Stages Of Kernel Development Research Articles

The role of maize sap beetles (Coleoptera: Nitidulidae) and maize weevils (Coleoptera: Curculionidae) in the spread of Aspergillus flavus in pre-harvest maize in Kenya

Abstract The spread of toxigenic Aspergillus into maize by insects and the subsequent aflatoxin contamination poses a risk to humans and animals and has been investigated in North and South America. To evaluate this effect in an African context, Greenhouse studies were conducted in 2022 to determine the role of sap beetles, Carpophilus dimidiatus Fabricius, 1792 (Coleoptera: Nitidulidae) and maize weevils, Sitophilus zeamais Motschulsky, 1855 (Coleoptera: Curculionidae) on infection of maize kernels by Aspergillus flavus Link and the resultant aflatoxin accumulation. To test the beetles’ efficacy, treatments were applied on partially opened primary ears at 3 different stages of kernel development (BBCH 75, 83, and 87). The treatments were: (i) distilled water, (ii) water with A. flavus spores, (iii) maize grits, (iv) maize grits with A. flavus spores, (v) C. dimidiatus, (vi) C. dimidiatus with A. flavus spores, (vii) S. zeamais, and (viii) S. zeamais with A. flavus spores. Data on kernel infection, maize rotting, yield, and aflatoxin content in kernels were collected. The highest kernel spoilage and yield loss were recorded for the co-inoculation of S. zeamais and A. flavus spores, followed by S. zeamais without A. flavus spores, and then C. dimidiatus with the fungal spores. Inoculation of maize at the BBCH 83 growth stage resulted in the highest kernel damage and aflatoxin contamination. S. zeamais and, to a lesser extent, C. dimidiatus effectively spread the A. flavus inoculum into non-wounded ears, resulting in fungal and aflatoxin contamination. The yield loss from S. zeamais-Aspergillus co-inoculation occurred due to the grain rotting and actual feeding of the maize weevils. Thus, insect management is important in reducing pre-harvest contamination of maize with mycotoxigenic fungi and their resultant toxins.

Expression Dynamics of lpa1 Gene and Accumulation Pattern of Phytate in Maize Genotypes Possessing opaque2 and crtRB1 Genes at Different Stages of Kernel Development.

Phytic acid (PA) acts as a storehouse for the majority of the mineral phosphorous (P) in maize; ~80% of the total P stored as phytate P is not available to monogastric animals and thereby causes eutrophication. In addition, phytic acid chelates positively charged minerals making them unavailable in the diet. The mutant lpa1-1 allele reduces PA more than the wild-type LPA1 allele. Further, mutant gene opaque2 (o2) enhances lysine and tryptophan and crtRB1 enhances provitamin-A (proA) more than wild-type O2 and CRTRB1 alleles, respectively. So far, the expression pattern of the mutant lpa1-1 allele has not been analysed in maize genotypes rich in lysine, tryptophan and proA. Here, we analysed the expression pattern of wild and mutant alleles of LPA1, O2 and CRTRB1 genes in inbreds with (i) mutant lpa1-1, o2 and crtRB1 alleles, (ii) wild-type LPA1 allele and mutant o2 and crtRB1 alleles and (iii) wild-type LPA1, O2 and CRTRB1 alleles at 15, 30 and 45 days after pollination (DAP). The average reduction of PA/total phosphorous (TP) in lpa1-1 mutant inbreds was 29.30% over wild-type LPA1 allele. The o2 and crtRB1-based inbreds possessed ~two-fold higher amounts of lysine and tryptophan, and four-fold higher amounts of proA compared to wild-type alleles. The transcript levels of lpa1-1, o2 and crtRB1 genes in lpa1-1-based inbreds were significantly lower than their wild-type versions across kernel development. The lpa1-1, o2 and crtRB1 genes reached their highest peak at 15 DAP. The correlation of transcript levels of lpa1-1 was positive for PA/TP (r = 0.980), whereas it was negative with inorganic phosphorous (iP) (r = -0.950). The o2 and crtRB1 transcripts showed negative correlations with lysine (r = -0.887) and tryptophan (r = -0.893), and proA (r = -0.940), respectively. This is the first comprehensive study on lpa1-1 expression in the maize inbreds during different kernel development stages. The information generated here offers great potential for comprehending the dynamics of phytic acid regulation in maize.

Experiments and modeling of forced ignition in methane/air mixtures with added NO

Ignition of fuel/oxidizer mixtures containing combustion products is important to the operation of advanced combustors. Previous work indicates that the presence of NO can reduce ignition delay times, yet the influence of NO on forced ignition is not clear. This work examines ignition kernels generated by spark discharges in CH4/air flows diluted with a mixture of NO and N2. Differences in chemistry initiated by the presence of NO are examined by comparing mixtures diluted with only N2 to mixtures diluted with both NO and N2. Ignition probability and kernel growth rates are determined using measurements of infrared radiation emissions from the developing ignition kernels. The presence of NO in the unburned mixture does not affect ignition probability. However, the addition of small quantities of NO on the order of 300–1200 parts per million increases the size of ignition kernels relative to those generated in mixtures diluted with pure N2 by up to 20%. Numerical modeling is performed to examine the role of low temperature chemistry on ignition behavior. The sensitivity of ignition kernel growth to the presence of NO is attributed to increased CH4 oxidation rates caused by low-temperature chemistry activated in the early stages of kernel development.

