Final Selection of Quality Protein Popcorn Hybrids

Quality Protein Popcorn (QPP) BC2F5 inbred lines were produced through an interpopulation breeding system between Quality Protein Maize dent (QPM) and elite popcorn germplasm. In 2019, five QPP F1 hybrids were selected for further evaluation due to superior agronomics, endosperm protein quality, and popping quality traits. Though these BC2F5 QPP hybrids were phenotypically similar to their popcorn parents, the QPP cultivars conveyed slightly inferior popping characteristics when compared to the original popcorn germplasm. The objective of this study was twofold. First, BC2F5 inbred lines were crossed to their popcorn parents and BC3F4 inbred lines were produced for hybridization to test the agronomic, protein, and popping trait effects from an additional QPP by popcorn backcross. Second, BC2- and BC3-hybrids were simultaneously evaluated alongside ConAgra Brands® elite cultivars and ranked for potential commercialization in the spring of 2020. These 10 QPP hybrids were grown alongside five ConAgra Brands® elite popcorn cultivars in three locations and agronomic, protein quality, and popping quality traits were evaluated. Significant improvements in popcorn quality traits were observed in the QPP BC3 cultivars compared to their BC2 counterparts, and yield averages were significantly lower in BC3-derived QPP hybrids compared to the BC2 population. Protein quality traits were not significantly different between QPP backcrossing populations and significantly superior to ConAgra elite popcorn varieties. Utilizing a previously published ranking system, six QPP hybrids, three from the BC2F5 population and three from the BC3F4 population, were evaluated as candidates for final selection. The successful evaluation and ranking system methodology employed is transferable to other hybrid production and testing programs. Incorporating this analysis with concurrent sensory studies, two QPP hybrids were chosen as premier cultivars for potential commercialization.

Novel insights into the effect of drought stress on the development of root and caryopsis in barley

Drought is a common natural disaster in barley production, which restricts the growth and development of barley roots and caryopses seriously, thereby decreasing yield and debasing grain quality. However, mechanisms for how drought stress affects barley caryopses and roots development under drought stress are unclear. In this paper, Suluomai1 was treated with drought from flowering to caryopses mature stage. The morphological and structural changes in roots growth and caryopses development of barley were investigated. Drought stress increased root/shoot ratio and eventually led to the 20.16% reduction of ear weight and 7.75% reduction of 1,000-grain weight by affecting the biomass accumulation of roots and caryopses. The barley roots under drought had more lateral roots while the vessel number and volume of roots decreased. Meanwhile, drought stress accelerated the maturation of caryopses, resulting in a decrease in the accumulation of starch but a significant increase of protein accumulation in barley endosperm. There was a significantly positive correlation (0.76) between the area of root vessel and the relative area of protein in endosperm cells under normal condition and drought increased the correlation coefficient (0.81). Transcriptome analysis indicated that drought induced differential expressions of genes in caryopses were mainly involved in encoding storage proteins and protein synthesis pathways. In general, drought caused changes in the morphology and structure of barley roots, and the roots conveyed stress signals to caryopses, inducing differential expression of genes related to protein biosynthesis, ultimately leading to the increase in the accumulation of endosperm protein. The results not only deepen the study on drought mechanism of barley, but also provide theoretical basis for molecular breeding, high-yield cultivation and quality improvement in barley.

Rice Endosperm Protein Administration to Juvenile Mice Regulates Gut Microbiota and Suppresses the Development of High-Fat Diet-Induced Obesity and Related Disorders in Adulthood

Obesity and related disorders, which are increasing in adults worldwide, are closely linked to childhood diet and are associated with chronic inflammation. Rice endosperm protein (REP) intake during adulthood has been reported to improve lipid metabolism and suppress the progression of diabetic kidney disease in animal models. However, the effects of REP intake during childhood on adulthood health are unclear. Therefore, we used a mouse model to experimentally investigate the preconditioning effects of REP intake during childhood on the development of obesity and related disorders in adulthood. Male C57BL/6J mice were pair-fed a normal-fat diet containing casein or REP during the juvenile period and then a high-fat diet (HFD) containing casein or REP during adulthood. Mice fed REP during the juvenile period showed better body weight, blood pressure, serum lipid profiles, lipopolysaccharide (LPS)-binding protein levels, and glucose tolerance in adulthood than those fed casein during the juvenile period. HFD-induced renal tubulo-glomerular alterations and hepatic microvesicular steatosis were less evident in REP-fed mice than in casein-fed ones. REP intake during the juvenile period improved HFD-induced dysbiosis (i.e., Escherichia genus proliferation and reduced gut microbiota diversity), thereby suppressing endotoxin-related chronic inflammation. Indeed, REP-derived peptides showed antibacterial activity against Escherichia coli, a major producer of LPS. In conclusion, REP supplementation during the juvenile period may regulate the gut microbiota and thus suppress the development of obesity and related disorders in adulthood in mice.

The Proteomic Analysis of Maize Endosperm Protein Enriched by Phos-tagtm Reveals the Phosphorylation of Brittle-2 Subunit of ADP-Glc Pyrophosphorylase in Starch Biosynthesis Process

AGPase catalyzes a key rate-limiting step that converts ATP and Glc-1-p into ADP-glucose and diphosphate in maize starch biosynthesis. Previous studies suggest that AGPase is modulated by redox, thermal and allosteric regulation. However, the phosphorylation of AGPase is unclear in the kernel starch biosynthesis process. Phos-tagTM technology is a novel method using phos-tagTM agarose beads for separation, purification, and detection of phosphorylated proteins. Here we identified phos-tagTM agarose binding proteins from maize endosperm. Results showed a total of 1733 proteins identified from 10,678 distinct peptides. Interestingly, a total of 21 unique peptides for AGPase sub-unit Brittle-2 (Bt2) were identified. Bt2 was demonstrated by immunoblot when enriched maize endosperm protein with phos-tagTM agarose was in different pollination stages. In contrast, Bt2 would lose binding to phos-tagTM when samples were treated with alkaline phosphatase (ALP). Furthermore, Bt2 could be detected by Pro-Q diamond staining specifically for phosphorylated protein. We further identified the phosphorylation sites of Bt2 at Ser10, Thr451, and Thr462 by iTRAQ. In addition, dephosphorylation of Bt2 decreased the activity of AGPase in the native gel assay through ALP treatment. Taking together, these results strongly suggest that the phosphorylation of AGPase may be a new model to regulate AGPase activity in the starch biosynthesis process.