Maize Organs Research Articles

Characteristics and Regulating Role in Thermotolerance of the Heat Shock Transcription Factor ZmHsf12 from Zea mays L.

Plant heat shock transcription factors (Hsfs) are important regulators of heat shock signal transduction pathway. There are 30 members of the Hsf family in maize, only two of which, ZmHsf06 and ZmHsf12, belong to subclass A1. Our previous work demonstrated that ZmHsf06-overexpressing Arabidopsis lines showed improved tolerance to heat and drought stresses. In this study, we isolated ZmHsf12 from young leaves of maize (Zea mays L.) using homologous cloning methods. The CDS (coding sequence) of ZmHsf12 is 1,494 bp and encodes a putative protein consisting of 497 amino acids which possesses domains such as DBD (DNA-binding domain), OD (oligomerization domain), NLS (nuclear localization signal), NES (nuclear export signal), and an AHA (activator) motif. The ZmHsf12-GFP fusion protein is localized to the cell nucleus. ZmHsf12 was expressed in many maize organs, and its expression was up-regulated by heat shock. Furthermore, we characterized the function of ZmHsf12 in yeast and Arabidopsis. Yeast cells overexpressing ZmHsf12 showed enhanced heat tolerance. ZmHsf12-overexpressing Arabidopsis seedlings displayed significant increases in both basal and acquired thermotolerance. Compared to WT seedlings, the ZmHsf12-overexpressing lines displayed both increased chlorophyll contents and higher survival rates. Also, the expression of AtHsps was increased higher in the ZmHsf12-overexpressing Arabidopsis lines after heat stress. The results of our study strongly suggested that ZmHsf12 may take part in plant response to heat stress.

Effect of planting patterns on yield, nutrient accumulation and distribution in maize and soybean under\xa0relay intercropping systems

Planting patterns affect nitrogen (N), phosphorus (P), and potassium (K) acquisition and distribution in maize and soybean under intercropping conditions. Here we reveal that strip relay-intercropping increases the N, P, and K uptake and distribution across plant organs (root, straw, and seed) of maize and soybean, accelerates the dry-matter production of intercrop-species, and compensates the slight maize yield loss by considerably increasing the soybean yield. In a two-year experiment, soybean was planted with maize in different planting patterns (SI, 50:50 cm and SII, 40:160 cm) of relay-intercropping, both planting patterns were compared with sole cropping of maize (SM) and soybean (SS). As compared to SI, SII increased the N, P, and K accumulation in each organ of soybean by 20, 32, and 18 (root) %, 71, 61, and 76 (straw) %, and 68, 65, and 62 (seed) %, respectively, whereas decreased the N, P, and K accumulation in each organ of maize by 1, 4, and 8 (root) %, 1, 10, and 3 (straw) %, and 5, 10, and 8 (seed) %, respectively. Overall, in SII, relay-cropped soybean accumulated 91% of total nutrient uptake (TNU) of sole soybean plants, and relay-cropped maize accumulated 94% of TNU of sole maize plants.

Changes in Organic and Inorganic Osmolytes of Maize (Zea mays L.) by Sulfur Application Under Salt Stress Conditions

Mineral nutrients have favourable potential in alleviation of salinity problem in plants. Sulfur has specific functions in regulating plant growth, metabolism, enzymatic reactions and osmolyte homeostasis in plants. Hence, an experiment was carried out to explore the role of sulfur in ameliorating salt toxicity in maize by changes in organic and inorganic osmolyte contents. A range of sulfur levels (40, 80 mM) were used to induce salinity tolerance in maize. Various treatments of salinity (25, 75 mM) were applied by using sodium chloride. Results revealed that glycine betaine, proline, total soluble sugars, total soluble proteins and total free amino acids contents were increased by applying salinity while the application of sulfur lowered the proline and increased other studied organic osmolyte contents in all studied maize organs (leaf, shoot, root). The maximum improvement in organic osmolyte contents were found at 40 mM sulfur, however, at 80 mM sulfur proline contents were reduced. Applied salinity increased leaf tissue concentration of Na+ and decreased that of K+, Ca2+, NO3-, PO43-, SO42- leading to a severely declined in K+/Na and Ca2+/Na+ ratio. However, application of sulfur reduced the Na+ contents and improved K+, Ca2+, NO3-, PO43-, SO42-, K+/Na+ and Ca2+/Na+ ratio in the salinity grown plants. Moreover, 40 mM level of sulfur was greatly effective in osmolyte homeostasis at all levels of salinity. This indicated that use of sulfur (40 mM) ameliorated the effect of salinity by changing organic and inorganic osmolyte contents in maize plants.

