Project Number: 1275-21000-172-00
Project Type: Appropriated

Start Date: Jul 24, 2003
End Date: Jul 23, 2008

Objective:
The underlying genetic bases of key attributes that influence the quality, nutritive value and marketable yield of fresh and/or processed product quality in major Solanaceous crops will be elucidated, and will facilitate the deployment in improved germplasm. Gene expression will be characterized and selectable marker strategies for improving selection efficiency will be developed. The specific goals are: 1) Development of tomato germplasm with enhanced quality attributes including fruit firmness and carotenoid content and characterization of the genetic control of these attributes. 2) Identification of quantitative trait loci that influence tomato anthracnose fruit rot resistance. 3) Development of new pepper germplasm for culinary and ornamental applications; determination of the inheritance of tissue-specific anthocyanin accumulation and characterization of the control of structural and regulatory genes for anthocyanin pigmentation

Approach:
The inheritance of tomato fruit firmness in firm and ultra-firm processing tomato germplasm developed from interspecific Lycopersicon esculentum x L. hirsutum crosses will be determined and genetic variance components estimated. The inheritance of tissue-specific carotenoid content in tomato fruit pericarp, columella and locule tissues will be characterized. Genetic stocks will be developed for use in basic studies on carotenoid accumulation and for use in development of enhanced germplasm. Using RT-PCR, the relationship between variation in lycopene content and tissue-specific expression of carotenoid biosynthetic genes will be assessed. Sequence information of genomic clones of differentially expressed genes will be used to develop selectable markers for enhanced fruit pigmentation. Recombinant L. esculentum inbred tomato lines (RILs) segregating for resistance to anthracnose fruit rot have been developed. AFLP and SSR markers that differentiate parental RIL lines will be utilized for identification of QTL linked to fruit rot resistance. Relative map positions will be determined using introgression line analysis. Pepper germplasm with unique fruit and foliage pigmentation patterns, as well as unique growth habits and fruit characteristics will be developed for culinary, ornamental and dual-purpose applications. The inheritance of growth habit, photoperiod sensitivity, and tissue-specific anthocyanin pigmentation will be studied and genotypes for respective anthocyanin regulatory genes determined via complementation. Utilizing cDNA or partial genomic clones of anthocyanin regulatory and structural genes, the expression of anthocyanin-related genes will be studied with viral-induced color break, related to viral RNA distribution, and the information utilized to develop selectable markers for these genes in pepper.