Progress 10/11/01 to 10/10/06
Outputs
This project discovered that the maturity gene 3 (ma3) encodes phytochrome B. The recessive allele, ma3R encodes a shortened version of the phytochrome B protein, and the protein is not detected in plant extracts. Initial experiments showed that the mutant plants strongly over-express phytochrome A; thus, in normal (non-mutant) plants, phytochrome B must regulate the phytochrome A gene. During 2003, we conducted several experiments in which the photoperiods and thermoperiods were shifted strongly out of phase with each other. With phase shifts (photoperiod forward) of 3, 6, 9, and 12 hours, there was a progressive inhibition of shoot height and promotion of tillering for several milo genotypes. Additionally, severe phase shifts caused downward bending of the shoot. Three-hour phase shifts generally hastened floral initiation and longer phase shifts delayed it. In general, the phy B mutant was insensitive to phase shifts, although modest growth inhibition occurred.This
project, over its life time, has made major discoveries in the roles of gibberellins, ethylene, and phytochromes in the growth and development of sorghum.
Impacts
This project has opened up the potential to significantly alter plant phenotype and responsiveness to the environment through alterations in the phytochrome system and the circadian clock. Approaches, which now appear feasible, include identifying alleles of the major phytochrome genes and genes in the branch pathways controlled by phytochrome action. These allelic genes can then be used in breeding programs or transformation experiments to produce genotypes with improved characteristics. The long term impact of this project will be to help move plant physiology from its focus on a few end products with regulatory activity (hormones) to focus more attention on plastic, interactive systems whose pathways relate to one another in ways previously obscure. Use of the phytochrome B mutant and circadian treatment have been unique features of this project which have revealed dramatic growth and developmental variability in grasses.
Publications
- Finlayson, S.A., H.L. Gohil, H. Kato-Noguchi, I.-J. Lee and P.W. Morgan, 2004. Circadian ethylene synthesis in Sorghum bicolor. Expression and control of the system at the whole plant level. J. Plant Growth, Reg. In Press.
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Progress 01/01/02 to 12/31/02
Outputs
We have extended an investigation of the role of phytochrome A in shade detection using newly constructed red and far-red diode array light sources which produce narrow band width light and new antibodies for phytochrome A. These experiments confirm and extend previous findings and a manuscript is being revised to include the new data. We also conducted plant growth chamber experiments comparing the effects of shifting the thermoperiod out of phase with the photoperiod. Forward shifts of 3, 6, 9 & 12 hours progressively inhibited shoot elongation, promoted tillering and promoted negative gravitropism. The 3 hour shift promoted and the 6, 9 & 12 hour shifts progressively delayed floral initiation. These experiments are still in progress.
Impacts
Adding temperature sensitivity, specifically to the timing of the thermoperiod, will give plant breeders a new means to regulate flowering and development of grass/grain species.
Publications
- No publications reported this period
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Progress 01/01/01 to 12/31/01
Outputs
Investigation of the role of phytochrome A in shade detection and the regulation of circadianly rhythmic ethylene biosynthesis was extended. Experiments were repeated with high and low intensity light sources which had high and low red/far-red ratios. The results supported the hypothesis that in the phyB mutant line, phytochrome A perceives shade and regulates ethylene biosynthesis. The source of the substrate for the rhythmic production of ethylene was investigated by graduate student H. Gohil who found that rhythmicity persists in detached shoots but not roots. Substrate did not accumulate with time in roots nor was it depleted in shoots, all of which indicates that roots are not the sole or major source of ACC converted to ethylene in the shoot. A manuscript is in preparation.
Impacts
Overgrowth of shoots at the expense of root development & yield usually occurs in all grain crops. Understanding the role of the three monocot phytochromes & circadian ethylene production may uncover means to minimize shade avoidance in cultivars designed for modern production systems. Such cultivars should have improved yield and improved drought resistance.
Publications
- Morgan, P.W., S.A. Finlayson, K.L., Childs, J.E. Mullet and W.L. Rooney. 2002. Opportunities to improve adaptability and yield in grasses: lessons from Sorghum. Crop Science (submitted).