ZmbZIP4 Contributes to Stress Resistance in Maize by Regulating ABA Synthesis and Root Development.

In plants, bZIP (basic leucine zipper) transcription factors regulate diverse processes such as development and stress responses. However, few of these transcription factors have been functionally characterized in maize (Zea mays). In this study, we characterized the bZIP transcription factor gene ZmbZIP4 from maize. ZmbZIP4 was differentially expressed in various organs of maize and was induced by high salinity, drought, heat, cold, and abscisic acid treatment in seedlings. A transactivation assay in yeast demonstrated that ZmbZIP4 functioned as a transcriptional activator. A genome-wide screen for ZmbZIP4 targets by immunoprecipitation sequencing revealed that ZmbZIP4 could positively regulate a number of stress response genes, such as ZmLEA2, ZmRD20, ZmRD21, ZmRab18, ZmNHX3, ZmGEA6, and ZmERD, and some abscisic acid synthesis-related genes, including NCED, ABA1, AAO3, and LOS5 In addition, ZmbZIP4 targets some root development-related genes, including ZmLRP1, ZmSCR, ZmIAA8, ZmIAA14, ZmARF2, and ZmARF3, and overexpression of ZmbZIP4 resulted in an increased number of lateral roots, longer primary roots, and an improved root system. Increased abscisic acid synthesis by overexpression of ZmbZIP4 also can increase the plant's ability to resist abiotic stress. Thus, ZmbZIP4 is a positive regulator of plant abiotic stress responses and is involved in root development in maize.

Transcriptomes of early developing tassels under drought stress reveal differential expression of genes related to drought tolerance in maize

Tassel, the male reproductive organs in maize, its development is adversely affected by drought during tasseling. To determine drought tolerance mechanisms of tassel differentiation at transcriptome level, RNA-Seq was performed using RNA of early developing tassel from 10 maize inbred lines under well-watered (control) and drought-stressed conditions, respectively. Results showed that the most active pathway for drought stress in maize were related to metabolic regulation at RNA level. And some genes, encoding enzymes involved in carbohydrate and lipid metabolism, were significantly down-regulated in drought-stressed plants. While, the transcription factors and genes, encoding catabolic or degradative enzymes, were over-expressed in maize early developing tassels under drought-stressed conditions, and among them, the transcripts of genes encoding exon-junction complexes involved in ‘RNA transcript’ and ‘mRNA surveillance’ pathways were significantly affected by drought stress. In addition, many other genes related to drought stress showed transcriptional changes at the later period of stress.

Distribution features and internal relations of heavy metals in soil–maize system of mining area, Anhui Province, Eastern China

ABSTRACTA total of 59 topsoil and corresponding maize plants were collected from this study area. The spatial distribution, correlation analysis, and multiple linear regression of heavy metals were researched detailedly in this article. The results showed that distribution characteristics of heavy metals (Pb, Cd, and Ni) in different parts of maize plants (immature stage) accumulated mostly in stems, with Pb mainly accumulated in roots (mature period), and Cd and Ni mostly in leaves. Except for the southeastern local region of this mining area, Mn and Cu possessed roughly similar spatial distribution characteristics. The results of partial correlation analysis indicated that Cu, Cd in the roots of the tested maize plants and Ni in soil may have antagonistic effects, Cu (soil)–Cu (stem) and Ni (soil)–Pb (stem) had a certain promoting effect. Besides, Cu, Pb, and Ni in soil promoted the absorption of Cu, Pb, and Ni in the leaves, whereas Cr and Pb in soil can promote the enrichment of Mn in maize grains. Our findings suggested that the concentrations of heavy metals in maize organs could be predicted accurately using the established models.

