Thin pericarp is one of crucial selection criteria for high-tender waxy corn hybrid development. A pericarp thickness of 2414 maize landrace accessions including 87 public waxy inbred lines was investigated to select accessions with thin pericarp and to broaden genetic diversity among waxy corn cultivars. Observed pericarp thickness of the 2414 accessions ranged from 16.0 ± 1.56 to 139.2 ± 39.55 µm with the average of 47.7 ± 13.15 µm. More than half of the accessions were below the suggested thickness of <50 µm for high-tender waxy corn hybrid development. Large sample size resulted in significant differences among endosperm types and among collection provinces. This, however, may not translate into considerable difference in tenderness since most averages of different types and collection provinces were <50 µm. Positive correlation (r = 0.55) between the average and standard deviation of pericarp thickness implied that more samples are needed to achieve same level of precision when it comes to selection for thick pericarp than that for thin pericarp. Top 10% thin-pericarped waxy landrace accessions were intercrossed to form a new waxy corn population from this result.

Huauzontle (Chenopodium berlandieri ssp. nuttalliae) is a locally important vegetable crop native to the highland valleys of Central Mexico and a potential source of genes for improving its Andean sister crop, quinoa (Chenopodium quinoa). A previous work involving two huauzontle lines identified one waxy genotype that lacked amylose due to mutations in granule-bound starch synthase I (GBSSI), major amylose-synthesis genes with two constituent subgenomes, A and B. We conducted this study to determine the extent of waxy genotypes and cryptic GBSSI mutations in 11 huauzontle accessions or landrace populations extending from Puebla in the southeast to Jalisco in the northwest. This represents one of the first published studies of genetic variation in C. berlandieri ssp. nuttalliae. Accessions were phenotyped for opaque versus translucent seed morphology and their seed starches were stained with Lugol's Stain. In addition, complete or partial GBSSI genes from their A and B genomes were polymerase chain reaction (PCR)-amplified, cloned and sequenced. Seven accessions were either wholly or partially non-waxy while six were either entirely or partially waxy. All waxy accessions carried the same putatively null alleles, designated gbssIa-tp (A-genome) and gbssIb-del (B-genome). The identification of publicly available genotypes carrying gbssIa-tp and their potential use in breeding waxy grain quinoa is discussed.