Pollen grain size was used to measure the effect of the presence of a low number of B-chromosomes. The pollen grains of forty-two plants distributed among two classes -those with one to five B-chromosomes and those without B-chromosomes were measured. No significant differences could be detected between the mean pollen grain size of B and non-B-chromosome classes. There is an indication of an effect on the variance in pollen grain size of the B-chromosome class

Munson, Alan

Peterson, Peter A.

English

Name not available

B-Chromosomes and Pollen Size in Maize

University of Northern Iowa

Proceedings of the Iowa Academy of ScienceVolume 69 | Annual Issue Article 251962B-Chromosomes and Pollen Size in MaizePeter A. PetersonIowa State UniversityAlan MunsonCornell CollegeCopyright © Copyright 1962 by the Iowa Academy of Science, Inc.Follow this and additional works at: https://scholarworks.uni.edu/piasThis Research is brought to you for free and open access by UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academyof Science by an authorized editor of UNI ScholarWorks. For more information, please contact scholarworks@uni.edu.Recommended CitationPeterson, Peter A. and Munson, Alan (1962) "B-Chromosomes and Pollen Size in Maize," Proceedings of the Iowa Academy of Science:Vol. 69: No. 1 , Article 25.Available at: https://scholarworks.uni.edu/pias/vol69/iss1/251962] CHROMOSOMES OF ARISAEMA 155 the root tips of A. formosana and A. consanguineum the chromo-some numbers 2n=28 (Figures 4-5) and 2n=l4 respectively. Table I. The Chromosome Numbers of Taiwan Arisaema. --------~---Species Chromo- Examiners Date of some Examina-!'fombers ti on A. consanguineum Schott" 0 . 14 Huang May, 1961 A. consanguineum Schott var. kc Ju ng-insularis (Hay.) Hnang A. fnrrnos:,na Hav. 28 Huang June, 1961 A. grapsospadix I-fay. A. heteroph)·Ilum BL c.140 '"Ito 1942 A. ringvns (Thunb.) Schott 28 "Ito 1942 A. ta iho kens is Hosoka\Y,l 28 "1.i5himoto 1941 " data from Darlington & Wylie 1955. 0 0 The material tL5ed for this species may have been mislabelled. Literature Cited Darlingtou, C. D. an<l A. P. Wylie. 1955. Chromosome Atlas of Flowering Plants, George Allen & Un\\'in Ltd., London, 37.5. Huang, T. C. 1960. Notes on the Arisaema of Taiwan. Taiwania, 7:93-104. Johansen, D. A. 1940. Plant Microtechnique. McGraw-Hill Book Company, New York & London. 40, 165. '.\faekawa, T. 1927. On Intersexualism in Arisaema japonica Bl. Jap. Jour. Bot. 3: 205-216. Sass, J. E. 1958. Botanical Microtechnique. The Iowa State College Press. Ames, Iowa. pp. 19, 106. B-Chromosomes and Pollen Size in Moize1 PETER A. PETERSON AND ALAN MUNSON:! Abstract. Pollen grain size was used to measure the effect of the presence of a low number of B-chromosomes. The pollen grains of forty-two plants distributed among two classes -those with one to flve B-chromosomes and those without B-chromosomes were measured. No significant differen.-:es could be detected between the mean pollen grain size of B and non-B-chromosome classes. There is an indication of an effect on the variance in pollen grain size of the B-chromosome class. INTRODUCTION Accessory chromosomes often called supernumerary or B-chromosomes are found among a wide range of plants and ani-mals. The persistence and distribution of these accessory chroma-1 Journal Paper No. J-4340 of the Iowa Agricultural and Home Economics Experi-ment Station, Ames, Iowa. Project No. 1335. •Iowa State University, Ames, Iowa Rnd Cornell College, Mt. Vernon, Iowa, re-spectively. The junior author was a participant in the 1961 NRtional Science Founda-tion Undergraduate Research Participation program. Part of this investigation was sup-ported by the Rockefeller Foundation. 1Peterson and Munson: B-Chromosomes and Pollen Size in MaizePublished by UNI ScholarWorks, 1962156 IOWA ACADEMY OF SCIENCE [Vol. 69 somes represent superficial support for their possible importance in a population. Mi.intzing ( 1959) has summarized the numerous investigations on the importance of these B-chromosomes. (Hereafter, acces-sory chromosomes will be referred to as B-chromosomes). The non-randomness of their distribution and the correlation of B-chromosomes with certain soil conditions as well as geographical location (Frost, 1958b; Bosemark, 1956) poses a question about their effect on plants in a gennal population. This has led to the suggestion that B-chromosomes have a posi-tive value. (Positive here implies a stimulating effect). There have been reports (Bosemark, 1957a; Frost, 1954) of slight in-creases in yield and vigor with plants possessing B-chromosomes. Further support for a positive effect comes from studies on Cen-turia