Myers, Oval Jr.

Rhodes, Billy B.

English

ScholarWorks@UARK

Journal of the Arkansas Academy of ScienceVolume 20 Article 91966Effect of Growth Substances on PhenotypicExpressions of the Knotted (Kn) Gene of Zea maysOval Jr. MyersUniversity of Arkansas, FayettevilleBilly B. RhodesUniversity of ArkansasFollow this and additional works at: http://scholarworks.uark.edu/jaasPart of the Botany CommonsThis article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able toread, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking priorpermission from the publisher or the author.This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academyof Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu, ccmiddle@uark.edu.Recommended CitationMyers, Oval Jr. and Rhodes, Billy B. (1966) "Effect of Growth Substances on Phenotypic Expressions of the Knotted (Kn) Gene ofZea mays," Journal of the Arkansas Academy of Science: Vol. 20 , Article 9.Available at: http://scholarworks.uark.edu/jaas/vol20/iss1/9~32Arkansas Academy of Science Proceedings, Vol. 20, 1966¦,EFFECT OF GROWTH SUBSTANCES ON PHENOTYPICEXPRESSIONS OF THE KNOTTED (Kn) GENE OF ZEA MAYSOval Myers, Jr., and Billy B. Rhodes*University of ArkansasINTRODUCTIONThe mutant gent Knotted {Kn) in Zea mays is so named becauseit is responsible for bulges and outgrowths, or so-called "knots", as-sociated with the lateral veins of the leaf blade. These knots may beclustered near the base of the blade or somewhat diffused to moredistal portions of the blade. Knofs may occur on the abaxial or adaxialsurface of the leaf, but are predominant on the abaxial surface. Thevascular bundles that pass through the knots are not disrupted nordistorted (1). The appearance of these abnormal growths, or knots, isonly one of several phenotypic effects of the gene. Other expressionsinclude dwarfing, decrease in length and increase in width of leaves,and decreased pollen production.Bryan and Sass (1) reported this gene to be a simple dominantlocated on the first chromosome between flouryj and brown-midrib2 .Nelson and. Postlethwait 1 hypothesized that knotting was due to adispersion of the cells of the intercalary meristem. According 1o theirhypothesis, meristematic cells are pushed outward as they divide, asdictated by the restraints of surrounding, differentiated cells. Othereffects, such as dwarfing, they termed "secondary" to the knotling ef-fect.Rhodes and Myers (4) found that dwarfing regularly preceeded theappearance of knots. They also found significant differences in thetime and amount of dwarfing, length and width of leaves, and the timeand amount of knotting between homozygous (KnKn) plants andheterozygous (Kn+) plants. On the basis of these findings they suggesta definite dosage effect of the Kn gene for these phenotypic expressions.Phinney (3) found that the gibberellin, GA3,induced normal growthin four Zea mays dwarf mutants, dj, d2, d3, and d5, while othergrowth substances failed to elicit such a response. He suggested thatthese GA3 -responding mutants might be controlling different steps ina biochemical pathway leading to the production of naturally occurringgibberellin similar to GA3,and necessary for normal growth.Nickerson (2) applied growth hormones to Kn mutants and succeed-ed in modifying the effects of the gene with naphthalenacetic acid andiNelson, O. E., and S. H. Postlethwait. 1963. Characterization ofdevelopment in maize through the use of mutants. II. The abnormalgrowth conditioned by the knotted mutant, (unpublished).'Assistant Professor and Graduate Student, Department of Botany andBacteriology.32Journal of the Arkansas Academy of Science, Vol. 20 [1966], Art. 9Published by Arkansas Academy of Science, 1966'33)Knotted (Kn) Gene of Zea maysgibberellic acid. Development of knots in four strains of maize carryingrhe gene was completely inhibited by daily treatment of 500 yg ofnaphtha lenacetic acid. Other effects produced by these treatmentsincluded suppression of flowering, reduction