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Progress 01/01/00 to 12/31/00
Outputs
Investigation of the role of phytochrome A in the detection of shade was completed and a manuscript has been prepared. Phytochrome A levels are higher in the phytochrome B-deficient sorghum line (58M) than the wild-type (100M) and treatments which elevate ethylene production and shoot growth elevate the levels of phytochrome A. These findings are consistent with PhyA mRNA levels. The absence of PhyB in 58M correlates with the upregulation of the PhyA gene. PhyC mRNA is not rhythmically expressed as are PhyA and PhyB genes, and it does not differ in 58M and 100M in shade or bright light. This is the first report indicating a role of Phytochrome A in shade detection or circadian ethylene production.
Impacts
Overgrowth of shoots at the expense of root development and yield usually occurs in all grain crops. Understanding the role of the three monocot phytochromes and circadian ethylene production may uncover means to minimize shade avoidance in cultivars designed for modern production systems. Such cultivars should have improved yield and improved drought resistance.
Publications
- Morgan P.W. and S.A. Finlayson 2000. Physiology and genetics of maturity and height. In: Sorghum: Origin, History, Technology and Production. C. W. Smith and R. A. Fredericksen, eds. John Wiley and Sons, Inc., New York, NY pp 227-259.
- Finlayson, S.A., J.E. Mullet, P.W. Morgan. 2000. Phytochrome A expression is regulated by phytochrome B and it may play a direct role in shade perception. Plant Physiology (submitted).
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Progress 01/01/99 to 12/31/99
Outputs
We determined that if the temperature step up and down is sufficient in magnitude and abrupt enough, ACC pool sizes cycle indicating that an ACC synthase and an ACC oxidase gene both cycle in rhythmic ethylene synthesis. In wild-type sorghum (100M) dim, FR-enriched light will promote ethylene biosynthesis strongly if given at dawn but not so if given 3 hr later. The phytochrome B-deficient line responds similarly whether given the same light treatment at either time. These results suggest that phytochrome A, which disappears during the day in wild type plants, detects the "shade light" and signals increased ethylene production. We have found that the phy A genes are over expressed in 58M and not so in 100M. We have tentative evidence for higher levels of phy A in 58M than in 100M. A line of sorghum with phenotypic features basically opposite of those of 100M was discovered, and it fails to make detectable levels of ethylene in the shoot. Studies are underway to
characterize ACC oxidase gene expression and ABA signal transduction to determine if either is responsible for the observed phenotype.
Impacts
Rhythmic ethylene biosynthesis is associated with shade avoidance behavior which maximizes shoot and leaf growth at the expense of root development and yield. If this study can provide effective options for managing these processes, the result could increase grain yields world wide.
Publications
- Finlayson, S.A., I-J Lee, J.E. Mullet and P.W. Morgan. 1999. The mechanism of rhythmic ethylene production in Sorghum bicolor: the role of phytochrome B and simulated shading. Plant Physiology 119: 1083-1089.
- Finlayson, S.A., He, C-J., Drew, M.C., Mullett, J.E. and Morgan, P.W. 1999. Phytochrome B and ethylene rhythms in sorghum: Biosynthetic mechanism and developmental effects. pp 145-150. In: A.K. Kanellis, C. Chang, D. Grierson, H. Klee and J.C. Pech eds. Biology and biotechnology of the Plant Hormone Ethylene II. Kluwer Academic Publishers, Dordrecht.
- Morgan, P.W. and S.A. Finlayson. 1999. Physiology and Genetics of Maturity and Height. In: Sorghum: Evolution, History, Production, and Technology. C.W. Smith and R.A. Frederiksen, eds. John Wiley and Sons, Inc., New York, NY. (In Press).
- Miller F.R., J.A. Dalberg, P.W. Morgan. 1999. Registration of A3/B3 cytoplasmic male-sterile, sorghum maturity and height parental lines. Crop Sci. 39: 306-307.
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Progress 01/01/98 to 12/31/98
Outputs
We have completed investigation of the mechanism of rhythmic ethylene production. In the phytochrome B deficient mutant, daily peaks of ethylene follow peaks of ACC oxidase mRNA levels and ACC concentrations; both rhythms are almost unrecognizable in wild type. When wild-type is caused to produce peaks of ethylene due to dim, far-red light, it does not show peaks of ACC oxidase enzyme activity, but rhythmic peaks of ACC concentrations occur. Thus, the mechanisms are different, being ACC oxidase-based in the former case and ACC synthase-based in the latter case.
Impacts
(N/A)
Publications
- Finlayson SA, Lee I-J, Morgan PW. 1998. Phytochrome B and the regulation of circadian ethylene production in Sorghum bicolor. Plant Physiology. 116: 17-25 (cover illustration article).
