The effects of sorghum bran addition on table tortillas and tortilla chip properties were evaluated. Texture, phenol content, antioxidant activity, and sensory characteristics were evaluated. Texture was measured by objective and subjective tests. Products were analyzed for phenols following the Folin-Ciocalteu procedure and for antioxidant potential following the ABTS (2,2'-azinobis (3- ethylbenzothiazoline-6-sulfonic acid) method. Sensory properties were evaluated using a nine point hedonic scale. Bran from two specialty sorghums: sumac (high tannin) and black (high anthocyanins) was added at 0, 5, and 10% to table tortillas and tortilla chips. For table tortillas the interaction of sorghum bran with an antistaling formula containing guar gum, carboxymethylcellulose and maltogenic alpha-amylase was assessed. Tortillas containing sorghum bran had a more friable structure than the control. This detrimental effect was overcome by the antistaling formula. Additives made fluffier tortillas with improved texture and appearance. Tortillas containing sorghum bran and the antistaling formula were acceptable to panelists. At 5% sorghum bran inclusion, there was no significant difference in sensory attributes from the control aside from appearance. Tortillas containing sorghum bran had a dark natural color comparable to that of blue corn tortillas. Tortilla chip texture was not significantly affected by addition of bran to the formula. As in table tortillas, addition of sorghum bran produced minor changes in the texture and flavor of the product, but a significant change in appearance acceptability. Tortilla chips had a dark color, comparable to the one of blue corn tortilla chips. Sumac bran yielded larger amounts of phenols and antioxidant activity than black bran. Levels of phenols and antioxidant potential increased with increased bran. Although processing caused a measurable loss of sorghum bran antioxidants, table tortilla and tortilla chips were still a significant source of phenols and antioxidant activity. The addition of sorghum bran produced tortillas and tortilla chips with increased levels of dietary fiber and antioxidants, without adversely affecting other sensory properties.

Sorghum [Sorghum bicolor (L.) Moench] production in Africa is widespread with low yields due to low inputs and the lack of sorghum hybrids. This situation has forced most of these farmers to grow maize hybrids since they are readily available in the seed market. Sorghum hybrids could be used if their potential was demonstrated. The objective of this study is to document the level of heterosis in Southern Africa sorghum germplasm. The performance of 52 F1 grain sorghum hybrids and their parental lines was evaluated in four environments. Measurements for grain yield, panicle exsertion, days to mid anthesis and plant height were analyzed to obtain estimates of high parent heterosis. High parent heterosis was observed to be 37.18% for yield, 82.77% for exsertion, -0.02% for days to mid anthesis and 23.7% for height. ICSR-939 and (87EON366*90EON328)-LD30 can be used as testers to develop more female lines for further hybrid seed production in breeding programs because they had the highest general combining ability. Protein content averaged 11.69%. ATx635 had significantly higher protein content than ATx631 (13.49% compared to 9.69%, respectively) and its hybrids had more protein than ATx631 hybrids (11.6% compared to 10.67% for ATx631). Mean heterosis for protein content was negative at -12.5%. This shows that hybrids had lower protein content than their parents since protein content is negatively correlated to grain yield (-0.35**). Starch content averaged 72.13% and ATx631 hybrids had more starch than ATx635 hybrids (73.16 compared to 72.37% respectively). Two hybrids, ATx.631/(87EON366*90EON328)-LD30 and ATx631/ ((TAM428*SV1)*CE151)-LD3 had the highest yields (5.04 t/ha and 4.93 t/ha, respectively). These hybrids also had small grains with good hardness and acceptable whiteness. They had good exsertion, flowered in good time and had acceptable plant heights. These two hybrids were compared to regional check varieties Macia and Tegemeo for all traits and they were either superior or within an acceptable range. These two hybrids are therefore recommended for release in the region. There is need therefore to start working on the various components of seed systems in the region so that seed of these two hybrids is made available to farmers who need the seed.