of the abnormal thicknessof knotted leaves, and the formation of flanges by the brace roots, witha single stele for the entire group. The dwarfing associated with thegene, however, was not altered by naphthlenacetic acid. Plants havingthe Kn gene were only one-half to two-thirds as tall as normal plants.The gibberellic acid, GA3,produced similar, but less pronounced, results.This study was undertaken in an attempt to clarify Nickerson'swork and to elucidate the role of certain growth hormones in modifyingthe dwarfing and knotting expressions of the knotted gene.MATERIALS AND METHODSThe material used in this study was derived from seed obtainedfrom the Maize Genetics Cooperative in 1964, and is in a genetic back-ground related to the single cross M14/W23.The growth hormone experiment diagramed in Figure 1 was con-Figure 1. Design of growth hormone experiment4T 8T 12TIAA NAA GA3 K C IAA NAA GAg K C IAA NAA GAg K C1 2 3 4 5 6 7 8 9 10 11 12 13 14 15I abc abc abc abc abc abc abc abc abc abc abc abc abc abc abcII abc abc abc abc abc abc abc abc abc abc abc abc abc abc abcIIIabc abc abc abc abc abc abc abc abc abc abc abc abc abc abcIV abc abc abc abc abc abc abc abc abc abc abc abc abc abc abcV abc abc abc abc abc abc abc abc abc abc abc abc abc abc abcExplanation of Symbols4T—four treatments GA3 (gibberellic acid)8T — eight treatments K (kinetin)12T — twelve treatments C (control)I to V—replications a — normal plants(++)1 to 15 — groups b — heterozygous plants (Kn+)IAA (indoleacetic acid) c — homozygous plants (KnKn)NAA (naphthalenacetic acid)ducted in the fall of 1965. Two hundred and twenty-five, five inchpots were prepared and placed in rows of five in the greenhouse. Theentire arrangement consisted of 15 groups, each group consisting of 15pots. On September 27, normal (++), heterozygous (Kn+), andhomozygous (KnKn) seed were planted. Plants began to emerge onOctober 3, and were later thinned to one plant per pot. Five treat-33Journal of the Arkansas Academy of Science, Vol. 20 [1966], Art. 9http://scholarworks.uark.edu/jaas/vol20/iss1/9Arkansas Academy of Science Proceedingsmerits, namely, indoleacetic acid (IAA), kinetin (K), gibberellic acid(GA3 ), naphtha lenacetic acid (NAA), and the control (C), were applied,beginning on October 6. Each treatment consisted of 10 pg. of one ofthe above substances dissolved in 1.0 ml. distilled water. The controlconsisted of 1.0 ml. distilled water. Sodium carbonate was used insmall amounts to dissolve kinetin. Each treatment was applied bymeans of a pipette to the hollow formed by the first unfolding leaf.The first five groups were given twelve treatments, one every two days,beginning on October 6 and ending on October 28. The second fivegroups were given eight treatments, beginning on October 6 and end-ing on October 20. The third five groups were given four treatments,beginning on October 6 and ending on October 12. Groups 1, 6, and11 received indoleacetic acid; groups 2, 7, and 12 received kinetin;groups 3, 8, and 13 received gibberellic acid; groups 4, 9, and 14received naphthalenacetic acid; and groups 5, 10, and 15 receivedcontrol treatments.Solutions were freshly prepared each week and stored in therefrigerator.Plant height and the number of knots were recorded every twodays after emergence for a four week period. Height was designatedas that distance from the base of the plant at soil level to the uppermostpart of the plant. A knot was counted as a single visible protuberanceon either side of the leaf blade.Source of Degrees of Sum of Mean F value F valuevariation freedom squares square found requiredTotal 224 47,653.0Replication 4 2,222.8 555.7 8.3Time Period 2 495.5 249.7 3.7 8.65Error A 8 532.3 66.5Treatment 4 16,739.5 4,184.8 49.9** 3.74Treatment x Time 8 934.4 116.8 1.3 2.90Error B 48 4,027.0 83.8Genotype 2 16,891.6 8,445.8 318.7** 4.78Genotype x Time 4 192.8 48.2 1.8 3.47Genotype x Treatment 8 862.6 107.8 4.0** 2.65Gen. X Treat. X Time 16 1,568.3 98.0 3.6** 2.15Error C 120 