- Lee I-J, Foster KR, Morgan PW. 1998. Photoperiodic control of gibberellin metabolism and flowering in sorghum. Plant Physiology. 116: 1003-1011.
- Lee I-J, Foster KR, Morgan PW. 1998. Effect of gibberellin biosynthesis inhibitors on native GA content, growth and floral initiation in Sorghum bicolor. J. Plant Growth Regulation 17: 185-196.
- Price HJ, Morgan PW, Johnston JS. 1998. Environmentally correlated variation in 2C nuclear DNA content measurements in Helianthus annuus L. Annals of Botany 82: 95-98.
- Finlayson SA, Lee I-J, Mullet JE, Morgan PW. 1999. The mechanism of rhythmic ethylene production in sorghum bicolor: the role of phytochrome B and simulated shading. Plant Physiology (in press, due publication in March).
- Finlayson SA, He C-J, Drew MC, Mullet JE, Morgan PW. 1999. Phytochrome B and ethylene rhythms in sorghum: biosynthetic mechanism and developmental effects. In: A.K. Kanellis, C. Chang, D. Grierson, H. Klee and J.C. Pech, eds., Biology and Biotechnology of the Plant Hormone Ethylene II. Kluwer Academic Publishers Dordrecht (In Press).
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Progress 01/01/97 to 12/31/97
Outputs
During the past year, manuscripts were prepared to report the regulation of rhythmic ethylene and gibberellin pulses or peaks in sorghum with or without the phytochrome B null mutation. Both manuscripts are in press and a third, detailing the effects of GA biosynthesis inhibitors on growth and flowering of sorghum is in an advanced draft. Rhythmic ethylene biosynthesis parallels expression of one circadian ACC Oxidase gene family member. Although no ACC synthase clone which cycles has been found, daily cycles in ACC concentrations have been observed suggesting either that ACC synthesis or conjugation is being regulated. Work on the linkage between ethylene biosynthesis and phenotype is underway.
Impacts
(N/A)
Publications
- LEGE KE, COTHREN JT, MORGAN PW. 1997. Nitrogen fertility and leaf age effects on ethylene production of cotton in a controlled environment. Plant Growth Regulation J. 22:23-28.
- FOSTER KR, LEE I-J, PHARIS RP, MORGAN PW. 1997. Effects of ring D-modified gibberellins on gibberellin levels in development and in selected Sorghum bicolor maturity genotypes. J. Plant Growth Regulation 16:79-87.
- FINLAYSON SA, LEE I-J, MORGAN PW. 1997. Phytochrome B and the regulation of circadian ethylene production in Sorghum bicolor. Plant Physiology (In Press).
- LEE I-J, FOSTER KR, MORGAN PW. 1997. Photoperiodic control of gibberellin metabolism and flowering in a phytochrome B mutant of Sorghum bicolor. Plant Physiology (In Press).
- MORGAN PW, FINLAYSON SA, LEE I-J, CHILDS KL, HE C-J, CREELMAN RA, DREW MC, MULLET JE. 1997. Regulation of circadianly rhythmic ethylene production by phytochrome B in sorghum. In A.K. Kanellis, C. Chang, H. Kende and D. Grierson, eds., "Biology and Biotechnology of the Plant Hormone Ethylene". Kluwer Academic Publishers, Dordrecht, The Netherlands. pp 105-111.
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Progress 01/01/96 to 12/30/96
Outputs
The maturity gene allele ma3R was shown to be a single base deletion which leadsto a premature stop codon in phytochrome B in genotype 58M. Gibberellin (GA) biosynthesis inhibitors which act before ent-kaurene and GA12 were shown to promote tillering, inhibit shoot growth and delay flowering in maturity genotypes varying at the Ma3 loci. These effects were reversed by GA3 . Inhibitors of the GA20 GA1 step had differential effects on 58M and non-ma3R genotypes, delaying flowering in the latter and not delaying or actually promoting flowering in the former. These compounds also failed to promote tillering in 58M. Extremely short (10h) or long (18, 20h) days altered rhythmic patterns of GA1 concentrations in non-ma3R and ma3R genotypes, respectively. The maturity genotypes produce ethylene in rhythmic, circadian peaks during the day mainly from shoot tissue. Ethylene peaks in 58M are usually 10X larger than non-ma3R genotypes. Establishing rhythmic ethylene production
requires both photoperiod and thermoperiod signals.
