
were divided into nine and eight classes, respectively, according
to the duration of the vegetative period or, more precisely, the
period from the development of full sprouts to ear formation (Table
2). A daily count of the number of plants that formed ears among
the F2 hybrids from crosses between `winter x spring'
and `winter x alternative' wheats allowed us to distinguish
20 groups of plants that differed in terms of the duration of
the period from the development of full sprouts to ear formation.
In the latter cross, there were no spring plants, only alternative,
semiwinter, and winter plants.
All F2 hybrids from `alternative x spring' crosses formed ears, although not simultaneously. There were no winter plants among these hybrids. Most of the F2 plants were intermediate between the parents in terms of the duration of the vegetative period. In one experiment, the duration of the vegetative period was the same as in the spring wheat in 10 % of the plants and the same as the Czech alternative in 6 % of the plants, whereas 84 % of the plants had intermediate duration of vegetative period. Some winter wheats from Bulgaria, Hungary, Serbia, and other relatively southern regions, (including Southern Russia) planted in the Moscow District in spring all formed ears at the end of summer-autumn. In experiments conducted over many years, we found this to be true of the varieties
Bankuti 1201, Bezostaya I, Aurora, Kooperatorka, and Sava. All F2 hybrids from crosses of these cultivars with spring types usually formed ears. They are divided into 7-12 classes (10-day intervals). The vast majority of
Table 2. Distribution of the F2 hybrids by classes (10-day interval) according to the length of the period from development of full sprouts to ear formation.
___________________________________________________________________________________________
Number of plants in class
Number
__________________________________________ Number
of 40- 50- 60- 70- 80- 90- 100- 110- winter
Cross plants 49 59 69 79 89 99 111 119 plants
___________________________________________________________________________________________
Lutescens 239 x Lutescens 62 366 85 152 35 18 12 12 8 10 34
Lutescens 329 x Czech alternative 367 0 10 152 31 13 10 11 12 128
Czech alternative x Lutescens 62 320 221 99 0 0 0 0 0 0 0
___________________________________________________________________________________________
hybrid plants were intermediate between the parents
in terms of the duration of the period from the development of
full sprouts to ear formation. Usually, the duration of this period
in 50 to 60 % of the plants was longer than that of the spring
wheat by 5-15 days, in 4 % of the plants equaled that of
the spring variety, and in 8 % equaled that of the winter cultivar.
Winter wheats, ryes, Triticales, and barleys formed
ears at the same time (Fedorov 1959, 1960, 1989) at relatively
high temperatures under conditions of continuous intense illumination
(approximately 50 klk) without previous vernalization. This also
was true of F2 hybrids from crosses of `winter x spring'
types. The duration of the vegetative period varied. In F2 hybrids
of the cross `Lutescens 329 x Lutescens 62', 18 groups
of plants were distinguished that differed in the duration of
the period from the development of full sprouts to ear formation.
This period lasted 3 days in Lutescens 62 and 116 days in Lutescens
329. Among the F2 hybrids, there was almost complete transition
from one parental variety to the other.
Two photoperiodic responses occur in plants: a strongly
expressed reaction in nonvernalized plants and a weakly expressed
reaction in vernalized plants. The former determines the duration
of the vegetative period in plants of spring planting, and the
second determines the same in plants of autumn planting.
Type of development (winter, alternative, or spring)
and duration of the vegetative period are determined by the reaction
of the plants to light during the initial period (tillering),
rather than by vernalization, as was suggested by Lysenko (1936)
and Pugsley (1971). Unlike spring cereals, winter cereals (winter
and alternative) were delayed during tillering (winter wheat under
both long- and short-day conditions and alternative wheat under
short-day conditions), which enhanced their winter hardiness.
Spring wheats reacted weakly to short-day conditions.
The difference in length of the vegetative period
of wheats and other plants (as type of development, resistance
against unfavorable environmental conditions) are determined to
a great extent by delay of the transition of the shoot apex from
the vegetative to the generative phase. The vegetative phase is
the best time for the adaptation of plants to environmental conditions;
after transition to the generative phase, plants lose the ability
to adapt.
References.
Fedorov AE. 1976. On photoperiodism, wintering and
vernalization in wheat. Cereal Res Commun 4(4):419.
Fedorov AE. 1989. Fodder Plants. Moscow Nauka. 160
pp.
Fedorov AE. 1989. Physiological-genetical basis for
the type of plant development and length of the vegetation period
in wheat. Cereal Res Commun 7(2):121.
Gupalo PI and Skripchinskii VV. 1971. Physiology
of Plant Development. Moscow Kolos 224 pp.
Lysenko TD. 1936. Theoretical Foundations of Vernalization.
Moscow Selckhozgiz 94 pp.
Pugsley AT. 1971. Genetical analysis of the spring-winter
habit of growth. Austral J Agric Res 22(1):21.
Razumov VI. 1961. Environmental and Plant Development.
Moscow Selckhozgiz 368 pp.
N.I. VAVILOV INSTITUTE OF GENERAL GENETICS
Gubkin st.3, 117809 Moscow, Russia, and the Agricultural Research
Institute of the Non-Chernozem Zone, Nemchinovka, 143013
Moscow region, Russia.