3,182.3 26.5**Highly significant.Table 1. Analysis of variance of height of plants treated with growthhormones.3434Journal of the Arkansas Academy of Science, Vol. 20 [1966], Art. 9Published by Arkansas Academy of Science, 1966.35Knotted (Kn) Gene of Zea maysRESULTS AND DISCUSSIONDwarfing. An analysis of variance for height is shown in Table 1.Highly significant F values were obtained for treatments, genotypes,genotype x treatment interaction, and genotype x treatment x timeinteraction. Time periods, with the exception of the genotype x treat-x time interaction, were not significant. This would seem tomentindicate that the duration of the treatments had little effect en theresults obtained.A ranking of means from all significant sources of variation isshown in Table 2. Duncan's new multiple range test was used to(q NHNIO CO<T>t^CTiCDl/3O10OaO O CO fI•*»« O CT> CT>(o C^ W rH t—t *O *"5 CO O3 CJ C^J r—i rH <—4 **5 CO CO CO CO C*3 Mr-t? i i 3u w v: i-J a> zssszzBszssss -H mmmmmmmmm a, ¦ ¦ « I 0 IIIIIIIII 0) IIIIIIIII ]?-Sli-i 4-J +-» -M 4 J 0) 4_i 4 J .M 4 i -t-J 4-J -4-J 4J -4-J |Q 4J4J4J4J+J4J4J4J4J *H5 0)P •-! i-l Or-I.-I.-I rH-H rHrt 3T! -SI I I III £ I I I I I I I I I T) III I II I I I ><£ wi -s « gI ttt £&££&& tt£t3333£ |H Ox a.ai uooot^-rH^oot^r- oi^nidiohoidn a>d) ¦•••••••¦ ¦•••••¦•• "*"_? mC SSSSSSSSS OOOOOUOOO UiliL<i^U CCD "3 IIII III II -H I I II I IIII C I I I IQJ 4_l -M 4-1 4-1 4 ' 4- +'M 4-J >H 4-'4-'4-'4-'4-l4-'-M-M4-' -M ¦M-f-'-H^-' MhU I IIIIIIII O I*IIIIIIII U IIII «5 s&°•H C10•4-< 0)O !-,C rt)in 10C C——IS «)_^r- isIDIO *f O^ O CO OO OO <D CT> OO W O O tO LO O O C** t*^O CO CO +*•C*) CQ 03 C-3 CO G lO CO CO #O CO Ol C^3M»—Ir-i O +-1$-a ¦*->U (0 0)PI E x c c+^l +J fl> rf rf rf rfrf tt tt tt tt «~t *"<ol is 6r3t_)3o»!^Onoi-'zU<!i-i2wa m c C IIIIIIIIIIIIIII a 7;CSl £h o -h O O ftTable 2. Ranking of height means.35Journal of the Arkansas Academy of Science, Vol. 20 [1966], Art. 9http://scholarworks.uark.edu/jaas/vol20/iss1/936Arkansas Academy of Science Proceedingsdetermine significant differences between means. Genotypes weresignificantly different at the 5% level of probability. In respect totreatments, height differences between NAA, K, and IAA were notsignificant, but all three treatments produced plants significantly shorterthan control plants. Genotype x treatment means indicate that relativedifferences in height due to genotype are not eliminated by treatments.NAA, IAA, and K did not eliminate dwarfing, but GA significantlyincreased height of KnKn plants above the KnKn controls, Kn+ plantsto the height of untreated H—(- plants, and +-f- plants to approximatelyone and one-fourth their normal height. Genotype x treatment x timemeans are ranked according to treatments. The relationship of genotypeto height regardless of treatment is evident. There seems to be norelationship between genotype or treatment, and time period.Knotting. An analysis of variance for knots is shown in Table 3.Since knots occur only on KnKn and Kn+ plants, the number of plantsin the analysis is 150 rather than the 225 considered for height.Source of Degrees of Sum of Mean F value F valuevariation freedom squares square obtained requiredTotal 149 1976.3Replication 4 107.2 26.8Time Period 2 35.2 17.6 0.70 8.65Error A 8 20.9 26.1Treatment 4 276.6 69.2 4.87** 3.74Treatment x Time 135.1 16.9 1.19 2.90Error B 48 679.6 14.2Genotype 1 174.9 174.9 48.58»* 7.08Genotype x Time 2 12.1 6.1 1.69 4.98Genotype x Treatment 4 136.7 34.2 9.50** 3.65Gen. x Treat, x Time 8 179.9 22.5 6.25** 2.82Error C 60 218.1 3.6?