AN ABSTRACT OF THE THESIS OF Rebecca Nelson Brown for the degree of Doctor of Philosophy ...

201 Pages·2011·3.43 MB·English

AN ABSTRACT OF THE THESIS OF
Rebecca Nelson Brown for the degree of Doctor of Philosophy in Horticulture
presented on July 2. 2001. Title: Traditional and Molecular Approaches to Zucchini
Yellow Mosaic Virus Resistance in Cucurbita
Abstract approved:
7 7
James R. Myers
Zucchini yellow mosaic virus (ZYMV) is an important disease of Cucurbita
worldwide. Resistant cultivars are the best means of control. ZYMV resistance is
quantitative in the wild species C. ecuadorensis, and is controlled by at least three genes
in tropical C moschata. Very little molecular work has been done in Cucurbita, and no
markers are available to assist in selecting for ZYMV resistance genes.
The objectives of this research were threefold: to develop molecular markers for
use in breeding for ZYMV resistance, to develop a framework map of Cucurbita, and
to transfer ZYMV resistance from C. ecuadorensis to C. maxima 'Golden Delicious'.
The identification of a DNA marker linked to ZYMV resistance from C moschata
TSIigerian Local' was attempted using random amplified polymorphic DNA (RAPD)
analysis of resistant and susceptible bulks from the crosses C moschata 'Waltham
Butternut' x CWaltham Butternut' x TSIigerian Local'). No marker consistently linked
to ZYMV resistance was identified. Marker polymorphism was 14% between the
parents.
The cross C pepo A0449 x (A0449 x TSTigerian Local') was used as the mapping
population to construct the framework map. The completed map consists of 153 loci
in 29 linkage groups covering 1,981 cM. Approximately 75% of the Cucurbita genome
is covered. Three morphological traits, two quantitative trait loci and a putative
secondary ZYMV resistance gene have been placed on the map; an additional eight
traits and nine RAPD markers remain unlinked.
A study of the inheritance of ZYMV resistance was conducted as part of the
efforts to mark and map resistance. Resistance appears to be controlled by at least
three dominant genes in C. pepo. Environment and time since inoculation affect
expression of resistance, and resistance should be treated as a quantitative trait.
Development of ZYMV-resistant 'Golden Delicious' has progressed through five
generations. In 2000, thirty-five plants were selected which were fiilly virus resistant
and had reasonable processing quality. ZYMV resistance levels throughout the project
were 31% for the F and 12% for the first backcross in 1998, 3% for the backcross
2
progeny of the 1998 selections in 1999, and 15% for the selfed progeny of the 1999
selections in 2000.
Traditional and Molecular Approaches to Zucchini Yellow Mosaic Virus Resistance in
Cucurbita
by
Rebecca Nelson Brown
A THESIS
submitted to
Oregon State University
in partial fulfillment of
the requirements for the
degree of
Doctor of Philosophy
Presentedjuly2,2001
Commencement June 2002
Doctor of Philosophy thesis of Rebecca Nelson Brown presented on
July 2. 2001.
APPROVED:
Major Professor, representing Herticulture
Head of Departing of Horticulture
71 KJ-
Dean of tfaje Graduate School
I understand that my thesis will become part of the permanent collection of Oregon
State University libraries. My signature below authorizes release of my thesis to any
reader upon request.
Rebecca Nelson Brown, Author
Acknowledgement
Many people helped to make this work possible. I would like to thank Augie
Gabert and the other folks at Sunseeds for getting me started on this project, and for
providing breeding lines, virus inoculum, and facilities. I would like to thank Jim
Myers for the willingness to take on a crop that was new to him, and find the money
to support this research. I would like to thank the members of my committee for their
advice and support, and the folks of the OSU vegetable crops program for their
support and assistance. Most of all I would like to thank my husband for supporting
me both financially and emotionally, and for his willingness to move to Oregon.
