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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Research Project #433962

Research Project: Identification of Baby Leaf Lettuce Varieties and Genes for Rapid and Uniform Growth, High Quality, and Disease Resistance

Location: Crop Improvement and Protection Research

Project Number: 2038-21530-002-019-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Nov 1, 2018
End Date: Aug 31, 2021

The main objective of this project is to identify new genetic resources and knowledge essential to breeding for baby leaf lettuce with rapid and uniform early growth, thick leaf texture, and resistance to downy mildew (DM) and bacterial leaf spot (BLS). The immediate goals include 1) identify lettuce varieties with vigorous and uniform early growth and good performance of photosynthetic apparatus using a non-destructive technique, 2) identify lettuce varieties with thick leaf texture in early stage, 3) find lettuce varieties with resistance to DM, 4) identify lettuce varieties with resistance to BLS, and 5) determine genes or genetic regions associated with vigorous and uniform growth, performance of photosynthetic apparatus, thick leaf texture, and resistance to DM and BLS.

A population of 450 lettuce accessions, that are already genotyped with single nucleotide polymorphisms (SNP) using genotyping by sequencing (GBS), will be tested for early growth rate, growth uniformity, chlorophyll content, leaf texture, and DM and BLS resistance. Plants will be grown in greenhouse or growth chambers and evaluated at seedling stage. Growth rate, uniformity, and chlorophyll content will be evaluated using Transect FluorCam (Photon Systems Instruments) by non-destructive phenotyping. Leaf texture will be evaluated by TA.XTplus Texture Analyser. Two races of lettuce DM (Bremia lactucae) and three strains of BLS (Xanthomonas campestris pv. vitians) will be used to test accessions for resistance. The phenotypic data and GBS data will be used to perform genome-wide association studies and identify quantitative trait loci (or genes) associated with the traits. New phenotyping technology, genetic information, and superior varieties will be made publicly available.