* Highly significant.Table 3. Analysis of variance of number of knots on mutant plantstreated with growth hormones.Highly significant F values were obtained for the same means asthose for height. The duration of treatment had little effect on theamount of knotting on the plants of this experiment.36Journal of the Arkansas Academy of Science, Vol. 20 [1966], Art. 9Published by Arkansas Academy of Science, 196637Knotted (Kn) Gene of Zea maysA ranking of the means for all significant sources of variation isshown in Table 4. Since the final count of knots was made four weeksafter emergence when knotting was slight, differences in some instanceswere not discernable. Differences that are valid statistically usingDuncan's new multiple range test are shown in Table 4. All treatments4-i co «N ioe>JOeoi'C >»C OOO PJr-lt-IOOOn >H2 2 o<<< < < *^o s s s o ssssss'-M III I I III Ift) rH 0)n-M +-» -M ft) -4-J -M -M -M + J +-1 f—<•) tf N U 0O MfP> *0O Tl5o iii .a i i i i i i xK M + + si!i+ + +I•O T5no ••-<,ijPj J-3 3 3 3 3 3 3 o as 55 ss as s= z; o£ H C I O>fl> #—I CM |' ) ¦ 4-1 U) 4-1 4-1 4J 4-1 4-1 4-> i i 4-1 4-1-M 4-1 4-1 4-J -HIB »!<<>C>g t< 0 NTf NTf O Id ¦* MCD Mf00 1/15 FH • l-l <H j3fHf-H P'o III XI IIIIII IIIIII ><no -h a -mtS s5 s5 ;2uu & s2 s2 i>2 s2 j2 vs s2 w _g£tO N(O CO O <l* W rfr~cor-(^-400 t^nh\i )*4 S^ O hi—ii—IIII III i'' III-^H +J+J+J+J+J-M O -M 4-" -t-"+j Tfooc^cvj^roo 10 ooc-gooQ) r-H 0) i-H-S III III |O IIIcccccsc dec.O1 1O in CM HH ! ^«0r-(^( 0 N BH »-JXoa;Illlll "S • • • %Ih| CO VNOOM *-Ml •—I >-Hc|In f <C « 4J fCDC CVJ OO OOtMOO +-"§ Illlll 5 lllll ... £S33i§^3 s^j jS iS s5 s5 3 w« & "^O II I I Ia a .av; HH b2 t2—_^^-^— cn^rc^on oo oajooiuiDMnnn Eoton i:«(VRo P.c >W + C5<T NNHO COH C t--CO«0<H'H'-IOOOOCsHi O -HUWHOZTable(D »r w oo ooo o owCoMa.( O3 %< 333 £c¦oMh&•.Hto4-"0cOm_^____ 10S O 4-*4J cm(0 91 US T) +¦£ 10 0)El x c c15 cSl I. .,....... g^i4. Ranking of knot means37Journal of the Arkansas Academy of Science, Vol. 20 [1966], Art. 9http://scholarworks.uark.edu/jaas/vol20/iss1/938iArkansas Academy of Science Proceedingsreduced the total number of knots when compared to the control popula-tion. KnKn plants had more knots when averaged over all experi-mental situations than Kn-f plants. NAA virtually eliminated knottingon both KnKn andKn+ plants. IAA inhibited knotting to a lesser extentthan NAA, but inhibited both genotypes to about the same degree.The effects of NAA and IAA seemed to be primarily on knotting,with leaves returning to normal in respect to length and width. Plantstreated with GA3 and K had fewer knots in most instances than controlplants, but other drastic effects produced suggest that the reduction ofknotting was not due to the same mechanism involved in knot reductionby NAA and IAA. K-treated plants had necrotic leaves bearing a whitecompound, presumably the sodium carbonate used to keep K in solution.GA3 -treated plants were extremely spindly, with very long, narrowleaves.In view of the fact that NAA treatments virtually eliminate knottingwhile not eliminating dwarfing, it seems that knotting is not responsiblefor dwarfing, but that these are separate and wholly independentexpressions of the same gene or closely linked genes.SUMMARYThe growth hormones gibberellic acid, indoleacetic acid, kinetin,and naphthalenacetic acid were tested for their effect on the knottingand dwarfing expressions of the Knotted (Kn) gene in Zea mays.Naphthalenacetic acid almost completely suppressed the production ofknots. Gibberellic acid, indoleacetic acid, and kinetin reduced knottingto a lesser degree. Naphthalenacetic acid, indoleacetic acid, andkinetin did not eliminate dwarfing, but gibberellic acid significantlyincreased the height of both heterozygous and homozygous plants.LITERATURE CITED1. Bryan, Arthur A., and J. EMaize; 51 — "Knotted LeafSass. 1946. Heritable Characters inJ. of Hered. 32(10): 343-346.2. Nickerson, Norton H. 1964News L. 38:131.Kn Suppression. Maize Genet. Coop.3. Phinney, Bernard L. 1961.Relation to the Gibberellins.Dwarfing Genes in Zea mays and theirp. 489-501. In Richard M. Klein (ed.).Plant Growth Regulation. Iowa State Univ. Press. Ames, Iowa.4. Rhodes, B. B., and Oval Myers, Jr. 1966. Dosage Effects of theKnotted Gene on Growth and Development in Maize. J. of Hered.57(3):91-94.38Journal of the Arkansas Academy of Science, Vol. 20 [1966], Art. 9Published by Arkansas Academy of Science, 1966