Genome-wide identification of B3 superfamily in pecan (Carya illinoensis): In silico and experimental analyses

The B3 superfamily comprises a class of transcription factors containing B3 functional domains that play crucial roles in plant growth and development. However, the identification and analysis of the B3 superfamily have not been reported in pecans. In this study, 75 B3 superfamily members were identified and divided into four families, namely ARF (31), RAV (10), LAV (8), and REM (26). The gene structure, conserved motifs and domain analysis indicated that each family was highly similar. The Ka/Ks results indicated that the CiB3s underwent purifying selection. Several growth- and development-related cis-elements, such as Box 4, GATA-motif, and G-Box, were found in the promoter of the B3 transcription factor. The results obtained from the transcriptomic analysis of different kernel development stages and different tissues of pecan and qRT-PCR, indicated that several transcription factors, particularly CiABI3, CiFUS3, and CiLEC2, were involved in regulating kernel development. In particular, the expression of CiFUS3 changed significantly between S3 and S5. Additionally, CiFUS3 is localized in the nucleus and has no self-transcriptional activity. A yeast one-hybrid experiment showed that CiFUS3 could bind to the RY-motif related to seed development. Overall, our study provides a reference for the role of CiFUS3 in oil synthesis and the functional study of B3 genes in pecan.

Comparative de novo Transcriptome Analysis of Two Cultivars With Contrasting Content of Oil and Fatty Acids During Kernel Development in Torreya grandis.

Vegetable oil is an indispensable nutritional resource for human health and mainly characterized by the composition and content of fatty acids (FAs). As a commercial species of gymnosperm, Torreya grandis produces oil-rich nuts with high unsaturated fatty acids content in the mature kernels. In this study, two cultivars, T. grandis ‘Xifei’ and T. grandis ‘Dielsii,’ with distinct oil content were employed to compare the profiles of FAs accumulation during kernel development. The accumulation rate of oil content was significantly different between ‘Xifei’ and ‘Dielsii.’ Besides, the final oil content of ‘Xifei’ (52.87%) was significantly higher than that of ‘Dielsii’ (41.62%) at maturity. The significant differences in main FAs were observed at almost each kernel development stages between the two cultivars. C16:0, C18:1, and C20:3 FA exhibited different accumulation patterns between cultivars. The content and the initiation of accumulation of C20:3 FA were different between the two cultivars. To explore the molecular mechanism associated with different content of oil and FAs between two cultivars, de novo transcriptome of kernels was compared between ‘Xifei’ (high oil) and ‘Dielsii’ (low oil) at three stages of oil accumulation, respectively. Totally 142,213 unigenes were assembled and 16,379 unigenes with a length of over 1,000 nt were successfully annotated, including 139 unigenes related to FA biosynthesis, elongation, and metabolism. Compared with ‘Dielsii,’ totally 1,476, 2,140, and 1,145 differentially expressed genes (DEGs) were upregulated in ‘Xifei’ at the stage of the initiative, the rapid rise, and the stationary oil accumulation, respectively; the number of downregulated DEGs reached 913, 1,245, and 904, respectively. Relative expressions of 11 DEGs involved in FAs biosynthesis and metabolism were confirmed by RT-qPCR. Abundant differentially expressed transcription factors and pathway DEGs were correlated to oil and FAs according to Pearson’s correlation analysis between transcriptome and metabolites (oil and FAs), suggesting their contributions to the differential oil and FAs between the two cultivars during kernel development of T. grandis. To conclude, our findings can provide novel insights into the developmental differences in metabolites and de novo transcriptome correlated to lipid accumulation and FA synthesis of kernels between cultivars with contrasting oil deposits and demystify the regulatory mechanism of high oil accumulation in T. grandis.

Time-resolved multiomics analysis of the genetic regulation of maize kernel moisture

Maize kernel moisture content (KMC) at harvest greatly affects mechanical harvesting, transport and storage. KMC is correlated with kernel dehydration rate (KDR) before and after physiological maturity. KMC and KDR are complex traits governed by multiple quantitative trait loci (QTL). Their genetic architecture is incompletely understood. We used a multiomics integration approach with an association panel to identify genes influencing KMC and KDR. A genome-wide association study using time-series KMC data from 7 to 70 days after pollination and their transformed KDR data revealed respectively 98 and 279 loci significantly associated with KMC and KDR. Time-series transcriptome and proteome datasets were generated to construct KMC correlation networks, from which respectively 3111 and 759 module genes and proteins were identified as highly associated with KMC. Integrating multiomics analysis, several promising candidate genes for KMC and KDR, including Zm00001d047799 and Zm00001d035920, were identified. Further mutant experiments showed that Zm00001d047799, a gene encoding heat shock 70 kDa protein 5, reduced KMC in the late stage of kernel development. Our study provides resources for the identification of candidate genes influencing maize KMC and KDR, shedding light on the genetic architecture of dynamic changes in maize KMC.

