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Crop Vulnerability Update for Juglans Genetic research & breeding capacities
ARS Juglans PGR management, disease and genetics research for PW at Davis, CA.
University genetics and breeding programs (UC Davis Walnut Improvement Program (WIP) in CA for PW; U. Missouri for black walnut (BW) nut and agroforestry uses; Purdue and US Forest Service (USFS) timber breeding and genetics program for BW in IN.
PW breeding programs at INRA, France; Ministry of Forestry, Peoples Republic of China, Iran, Turkey
Reference genomes for PW, BW, BN; sequence information and genomic resources for PW, BW, and multiple Juglans species NPGS PGR Status & Impacts
Status: Collection of 700+ accessions of PW, BW, and Juglans spp. in field orchards at NCGR-Davis, including older commercial cultivars, heirloom cultivars, and CWR. 20+ accessions of BN in NCGR-Corvallis. Non-NPGS collection of BW nut accessions at U. Missouri, and BW timber accessions at Purdue
Impacts: Protects and improves major US nut and timber crop with $1 Billion/yr farmgate value for PW; $500 Billion value for standing BW timber; BW wood exports of $325 Million/yr.
NPGS preserves and distributes base PGR as potential sources of host-plant resistance to diseases and pests, and abiotic stress tolerance; materials for PW and BW research; and base genetics for PW and BW cultivars. Priority Issues
More land to re-propagate, rejuvenate, and expand NCGR-Davis field orchards.
Assess genetic diversity in situ; develop conservation plan for endangered US BN and BW populations.
Develop cryopreservation technology
Acquire CWR from threatened LA spp.
Subtropical genebank site for cold-susceptible Juglans spp.
More diverse, adapted, vigorous rootstocks.
Additional budgetary support crucial for expanded PW and BW breeding and PGR evaluation capacity, especially for host-plant response to pest and diseases; chilling; phenology and nut-bearing.
Additional budgetary support for the PGR management. Vulnerabilities &Threats
Numerous evolving pests and pathogens, butternut (BN) canker disease, Asian walnut moth, and spotted lantern fly
Extremely narrow genetic base for Persian walnut (PW); reliance on 4 clonal scion cultivars and few rootstock cultivars for CA.
Rapid decline of US forest populations of BN.
Gaps in collection coverage of Latin American (LA) Juglans spp.; crop wild relatives (CWR) threatened in situ.
Reduced budgetary support and operational capacity for breeding and plant genetic resource (PGR) management, threatening health of National Clonal Germplasm Repository (NCGR)-Davis collection.<br>