Maize productivity, heavy metals uptake and their availability in contaminated clay and sandy alkaline soils as affected by inorganic and organic amendments

Contamination of arid and semi-arid ecosystems by toxic heavy metals is a serious concern due to its impact on growth and productivity of crop and health risk through food chain. Therefore, the aims of this investigation were to study the impact of inorganic (i.e. nano hydroxyapatite, NHA and polyacrylamide, PAM) and organic (i.e. sugar beet factory lime, SBFL and biochar, BI) soil amendments on maize productivity grown in contaminated silty clay (i.e. fluvial, lacustrine) and sandy (i.e. marine) alkaline soils. In addition, the effect of those amendments on the content of heavy metals in plant organs and their fractions in alkaline soils at harvest as well as human health risk assessment were investigated. Application of amendments, particularly SBFL, followed by NHA and BI resulted in an improvement for maize growth and its productivity in comparison to PAM application and untreated soil. However, application of NHA significantly reduced the mobile fraction of Cd, Pb and Ni in soil and consequently in different maize organs, followed by application of SBFL and BI in comparison to untreated soil or soil treated with PAM. Additionally, transfer factors and health risk of metals were lesser when NHA and SBFL were applied into soil than those obtained from application of PAM. In conclusion, applications of NHA, SBFL and BI into contaminated alkaline soils with toxic heavy metals can be considered a vital option for ameliorating such soils from the view of environment and sustainable management in terms of heavy metals immobilization and reducing the metals content in plant organs.

Silicon nutrition mitigates salinity stress in maize by modulating ion accumulation, photosynthesis, and antioxidants

Silicon is known to improve resistance against salinity stress in maize crop. This study was conducted to evaluate the influence of silicon application on growth and salt resistance in maize. Seeds of two maize genotypes (salt-sensitive ‘EV 1089’ and salt-tolerant ‘Syngenta 8441’) were grown in pots containing 0 and 2 mM Si with and without 50 mM NaCl. After detailed investigation of ion concentrations in different maize organs, both genotypes were further selected in hydroponic experiment on basis of their contrasting response to salinity stress. In the second experiment, pre-germinated seedlings were transplanted into nutrient solution with 0 and 60 mM NaCl with and without 2 mM Si. Both genotypes differed significantly in their response to salinity. Silicon addition alleviated both osmotic and oxidative stress in maize crop by improving the performance of defensive machinery under salinity stress. Silicon application also improved the water-use efficiency in both tested genotypes under both normal and salinity stress conditions. In conclusion, this study implies that the silicon-treated maize plants had better chance to survive under salinity conditions and their photosynthetic and biochemical apparatus was working far better than that of silicon-non-treated plants.

A genomic region harboring the Pl1 allele from the Peruvian cultivar JC072A confers purple cob on Japanese flint corn (Zea mays L.).

Purple corn is a maize variety (Zea mays L.) with high anthocyanin content. When purple corn is used as forage, its anthocyanins may mitigate oxidative stresses causing lower milk production in dairy cows. In this study, we analyzed quantitative trait loci (QTLs) for anthocyanin pigmentation of maize organs in an F2 population derived from a cross between the Peruvian cultivar ‘JC072A’ (purple) and the inbred line ‘Ki68’ (yellowish) belonged to Japanese flint. We detected 17 significant QTLs on chromosomes 1–3, 6, and 10. Because the cob accounts for most of the fresh weight of the plant ear, we focused on a significant QTL for purple cob on chromosome 6. This QTL also conferred pigmentation of anther, spikelet, leaf sheath, culm, and bract leaf, and was confirmed by using two F3 populations. The gene Pl1 (purple plant 1) is the most likely candidate gene in this QTL region because the amino acid sequence encoded by Pl1-JC072A is similar to that of an Andean allele, Pl-bol3, which is responsible for anthocyanin production. The markers designed for the Pl1 alleles will be useful for the breeding of F1 lines with anthocyanin pigmentation in cobs.

