Elements of the S-gene complex II. Mutation and complementation at the SI locus in Nicotiana alata

Pandey, K. K.

doi:10.1038/hdy.1967.31

Cited by 49 publications

(43 citation statements)

References 29 publications

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“…Interallelic complementation involving the regulatory elements of the S complex has been previously reported in Oenothera and Nicotiana (Lewis, 1958;Pandey, 1967;Fincham and Sastry, 1974).…”

Section: Methodsmentioning

confidence: 99%

Further evidence for egg transformation in Nicotiana

Pandey

1980

Heredity

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SUMMARYTransformation of the egg by irradiated pollen has now been achieved in all five Nicotiana species tested, using self-compatible as well as self-incompatible species as the female parent. The self-incompatibility gene (S) and flower colour and pollen colour genes have been transferred in this manner. In one species combination, N. bonariensis 9 (n = 9) x N. glauca (n = 12) donor, the transformed progeny having an S allele from the donor parent, were fertile and fully maternal in general morphology and chromosome number. Sexual hybrids are morphologically distinct from both parents and are completely sterile. This rules Out the possibility that any pollen may have escaped the lethal dose of radiation and achieved normal fertilisation.Transformation may occur in association with parthenogenetic diploidy, or a second, normal fertilisation by unirradiated pollen. The transferred gene may be expressed in the first (Ti) generation or may be suppressed until the following sexual generation (T2). The observations suggest that a major gene closely linked with the S locus promotes development of the S transformed egg into a viable diploid seed, thus aiding recovery of transformed progeny. On the reasonable assumption that the S locus is only one of several genes that are transformed together in one act of pseudofertilisation it is suggested that the S locus may be used as a selection marker in the practical application of egg transformation in plant improvement.

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Section: Methodsmentioning

confidence: 99%

Further evidence for egg transformation in Nicotiana

Pandey

1980

Heredity

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“…of the fragment functions, thereby circumventing inhibition of pollen tube growth. In other studies, however, 11 out of 24 self-compatible mutations in Nicotiana alata were found to be free of centric fragments (12), although Pandey (4) has argued that chromosomal fragments may be inserted into the normal karyotype and carried there rather than on centric fragments. This may indeed be the case, but since centric fragments have never been associated with induced self compatibility in any species outside the Solanaceae (12), and Lewis (13) has presented evidence that they do not occur in Oenothera organensis (Onagraceae), we must conclude that they are not inevitable associates of S allele mutations.…”

mentioning

confidence: 99%

“…They postulated that these fragments carried an S allele which interfered with the functioning of the normal S allele, thus inducing the self-fertile condition. Another view is that these fragments may serve also (or instead) to complement a genome which contains an otherwise lethal mutation and it is this mutation which causes the self-compatibility (4). More recently, de Nettancourt et al (11) presented the very interesting hypothesis that centric fragments in Nicotiana alata may contain a nucleolar organizing region and, while the normal n.o.r.…”

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confidence: 99%

“…The stigma of Oenothera organensis will accommodate nearly 5,000 pollen grains, a fact which allowed Lewis (3) to screen 65 x 106 pollen grains for mutants in the S allele. Taking advantage of the small pollen grains and large stigmatic surfaces of Nicotiana alata, Pandey (4) found that over 17,000 pollen grains could be screened in each pollination. These large numbers allow rare mutational events to be detected and their frequencies to be measured with great accuracy.…”

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Self-incompatibility systems as bioassays for mutagens