11
TABLE OF CONTENTS
Page
INTRODUCTION 1
Economic significance of Cucurbita 1
The Impact of Viruses on Squash Production 3
Research Objectives 4
LITERATURE REVIEW 6
Zucchini Yellow Mosaic Virus 6
Resistance to Other Viruses in Cucurbita 8
Classical Cross Protection 10
Genetically Engineered Cross Protection 11
Genetics of Virus Resistance in Other Cucurbits 12
Cucumber 12
Melon 13
Watermelon 14
The Use and Development of Molecular Breeding
Tools in Cucurbita 15
Molecular Genetics and Mapping — Cucumis and
Citrullus 18
Cucumis 18
C. melo 18
C sativus 20
Citrullus 22
in
TABLE OF CONTENTS (continued)
Page
Random Amplified Polymorphic DNA (RAPDs) as a Tool for the Identification
of Trait-Linked Markers and Molecular Map Construction 23
Advantages of RAPD Markers 25
Potential Difficulties with RAPD Markers 27
The Inheritance of Morphological Traits in Cucurbita 29
The Genetics of Fruit Color in Cucurbita pepo 29
Base Colors 30
Green, Yellow or White Fruit 30
Precocious Yellow Fruit 34
Inhibition of mature fruit color: I fOi I-mc. 35
m
Color modifiers 36
Extending the effects of B: Ep-1 and Ep-2 36
Pigment intensifiers: LI and L2 37
Striped Fruit 39
Other effects oi L2. 42
Dark Stems and Fruit 42
The color reducing gene r 43
Quiescent intense {qi) 44
Plain light fruit coloration {pi) 44
Turning orange at maturity: mo-1 and mo-2 45
Fruit Color Genes in Cucurbita moschata and
Cucurbita maxima 46
Precocious yellow 46
Genes for Green and Motded Green Fruit in C. moschata 48
Genes for Blue, Green and Red Fruit in
C maxima 48
IV
TABLE OF CONTENTS (continued)
Page
Genes for other fruit traits 49
Warts 49
Rind Hardness (Lignification) 49
Fruit Flesh Color and Carotenoid Content 51
Fruit Shape 52
Genes Affecting Leaves and Stems 54
MotdeLeaf. 54
Genetic Yellowing in Leaves: Ses-B 55
Internode Length: Vine or Bush? 56
Powdery Mildew Resistance 59
A FRAMEWORK MAP OF CUCURBITA 60
Introducdon 60
Materials and Methods 60
Plant Materials 60
Morphological Traits 62
Disease Resistance 62
DNA Extraction 63
Polymerase Chain Reaction 64
Data Analysis 65
Results and Discussion 67
Morphological and Disease Resistance Traits 67
Days and nodes to first flower 67
Leaf mottle 70
Leaf shape and texture 74
Internode length and plant habit, tendrils 78
Fruit shape and set 79
Fruit rind color 83
TABLE OF CONTENTS (continued)
Page
Fruit Flesh Color 87
Fruit surface texture 88
Powdery mildew resistance 90
ZYMV resistance 92
RAPD Markers 94
The Map 95
References 105
A SEARCH FOR A RAPD MARKER LINKED TO ZYMV RESISTANCE
FROM CUCURBITA MOSCHATA 'NIGERIAN LOCAL' USING BULKED
SEGREGANT ANALYSIS 108
Introduction 108
Materials and Methods 109
Plant Material 109
Virus inoculation 109
DNA extraction 110
RAPD screening 110
AFLP screening Ill
Results and Discussion 112
Segregation of ZYMV resistance 112
RAPD Analysis 113
AFLP Screening 113
Conclusion 113
References 115
Vl
TABLE OF CONTENTS (continued)
Page
BREEDING 'GOLDEN DELICIOUS' TYPE CUCURBITA MAXIMA FOR
RESISTANCE TO ZUCCHINI YELLOW MOSAIC VIRUS 117
Introduction 117
Materials and Methods 119
Plant Material 119
Greenhouse and Field Techniques 121
ZYMV Resistance Screening 122
Processing Quality 124
Results and Discussion 125
Conclusions 141
References 143
SUMMARY 145
BIBLIOGRAPHY 148
APPENDIX 166