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The aim of this study is to determine the effect of the digestibility of cassava starch by the enzymes extracted from corn malt, which will constitute one of the answers to the problem of integrating local products into the process in a modern brewery. Cassava starch solutions of different concentrations (E0: 0 g/L; E1: 1 g/L; E2: 1.1 g/L; E3: 1.2 g/L; E4: 1.3 g/L; E5: 1.4 g/L and E6: 1.5 g/L) were prepared and subjected to two treatments (gelatinized and non-gelatinized) and 5 mL of each were placed in a test tube. Three millilitres (3 mL) of the solution containing amylases extracted from malt corn was then added to each of the test tubes containing the cassava flour solutions. All the treatments were subjected to three temperature stages (50 °C for 15 min, 90 °C for 20 min, and 100 °C for 75 min). Twenty-eight (28) objects (two duplicates) were experimented in a complete factorial design (2 treatments × 2 temperature levels). The results obtained showed that gelatinization had no effect, which could be due to the high optimum temperatures of corn enzyme activity. The concentrations also did not have significant differences which shows that these concentrations can well be used on an industrial scale to digest cassava starch by corn malt enzymes.

Cytosolic glutamine synthetase (GS1) is the enzyme mainly responsible of ammonium assimilation and reassimilation in maize leaves. The agronomic potential of GS1 in maize kernel production was investigated by examining the impact of an overexpression of the enzyme in the leaf cells. Transgenic hybrids exhibiting a three-fold increase in leaf GS activity were produced and characterized using plants grown in the field. Several independent hybrids overexpressing Gln1-3, a gene encoding cytosolic (GS1), in the leaf and bundle sheath mesophyll cells were grown over five years in different locations. On average, a 3.8% increase in kernel yield was obtained in the transgenic hybrids compared to controls. However, we observed that such an increase was simultaneously dependent upon both the environmental conditions and the transgenic event for a given field trial. Although variable from one environment to another, significant associations were also found between two GS1 genes (Gln1-3 and Gln1-4) polymorphic regions and kernel yield in different locations. We propose that the GS1 enzyme is a potential lead for producing high yielding maize hybrids using either genetic engineering or marker-assisted selection. However, for these hybrids, yield increases will be largely dependent upon the environmental conditions used to grow the plants.Amiour et al. use a multi-year field trial evaluation and association mapping to determine if increased enzyme activity and native allelic variations at the GS1 loci in maize contribute to differences in grain yield. Overexpression of GS1 and polymorphisms in the corresponding loci were associated with kernel yield, indicating that GS1 expression can directly control kernel production and that GS1 has a potential lead in the production of high yielding maize hybrids depending on environmental conditions.

Increasing planting density is a key strategy for enhancing maize yields 1 – 3 . An ideotype for dense planting requires a ‘smart canopy’ with leaf angles at different canopy layers differentially optimized to maximize light interception and photosynthesis 4 – 6 , among other features. Here we identified leaf angle architecture of smart canopy 1 ( lac1 ), a natural mutant with upright upper leaves, less erect middle leaves and relatively flat lower leaves. lac1 has improved photosynthetic capacity and attenuated responses to shade under dense planting. lac1 encodes a brassinosteroid C-22 hydroxylase that predominantly regulates upper leaf angle. Phytochrome A photoreceptors accumulate in shade and interact with the transcription factor RAVL1 to promote its degradation via the 26S proteasome, thereby inhibiting activation of lac1 by RAVL1 and decreasing brassinosteroid levels. This ultimately decreases upper leaf angle in dense fields. Large-scale field trials demonstrate that lac1 boosts maize yields under high planting densities. To quickly introduce lac1 into breeding germplasm, we transformed a haploid inducer and recovered homozygous lac1 edits from 20 diverse inbred lines. The tested doubled haploids uniformly acquired smart-canopy-like plant architecture. We provide an important target and an accelerated strategy for developing high-density-tolerant cultivars, with lac1 serving as a genetic chassis for further engineering of a smart canopy in maize. A natural mutant of maize exhibits leaf characteristics in line with the ‘smart canopy’ ideotype for high-density planting and boosts yields in large-scale field trials.

