Red light-emitting diodes (LEDs) are a potential light source for growing plants in spaceflight systems because of their safety, small mass and volume, wavelength specificity, and longevity. Despite these attractive features, red LEDs must satisfy requirements for plant photosynthesis and photomorphogenesis for successful growth and seed yield. To determine the influence of gallium aluminium arsenide (GaAlAs) red LEDs on wheat photomorphogenesis, photosynthesis, and seed yield, wheat (Triticum aestivum L., cv. 'USU-Super Dwarf') plants were grown under red LEDs and compared to plants grown under daylight fluorescent (white) lamps and red LEDs supplemented with either 1% or 10% blue light from blue fluorescent (BF) lamps. Compared to white light-grown plants, wheat grown under red LEDs alone demonstrated less main culm development during vegetative growth through preanthesis, while showing a longer flag leaf at 40 DAP and greater main culm length at final harvest (70 DAP). As supplemental BF light was increased with red LEDs, shoot dry matter and net leaf photosynthesis rate increased. At final harvest, wheat grown under red LEDs alone displayed fewer subtillers and a lower seed yield compared to plants grown under white light. Wheat grown under red LEDs+10% BF light had comparable shoot dry matter accumulation and seed yield relative to wheat grown under white light. These results indicate that wheat can complete its life cycle under red LEDs alone, but larger plants and greater amounts of seed are produced in the presence of red LEDs supplemented with a quantity of blue light.

The role of the scutellum and the aleurone in a-amylase production in the high-sugar sweet corn cultivars Illini X-tra Sweet (shrunken-2, sh2) and Illinois 677a (sugary, sugary enhancer; su se) was compared to that in the starchy (Su) hybrid Funks G4646 with the use of a-amylase enzyme assays, isoelectric focusing, electron microscopy, and laser scanning confocal microscopy. The scutellum of Illinois 677a had low levels of a-amylase activity compared to that of Funks G4646 through 10 days after imbibition, and the aleurone of Illini X-tra Sweet had negligible activity. On the isoelectric focusing gels, the Illinois 677a scutellum had fewer a-amylase isozymes at 7 days compared to the Funks G4646 scutellum. The Illini X-tra Sweet aleurone had no a-amylase isozymes. Funks G4646 scutellar epithelial and aleurone cells contained abundant rough endoplasmic reticulum, polysomes, and dictyosomes at 5 and 7 days, respectively. The scutellar epithelial cells of Illinois 677a contained fewer of these structures by 5 days, and the Illini X-tra Sweet aleurone contained mostly lipid bodies through 7 days. Few cytoplasmic membranes and little RNA were detected with laser scanning confocal microscopy in the Illini X-tra Sweet aleurone compared to Funks G4646 at 7 days. These data suggest that the scutellum of Illinois 677a and the aleurone of Illini X-tra Sweet have impaired abilities to produce a-amylase.The main storage products in cereal grains are carbohydrates, specifically amylose and amylopectin (1). During germination, the principle enzyme involved in carbohydrate breakdown is a-amylase, which hydrolyzes a(1-4) bonds in amylose and amylopectin, releasing fragments that can be further broken down by ,B-amylase, a-glucosidase, and debranching enzymes. a-Amylase is synthesized de novo in two specific tissues of the cereal grain, the scutellar epithelium of the embryo and the aleurone layer of the endosperm (1

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The aleurone of RB‐3 shrunken‐2 (sh2) maize kernels is deficient in α‐amylase activity during germination, but exogenous applications of gibberellic acid (GA3) (0.001–10 μm) induced low levels of activity. The highest activity was measured in the aleurone of kernels treated with 10 μm GA3 (14,600 ± 945 units), but was lower than untreated Starchy (Su) aleurone tissues (35,280 ± 5,010 units). On isoelectric focusing gels, no α‐amylase isozymes were detected in the untreated sh2 aleurone using starch zymograms or immunoblots, but the 1.0 and 10 μmmm GA3 treatments induced nearly all the isozymes (eight to ten) present in the Su aleurone. There was a very low level of α‐amylase mRNA in the untreated sh2 aleurone, an intermediate level in the 1.0 μm GA3‐treated sh2 aleurone, and the highest level in the untreated Su aleurone. On the confocal microscope, the 1.0 μm GA3‐treated aleurone cells had enhanced levels of cytoplasmic membranes and RNA compared to untreated sh2 aleurone cells. The 1.0 μm GA3 treatment also induced shoot elongation in the sh2 seedlings. The data demonstrate that the sh2 aleurone is deficient in its function to produce α‐amylases, and exogenous GA3 can partially restore cell function in the sh2 kernels.