Mulcahy¹,

Johnson²

1978

Environ Health Perspect

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Many flowering plants are unable to set seeds with their own pollen because a system known as gametophytic self-incompatibility is operating. The basis of this system is a single multiallelic locus S, and if the S allele carried by a pollen grain matches one of the two S alleles carried in the style, as it is certain to do upon self-pollination, then pollen tube growth is inhibited. Should one of the self-pollen grains carry a mutated S allele, however, it would not match either of those carried in the style and would therefore, not be inhibited. Gametophytic self-incompatibility thus provides a mechanism for discriminating between such mutant and nonmutant pollen grains. Knowing the numbers of pollen grains available to the stigma, and also the numbers of seeds produced, it becomes possible to estimate the frequency with which mutations occur at the S locus. Assay systems of mutagenesis which employ gametophytic self incompatibility will allow very large numbers of pollen grains to be screened for S allele mutants, which should indicate the mutagenicity of the environment. These systems have the added benefit that screening is done by the stylar tissues, rather than technicians. Finally, they may be used to construct largely autonomous assay systems which would provide continuous monitoring of the environment.Flowering plants have evolved a variety of mechanisms which insure that accidental selfpollination is not followed by self-fertilization. Such mechanisms are known as self-incompatibility systems and generally function by preventing either the germination or the tube growth of self pollen. Gametophytic forms of self-incompatibility, certainly the most widespread type in existence, are so named because their function basis is the haploid, or gametophytic, genotype that is carried within the individual pollen grains.In the simplest case of gametophytic selfincompatibility, a single multiallelic locus, S, controls the reaction between pollen and style. If the S allele in the pollen matches either of the two S alleles in the stylar cells, pollen tube growth is inhibited. It is important to note that, with this form of self-incompatibility, pollen grains from a single plant differ in their incompatibility type; this fact provides the basis of a system for monitoring environmental mutagenesis. If a plant possesses a rigorous form of gametophytic self-incompatibility, numerous self-pollinations, involving many millions of pollen grains, will not result in a single seed, unless, however, the S allele carried by a particular * Department of Botany, University of Massachusetts, Amherst, Massachusetts 01003.December 1978 pollen grain has mutated. In that case, the pollen S allele will not match those of the style, and pollen tube growth will proceed normally, resulting in fertilization and the formation of a seed. Determining the numbers of seeds resulting from pollination by a known number of pollen grains provides a good measure of mutation rates at the S locus.

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“…After mutagenic treatment, three types of genetic changes (generation of a new S-allele, self-compatibility mutations associated with the presence of a centric fragment, self-compatibility mutations not associated with a centric fragment) may theoretically be expected to express themselves in the pollen grains (Lewis, 1946(Lewis, , 1948(Lewis, , 1949(Lewis, , 1951Pandey, 1956Pandey, , 1965Pandey, , 1967bPandey, , 1969cPandey, , 1970aPandey, , 1970bBrewbaker and Shapiro, 1959;Brewbaker and Emery, 1960;Brewbaker and Natarajan, 1960;Hoffmann, 1971;de Nettancourt et al, 1971;Hogenboom, 1972). These mutations are automatically selected after selfing and sorted out with relative ease in the next generation.…”

Section: Introductionmentioning

confidence: 99%

The effects of different mutagens on self-incompatibility in Nicotiana alata Link and Otto

Gastel¹,

Nettancourt²

1975

Heredity

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SUMMARYPollen mother cells of J'Iicotiana alata were exposed to acute doses of X-rays or fast neutrons and, at anthesis, the pollen produced was used to pollinate unirradiated plants of the same clone. The results indicate that fast neutrons are slightly more effective than X-rays for inducing self-compatible pollenpart mutations but that neither fast neutrons nor X-rays have the capacity to generate new self-incompatibility alleles. An unexpectedly high fraction of the self-compatibility mutations induced does not display the centric fragment which usually characterises such mutations. The ratio of fragment to non-fragment self-compatibility mutations of fast neutrons is identical to that of X-rays. The possible use of permanent self-compatibility mutations for production of F1 hybrid seed is discussed.

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Elements of the S-gene complex II. Mutation and complementation at the SI locus in Nicotiana alata

Cited by 49 publications

References 29 publications

Further evidence for egg transformation in Nicotiana

Further evidence for egg transformation in Nicotiana

Self-incompatibility systems as bioassays for mutagens

The effects of different mutagens on self-incompatibility in Nicotiana alata Link and Otto

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