Cassava {Manihot esculenta Crantz) staroh is traded in international markets more than starch from any other source. The starch industry requires cassava cultivars with novel starch characteristics for commercial exploitation. A natural source of waxy (amylose-free) cassava starch, clone AM 206-5, was identified at the International Center for Tropical Agriculture (CIAT). The granule-bound starch synthase I {GBSSl) gene is related to the waxy starch trait. The objectives of this study were to introgress the waxy starch mutation into Thailand's cassava breeding populations, to analyze the inheritance of waxy starch in cassava, and to develop molecular markers for this trait. AM 206-5 {wxwx) was crossed with several elite oultivars {WxWx) to transfer the wx alíele. Unrelated "F/' {Wxwx) genotypes were crossed among themselves to produce a "Fg" segregating population with negligible levels of inbreeding depression. The waxy starch phenotype was recovered in 25.7% ofthe 11,192 genotypes tested. This result provides further evidence that cassava is a functional diploid and that only one copy of GBSSl is present in cassava. A full-length genomic DNA sequence of GBSSl was isolated and characterized from C8, a waxy starch "f^" clone derived from AM 206-5. We exploited these sequence differences to develop two diagnostic single-nucleotideamplified polymorphism (SNAP) markers to differentiate homozygous waxy {wxwx) from the heterozygous {Wxwx) and homozygous {WxWx) nonwaxy genotypes.

The demand by industries for large-seeded peanuts is increasing in Thailand and Southeast Asia. New large-seeded peanut lines were recently developed in Thailand to respond to the demand. In this study, a multilocation yield trial was performed to identify the best genotype(s) in Thailand’s central region and investigate the genotype–environment interaction (GEI) on peanut production. Twelve promising large-seeded peanut lines and two check varieties (KU50 and KK6) were planted at 12 different planting locations during the dry and rainy seasons of 2018 and the dry season of 2019. This study found significant yield potential variability in the promising lines of peanuts evaluated at different planting locations. A combined analysis of variance presented that the environment and genotypes had a considerable impact (p < 0.001) on the pod and seed yield. The GEI showed a high impact (p < 0.01) on pod yield and an effect (p < 0.05) on seed yield. The environment presented the most significant influence on pod and seed yield variations, followed by genetics and GEI. The total variation in seed yield was 64.22%, composed of PC1 and PC2 values at 45.71% and 18.51%, respectively. The GGE biplot analysis of the yield potentials at each location indicated that KUP12BS029-1-1-3 was the ideal genotype, with a high yield potential and most stability at multilocations, followed by KUP12BS030-3-4-1 and KUP12BS030-1-4-3. These promising lines will be released as new peanut varieties in central Thailand and are recommended as parental lines in breeding programs for large-seeded and yield potential in Thailand and Southeast Asia.