The SULTR gene family in maize (Zea mays L.): Gene cloning and expression analyses under sulfate starvation and abiotic stress

Sulfur is an essential macronutrient required for plant growth, development and stress responses. The family of sulfate transporters (SULTRs) mediates the uptake and translocation of sulfate in higher plants. However, basic knowledge of the SULTR gene family in maize (Zea mays L.) is scarce. In this study, a genome-wide bioinformatic analysis of SULTR genes in maize was conducted, and the developmental expression patterns of the genes and their responses to sulfate starvation and abiotic stress were further investigated. The ZmSULTR family includes eight putative members in the maize genome and is clustered into four groups in the phylogenetic tree. These genes displayed differential expression patterns in various organs of maize. For example, expression of ZmSULTR1;1 and ZmSULTR4;1 was high in roots, and transcript levels of ZmSULTR3;1 and ZmSULTR3;3 were high in shoots. Expression of ZmSULTR1;2, ZmSULTR2;1, ZmSULTR3;3, and ZmSULTR4;1 was high in flowers. Also, these eight genes showed differential responses to sulfate deprivation in roots and shoots of maize seedlings. Transcript levels of ZmSULTR1;1, ZmSULTR1;2, and ZmSULTR3;4 were significantly increased in roots during 12-day-sulfate starvation stress, while ZmSULTR3;3 and ZmSULTR3;5 only showed an early response pattern in shoots. In addition, dynamic transcriptional changes determined via qPCR revealed differential expression profiles of these eight ZmSULTR genes in response to environmental stresses such as salt, drought, and heat stresses. Notably, all the genes, except for ZmSULTR3;3, were induced by drought and heat stresses. However, a few genes were induced by salt stress. Physiological determination showed that two important thiol-containing compounds, cysteine and glutathione, increased significantly under these abiotic stresses. The results suggest that members of the SULTR family might function in adaptations to sulfur deficiency stress and adverse growing environments. This study will lay a foundation for better understanding the functional diversity of the SULTR family and exploring genes of interest for genetic improvement of sulfur use efficiency in cereal crop plants.

Preliminary Studies to Characterize the Temporal Variation of Micronutrient Composition of the Above Ground Organs of Maize and Correlated Uptake Rates.

The improvement of agronomic practices and the use of high technology in field crops contributes for significant increases in maize productivity, and may have altered the dynamics of nutrient uptake and partition by the plant. Official recommendations for fertilizer applications to the maize crop in Brazil and in many countries are based on critical soil nutrient contents and are relatively outdated. Since the factors that interact in an agricultural production system are dynamic, mathematical modeling of the growth process turns out to be an appropriate tool for these studies. Agricultural modeling can expand our knowledge about the interactions prevailing in the soil-plant-atmosphere system. The objective of this study is to propose a methodology for characterizing the micronutrient composition of different organs and their extraction, and export during maize crop development, based on modeling nutrient uptake, crop potential evapotranspiration and micronutrient partitioning in the plant, considering the production environment. This preliminary characterization study (experimental growth analysis) considers the temporal variation of the micronutrient uptake rate in the aboveground organs, which defines crop needs and the critical nutrient content of the soil solution. The methodology allowed verifying that, initially, the highest fraction of dry matter, among aboveground organs, was assigned to the leaves. After the R1 growth stage, the largest part of dry matter was partitioned to the stalk, which in this growth stage is the main storage organ of the maize plant. During the reproductive phase, the highest fraction of dry matter was conferred to the reproductive organs, due to the high demand for carbohydrates for grain filling. The micronutrient (B, Cu, Fe, Mn, and Zn) content follows a power model, with higher values for the initial growth stages of development and leveling off to minimum values at the R6 growth stage. The proposed model allows to verify that fertilizer recommendations should be related to the temporal variability of micronutrient absorption rates, in contrast to the classic recommendation based on the critical soil micronutrient content. The maximum micronutrient absorption rates occur between the reproductive R4 and R5 growth stages. These evaluations allowed to predict the maximum micronutrient requirements, considered equal to respective stalk sap concentrations.