A frame-shift mutation in MATRILINEAL, a pollen-specific phospholipase, triggers haploid induction in maize, which may be useful in developing improved haploid induction systems for crop breeding. Haploid induction in maize Haploid inbred lines are a valuable tool for genetic research and the hybrid breeding of crop plants. Timothy Kelliher et al . now examine the genetic basis of haploid induction in maize, and find that a frame-shift mutation in MATRILINEAL , a pollen-specific phospholipase, triggers haploid induction in these lines. This finding may be useful for the development of improved haploid induction systems for crop breeding. Sexual reproduction in flowering plants involves double fertilization, the union of two sperm from pollen with two sex cells in the female embryo sac. Modern plant breeders increasingly seek to circumvent this process to produce doubled haploid individuals, which derive from the chromosome-doubled cells of the haploid gametophyte. Doubled haploid production fixes recombinant haploid genomes in inbred lines, shaving years off the breeding process 1 . Costly, genotype-dependent tissue culture methods are used in many crops 2 , while seed-based in vivo doubled haploid systems are rare in nature 3 and difficult to manage in breeding programmes 4 . The multi-billion-dollar maize hybrid seed business, however, is supported by industrial doubled haploid pipelines using intraspecific crosses to in vivo haploid inducer males derived from Stock 6, first reported in 1959 (ref. 5 ), followed by colchicine treatment. Despite decades of use, the mode of action remains controversial 6 , 7 , 8 , 9 , 10 . Here we establish, through fine mapping, genome sequencing, genetic complementation, and gene editing, that haploid induction in maize ( Zea mays ) is triggered by a frame-shift mutation in MATRILINEAL ( MTL ), a pollen-specific phospholipase, and that novel edits in MTL lead to a 6.7% haploid induction rate (the percentage of haploid progeny versus total progeny). Wild-type MTL protein localizes exclusively to sperm cytoplasm, and pollen RNA-sequence profiling identifies a suite of pollen-specific genes overexpressed during haploid induction, some of which may mediate the formation of haploid seed 11 , 12 , 13 , 14 , 15 . These findings highlight the importance of male gamete cytoplasmic components to reproductive success and male genome transmittance. Given the conservation of MTL in the cereals, this discovery may enable development of in vivo haploid induction systems to accelerate breeding in crop plants.

Sucrose is produced in, and translocated from, photosynthetically active leaves (sources) to support non-photosynthetic tissues (sinks), such as developing seeds, fruits, and tubers. Different plants can utilize distinct mechanisms to transport sucrose into the phloem sieve tubes in source leaves. While phloem loading mechanisms have been extensively studied in dicot plants, there is less information about phloem loading in monocots. Maize and rice are major dietary staples, which have previously been proposed to use different cellular routes to transport sucrose from photosynthetic cells into the translocation stream. The anatomical, physiological, and genetic evidence supporting these conflicting hypotheses is examined. Upon entering sink cells, sucrose often is degraded into hexoses for a wide range of metabolic and storage processes, including biosynthesis of starch, protein, and cellulose, which are all major constituents for food, fibre, and fuel. Sucrose, glucose, fructose, and their derivate, trehalose-6-phosphate, also serve as signalling molecules to regulate gene expression either directly or through cross-talk with other signalling pathways. As such, sugar transport and metabolism play pivotal roles in plant development and realization of crop yield that needs to be increased substantially to meet the projected population demand in the foreseeable future. This review will discuss the current understanding of the control of carbon partitioning from the cellular to whole-plant levels, focusing on (i) the pathways employed for phloem loading in source leaves, particularly in grasses, and the routes used in sink organs for phloem unloading; (ii) the transporter proteins responsible for sugar efflux and influx across plasma membranes; and (iii) the key enzymes regulating sucrose metabolism, signalling, and utilization. Examples of how sugar transport and metabolism can be manipulated to improve crop productivity and stress tolerance are discussed.

Increasing grain yield of maize ( Zea mays L.) is required to meet the rapidly expanding demands for maize-derived food, feed, and fuel. Breeders have enhanced grain productivity of maize hybrids by pyramiding desirable characteristics for larger ears. However, loci selected for improving grain productivity remain largely unclear. Here, we show that a serine/threonine protein kinase encoding gene KERNEL NUMBER PER ROW6 (KNR6) determines pistillate floret number and ear length. Overexpression of KNR6 or introgression of alleles lacking the insertions of two transposable elements in the regulatory region of KNR6 can significantly enhance grain yield. Further in vitro evidences indicate that KNR6 can interact with an Arf GTPase-activating protein (AGAP) and its phosphorylation by KNR6 may affect ear length and kernel number. This finding provides knowledge basis to enhance maize hybrids grain yield. Selection of kernel number per ear has improved maize yield, but the genetic base is unclear. Here, the authors reveal that a serine/threonine protein kinase KNR6 is a positive regulator of the trait and show in vitro evidences that KNR6 may function through phosphorylating an Arf GTPase-activating protein.