A sorghum gene SbLRR2, which is predicted to encode a simple extracellular leucine-rich repeat (LRR) protein, was previously isolated among a collection of fungal pathogen-induced sorghum cDNA clones generated by suppression subtractive hybridization. Phylogenetic analysis revealed that they are distinct from the simple extracellular LRR proteins reported previously. Subcellular localization analysis demonstrated that the SbLRR2-EYFP fusion protein was targeted to the extracellular space in tobacco leaf cells. Peptide N-Glycosidase F treatment revealed that the SbLRR2 is N-glycosylated with non-fucosylated oligosaccharides when transiently expressed in Nicotiana benthamiana leaves. Functional analysis was performed in SbLRR2 over-expression (OE) Arabidopsis plants which showed enhanced resistance against the necrotrophic pathogens Botrytis cinerea and Alternaria brassicicola. In addition, the OE lines were found to have elevated expression of several jasmonate acid (JA)-associated genes and higher endogenous JA contents. Hence, the SbLRR2-mediated defense responses in transgenic Arabidopsis are likely to be dependent on JA-signaling through increased JA production. On the other hand, the OE lines remained susceptible to Pseudomonas syringae pv. tomato as the wild type plants. Consistently, there was no up-regulation of salicylic acid (SA) defense marker gene expression or SA levels in the OE lines. Using yeast two-hybrid analysis, SbLRR2 was further shown to interact with Arabidopsis hypersensitive-induced response protein 1. Such interaction may suppress hypersensitive response which is known to enhance necrotrophic pathogen invasion. These data suggested a positive regulatory role of SbLRR2 in plant defense. Further phenotypic analysis of transgenic SbLRR2 revealed its novel role in enhancing lead [Pb(II)] tolerance in Arabidopsis. OE-lines were showed to alleviate Pb(II)-induced root inhibition, reduce the accumulation of Pb(II), and enhance transcription of AtPDR12 which was previously shown to function as a potential Pb(II) efflux pump contributing to Pb(II) detoxification. However, all the Pb(II) tolerance responses were abolished when SbLRR2 was transformed into the atpdr12 mutant. Meanwhile, the extracellular localization of SbLRR2 was shown to be essential for the enhanced Pb(II) tolerance in transgenic Arabidopsis. Together, these results indicated that SbLRR2-mediated Pb(II) tolerance was dependent on AtPDR12 via Pb(II) extrusion. Further investigations revealed the Pb(II)-induced transcriptional activation of SbLRR2 and several highly conserved AtPDR12 homologs in sorghum seedlings, suggesting the possibilities of a common molecular mechanism for Pb(II) tolerance in diverse plant species. Finally, an iTRAQ-based LC-MS/MS quantitative proteomics approach was used to investigate of lead responses in Arabidopsis. A total of 114 proteins showed significant changes in protein abundance with 58 up-regulated and 56 down-regulated proteins. Analysis of changes in the protein profile revealed that the photosynthesis, photorespiration and protein biosynthesis in Arabidopsis were inhibited under lead toxicity. On the other hand, abundances of proteins involved in the antioxidant system, glucosinolate-myrosinase system and JA biosynthesis pathway were elevated upon Pb(II) treatment. Further investigation revealed that Pb(II) stress induced a rapid increase of JA contents in Arabidopsis whereas a JA biosynthesis deficient mutant (AOS) showed hypersensitivity to Pb(II) toxicity, strongly implicating a significant role of JA in Pb(II) response. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

Physiological responses of 12 sorghum (Sorghum bicolor L.) genotypes previously classified as drought resistant and susceptible upon grain yield basis were evaluated under dry and wet moisture treatments at Tucson, Arizona in 1983. In addition, the relationship of these physiological responses and their heritability estimates were also determined. Apparent photosynthesis, transpiration, diffusive resistance, temperature differentials, and leaf temperature were measured under field conditions at three intervals from planting date: 48, 62, and 77 days, respectively. Stomatal density and epicuticular wax content were determined toward the end of the season when full canopy development was reached. Stress significantly affected all characteristics measured for each genotype by a reduction in apparent photosynthesis rates, transpiration, and temperature differentials, and an increase in diffusive resistance, leaf temperature and stomatal density. The wax content response varied among genotypes irrespective of the dry and wet moisture treatments. Except for the wax content and stomatal density, all the other parameters demonstrated a high significant correlation with photosynthesis at .001 level; nevertheless, greater values were observed in the stress treatment. Analysis of variance failed to detect significant differences among the 12 germplasm sources, except for the stomatal density. Multiple regression analysis showed that leaf diffusive resistance was the first variable incorporated for photosynthesis prediction in both the dry and wet treatments. The offspring and mid-parent regression for each characteristic under both treatments provided heritability estimates (h('2) (+OR-) SE), indicating higher heritability values under the dry treatment.

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This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project. / Revised May 1916.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

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