Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1986 I. Methods for breeding high-protein cultivars of soybeans; II. Transfer of Phytophthora resistance in soybean [Glycine max (L.) Merr] by backcrossing Othello Batulan Capuno Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Agricultural Science Commons, Agriculture Commons, and the Agronomy and Crop Sciences Commons Recommended Citation Capuno, Othello Batulan, "I. Methods for breeding high-protein cultivars of soybeans; II. Transfer of Phytophthora resistance in soybean [Glycine max (L.) Merr] by backcrossing " (1986). Retrospective Theses and Dissertations. 7983. https://lib.dr.iastate.edu/rtd/7983 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. 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BY BACKCROSSING Iowa State University PH.D. 1986 University Microfilms IntGrnStiOnSi 300 N. zeeb Road, Ann Arbor, Ml 48106 I. Methods for breeding high-protein cultivars of soybeans. II. Transfer of Phytophthora resistance in soybean [Glycine max (L.) Merr.] by backcrossing by Othello Batulan Capuno A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY Department: Agronomy Major: Plant Breeding and Cytogenetics Approved : Signature was redacted for privacy. In Charge of Major Work Signature was redacted for privacy. Foy the Flajor Department Signature was redacted for privacy. For the Graduate College Iowa State University Ames, Iowa 1986 11 TABLE OF CONTENTS Page GENERAL INTRODUCTION 1 SECTION I. METHODS FOR BREEDING HIGH-PROTEIN CULTIVARS OF SOYBEAN 3 INTRODUCTION 4 REVIEW OF LITERATURE 7 Prospects for Soybean Cultivars with High Yield and High Protein Percentage 7 Methods Used for Yield and Protein Improvement in Soybean- 8 Studies Designed for Protein Improvement in Soybean 10 MATERIALS AND METHODS 14 RESULTS 23 DISCUSSION 55 SUMMARY AND CONCLUSIONS 60 APPENDIX A. MEAN VALUES FOR SEVEN TRAITS OF BC^Fg-DERIVED AND F4-DERIVED LINES AND VINTON 81 FOR THREE CROSSES AT INDIVIDUAL LOCATION IN 1984 62 APPENDIX B. MEAN VALUES FOR SEVEN TRAITS OF BC^Fg-DERIVED AND F^-DERIVED LINES, PARENTS, AND CHECK CULTIVARS FOR THE THREE CROSSES AVERAGED ACROSS THREE LOCATIONS IN 1984 72 APPENDIX C. MEAN VALUES FOR SEVEN TRAITS OF LINES FROM THREE CROSSES AT INDIVIDUAL LOCATIONS AND COMBINED ACROSS LOCATIONS IN 1984 82 APPENDIX D. MEAN VALUES FOR SEVEN TRAITS OF BC^Fo-DERIVED AND F4-DERIVED LINES, PARENTS AND CHECK CULTIVARS FOR THREE CROSSES AVERAGED ACROSS LOCATIONS IN 1983 AND 1984 84 ill SECTION II. TRANSFER OF PHYTOPHTHORA RESISTANCE IN SOYBEAN ([Glycine max (L.) Merr.] BY BACKCROSSING 100 INTRODUCTION 101 LITERATURE REVIEW 103 Inheritance of Resistance to Phytophthora Root and Stem Rot in Soybean 103 Use of Backcross Method in Transferring a Specific Gene for Resistance to Phytophthora Rot 107 MATERIALS AND METHODS 110 RESULTS 124 DISCUSSION 138 SUMMARY AND CONCLUSION 141 GENERAL CONCLUSION 143 BIBLIOGRAPHY 144 ACKNOWLEDGEMENTS 151 1 GENERAL INTRODUCTION Two important aspects of soybean breeding were dealt with in this dissertation. Both studies were intended to enhance efficiency in the development of improved soybean cultivars. One objective in soybean breeding programs is the development of cultivars with high protein content. The demand for soybeans high in protein percentage for human consumption is increasing, especially in the manufacture of tofu. One of the commonly-used cultivars in the U.S. with high protein content for tofu production is Vinton 81. One limitation of this cultivar is that it has lower yield potential than that of other available cultivars. The need to find an effective breeding method to develop soybean cultivars with high yield and comparable protein percentage to Vinton 81 is important. The objective of this study was to determine whether single-cross or backcross populations would offer the best opportunity to select for higher yield than that of Vinton 81 while