Impacts
(N/A)
Publications
- FOSTER, K.R., LEE, I.-J., PHARIS, R. P., MORGAN, P.W. 1997. Effects of ring D-modified gibberellins on gibberellins levels in development and in selected Sorghum bicolor maturity genotypes. J. Plant Growth Regulation (accepted).
- FINLAYSON, S.A., REID, D. M., MORGAN, P.W. 1997. Root and leaf specific isozymes of ACC Oxidase in corn (Zea mays L.) and sunflower (Helianthus annuus L.) seedlings: In vivo response to CO2 and in vitro characterization. Phytochemistry(acce CHILDS, K.
- L., MILLER, F.R., CORDONNIER-PRATT, M.M., PRATT, L.H., MORGAN, P. W., MULLET, J.E. 1997. The Sorghum bicolor photoperiod sensitivity gene, Ma3 encodesa phytochrome B. Plant Physiology (in press).
- REED, J.W., FOSTER, K.R., MORGAN, P. W., CHORY, J. 1996. Phytochrome B affects responsiveness to gibberellins in Arabidopsis. Plant Physiology 112:337-342.
- DE PROFT, M. P., MORGAN, P.W. 1995. Gibberellins from Chichorium intybus roots. Med. Fac. Landbouww. Univ. Gent, 60/3b, pp 1135-1141.
- MORGAN, P. W., et al. 1997. Regulation of circadianly rhythmic ethylene production by phytochrome B in sorghum. In A.K. Kanellis ed. "Biology and biotechnology of the plant hormone ethylene". Kluwer Acad Publ, Dordrecht, Neth.(in press).
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Progress 01/01/95 to 12/30/95
Outputs
Inhibitors acting at 3 different steps in the gibberellin (GA) biosynthesis pathway were shown to inhibit growth, delay flowering, and reduce GA levels, especially GA1 , in sorghum maturity genotypes. GA3 overcame effects of the inhibitors on growth and flowering. C-16,17 dihydro GA5 derivatives were shown to hasten floral initiation and floral development, not to alter tillering but to reduce shoot growth. The primary effect of these compounds was to inhibit conversion of GA20 to GA1. Results of both of these studies suggest that GAs play a role in regulation of flowering. Manuscripts are in preparation. Growing genotypes 58M, 90M and 100M at photoperiods which alter floral initiation altered timing of GA20 and GA1 biosynthesis rhythms. This study is being extended. Ethylene biosynthesis in the maturity genotypes was found to be circadian, originate mainly from the roots, and respond to night and day interruptions. 58M overproduces ethylene and exhibits high
aerenchyma formation in its roots. This study is continuing.
Impacts
(N/A)
Publications
- Childs K.L., K.R.Foster,I-J.Lee,J.E.Mullet,F.R.Miller,P.W.Morgan.1995.Reg. offlowering & gibberellin metabolism in phytochrome mutants ofthe short day monocot Sorghum bicolor. Prog.Abs.#380,15th Intl Conf of Plant Growth Sub. July 14-18, 19
- Foster K.R., P.W. Morgan.1995.Genetic regulation of development in Sorghum bicolor. IX. The ma3R allele disrupts diurnal control of gibberellin biosynthesis. Plant Physiology 108:337-343.
- Childs K.L., J-L.Lu, J.E.Mullet, P.W.Morgan.1995.Genetic reg. of dev.in Sorghum bicolor.X.Greatly attenuated photoperiod sens. in a phytochrome-def. sorghum possessing a biolog. clock but lacking a R-HIR.Plant Phys.108:345-351.
- Morgan P.W. 1994. Genetic regulation of flowering in Sorghum. pp. 217-226. In: Proceed.49th Annual Corn and Sorghum Industry Research Conference 1994. Amer. Seed TradeAssoc.
- Lee, I-J., K.R. Foster, P.W. Morgan. 1995. Effect of GA biosynthesis inhibitors on growth,floral initiation and native GA content in Sorghum bicolor (L.) Moench. Plant Physiol108:(Suppl):79. (ABSTRACT).