Effect of Growth Substances on Phenotypic Expressions of the Knotted (Kn) Gene of Zea mays

UARK (University of Arkansas )

Journal of the Arkansas Academy of Science Volume 20 Article 9 1966 Effect of Growth Substances on Phenotypic Expressions of the Knotted (Kn) Gene of Zea mays Oval Jr. Myers University of Arkansas, Fayetteville Billy B. Rhodes University of Arkansas Follow this and additional works at: https://scholarworks.uark.edu/jaas  Part of the Botany Commons Recommended Citation Myers, Oval Jr. and Rhodes, Billy B. (1966) "Effect of Growth Substances on Phenotypic Expressions of the Knotted (Kn) Gene of Zea mays," Journal of the Arkansas Academy of Science: Vol. 20 , Article 9. Available at: https://scholarworks.uark.edu/jaas/vol20/iss1/9 This article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able to read, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu. ~32Arkansas Academy of Science Proceedings, Vol. 20, 1966¦,EFFECT OF GROWTH SUBSTANCES ON PHENOTYPICEXPRESSIONS OF THE KNOTTED (Kn) GENE OF ZEA MAYSOval Myers, Jr., and Billy B. Rhodes*University of ArkansasINTRODUCTIONThe mutant gent Knotted {Kn) in Zea mays is so named becauseit is responsible for bulges and outgrowths, or so-called "knots", as-sociated with the lateral veins of the leaf blade. These knots may beclustered near the base of the blade or somewhat diffused to moredistal portions of the blade. Knofs may occur on the abaxial or adaxialsurface of the leaf, but are predominant on the abaxial surface. Thevascular bundles that pass through the knots are not disrupted nordistorted (1). The appearance of these abnormal growths, or knots, isonly one of several phenotypic effects of the gene. Other expressionsinclude dwarfing, decrease in length and increase in width of leaves,and decreased pollen production.Bryan and Sass (1) reported this gene to be a simple dominantlocated on the first chromosome between flouryj and brown-midrib2 .Nelson and. Postlethwait 1 hypothesized that knotting was due to adispersion of the cells of the intercalary meristem. According 1o theirhypothesis, meristematic cells are pushed outward as they divide, asdictated by the restraints of surrounding, differentiated cells. Othereffects, such as dwarfing, they termed "secondary" to the knotling ef-fect.Rhodes and Myers (4) found that dwarfing regularly preceeded theappearance of knots. They also found significant differences in thetime and amount of dwarfing, length and width of leaves, and the timeand amount of knotting between homozygous (KnKn) plants andheterozygous (Kn+) plants. On the basis of these findings they suggesta definite dosage effect of the Kn gene for these phenotypic expressions.Phinney (3) found that the gibberellin, GA3,induced normal growthin four Zea mays dwarf mutants, dj, d2, d3, and d5, while othergrowth substances failed to elicit such a response. He suggested thatthese GA3 -responding mutants might be controlling different steps ina biochemical pathway leading to the production of naturally occurringgibberellin similar to GA3,and necessary for normal growth.Nickerson (2) applied growth hormones to Kn mutants and succeed-ed in modifying the effects of the gene with naphthalenacetic acid andiNelson, O. E., and S. H. Postlethwait. 1963. Characterization ofdevelopment in maize through the use of mutants. II. The abnormalgrowth conditioned by the knotted mutant, (unpublished).'Assistant Professor and Graduate Student, Department of Botany andBacteriology.32Journal of the Arkansas Academy of Science, Vol. 20 [1966], Art. 9Published by Arkansas Academy of Science, 1966'33)Knotted (Kn) Gene of Zea maysgibberellic acid. Development of knots in four strains of maize carryingrhe gene was completely inhibited by daily treatment of 500 yg ofnaphtha lenacetic acid. Other effects produced by these treatmentsincluded suppression of flowering, reduction of the abnormal thicknessof knotted leaves, and the formation of flanges by the brace roots, witha single stele for the entire group. The dwarfing