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Empoasca Leafhopper Species Resistance in Common Bean, Phaseolus Vulgaris: Field Screening and Qtl Identification

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Empoasca Leafhopper Species Resistance in Common Bean, Phaseolus Vulgaris: Field Screening and Qtl Identification EMPOASCA LEAFHOPPER SPECIES RESISTANCE IN COMMON BEAN, PHASEOLUS VULGARIS: FIELD SCREENING AND QTL IDENTIFICATION By Elizabeth Ilona Brisco A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Plant Breeding, Genetics and Biotechnology Program / Crop and Soil Sciences 2012 ABSTRACT EMPOASCA LEAFHOPPER SPECIES RESISTANCE IN COMMON BEAN, PHASEOLUS VULGARIS: FIELD SCREENING AND QTL IDENTIFICATION By Elizabeth Ilona Brisco Empoasca species leafhoppers are a major insect pest of common bean, Phaseolus vulgaris that cause significant economic losses in both tropical (E. kraemeri) and temperate (E. fabae) regions of the Americas resulting in up to 80% crop yield reductions. Chemical controls are costly, reducing profitability by increasing input costs, and potentially causing damage to the environment and human health. Breeding beans for leafhopper resistance can provide an alternative control of this pest. The current study examined Empoasca spp. resistance by evaluating leaf curl and leaf burn damage as well as Empoasca spp. nymph counts in an inbred backcross line population (Matterhorn*/EMP507) of beans in temperate and tropical climates. Field screening in Michigan and Puerto Rico in 2009-2011 identified the existence of tolerance, antixenosis and antibiosis mechanisms of resistance to E. fabae and E. kraemeri in this population. Thirteen QTL associated with resistance to E. fabae and E. kraemeri were identified on six bean chromosomes that explained from 22.8 % to 61.5 % of the phenotypic variation of individual traits. A major QTL (LH7.1) associated with multiple resistance traits was detected for both leafhopper species in multiple seasons on Pv07. This QTL was tightly linked to the P gene that confers the presence of color in the seed coat, validating a similar QTL identified in previous studies. A novel QTL for E. fabae nymph counts was identified on Pv02 that may be associated with antibiosis resistance. Resistance to each leafhopper species appear to be controlled by separate genetic mechanisms in common bean. TABLE OF CONTENTS LIST OF TABLES ......................................................................................................................... vi LIST OF FIGURES ........................................................................................................................ x CHAPTER 1: Literature Review .................................................................................................... 1 I. Common Bean .................................................................................................................... 1 A. Introduction ...................................................................................................................... 1 B. Center of Origin ............................................................................................................... 2 C. Production ........................................................................................................................ 4 II. Empoasca Species Leafhoppers .......................................................................................... 5 A. Classification .................................................................................................................... 5 B. Life History ...................................................................................................................... 6 C. Feeding Damage ............................................................................................................... 7 III. Plant Resistance .................................................................................................................. 9 A. Biotic Stress...................................................................................................................... 9 B. Mechanisms of Resistance ............................................................................................. 10 C. Techniques for Testing for Insect Resistance ................................................................ 12 D. Leafhopper Resistance in Common Bean ...................................................................... 14 IV. Marker-Assisted Selection and Quantitative Trait Loci Analysis .................................... 16 A. Quantitative Trait Variation ........................................................................................... 16 B. Molecular Markers and Bean Linkage Maps ................................................................. 17 C. Mapping Empoasca Resistance in Common Bean ........................................................ 18 V. Objectives ......................................................................................................................... 19 Literature Cited ............................................................................................................................. 22 CHAPTER 2: Field Screening of Empoasca kraemeri and Empoasca fabae resistance in an Inbred Backcross Line Population in Common Bean ................................................................... 29 Abstract ......................................................................................................................................... 29 I. Introduction ....................................................................................................................... 30 A. Leafhopper Feeding Injury ............................................................................................. 30 B. Host Plant Resistance ..................................................................................................... 31 II. Study Objectives ............................................................................................................... 32 III. Material and Methods ....................................................................................................... 32 A. Plant material.................................................................................................................. 32 B. Field Screening ............................................................................................................... 33 C. Trichome Density ........................................................................................................... 35 D. Analysis .......................................................................................................................... 35 IV. Results ............................................................................................................................... 37 A. Choice Tests ................................................................................................................... 37 i. Puerto Rico Choice Tests ............................................................................................ 43 ii. Michigan Choice Tests ............................................................................................... 48 B. Leaf Curl by Leaf Burn: Resistance Categories ............................................................. 52 C. Resistance Classes and Nymph Counts .......................................................................... 59 D. No-Choice Tests ............................................................................................................. 62 iii E. Comparison of Choice and No-Choice Field Tests ........................................................ 67 F. Agronomic Traits ........................................................................................................... 71 V. Discussion ......................................................................................................................... 73 A. GxE Interactions ............................................................................................................. 73 B. Empoasca Feeding Damage ........................................................................................... 74 i. Puerto Rico.................................................................................................................. 74 ii. Michigan ..................................................................................................................... 76 iii. Conclusions ................................................................................................................. 77 C. Empoasca Nymph Counts .............................................................................................. 79 i. Puerto Rico.................................................................................................................. 79 ii. Michigan ..................................................................................................................... 80 iii. Conclusions ................................................................................................................. 81 D. No-Choice Tests ............................................................................................................. 82 i. Leaf Curl ..................................................................................................................... 82 ii. Leaf Burn .................................................................................................................... 84 iii. Conclusions ................................................................................................................. 84 E. Agronomic Traits ..........................................................................................................
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