Antioxidant Capacity of Lignin and Phenolic Compounds from Corn Stover

Corn stover, remaining after maize production, is produced worldwide. Despite being a residue, it contains bioactive compounds. Phenolic acids and lignin from maize plants were quantified to assess the possibility of valorization of this biomass. Extracts of the dry stem, root, cob, husk, leaf and grain of the maize plant were prepared using ethanol and alkaline hydrolysis. These were further subjected to acid hydrolysis to extract lignin and subsequently evaluated for their total phenolic content (TPC) and antioxidant capacity using two methods: measurement of the scavenging capacity against DPPH radical (2,2-diphenyl-1-picryl-hydrazyl) and the oxygen radical absorbance capacity (ORAC). The extracts showed a TPC of 219.67–1420.94 mg EAG 100 g−1. The antioxidant capacity of the extracts by DPPH scavenging was 1.11–11.75 mmol ET g−1, and their ORAC was 15.43–591.41 µmol ET g−1. Two phenolic acids (p-coumaric and ferulic acid) were identified in the samples using UPLC–PDA. The total lignin content (4.88–32.12%), TPC (3.4–16.9 mg EAG 100 g−1) and antioxidant capacity by DPPH scavenging (1.8–2.55 mmol ET g−1), as well as ORAC (0.8–3.9 µmol ET g−1), of the maize organs were assessed. The results suggest that corn stover is a potential source of natural antioxidants.

Optimized tillage practices and row spacing to improve grain yield and matter transport efficiency in intensive spring maize

Subsoiling tillage practices and wide-narrow planting patterns could greatly improve grain yield through increasing post-silking dry matter accumulation of spring maize (Zea mays L.) under high plant density. However, the relationship between increased yield and vascular bundles structure, post-silking matter transport efficiency has not been unknown. Therefore, a field experiment was conducted on the Northeast plain of Liaoning Province in China in 2013 and 2014 to investigate the effects of four cultivation modes on post-silking matter transport under high plant density (105,000 plants ha−1). A widely grown maize hybrid Zhongdan 909, which exhibits high grain yield and tolerance to high plant density, has been used in our study. The four cultivation modes were (1) traditional rotary tillage (20cm) plus uniform plant spacing (60cm; RU; control); (2) subsoiling tillage (35–40cm) plus uniform plant spacing (60cm; SU); (3) traditional rotary tillage (20cm) plus wide-narrow (80+40cm) plant spacing (RW); and (4) subsoiling tillage plus wide-narrow plant spacing (SW). Compared to RU, wide-narrow planting (RW, SW) significantly optimized the canopy structure at silking, while SU and SW significantly optimized the soil structure, thus improved the photosynthetic rate and canopy radiation use efficiency (RUE), and post-silking dry matter accumulation (+5.2% [SU], +6.5% [RW], and +13% [SW]), and simultaneously reduced the C/N ratio in stems at maturity (−4% [SU], −27% [RW] and −39% [SW]), which led to the balancing of C and N in organs of maize at grain filling stage. Moreover, it also enhanced the differentiation of the vascular bundle system at the early growth stage, and maintained its function after silking by the better environmental conditions, which greatly improved the matter transport efficiency (+42%), and increased the grain filling rate. As a result, the yield for SU, RW, and SW increased by 5%, 7.5%, and 22%, respectively, compared to RU. These suggested that the optimization practices noticeably increased the canopy RUE after silking for spring maize by improving matter transport efficiency, stem vascular structure, and maintaining the balance between C and N metabolism, which eventually increased the grain yield under high plant density conditions. It might provide information of appropriate cultivation practices in enhancing grain yield for maize.

Dynamic change of mineral nutrient content in different plant organs during the grain filling stage in maize grown under contrasting nitrogen supply

