The genetic control of gibberellic acid insensitivity and coleoptile length in a “dwarf” wheat

The Norin-10 dwarfing genes, Rht-B1b (Rht1) and Rht-D1b (Rht2), have been used to reduce plant height and increase grain yield in wheat breeding programs worldwide. Other dwarfing genes are available to reduce plant height of wheat but little is known of their effects on grain yield. A set of random, F5-derived wheat lines containing either minor genes for reduced plant height, or major gibberellic acid (GA) sensitive Rht8 and Rht9 dwarfing genes, were obtained from 3 different populations. Environment mean yields ranged from 2.5 to 4.6 t/ha. Genotypic variation was large and significant (P < 0.05) for plant height, grain yield and its components, and kernel number and size. Approximately 30% of lines were as short as variety Hartog, while kernel number per m2, harvest index, and grain yield of the shortest GA-sensitive lines were not significantly different (P < 0.05) from the commercial semidwarf checks Janz or Hartog. Furthermore, genotypic differences in plant height were genetically correlated (rg) with variation in kernel number (rg = −0.76*), harvest index (−0.71*), and grain yield (−0.62*). These correlated effects were confirmed with retrospective selection for height and were consistent with reported height effects of Rht-B1b and Rht-D1b dwarfing genes on kernel number and harvest index in wheat. Plant height differences among GA-sensitive lines were independent of variation in seedling characteristics (r2 = 0.01–0.02 n.s.), while a number of reduced-height lines produced 50% longer coleoptiles and greater seedling biomass than Janz. These studies demonstrate a correlation between the shorter height of GA-sensitive dwarfing genes and increased grain yield, and suggest their potential for improving wheat establishment through greater coleoptile length and early vigour.

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The nature and genetic control of gibberellin insensitivity in dwarf wheat grain

Heredity ◽

10.1038/hdy.1975.66 ◽

1975 ◽

Vol 35 (1) ◽

pp. 55-65 ◽

Cited By ~ 68

Author(s):

Michael D Gale ◽

Geraldine A Marshall

Keyword(s):

Genetic Control ◽

Wheat Grain ◽

Dwarf Wheat

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Genetic analysis of coleoptile length and diameter in wheat

Australian Journal of Agricultural Research ◽

10.1071/ar04037 ◽

2004 ◽

Vol 55 (7) ◽

pp. 733 ◽

Cited By ~ 46

Author(s):

G. J. Rebetzke ◽

R. A. Richards ◽

X. R. R. Sirault ◽

A. D. Morrison

Keyword(s):

Genetic Control ◽

Genotypic Variation ◽

Soil Surface ◽

Strongly Correlated ◽

Coleoptile Length ◽

Dwarfing Gene ◽

Diallel Mating Design ◽

Different Temperatures ◽

Australian Wheat ◽

Temperature Interaction

Lack of moisture near the soil surface commonly delays sowing, reducing grain yields of Australian wheat (Triticum aestivum) crops. Deep sowing would allow growers to make use of soil moisture lying below the drying topsoil, but the short coleoptiles of semidwarf wheats reduce emergence when sowing at depths greater than 5 cm. Selection of longer, thicker coleoptiles would help in improving emergence in hard or crusted soils, or when deep sowing, yet little is known of genetic control of coleoptile size in wheat. A diallel mating design was generated from crosses between 12 Australian and overseas wheats, and assessed for coleoptile size at different temperatures (11, 15, 19, and 23°C). Repeatabilities for coleoptile diameter and length were moderate to high on an entry-mean basis (R2 = 0.48 and 0.77, respectively), reflecting large genotype and small genotype × temperature interaction variances. Genotypic variation among parents translated into large and significant (P < 0.01) differences among F1 progeny (94–142 mm and 1.56–1.84 mm for length and diameter, respectively). General (GCA) and specific combining ability (SCA), and reciprocal effects were significant (P < 0.01) for length and diameter. Baker’s GCA/SCA ratio was high (0.62–0.77) for coleoptile length but intermediate for diameter (0.38–0.64), indicating strong additive genetic control for length. Further, GCA effects and parental means were strongly correlated (r = 0.81–0.91, P < 0.01) indicating parent length to be a useful predictor of progeny performance. Coleoptile lengths for progeny derived from Rht8, Rht9, and Rht12 dwarfing gene donors were generally shorter (c. –7 to –13%) but were still an average 47% longer than coleoptiles of Rht-B1b and Rht-D1b controls. The genetic correlation for coleoptile length and diameter was small (rg = –0.25 ± 0.15n.s.) suggesting that the two traits are genetically independent. Development of wheats with longer, thicker coleoptiles should be readily achieved in selection among partially inbred families from crosses targetting improved establishment.

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Dwarf Flower Stalk in Onion: Characterization, Genetic Control, and Physiological Response to Ethephon and Gibberellic Acid

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.116.3.574 ◽

1991 ◽

Vol 116 (3) ◽

pp. 574-579 ◽

Cited By ~ 4

Author(s):

Haim D. Rabinowitch ◽

Batya Friedlander ◽

Ross Peters

Keyword(s):

Gibberellic Acid ◽

Genetic Control ◽

Slow Growth ◽

Recessive Gene ◽

Pleiotropic Effect ◽

Expression Stability ◽

Flower Stalk ◽

External Application ◽

Onion Seed ◽

Normal Flower

Recently, a dwarf scape mutant was found in `Autumn Beit-Alpha' onion (Allium cepa L.). The development of dwarf scape in onion, the genetic control of this attribute, and its response to external application of ethephon and GA3 were studied. Data from segregating populations conclusively showed that a single recessive gene, designated dw1, controls scape dwarfness in onions. Its expression is slightly modified by minor genes. Relatively slow growth and early cessation of cell elongation are the characteristics associated with scape dwarfness. A similar developmental pattern characterized emerging normal flower stalks treated with ethephon. GA3 application at 50 ppm had no effect on scape elongation of dwarf plants. In each of 3 years, dwarf genotypes always produced scapes about half the length of normal ones. The marked expression stability of the dw1 gene will facilitate its introduction into onion cultivars. Providing there is no negative pleiotropic effect, the dwarfness gene is expected to reduce lodging and, thus, improve mechanical harvest of onion seed. Chemical names used: 2-chloroethyl phosphoric acid (ethephon), gibberellic acid (GA3).

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