Exploring the potential usefulness of US maize expired Plant Variety Protection Act lines for maize breeding in sub-Saharan Africa

Maize (Zea mays L.) inbred lines with expired Plant Variety Protection Act (ExPVP) certificates are publicly available and potentially represent a new germplasm resource for many public and private breeding programs. The use of these inbred lines for maize breeding in sub-Saharan African (SSA) was little investigated. Hence, this study was conducted to explore their potential usefulness. Ninety-six ExPVP lines, two temperate public lines, and 14 tropical lines were evaluated in five different trials from 2016 to 2018 in Burkina Faso to determine their phenotypic characteristics; resistance to drought, heat, and three diseases; and to identify elite ExPVP lines for local maize breeding programs. Cluster analysis based on phenotypic traits highlighted a clear distinction between the different groups (nonstiff stalk [NS] vs. Iowa Stiff Stalk Synthetic [SS] heterotic groups and temperate vs. tropical germplasms). The screening showed that 3, 28, and 68% of ExPVP lines were resistant, tolerant, and susceptible to maize leaf blight disease, respectively. However, the lines were either tolerant or resistant to Curvularia leaf spot and maize streak virus. Approximately 30% of ExPVP lines presented a tolerance to the three maize diseases tested and 8% of the lines were tolerant to drought. Heat stress was severe to both ExPVP and tropical lines. Yield potential of ExPVP lines varied from 1.68 to 2635.63 kg ha(-1) vs. 798.76 to 1707.56 kg ha(-1) for tropical lines. The ExPVP lines identified showing tolerance to stresses and a high-yield performance can be integrated in inbred-hybrid development program.