associated with thegene, however, was not altered by naphthlenacetic acid. Plants havingthe Kn gene were only one-half to two-thirds as tall as normal plants.The gibberellic acid, GA3,produced similar, but less pronounced, results.This study was undertaken in an attempt to clarify Nickerson'swork and to elucidate the role of certain growth hormones in modifyingthe dwarfing and knotting expressions of the knotted gene.MATERIALS AND METHODSThe material used in this study was derived from seed obtainedfrom the Maize Genetics Cooperative in 1964, and is in a genetic back-ground related to the single cross M14/W23.The growth hormone experiment diagramed in Figure 1 was con-Figure 1. Design of growth hormone experiment4T 8T 12TIAA NAA GA3 K C IAA NAA GAg K C IAA NAA GAg K C1 2 3 4 5 6 7 8 9 10 11 12 13 14 15I abc abc abc abc abc abc abc abc abc abc abc abc abc abc abcII abc abc abc abc abc abc abc abc abc abc abc abc abc abc abcIIIabc abc abc abc abc abc abc abc abc abc abc abc abc abc abcIV abc abc abc abc abc abc abc abc abc abc abc abc abc abc abcV abc abc abc abc abc abc abc abc abc abc abc abc abc abc abcExplanation of Symbols4T—four treatments GA3 (gibberellic acid)8T — eight treatments K (kinetin)12T — twelve treatments C (control)I to V—replications a—normal plants(++)1 to 15—groups b— heterozygous plants (Kn+)IAA (indoleacetic acid) c — homozygous plants (KnKn)NAA (naphthalenacetic acid)ducted in the fall of 1965. Two hundred and twenty-five, five inchpots were prepared and placed in rows of five in the greenhouse. Theentire arrangement consisted of 15 groups, each group consisting of 15pots. On September 27, normal (++), heterozygous (Kn+), andhomozygous (KnKn) seed were planted. Plants began to emerge onOctober 3, and were later thinned to one plant per pot. Five treat-33Journal of the Arkansas Academy of Science, Vol. 20 [1966], Art. 9https://scholarworks.uark.edu/jaas/vol20/iss1/9Arkansas Academy of Science Proceedingsmerits, namely, indoleacetic acid (IAA), kinetin (K), gibberellic acid(GA3 ), naphtha lenacetic acid (NAA), and the control (C), were applied,beginning on October 6. Each treatment consisted of 10 pg. of one ofthe above substances dissolved in 1.0 ml. distilled water. The controlconsisted of 1.0 ml. distilled water. Sodium carbonate was used insmall amounts to dissolve kinetin. Each treatment was applied bymeans of a pipette to the hollow formed by the first unfolding leaf.The first five groups were given twelve treatments, one every two days,beginning on October 6 and ending on October 28. The second fivegroups were given eight treatments, beginning on October 6 and end-ing on October 20. The third five groups were given four treatments,beginning on October 6 and ending on October 12. Groups 1, 6, and11 received indoleacetic acid; groups 2, 7, and 12 received kinetin;groups 3, 8, and 13 received gibberellic acid; groups 4, 9, and 14received naphthalenacetic acid; and groups 5, 10, and 15 receivedcontrol treatments.Solutions were freshly prepared each week and stored in therefrigerator.Plant height and the number of knots were recorded every twodays after emergence for a four week period. Height was designatedas that distance from the base of the plant at soil level to the uppermostpart of the plant. A knot was counted as a single visible protuberanceon either side of the leaf blade.Source of Degrees of Sum of Mean F value F valuevariation freedom squares square found requiredTotal 224 47,653.0Replication 4 2,222.8 555.7 8.3Time Period 2 495.5 249.7 3.7 8.65Error A 8 532.3 66.5Treatment 4 16,739.5 4,184.8 49.9** 3.74Treatment x Time 8 934.4 116.8 1.3 2.90Error B 48 4,027.0 83.8Genotype 2 16,891.6 8,445.8 318.7** 4.78Genotype x Time 4 192.8 48.2 1.8 3.47Genotype x Treatment 8 862.6 107.8 4.0** 2.65Gen. X Treat. X Time 16 1,568.3 98.0 3.6** 2.15Error C 120 3,182.3 26.5**Highly significant.Table 1. Analysis of variance of height of plants treated with growthhormones.3434Journal of the Arkansas Academy of Science, Vol. 