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Progress 01/01/94 to 12/30/94
Outputs
A study comparing the biological clock and the existence of a high irradiance response to red light in ma(subscript 3)(superscript R)-containing and non-ma(subscript 3)(superscript R)-containing genotypes was completed. This study also showed that >12 hour days delays floral initiation in ma(subscript 3)(superscript R)-containing genotypes; a manuscript was submitted reporting these results. A study of the effect of ma(subscript 3)(superscript R) gene dose on plant development was completed and published. We studied the diurnal pattern of gibberellin pool sizes in ma(subscript 3)(superscript R) and non-ma(subscript 3)(superscript R) genotypes and found GA(subscript 12), GA(subscript 53), GA(subscript 20) and GA(subscript 1) to be produced in a mid-day peak in a non-ma(subscript 3)(superscript R) genotype while the ma(subscript 3)(superscript R) genotype made GA(subscript 12) and GA(subscript 53) in a similar pattern and GA(subscript 20) and GA(subscript 1) in pulses
which peaked at dawn. Peaks and valleys differed by 2-fold. This study has been submitted for publication. We have used 5 gibberellin biosynthesis inhibitors to manipulate flower initiation in sorghum. Several inhibitors delayed floral initiation in non-ma(subscript 3)(superscript R) lines, and it could be restored with GA(subscript 3).
Impacts
(N/A)
Publications
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Progress 01/01/93 to 12/30/93
Outputs
Maturity gene 3 (Ma(subscript 3)) apparently codes for phytochrome B in sorghum which is absent in plants with the allele ma(subscript 3)(superscript R). The biological clock was characterized in sorghum plants varying in maturity gene 3 via expression of mRNAs for chlorophyll a/b binding protein and the small sub-unit of RUBISCO. Both mRNAs were expressed in a circadian rhythm with the same period in plants homozygous for Ma(subscript 3) and ma(subscript 3)(superscript R); however, ma(subscript 3)(superscript R) plants produced much lower-levels of these mRNAs. Additionally, decreasing the night length from 12 to 0 hours progressively delayed flower initiation in supposedly "photoperiod insensitive" ma(subscript 3)(superscript R) plants. Experiments with m(subscript 3)(superscript R)Ma(subscript 3) or ma(subscript 3)(superscript R)ma(subscript 3) heterozygous plants have demonstrated that phytochrome B is absent in ma(subscript 3)(superscript R)ma(subscript
3)(superscript R) plants, present in reduced amount in the heterozygous lines. Heterozygous plants were near in height, tillering and flower initiation/flower anthesis dates, to homozygous dominant plants suggesting partial dominance. Gibberellin levels were intermediate. GA(subscript 12), GA(subscript 20), and GA(subscript 1) have been found to cycle in levels (high during day) in 90M and 100M. Only GA(subscript 12) levels cycle in 58M. The data provide evidence for diurnal and possibly circadian regulation of GA biosynthesis in sorghum.
Impacts
(N/A)
Publications
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Progress 01/01/92 to 12/30/92
Outputs
Sorghum maturity genotype 58M, which contains a mutant gene named ma(subscript 3)(superscript R), was shown to be deficient in a type 2, phyB-like phytochrome based on detection by 3 antibodies and levels in etiolated and green plants. Genotype 58M was f to exhibit abnormal circadian clock regulation of chlorophyll a/b/ binding protein mRNA and exhibit much delayed flowering in continuous light. Absence of the phyB-like phytochrome causes 58M to flower much earlier than the short day wild type but some dark signal is necessary for such early flower initiation. These behaviors suggest roles for phyA and phyB in photoperiodism. Analysis of gibberellins through a 24 hour photoperiod revealed successive increases along the biosynthetic pathway from GA(subscript 53) onward. Levels of GA(subscript 1), the growth-activated GA, increased around dawn. End-of-day far red light treatment also appear to increase the levels of GA(subscript 53) and GA(subscript 19). Additional
replications are being analyzed to complete these studies. Measurement of leaf elongation rates shows that growth is limited to the light period in agreement with the time of maximum gibberellin biosynthesis. Crosses have been completed to generate Ma(subscript 3)ma(subscript 3)(superscript R), and ma(subscript 3)ma(subscript 3)(superscript R) heterozygous lines; they flower and grow similar to the dominant parent. Gibberellin and phytochrome analyses of these lines are in progress.
Impacts
(N/A)
Publications
- CHILDS, K.L., CORDONNNIER-PRATT, M.M., PRATT, L.H. and MORGAN, P.W. 1992. Genetic regulation of development in Sorghum bicolor. VII ma(subscript 3)(superscript R) flowering mutant lacks a phytochrome that predominates in green tissue.
- AMBLER, J.R., MORGAN, P.W. and JORDAN, W.R. 1992. Amounts of zeatin and zeatin riboside in xylem sap of senescent and nonsenescent sorghum. Crop Science, 32:411-419.
