Developing an Early-Screening Protocol for Zinc Efficiency in Dry Bean (Phaseolus vulgaris L.).

Zinc (Zn) deficiency is the most common soil micronutrient deficiency worldwide and dry bean (Phaseolus vulgaris L.) is one of the most susceptible crops to Zn deficiency. North Dakota is the leading dry bean producer in the United States and much of the soil in the state has very low levels of plant-available Zn (<1 ppm). In the plant, Zn deficiency can induce chlorosis, delay maturity, and most importantly, decrease seed yield. The symptoms of Zn deficiency in dry bean can appear as early as 14 d after planting. If a plant is able to produce adequate seed yield under Zn-deficient soil conditions, it is considered Zn efficient. In dry bean, studies have reported Zn efficiency is inherited by a single dominant gene. The narrow sense heritability for Zn concentration in dry bean seeds reported in various studies is also high (h²=~0.84) which indicates that early selections for Zn efficiency can be made. A protocol for detection of Zn-efficient genotypes at early growth stages has been developed. Seven known Zn-efficient and six known Zn-deficient dry bean genotypes will be used as checks. To develop the most reliable screening method, we will compare two soil- and two hydroponic-based systems in the greenhouse. A RCBD with a split plot arrangement will be used. Six phenotypic traits including shoot weight, root weight, total dry weight, leaf greenness, leaf area, and internode length will be measured. Based on the genotype by treatment interaction values, a protocol will be selected and optimized to screen ~560 dry bean genotypes from both Andean and Middle American origins in order to identify new genotypes with Zn efficiency. Subsequently, a Genome-wide Association Study (GWAS) in this large gene pool will facilitate the detection of genomic regions associated with Zn efficiency and markers that could be used in dry bean breeding programs.