20 [1966], Art. 9Published by Arkansas Academy of Science, 1966.35Knotted (Kn) Gene of Zea maysRESULTS AND DISCUSSIONDwarfing. An analysis of variance for height is shown in Table 1.Highly significant F values were obtained for treatments, genotypes,genotype x treatment interaction, and genotype x treatment x timeinteraction. Time periods, with the exception of the genotype x treat-x time interaction, were not significant. This would seem tomentindicate that the duration of the treatments had little effect en theresults obtained.A ranking of means from all significant sources of variation isshown in Table 2. Duncan's new multiple range test was used to(q NHNIO CO<T>t^CTiCDl/3O10OaO O CO fI•*»« O CT> CT>(o C^ W rH t—t *O *"5 CO O3 CJ C^J r—i rH <—4 **5 CO CO CO CO C*3 Mr-t? i i 3u w v: i-J a> zssszzBszssss -H mmmmmmmmm a, ¦ ¦ « I 0 IIIIIIIII 0) IIIIIIIII ]?-Sli-i 4-J +-» -M 4 J 0) 4_i 4 J .M 4 i -t-J 4-J -4-J 4J -4-J |Q 4J4J4J4J+J4J4J4J4J *H5 0)P •-! i-l Or-I.-I.-I rH-H rHrt 3T! -SI I I III £ I I I I I I I I I T) III I II I I I ><£ wi -s « gI ttt £&££&& tt£t3333£ |H Ox a.ai uooot^-rH^oot^r- oi^nidiohoidn a>d) ¦•••••••¦ ¦•••••¦•• "*"_? mC SSSSSSSSS OOOOOUOOO UiliL<i^U CCD "3 IIII III II -H I I II I IIII C I I I IQJ 4_l -M 4-1 4-1 4'4- +'M 4-J >H 4-'4-'4-'4-'4-l4-'-M-M4-' -M ¦M-f-'-H^-' MhU I IIIIIIII O I*IIIIIIII U IIII «5 s&°•H C10•4-< 0)O !-,C rt)in 10C C——IS «)_^r- isIDIO *f O^ O CO OO OO <D CT> OO W O O tO LO O O C** t*^O CO CO +*•C*) CQ 03 C-3 CO G lO CO CO #O CO Ol C^3M»—Ir-i O +-1$ -a ¦*->U (0 0)PI E x c c+^l +J fl> rf rf rf rfrf tt tt tt tt «~t *"<ol is 6r3t_)3o»!^Onoi-'zU<!i-i2wa m c C IIIIIIIIIIIIIII a 7;CSl £h o -h O O ftTable 2. Ranking of height means.35Journal of the Arkansas Academy of Science, Vol. 20 [1966], Art. 9https://scholarworks.uark.edu/jaas/vol20/iss1/936Arkansas Academy of Science Proceedingsdetermine significant differences between means. Genotypes weresignificantly different at the 5% level of probability. In respect totreatments, height differences between NAA, K, and IAA were notsignificant, but all three treatments produced plants significantly shorterthan control plants. Genotype x treatment means indicate that relativedifferences in height due to genotype are not eliminated by treatments.NAA, IAA, and K did not eliminate dwarfing, but GA significantlyincreased height of KnKn plants above the KnKn controls, Kn+ plantsto the height of untreated H—(- plants, and +-f- plants to approximatelyone and one-fourth their normal height. Genotype x treatment x timemeans are ranked according to treatments. The relationship of genotypeto height regardless of treatment is evident. There seems to be norelationship between genotype or treatment, and time period.Knotting. An analysis of variance for knots is shown in Table 3.Since knots occur only on KnKn and Kn+ plants, the number of plantsin the analysis is 150 rather than the 225 considered for height.Source of Degrees of Sum of Mean F value F valuevariation freedom squares square obtained requiredTotal 149 1976.3Replication 4 107.2 26.8Time Period 2 35.2 17.6 0.70 8.65Error A 8 20.9 26.1Treatment 4 276.6 69.2 4.87** 3.74Treatment x Time 135.1 16.9 1.19 2.90Error B 48 679.6 14.2Genotype 1 174.9 174.9 48.58»* 7.08Genotype x Time 2 12.1 6.1 1.69 4.98Genotype x Treatment 4 136.7 34.2 9.50** 3.65Gen. x Treat, x Time 8 179.9 22.5 6.25** 2.82Error C 60 218.1 3.6?* Highly significant.Table 3. Analysis of variance of number of knots on mutant plantstreated with growth hormones.Highly significant F values were obtained for the same means asthose for height. The duration of treatment had little effect on theamount of knotting on the plants of this experiment.36Journal of the Arkansas Academy of Science, Vol. 20 [1966], Art. 9Published by Arkansas Academy of Science, 196637Knotted (Kn) Gene of Zea maysA ranking of the means for all significant sources of variation isshown in Table 4. Since the final count of knots was made four weeksafter emergence when knotting was slight, differences in some instanceswere not discernable. Differences that are valid statistically usingDuncan's new multiple range test are shown in Table 4. All treatments4-i co «N ioe>JOeoi'C >»C OOO PJr-lt-IOOOn >H2 2 o<<< < < *^o s s s o ssssss'-M III I I III Ift) rH 0)n -M +-» -M ft) -4-J -M -M -M + J +-1 f—<•) tf N U 0O MfP> *0O Tl5o iii .a i i i i i i xK M + + si!i+ + +I•O T5no ••-<,ijPj J-3 3 3 3 3 3 3 o as 55 ss as s= z; o£ H C I O>fl> #—I CM |' ) ¦ 4-1 U) 4-1 4-1 4J 4-1 4-1 4-> i i 4-1 4-1-M 4-1 4-1 4-J -HIB »!