Abstract The introduction of new hybrids and integrated crop-soil management has been causing maize grain yield to increase. However, less attention has been paid on the nutrient concentration of the grain; this aspect is of great importance to supplying calories and nutrients in the diets of both humans and animals worldwide. Increasing the retranslocation of nutrients from vegetative organs to grain can effectively increase the nutrient concentration of grain and general nutrient use efficiency. The present study involved monitoring the dynamic change of macro- and micronutrients in different organs of maize during the grain filling stage. In addition, the mobility of different elements and their contribution to grain nutrient content were evaluated in a 2-year experiment under low (LN, no N supplied) and high N (HN, 180 kg N ha−1) supply. Under HN supply, the net remobilization efficiency (RE) of the vegetative organs as a whole (calculated as nutrient remobilization amount divided by nutrient content at silking) of N, P, K, Mn, and Zn were 44%, 60%, 13%, 15%, and 25%, respectively. The other nutrients (Mg, Ca, Fe, Cu, and B) showed a net accumulation in the vegetative organs as a whole during the grain filling stage. Among the different organs, N, P, and Zn were remobilized more from the leaves (RE of 44%, 51% and 43%, respectively) and the stalks (including leaf sheaths and tassels) (RE of 48%, 71% and 43%, respectively). K was mainly remobilized from the leaves with RE of 51%. Mg, Ca, Fe, Mn, and Cu were mostly remobilized from the stalks with the RE of 23%, 9%, 10%, 42%, and 28%, respectively. However, most of the remobilized Mg, Ca, Fe, Mn, Cu, and Zn were translocated to the husk and cob, which seemingly served as the buffer sink for these nutrients. The REs of all the nutrients except for P, K, and Zn were vulnerable to variations in conditions annually and were reduced when the grain yield and harvest index were lower in 2014 compared with 2013. Under LN stress, the RE was reduced in P and Zn in 2013, increased in Cu and unchanged in other nutrients. The concentration of these nutrients in the grain was either unchanged (P, K, Ca, Zn, and B) or decreased (N, Mg, Fe, Mn, and Cu). It is concluded that grain N, P, K, Mn, and Zn, but not Mg, Ca, Fe, Cu, and B concentration, can be improved by increasing their remobilization from vegetative organs. However, enhancing the senescence of maize plant via LN stress seems unable to increase grain mineral nutrient concentration. Genetic improvement aiming to increase nutrient remobilization should take into account the organ-specific remobilization pattern of the target nutrient.

Maize biomass simulation based on dynamic photosynthate allocation.

Photosynthate allocation is critical to crop growth and biomass formation, and it is also a key part of crop simulation. A photosynthate allocation model of maize was established based on photosynthate allocation mechanisms as well as the photosynthate allocation characteristics of maize at different stages. This model was then coupled with the CO2 assimilation module of WOFOST crop model to simulate the biomass dynamics of different organs of maize on daily scale. It was validated by 5 years' field experiment data of spring maize from Jinzhou Agricultural Ecosystem Research Station. The results showed that, the model could explain about 95.4% of maize's total biomass change, while 87.0%, 85.3%, 67.9%, 76.5% and 87.5% of vegetative, leaf, root, stem, and ear biomass variations, respectively. This model could fulfill accurate simulation of different organ biomass dynamics of maize.

Effects of heavy metals and chelants on phytoremediation capacity and on rhizobacterial communities of maize

Heavy metals (HMs) are one of the major ecological problem related to human activities. Phytoremediation is a promising “green technology” for soil and water reclamation, and it can be improved by means of the use of chelants. In the past particular attention was paid on the effects of HMs and/or chelants on plant health, but much less on their effects on rhizosphere communities. To shed light on the interaction among plant-HM-chelant-rhizobacterial community a pot experiment was set up. Maize plants were grown on uncontaminated, multi-metal (copper and zinc) contaminated and chelants artificially amended soils. A high concentration of HMs was detected in the different maize organs; chelants improved the accumulation capacity of the maize plants. The rhizosphere bacterial community isolated from control plants showed the largest biodiversity in terms of bacterial genera. However, the addition of HMs reduced the number of taxa to three: Bacillus, Lysinibacillus and Pseudomonas. The effects of HM treatment were counteracted by the addition of chelants in terms of the genetic biodiversity. Furthermore, several bacterial strains particularly resistant to HMs and chelants were isolated and selected. Our study suggests that the combined use of resistant bacteria and chelants could improve the phytoremediation capacity of maize.

Signaling from maize organ primordia via FASCIATED EAR3 regulates stem cell proliferation and yield traits

Shoot apical meristems are stem cell niches that balance proliferation with the incorporation of daughter cells into organ primordia. This balance is maintained by CLAVATA-WUSCHEL feedback signaling between the stem cells at the tip of the meristem and the underlying organizing center. Signals that provide feedback from organ primordia to control the stem cell niche in plants have also been hypothesized, but their identities are unknown. Here we report FASCIATED EAR3 (FEA3), a leucine-rich-repeat receptor that functions in stem cell control and responds to a CLAVATA3/ESR-related (CLE) peptide expressed in organ primordia. We modeled our results to propose a regulatory system that transmits signals from differentiating cells in organ primordia back to the stem cell niche and that appears to function broadly in the plant kingdom. Furthermore, we demonstrate an application of this new signaling feedback, by showing that weak alleles of fea3 enhance hybrid maize yield traits.

