/z PURDUE UNIVERSITY THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION •EMTrrr.im ^6U6 ^os&g6 Effects on ^B.pbohydPati6_______ Content of - "°rn -------------------------------------------- COMPLIES WITH THE UNIVERSITY REGULATIONS ON GRADUATION THESES AND IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE DEGREE OF ijQsto.ii .of-Philosophy Professor in Charge of Thesis Heah or School or Department TO THE LIBRARIANS---- m THIS THESIS IS NOT TO BE REGARDED AS CONFIDENTIAL. PBorcrsfioR nr obajiqb GRAD. SCHOOL FORM 9 GENE DOSAGE EFFECTS ON CARBOHYDRATE CONTENT OF CORN ENDOSPERM A Thesis Submitted to the Faculty of Purdue University by Gerald Dunn In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy August, 1951 ProQuest Number: 27714302 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 27714302 Published by ProQuest LLC (2019). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106 - 1346 ACKNOWLEDGMENT The w riter wishes to express his sincere appreciation to Dr. H. H. Kramer, who suggested and directed the work, for his constructive criticism , advice and encouragement during the study, and to Elsie Mihelich Armstrong for the analytical work, which was performed in a very capable and cooperative manner. TABLE OF CONTENTS Page ABSTRACT ....................................................................................................... i INTRODUCTION .............................................................................................. 1 REVIEW OF LITERATURE ........................................................................... 2 MATERIALS AND METHODS ......................................................................... 9 Breeding Procedure ...................................................................... 9 Isolation of S ta rc h ................................... 12 Amylose Determination ............................................................. 13 Analysis For Percent of Starch ........................................ 15 RESULTS ......................................................................................................... 17 The Eight Parental Lines Used in Reciprocal Crosses in 1950 ...................................................................... 10 The Effect of Gene Dosage on Phenotype ..................... 19 Evidence for the Heterozygosity of P7 For the Sugary-2 Locus .................................................................. 24 Gene Dosage Effects on Amylose Content ..................... 26 The Effect of Dosage and Seed Size on the Starch Fraction ......................................................................... 31 The Relationship Between Starch and Amylose Content ........................................................................................... 36 The Water-Soluble KLysaccharides .................................... 37 DISCUSSION .................................................................................................. 41 SUMMARY ....................................... 46 LITERATURE CITED AND BIBLIOGRAPHY ........................................ 4& VITA LISTS OF TABLES AND FIGURES List of Tables Table Page 1. The Percent Amylose, Starch and Water-Soluble Polysaccharides of the Eight Parental Lines............ 17 2. The Phenotype and Genotype of the Crosses and Their Parents .......................................................... 20 3. The Percent Starch and Amylose of the Crosses P7 x P3 and P7 x P4 .................................................................. 25 4. The Effects of Dosage of su on Amylose ..................... 27 5. The Effects of Dosage of su2 on Amylose 29 6. The Effects of Dosage of du on Amylose ..................... 30 7. The Effects of Dosage of su and Seed Size on S ta rc h ................................................................................................ 31 S. The Effects of Dosage of su2 on Starch ..................... 33 9. The Effects of Dosage of du on Starch ........................ 35 10. The Percent of Water-soluble Polysaccharides of Various Genotypes .............................. 39 List of Figures Figure Page 1. The Phenotypic Effect of Dosage of su, in the Presence of su?du .................................................................... 21 2. The Phenotype Effect of Dosage of su and su? .... 23 3. Relation Between Percent Starch and Percent Amylose ............................................................................ 3# ABSTRACT In 1947, a cross was made between the two non-isogenic lines, sudu, sugary, dull, x su2 > sugary-2. In 1946, the F-, was selfed and segregation noted on four of the F, ears for normal, dull, sugary and sugary-2 seeds. Two different tester stocks were employed in 1949 to identify the eight true breeding genotypes. One of these, suamdu. amylaceous sugary, was used to determine the geno typic constitution with respect to du. The other tester, a homozygous suy stock, considered identical to su2> served to identify the genotype with respect to su2. Seven of the true breeding genotypes were thus isolated in 1949; the remaining one, susupDu. was later found to be segregating for the su2 gene. In 1950 a selfed row was grown from each of the eight genotypes, and reciprocal crosses were made between these eight lines to obtain all possible combinations of the three genes. Bulked pollen was used from each genotype. After classification, the seecb were bulked within each genotype, and weight in grams was taken of three 100 kernel samples. Chemical analyses were made for percent starch, amylose and water-soluble polysaccharides. The su gene was most effective in reducing to tal starch, su2 intermediate, and very little reduction resulted from the du gene. Both Su and Su2 showed a high degree of dominance for percent starch. Dosage effects were negligible for starch content. No genic interaction occurred for starch, the reduction in most genotypes resulting from the action of su or su2 alone. Seed size, considerably reduced in su genotypes, was strongly correlated with the amount of carbohydrates present. The su2 gene was most efficient in increasing amylose content. A strong interaction was evident between su and du for this fraction of the starch; su2 and du appear to act additively in this respect. The trip le recessive, susu2du, analyzed only 9% for starch, but 77% of this was amylose. Comparable values for the normal genotype were 59% and 25% respectively. The normal alleles of au and du were highly dominant for percent amylose, but Su2 was incompletely dominant to su?. The effects of gene dosage were somewhat more evident than for starch, but were s till insignificant. A highly significant negative correlation existed be tween percent of starch and of amylose. Water-soluble polysaccharides were associated with the presence of the _su gene; the genotypes not homozygous for th is gene had less than 1% of these constituents, with five exceptions. GENE DOSAGE EFFECTS ON CARBOHYDRATE CONTENT OF CORN ENDOSPERM INTRODUCTION Within the past ten years increasing attention has been given to the problem of developing crops which are suitable for a specific industrial use. This has been possible because of our increased knowledge concerning the role of the gene in controlling chemical reactions, and be cause of the development of more refined chemical techniques. The work reported here concerns the problem of producing a high amylose corn, with properties sim ilar to cellulose, which would be of considerable value industrially because of its ability to form strong films and fib ers. The project was begun about five years ago, and is being carried out cooperatively by the Departments of Agronomy and of Agricul tural Chemistry of Purdue University. It has involved an accumulation of most of the known endosperm genes, gnd the genetic and chemical study of their action in affecting development of the carbohydrates of the endosperm. This phase of the study deals with the interaction of the three endosperm genes sugary, su, sugary-2, su?, and dull, du. Chemical determinations w ill be presented for percent starch, amylose and water soluble polysaccharides for most of the possible genotypes from the cross of two non-isogenic lines, sugary dull x sugary-2.