Vegetable Breeding and Genetics

Dr. Ainong Shi

Cowpea Breeding and Genetics

The cowpea (Southern pea) breeding program at the University of Arkansas has over 50 years of history and has released more than 12 varieties. Some of the releases have been very useful to the processing industry and some have been widely grown by home gardeners. The breeding program has emphasized improved plant architecture, earliness, concentrated flowering and fruiting as well as improved yield and processing quality. The program has centered on developing commercial varieties growing in Southern U.S. We continue to develop cowpea cultivars with upright and bush-type characteristics that can easily be harvested by direct combining or by hand. We are also developing vining growth habit for forage or cover crop. The program also develops a diversity of cowpea with various mature seed pattern and pattern color such as blackeye, pinkeye, and red holstein, and various seed coat color such as black, brown, blue, cream, green, purple, red, tan, and yellow cowpea.cowpea

The cowpea breeding program is building genotyping by sequencing (GBS) and SNP platform for molecular breeding in cowpea: to discover genome-wide SNP through GBS and genome-wide EST-SNP from EST sequences; analyze genetic diversity for U.S. cultivars, for world-wide accessions, and for advanced lines developed by University of Arkansas Southern Pea (cowpea) breeding program; conduct genome-wide association and identify SNP markers for agronomic traits, morphologic traits, disease resistance traits, and seed protein and sugar content; and develop a SNP set for cowpea variety identification.

Genetic improvement in spinach

The spinach breeding program at the University of Arkansas has been operable more than 40 years since early 1970's and was the first public sector breeding program in the United States. The major breeding contributions have been in the areas of disease resistant varieties, such as ‘Fallgreen’, released in 1987, ‘F380’ in 1998, and ‘Wintergreen’ in 2003. These are white rust resistant varieties, which have widely been used as germplasm for rust resistance and as parents by seed companies to develop hybrids. More than nine varieties of spinach have been released and over a hundred excellent advanced breeding spinach lines have been developed. The spinach breeding and genetics program continues to develop high yield varieties with uniformity, a good germination percentage, slow bolting, disease resistance/tolerance, and with high nutritional components as the spinach breeding goals. The program also develops diverse spinach varieties with different leaf texture of smooth or savoy (puckered), different leaf shapes of round or oval, leaf tips pointed or round, leaf edges with cupped in, cupped out or flat, different leaf color of dark or light green, leaf surface of shiny or matte, and stem long or short.

spinachThe main disease and pest in spinach are downy mildew caused by Peronospora farinose f. sp. Spinaciae, white rust caused by Albugo occidentalis, Verticillium wilt, Fusarium wilt, Stemphylium leaf spot, leafminer, and aphids. The most effective method to control disease and pest is to use host resistant and breeding resistant cultivars. Because the pathogen and pest changes its race or biotype fast and continuously, new resistant sources need to develop. Molecular markers, especially SNP markers, will provide breeders a tool to select disease resistance through MAS and GWS. The spinach breeding program will continue to screen disease resistant sources and transfer resistance to elite spinach varieties in order to release high yield cultivars with disease/pest resistance. Spinach molecular breeding studies include discovering genome-wide SNPs for spinach; construct genetic maps for spinach; conduct QTL mapping for important quality traits like downy mildew and white rust disease resistance, and genome-wide association for important quantitative traits like drought and heat tolerance, and leaf shape and texture; analyze genetic diversity for spinach cultivars growing in North America and world-wide; develop a SNP set for spinach cultivar identification; conduct MAS or GWS in spinach breeding program; and release spinach cultivars and develop spinach with specific traits such as disease resistance, heat and drought tolerance, and various leaf texture and leaf shapes.

Improvement of greenhouse and hydroponics leaf vegetable crops

germplasm

Collaborating with Dr. Michael Evans to develop new selections and fresh leaf vegetables for use by hydroponics will be a part of the vegetable breeding program of University of Arkansas. The objective is to grow leaf vegetables in greenhouse conditions with lower inputs, pest resistance, heat tolerance, rapid production cycle, andyear round yield.

Spinach is one of the crops that University of Arkansas researchers are working on as a greenhouse vegetable crop. The vegetable breeding program focuses on developing heat-tolerant spinach varieties and cultivars that can grow in greenhouse through summer time. The program is screening heat-tolerant spinach from cultivars, hybrids, and germplasm released in North American, from all USDA spinach accessions originally collected world-wide, and from advanced breeding lines from Arkansas spinach program. After the heat-tolerant germplasm is identified, the program will use the heat-tolerant germplasm as donor to transfer heat-tolerance into elite lines to release heat tolerance, slow-bolting, disease resistant and high yield spinach cultivars. At the same time, the program will identified heat-tolerant QTL/genes and linked SNP markers associated with heat-tolerance and use them in molecular breeding in order to rapidly advancespinach breeding through MAS. The University of Arkansas vegetable breeding program will be devoted to developing dandelions as a vegetable crop growing ingreenhouse conditions. The program will deal with dandelions as a new crop for breeding program: collecting dandelion accessions, screening dandelion lines, selecting dandelion as varieties, developing and breeding new dandelion cultivars. Meanwhile, building SNP platform and GBS platform will be part of the breeding program to enhance dandelion molecular breeding. Because dandelions have apomixis ability,using F1 vigor as a cultivar in dandelion breedingcan fix the F1 without segregation in next generations. Besides spinach and common dandelion, the vegetable breeding program is conducting classic and molecular breeding for other vegetables for hydroponics food crops such as chicory, kale, and collards.