maintaining its current level of protein percentage. Another objective in many soybean breeding programs is the transfer of Phytophthora resistance into susceptible cultivars. With the exception of the study of Wilcox et al. (1971), no studies have been conducted to evaluate the efficiency of the backcross procedure in the transfer of Phytophthora resistance into susceptible cultivars. The main goals of this study were to determine the number of backcross generations required to transfer a major gene for Phytophthora resistance into a cultivar and obtain lines with the yield potential of 2 the recurrent parent, and to determine in what back cross generation a composite of visually similar lines could be made that would yield as much as the recurrent parent. 3 SECTION I. METHODS FOR BREEDING HIGH-PROTEIN CULTIVARS OF SOYBEAN 4 INTRODUCTION The protein percentage in the seed of currently-grown soybean cultivars in the U.S. is approximately 40.5% on a dry-weight basis (Hartwig, 1979). This protein percentage is far below the maximum value of 53% available in plant introductions that are part of the U. S. collection. Protein percentage in soybean can be genetically manipulated as evidenced by the high-protein cultivars Provar, Protana, Vinton, and Vinton 81. Further, the mean heritability for protein percentage in published reports is 76%, which suggests that selection for this trait could be successful (Table 1). High-protein soybean cultivars are desirable for human consumption, especially in the manufacture of tofu. Tofu is a wet cake obtained by adding calcium sulphate to heated soybean milk. It is composed of water, protein, oil, carbohydrates, and ash of varying compositions. Wang et al. (1983) found that soybean cultivars with high protein content produced tofu with a higher ratio of protein to oil than did cultivars with smaller amounts of protein. The original protein and oil content of the beans is a factor in tofu yield and in the final protein and oil content of the tofu (Smith et al., 1960). Some soybean cultivars with high protein content were released, but their seed yields were inferior to commonly-grown cultivars. Therefore, it is important to improve the yielding capacity of soybean cultivars with high protein content. One of the most recent cultivars released with a high-protein percentage is Vinton 81. This cultivar was released as a large-seeded 5 specialty cultiver similar to Vinton but possesses an allele at the Rps^ locus that provides resistance to races 1 to 3 and 6 to 9 of phytopthora rot. It originated from the BC^F2 generation of the cross L60-347-4-4G-2-B x Vinton [5]. L60-347-4-4G-2-B is an Fy line selected by the Ohio Agricultural Research and Development Center from the cross Harosoy x Higan for its resistance to phytopthora rot. Vinton is a large seeded specialty cultivar with about 45% protein and 22 g/100 seeds. However, the yield of Vinton 81 is lower than that of other presently grown cultivars. A quick and efficient method is important in improving the yield potential of Vinton 81, while maintaining its current level of protein percentage. This study was conducted using and BC^Fg-derived lines from crosses between Vinton 81 and three high-yielding parents of different maturity groups. The objectives were 1) to determine which kind of method (single cross vs backcross) would offer the best opportunity to improve seed yield while retaining the level of protein of Vinton 81, and 2) to identify individual lines with higher yield and comparable protein percentage to Vinton 81. 6 Table 1. Summary of heritability for protein percentage in soybean as reported by several authors^ Authors Crosses^ Heritability^ Percent Johnson et al. (1955) 1. AA X AA 39 2. AA X AA 83 Thorne and Fehr (1970b) 3. AA X UH 91 4. (AA X UH) X AM 91 Shannon et al. (1972) 5. AM X AM 88 6. AA X AM 89 7. AA X AA 92 Shorter et al. (1976) 8.