Main conclusion The changes in the expression of key sugar metabolism enzymes (SPS and SUS), sucrose content and arrangement of chloroplast starch may play a significant role in the cold response in M. giganteus  and maize plants. To understand the mechanism of the chilling-response of two closely-related C 4 plants, we investigated the changes in the expression of sucrose phosphate synthase (SPS) and sucrose synthase (SUS) as well as changes in their potential products: sucrose, cellulose and starch in the leaves of Miscanthus  ×  giganteus and Zea mays . Low temperature (12–14 °C) increased SPS content in Miscanthus (MG) and chilling-sensitive maize line (Zm-S), but not in chilling-tolerant one (Zm-T). In Zm-S line, chilling also caused the higher intensity of labelling of SPS in the cytoplasm of mesophyll cells, as demonstrated by electron microscopy. SUS labelling was also increased by cold stress only in MG plants what was observed in the secondary wall between mesophyll and bundle sheath cells, as well as in the vacuoles of companion cells. Cold led to a marked increase in total starch grain area in the chloroplasts of Zm-S line. In turn, Fourier transform infrared spectroscopy (FTIR) showed a slight shift in the cellulose band position, which may indicate the formation of more compact cellulose arrangement in Zm-T maize line. In conclusion, this work presents new findings supporting diversified cold-response, not only between two C 4 plant species but also within one species of maize.

Substrate (futile) cycling involving carbohydrate turnover has been widely reported in plant tissues, although its extent, mechanisms, and functions are not well known. In this study, two complementary approaches, short and steady-state labeling experiments, were used to analyze glucose metabolism in maize (Zea mays) root tips. Unidirectional rates of synthesis for storage compounds (starch, Suc, and cell wall polysaccharides) were determined by short labeling experiments using [U-14C]glucose and compared with net synthesis fluxes to determine the rate of glucose production from these storage compounds. Steady-state labeling with [1-13C]glucose and [U-13C]glucose showed that the redistribution of label between carbon C-1 and C-6 in glucose is close to that in cytosolic hexose-P. These results indicate a high resynthesis flux of glucose from hexose-P that is not accounted for by glucose recycling from storage compounds, thus suggesting the occurrence of a direct glucose-P-to-glucose conversion. An enzyme assay confirmed the presence of substantial glucose-6-phosphatase activity in maize root tips. This new glucose-P-to-glucose cycle was shown to consume around 40% of the ATP generated in the cell, whereas Suc cycling consumes at most 3% to 6% of the ATP produced. The rate of glucose-P cycling differs by a factor of 3 between a maize W22 line and the hybrid maize cv Dea, and is significantly decreased by a carbohydrate starvation pretreatment.

Prime editing is a novel and universal CRISPR/Cas-derived precision genome-editing technology that has been recently developed. However, low efficiency of prime editing has been shown in transgenic rice lines. We hypothesize that enhancing pegRNA expression could improve prime-editing efficiency. In this report, we describe two strategies for enhancing pegRNA expression. We construct a prime editing vector harboring two pegRNA variants for W542L and S621I double mutations in ZmALS1 and ZmALS2 . Compared with previous reports in rice, we achieve much higher prime-editing efficiency in maize. Our results are inspiring and provide a direction for the optimization of plant prime editors.

Western Jilin Province is one of the world's three major saline–alkali land distribution areas, and is also an important area of global climate change and carbon cycle research. Rhizosphere soil microorganisms and enzymes are the most active components in soil, which are closely related to soil carbon cycle and can reflect soil organic carbon (SOC) dynamics sensitively. Soil inorganic carbon (SIC) is the main existing form of soil carbon pool in arid saline–alkali land, and its quantity distribution affects the pattern of soil carbon accumulation and storage. Previous studies mostly focus on SOC, and pay little attention to SIC. Illumina Miseq high-throughput sequencing technology was used to reveal the changes of community structure in three maize fields (M1, M2 and M3) and three rice fields (R1, R2 and R3), which were affected by different levels of salinization during soil development. It is a new research topic of soil carbon cycle in saline–alkali soil region to investigate the effects of soil microorganisms and soil enzymes on the transformation of SOC and SIC in the rhizosphere. The results showed that the root—soil—microorganism interaction was changed by saline–alkali stress. The activities of catalase, invertase, amylase and β -glucosidase decreased with increasing salinity. At the phylum level, most bacterial abundance decreases with increasing salinity. However, the relative abundance of Proteobacteria and Firmicutes in maize field and Firmicutes , Proteobacteria and Nitrospirae in rice field increased sharply under saline–alkali stress. The results of redundancy analysis showed that the differences of rhizosphere soil between the three maize and three rice fields were mainly affected by ESP, pH and soil salt content. In saline–alkali soil region, β -glucosidase activity and amylase were significantly positively correlated with SOC content in maize fields, while catalase and β -glucosidase were significantly positively correlated with SOC content in rice fields. Actinobacteria , Bacteroidetes and Verrucomicrobia had significant positive effects on SOC content of maize and rice fields. Proteobacteria , Gemmatimonadetes and Nitrospirae were positively correlated with SIC content. These enzymes and microorganisms are beneficial to soil carbon sequestration in saline–alkali soils.