Location: Crop Genetics Research Unit
Project Number: 6066-21220-012-14
Start Date: Apr 01, 2014
End Date: May 31, 2015
Field trial for testing F2 plants of three PI 458130 populations (PI 458130 x PI 399045, 5601T x PI 458130, and PI 458130 x PI 424324B) will be conducted in Stoneville, Mississippi, using a randomized block design in 2014. For all populations, seeds to be planted at a rate of 33 m-1 of row, in 2.74 m-long single-row plots with a 0.91-m row spacing. Inoculation with Phomopsis (P.) longicolla isolates from Mississippi will be performed at R5–R6 growth stages using a battery-operated backpack sprayer (30 psi) with a hand held boom containing a single nozzle with an adjustable orifice. Seeds arbitrarily selected from each replication of each line will be collected when the plants are mature. In this proposed research, a total of 25 seeds of each F2 plant in each population will be assayed for the percentage of P. longicolla seed infection. Analysis of variance will be conducted using general linear mixed model procedure (PROC Mixed) of SAS (version 9.2, SAS Institute, Cary, NC). Soybean plant means will be compared by Fisher’s protected least significant difference (LSD) at P = 0.05. Based on the parental, F2, and F1 means and distributions, we will try to discern the best place to make a break for classifying each F2 as R or S. Depending on the distributions, we can estimate if the inheritance is qualitative or quantitative. If qualitative and the distributions indicate one or two genes, we can use chi-square to determine goodness of fit. If quantitative, we will look for Quantitative trait locus (QTL). In addition, leaf samples from each F2 plants will be collected individually for DNA extraction, and for the second year’s research with collaborators on genetic mapping of the resistance gene in PI 458130.