Defining the SUMO System in Maize: SUMOylation Is Up-Regulated during Endosperm Development and Rapidly Induced by Stress.

In response to abiotic and biotic challenges, plants rapidly attach small ubiquitin-related modifier (SUMO) to a large collection of nuclear proteins, with studies in Arabidopsis (Arabidopsis thaliana) linking SUMOylation to stress tolerance via its modification of factors involved in chromatin and RNA dynamics. Despite this importance, little is known about SUMOylation in crop species. Here, we describe the plant SUMO system at the phylogenetic, biochemical, and transcriptional levels with a focus on maize (Zea mays). In addition to canonical SUMOs, land plants encode a loosely constrained noncanonical isoform and a variant containing a long extension upstream of the signature β-grasp fold, with cereals also expressing a novel diSUMO polypeptide bearing two SUMO β-grasp domains in tandem. Maize and other cereals also synthesize a unique SUMO-conjugating enzyme variant with more restricted expression patterns that is enzymatically active despite a distinct electrostatic surface. Maize SUMOylation primarily impacts nuclear substrates, is strongly induced by high temperatures, and displays a memory that suppresses subsequent conjugation. Both in-depth transcript and conjugate profiles in various maize organs point to tissue/cell-specific functions for SUMOylation, with potentially significant roles during embryo and endosperm maturation. Collectively, these studies define the organization of the maize SUMO system and imply important functions during seed development and stress defense.

Analysis of gene expression and histone modification between C4 and non-C4 homologous genes of PPDK and PCK in maize.

More efficient photosynthesis has allowed C4 plants to adapt to more diverse ecosystems (such as hot and arid conditions) than C3 plants. To better understand C4 photosynthesis, we investigated the expression patterns of C4 genes (C4PPDK and PCK1) and their non-C4 homologous genes (CyPPDK1, CyPPDK2, and PCK2) in the different organs of maize (Zea mays). Both C4 genes and non-C4 genes showed organ-dependent expression patterns. The mRNA levels of C4 genes were more abundant in leaf organ than in seeds at 25days after pollination (DAP), while non-C4 genes were mainly expressed in developing seeds. Further, acetylation of histone H3 lysine 9 (H3K9ac) positively correlates with mRNA levels of C4 genes (C4PPDK and PCK1) in roots, stems, leaves, and seeds at 25 DAP, acetylation of histone H4 lysine 5 (H4K5ac) in the promoter regions of both C4 (C4PPDK and PCK1) and non-C4 genes (CyPPDK1, CyPPDK2, and PCK2) correlated well with their transcripts abundance in stems. In photosynthetic organs (stems and leaves), dimethylation of histone H3 lysine 9 (H3K9me2) negatively correlated with mRNA levels of both C4 and non-C4 genes. Taken together, our data suggest that histone modification was involved in the transcription regulation of both C4 genes and non-C4 genes, which might provide a clue of the functional evolution of C4 genes.

Desempenho de larvas de Helicoverpa armigera(Hübner) (Lepidoptera: Noctuidae) em diferentes fontes alimentares

RESUMO Recentemente observada no Brasil, Helicoverpa armigera tornou-se praga relevante, tanto pela rápida disseminação como pela importância econômica das culturas nas quais se estabeleceu, como a soja e o milho. A compreensão do processo de estabelecimento em diferentes regiões e sistemas de produção e da dinâmica populacional de uma praga reconhecidamente polífaga, como base para o seu manejo, depende do conhecimento sobre o efeito de espécies vegetais como alimento, na biologia da espécie. Conduziu-se experimento em laboratório, fornecendose às lagartas órgãos reprodutivos de soja, milho, canola, aveia-preta, aveia-branca, nabo e azevém. Concluiu-se que as diferentes fontes alimentares afetam o desenvolvimento larval de H.armigera. Espigas de milho e de trigo e síliquas de canola são os melhores alimentos para o desenvolvimento de H.armigera. Espigas de azevém, por outro lado, são o pior alimento. Panículas de aveia-preta e aveia-branca e síliquas de nabo são menos adequadas que vagens de soja, como fonte de alimento para as lagartas.