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Progress 01/01/91 to 12/30/91
Outputs
We have found that a mutant sorghum plant which is tall, does not tiller and flowers very early overproduces the plant hormones called gibberellins. The mutant also fails to demonstrate several responses controlled by the light-sensing pigment called phytochrome. Thus, the plants don't grow normally when given weak red light and they do not control synthesis of anthocyanin pigments normally. All of these abnormalities are associated with the absence of a major phytochrome pigment in the mutant, based on detection with an antibody made to pea phytochrome. Recently we found that the phytochrome missing from the mutant is a green plant or light stable phytochrome. In normal plants the unstable phytochrome decreases and the stable phytochrome remains constant when they are exposed to light. The absence of this phytochrome appears to correlate with the overproduction of gibberellins and the lack of control of flowering in the mutant plants. Work is under way to evaluate
cyclic or time keeping processes in the mutant along with daily patterns of production of gibberellins.
Impacts
(N/A)
Publications
- BEALL, F.D., MORGAN, P. W., MANDER, L. N., MILLER, F. R. and BABB, K. H. 1991. Genetic regulation of development in Sorghum bicolor. V. The ma(superscript R)(subscript 3) allele results in gibberellin enrichment.Plant Physiology 95:116-125.
- MATHEUSSEN, A. M., MORGAN, P. W. and FREDERIKSEN, R. A. 1991. Implication of gibberellins in head smut (Sporisorium reilianum) of Sorghum bicolor. Plant Physiology 96:537-544.
- CHILDS, K. L., PRATT, L. H. and MORGAN, P. W. 1991. Genetic regulation of development in Sorghum bicolor. Vi. The ma(superscript R)(subscript 3) allele results in abnormal phytochrome physiology. Plant Physiology 97:714-719.
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Progress 01/01/90 to 12/30/90
Outputs
Work to determine whether the ma R/3 allele causes elevated levels of gibberellins was completed. A manuscript reporting that sorghum plants homozygous for ma R/3 have elevated levels of GAs, have symptoms of elevated levels of GAs (longer leaf blades and leaf sheaths, reduced tillering and adventitious root formation, earlier flowering), are GA-responsive (elongation of leaf sheaths and blades, inhibition of tillering, hastening of floral initiation) and are GA-synthesis inhibitor responsive (opposite reponses to GA application) is in press. Thus the ma R/3 allele causes plants to contain elevated levels of GAs and these plants are not receptor or transduction mutants. We have further determined that the ma R/3 allele causes a mutation in the phytochrome system. Etiolated plants containing ma R/3 produce lower levels of anthocyanins when exposed to white light than plants with Ma(3) or ma(3), and phytochrome will not regulate the accumulation of the pigment in ma
R/3 plants as in the others. Further, ma R/3-containing plants do not deetiolate in red light and they contain lower levels of chlorophyll and anthocyanins when grown in white light. However, assays of photoreversible phytochrome and immunologically detected phytochrome (both from etiolated plants showed no major differences between ma R/3 and Ma(3) or ma(3) plants, excpt for the absence of a minor, presumed degradation product from the ma R/3 line only.
Impacts
(N/A)
Publications
- BEALL, F.D., MORGAN, P.W., MANDER, L.N., MILLER, F.R. and BABB, K.H. 1990. Genetic regulation of development in Sorghum bicolor. V. The ma R/3 allele results in gibberellin enrichment. Plant Physiology (in-press).
- MORGAN, P.W., BEALL, F.D., MILLER, F.R., MANDER, F.R. and BABB, K.H. 1990. A Sorghum bicolor gene increases GA concentrations in GA- and tetcyclacis-responsive plants. Plant Physiol. 93(Suppl.):5 (ABSTRACT).
- CHILDS, K.L., PRATT, L.H. and MORGAN, P.W. 1990. Three Sorghum bicolor genotypes differing in one photoperiodism gene have normal phytochrome but different R/FR light sensitivity. Plant Physiol. 93(Suppl.):130 (ABSTRACT).
- MORGAN, P.W., BEALL, F.D., BABB, K.H. and MILLER, F.R. 1990. Gibberellin-enriching gene in early sorghum genotype. Agronomy Abstracts p. 127 (ABSTRACT).
- MATHEUSSEN, A.M., MORGAN, P.W. and FREDERIKSEN, R.A. 1990. Changes in gibberellin content in sorghum panicles infected with head smut. Agronomy Abstracts p. 126 (ABSTRACT).
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