<<>C>g t< 0 NTf NTf O Id ¦* MCD Mf00 1/15 FH • l-l <H j3fHf-H P'o III XI IIIIII IIIIII ><no -h a -mtS s5 s5 ;2uu & s2 s2 i>2 s2 j2 vs s2 w _g£tO N(O CO O <l* W rfr~cor-(^-400 t^nh\i )*4 S^ O hi—ii—IIII III i'' III-^H +J+J+J+J+J-M O -M 4-" -t-"+j Tfooc^cvj^roo 10 ooc-gooQ) r-H 0) i-H-S III III |O IIIcccccsc dec.O1 1O in CM HH ! ^«0r-(^( 0 N BH »-JXoa;Illlll "S• • •%Ih| CO VNOOM *-Ml •—I >-Hc|In f <C « 4J fCDC CVJ OO OOtMOO +-"§ Illlll 5 lllll ... £S33i§^3 s^j jS iS s5 s5 3 w« & "^O II I I Ia a .av; HH b2 t2—_^^-^— cn^rc^on oo oajooiuiDMnnn Eoton i:«(VRo P.c >W + C5<T NNHO COH C t--CO«0<H'H'-IOOOOCsHi O -HUWHOZTable(D »r w oo ooo o owCoMa.( O3 %< 333 £c¦oMh&•.Hto4-"0cOm_^____ 10S O 4-*4J cm(0 91 US T) +¦£ 10 0)El x c c15 cSl I. . ,....... g^i4. Ranking of knot means37Journal of the Arkansas Academy of Science, Vol. 20 [1966], Art. 9https://scholarworks.uark.edu/jaas/vol20/iss1/938iArkansas Academy of Science Proceedingsreduced the total number of knots when compared to the control popula-tion. KnKn plants had more knots when averaged over all experi-mental situations than Kn-f plants. NAA virtually eliminated knottingon both KnKn andKn+ plants. IAA inhibited knotting to a lesser extentthan NAA, but inhibited both genotypes to about the same degree.The effects of NAA and IAA seemed to be primarily on knotting,with leaves returning to normal in respect to length and width. Plantstreated with GA3 and K had fewer knots in most instances than controlplants, but other drastic effects produced suggest that the reduction ofknotting was not due to the same mechanism involved in knot reductionby NAA and IAA. K-treated plants had necrotic leaves bearing a whitecompound, presumably the sodium carbonate used to keep K in solution.GA3 -treated plants were extremely spindly, with very long, narrowleaves.In view of the fact that NAA treatments virtually eliminate knottingwhile not eliminating dwarfing, it seems that knotting is not responsiblefor dwarfing, but that these are separate and wholly independentexpressions of the same gene or closely linked genes.SUMMARYThe growth hormones gibberellic acid, indoleacetic acid, kinetin,and naphthalenacetic acid were tested for their effect on the knottingand dwarfing expressions of the Knotted (Kn) gene in Zea mays.Naphthalenacetic acid almost completely suppressed the production ofknots. Gibberellic acid, indoleacetic acid, and kinetin reduced knottingto a lesser degree. Naphthalenacetic acid, indoleacetic acid, andkinetin did not eliminate dwarfing, but gibberellic acid significantlyincreased the height of both heterozygous and homozygous plants.LITERATURE CITED1. Bryan, Arthur A., and J. EMaize; 51—"Knotted LeafSass. 1946. Heritable Characters inJ. of Hered. 32(10): 343-346.2. Nickerson, Norton H. 1964News L. 38:131.Kn Suppression. Maize Genet. Coop.3. Phinney, Bernard L. 1961.Relation to the Gibberellins.Dwarfing Genes in Zea mays and theirp. 489-501. In Richard M. Klein (ed.).Plant Growth Regulation. Iowa State Univ. Press. Ames, Iowa.4. Rhodes, B. B., and Oval Myers, Jr. 1966. Dosage Effects of theKnotted Gene on Growth and Development in Maize. J. of Hered.57(3):91-94.38Journal of the Arkansas Academy of Science, Vol. 20 [1966], Art. 9Published by Arkansas Academy of Science, 1966

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Effect of Growth Substances on Phenotypic Expressions of the Knotted (Kn) Gene of Zea mays

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