scabiosa. The B's in this species maintain themselves in a population despite small losses in successive generations and the lack of a mechanism such as non-disjunction that would enhance their retention. This type of evidence indicates that in a natural population there is a selection for B-chromosomes. Another example of the positive effects of B's is the action of such chromosomes on pigment production in Haplopappus (Jackson and Newmark, 1960). The deleterious effects of B-chromosomes on various traits have been emphasized by a number of workers (Randolph, 1941; Mi.intzing, 1943, 1954, 1959; Frost, 1958a, 1959). In this report, a study was unde1taken to determine the effect of B-chromosomes on pollen size. Pollen grain size is considered a sensitive indicator of any possible genetical effect of B-chromo-somes since it is a direct manifestation of the genotype of the gametophyte. There are several cases of genotypic control of the expression of pollen grain physiology and morphology. For ex-ample the waxy ( wx) allele in the presence of iodine ca1;ses red coloration of the pollen grains in contrast to the purple staining pollen of the starchy (Wx) allele (Demerec, 1924). Another ex-ample of genotypic control of gametophytic expression occurs in the presence of the sp allele. Small pollen results and such grains are readily perceived among normal pollen grains following the quartet stage of meiosis ( Manglesdorf, 1931). Two aspects of B-chromosome influence on phenotypic changes in pollen grain size were examined. These include the effect of B-chromosomes on mean pollen grain size and, sec-ondly, the effect of B-chromosomes on the variation of pollen grain size within each sample of pollen grains with and without B-chromosomes. 2Proceedings of the Iowa Academy of Science, Vol. 69 [1962], No. 1, Art. 25https://scholarworks.uni.edu/pias/vol69/iss1/251962] MAIZE POLLEN SIZE 157 In the latter determination, the variation in sizes of pollen grains in individual anthers with B-chromosomes segregating would be compared with the variation in a sample of pol-len grains from an anther without B-chromosomes. In this pro-cedure, a direct effect of B-chromosomes could be determined since compensatory types of changes could be detected in the mean size of a sample. Using the variation within a sample, how-ever, as an estimate of B-chromosome effect on pollen grain size, the possible averaging-out of individual pollen grain measurements that might result in an unchanged mean would be obviated. In this case, therefore, the variation itself would be an c:..timate of the effect of B-chromosomes. MATERIALS Al'\D IVIETHODS Forty-two plants chosen at random from five ear progenies ( rne0-912. 9.36, 939. 942 and 943) arising from single cros~es of a recurrent standard line to B-chromosome containing plants pos-sessing 0, 1, 2, 4 or 5 B-chromosornes were used in the determina-tion of pollen grain size (Table 1). These ear progenies have a common genetic background. B-chromosome number was de-termined from root tip studies of greenhouse germinated plants Table I. The distribution of B-chromosomc containing plants used in the asses~ment of B-chromosome effect on pollen size Number of B-chromosomes 0 1 2 4 5 1960 912 7 13 932 1 1 939 3 2 942 1 2 4 1 943 1 6 Total plants = 10 21 7 3 1 Total pollen grains Plants x30 = 300 630 210 90 30 that were later ( 3-4 leaf stage) transferred to the field. A section of tassel ( 4-6 cm) was collected from that part immediately be-low the location where the anthers were being extruded from the spikelets for that day. This segment from the main stalk of the tassel is expected to shed the following day. Pollen of a single anther was stained in lactophenol aniline blue. Measurements of thirty individual pollen grains for each plant were made with a lOx optical micrometer. In the tables, the units presented as mean pollen grain size represent the values from the readings of the micrometer scale and these values should be multiplied x .0176 for the metric equivalent. Example: mean pollen grain size = .0947 mm; (scale reading = 5.574 x .0176 = .0947 mm.) 3Peterson and Munson: B-Chromosomes and Pollen Size in MaizePublished by UNI ScholarWorks, 1962158 IOWA ACADEMY OF SCIENCE [Vol. 69 RESULTS AND DrscussmN A number of comparisons were made regarding the effect of B-chromosomes on pollen grain size. No significant difference was found between the means in any comparisons (Table 2). This in-cludes a comparison of the mean pollen grain sizes between the Table 2. Comparison of pollen size from plants with various numbers of B-chromosomes of 1960-912, 936, 939, 942 and 943 t value #of #of x =mean size calculated d.f. tabular ( 10%) B's plants of pollen ------ ----~---A. All plants, 5 different ear progenies 0 10 5.574 0.166 40 1.684 1-5 32 5.591 B. 1960-912 only 0 7 5.514 0.8782 18 1.734 1 13 5.595 c. Comparison between 0 and 1, 1 and 2 0 10 5.574 0.5190 29 l.699 1 21 5.626 0.7250 26 1.706 2 7 5.537 class without B's and the class containing from 1-5 B's (Table 2, A). In a comparison of 0-B and 1-B cont<!ining plants of one-ear progeny ( 1960-912), the difference iu the mean pollen grain sizes of the two classes were not significant, (Table 2, B). Comparisons were made between the 0-B and 1-B and in ad-dition, the 1-B and 2-B chromosome classes. The lower mean value of the 2-B-chromosome class suggests that there is no indi-cation of a linear trend in the pollen grain size for the higher number of B-chromosomes (Table 2, C). This lack of a significant difference in the mean size of pollen grains of plants with and without B's might be a result of the av-eraging-out of increases and dec.:reases in the dimensions of indi-vidual pollen grains. This would result in an unchanged mean. In view of the possibility that the presence of B-chromosomes might contribute to an increase in variance it was desirable to compare the within-plant variance for pollen grain size in the non-B and B-chromosome classes. Table 3. Comparison of the within-plant variance between non-B and B-chromosome containing plants for pollen grain size #of F value B's d.f. s-~ calculated Tabular ( 10%) 0 290 0.09921 1-5 928 1.135 1.133 0.112604 4Proceedings of the Iowa Academy of Science, Vol. 69 [1962], No. 1, Art. 25https://scholarworks.uni.edu/pias/vol69/iss1/251962] MAIZE POLLEN SIZE 159 In a test of the homogeneity of variance with a one-tail F test, there is an indication of a slightly greater amount of variance in the B-chromosome class at the 10% level of significance. This will be further tested with a larger number of B-chromosomes. In reference to effects of B-chromosomes on other criteria such as pollen fertility, yield and other plant characters, Miintzing ( 1943, 1954), Frost ( 19.58a, 1959) and Bosemark ( 1957 a) have reported deleterious effects accompanying the presence of B-chromosomes. Bosemark ( 1957a, b) using Festuca pratensis has reported stimulatory effects with low numbers of B-chromosomes. The findings presented in this report regarding the effect of a low number of B-chromosomes indicate no significant differences in the mean size of pollen grains. There is, however, an indication of a slighter greater amount of variance in the B-chromosome containing class. ACKNOWLEDGEMENTS The authors are grateful to Miss Sylvia Zvingilas, Mr. Hubert Haensel and Dr. S. Eberhart for their aid and counsel with the statistical aspects. Literature Cited Bosemark, N. 0. 1956. On accessory chromosomes in Festuca pratensis. III. Frequency and geographical distribution of plants with accessory chromosomes. Hereditas 42: 189-210. 1937a. On acces3ory chromosomes in Fest11ca pratensis. V. Influence of accessory chromosomes on fertility and vegetative development. Heredi-tas 43: 211-235. 1957b. Further studies on accessory chromosomes in grasses. Hereditas 43: 236-297. Demerec, M. 1924. A case of pollen dimorphism in maize. Amer. }our. Bot. 11: 461-464. Frost, S. 1954. The genetic effect of accessory chromosomes in Centauria scabiosa. Hercditas 40: 529-533. 1958a. Studies of the genetical effects of accessory chromosomes in Centauria scabiosa. Hereditas 44: 112-122. 1958b. The geographical distribution of accessory chromosomes in Centauria scabiosa. Hereditas 44: 75-111. 1959. Studies on accessory chromosomes in some plant species. Berlingska Boktryckeriet 9 pp. Jackson, R. C. and P. Newmark. 1960. Effects of supernumerary chromo-somes on production of pigment in Haplopappus gracilis. Science 132: 1316-1317. Mangelsdorf, P. C. 1931. Modification of Mendelian ratios in maize by mechanical separation of gametes. Nat. Acad. Sci. Proc. 17: 698-700. Miintzing, A. 1943. Genetical effects of duplicated fragment chromosomes in rye. Hereditas. 29: 91-112. 1954. Cyto-genetics of accessory chromosomes ( B-chromosomes). Proc. IX Internat. Congr. Genet. Caryologia. (Suppl.) 6: 282-301. Miintzing, A. 1959. A new category of chromosomes. Proc. of the X Intcrnat. Congr. of Genetics. 1: 453-467. Randolph, L. F. 1941. Genetic characteristics of the B chrom<>somes in maize. Genetics 26: 608-631. 5Peterson and Munson: B-Chromosomes and Pollen Size in MaizePublished by UNI ScholarWorks, 1962

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B-Chromosomes and Pollen Size in Maize

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