Expression analysis of opaque2, crtRB1 and shrunken2 genes during different stages of kernel development in biofortified sweet corn

Sweet corn is a popular food worldwide. Traditional shrunken2 (sh2)-derived sweet corn possesses low lysine (0.150–0.250%), tryptophan (0.030–0.040%) and provitamin-A (proA: 3–4 μg/g). Here transcript profiles of a newly developed 12 sh2-based sweet corn inbreds possessing mutant opaque2 (o2) and β-carotene hydroxylase (crtRB1) genes were analyzed during three stages of kernel development viz., 20-, 24- and 28- days after pollination (DAP). Introgressed inbreds had higher lysine (0.309%), tryptophan (0.077%) and proA (17.28 μg/g). Across stages of kernel development, transcript levels of mutant sh2, o2 and crtRB1 genes were significantly lower than the wild type (sh2+, o2+ and crtRB1+) alleles. Among genes, sh2 had the highest level of transcripts accumulation followed by crtRB1 and o2. While o2 and crtRB1 transcripts attained peaks at 24-DAP, the highest peak for sh2 was recorded at 28-DAP. Strong negative correlation (r = −0.99 to −0.71) was observed between the transcripts and corresponding nutrients. The study provided insight of complex regulation of sh2, o2 and crtRB1 genes during various stages of kernel development. This is a first of its kind study to analyze the transcript level variation of mutant allele of sh2, o2 and crtRB1 genes among novel biofortified sweet corn genotypes.

Phenological growth stages of ‘Barcelona’ hazelnut (Corylus avellana L.) described using an extended BBCH scale

A wide range of hazelnut (Corylus avellana) cultivars are produced around the world. Cultivars are often listed by the time of bloom, from early to mid and late season. To date, phenological stages have been recorded using alphanumerical codes, although data analysis is difficult with such codes. This study converted the alphanumerical codes to fully numerical codes using the Biologische Bundesanstalt Bundessortenamt und Chemische Industrie (BBCH) scale. A hazelnut BBCH scale was created for the cultivar 'Barcelona', which is considered a reference for phenological stages. The scale was constructed with at least two digits (0 to 9) for the main growth stages and three digits for female flowering and fruit development. The first number indicates the general growth stage, the second number indicates the growth stage at a specific time, and the third digit, when present, indicates the proportion at that stage on the tree. The hazelnut BBCH scale describes in 38 stages within 7 of the 10 available stages. The BBCH stages used are 5 (inflorescence emergence), 6 (flowering), 0 (bud development), 1 (leaf development), 7 (fruit development), 8 (fruit ripening), and 9 (senescence). The hazelnut is unusual in that it flowers in winter. Thus, the scale was extended from flower initiation (spring to summer of the year before harvest), male and female flowering (winter before harvest) and bud and leaf development (spring before harvest). During the spring before harvest, and summer before harvest, fruit developmental stages and fruit ripening are monitored and finally, senescence finalises the hazelnut life cycle in autumn after the harvest. Thus, the BBCH hazelnut cycle has a duration of at least 18 months and gives a good idea of hazelnut development. Finally, this new scale will add new information on the kernel development stages which were not evaluated in the former phenological scale. It will help producers to have a better idea of the fruit ripening and potential harvest date.

Identification of genes involved in the formation of soluble dietary fiber in winter rye grain and their expression in cultivars with different viscosities of wholemeal water extract

The grain of rye (Secale cereale L.) used for baking contains a large amount of non-starch polysaccharides, making it an excellent component of functional foods. But rye grain intended for alcohol production and forage use should have a reduced content of these polysaccharides. A comprehensive parameter that can predict the best field of application for winter rye grain is the viscosity of its wholemeal water extract. However, our understanding of the genetic background underlying this key trait and associated features of rye grain is poor. By analyzing six Russian winter rye cultivars, we identified the most contrasting forms and characterized the peculiarities of their water-soluble carbohydrates capable of influencing the viscosity of water extracts. Then, using phylogenetic and transcriptomic analyses, we identified in the rye genome many genes encoding putative glycosyltransferases and glycosylhydrolases responsible for the synthesis and degradation of arabinoxylans, mixed-linkage glucans, cellulose, and some other polysaccharides. We determined the dynamics of mRNA abundance for these genes at three stages of kernel development. Comparisons of gene expression levels in two contrasting cultivars revealed specific members of multigene families that may serve as promising targets for manipulating non-starch polysaccharide content in rye grain. High-viscosity cultivars were characterized by up-regulation of many glycosyltransferases involved in the biosynthesis of arabinoxylans and other cell-wall polysaccharides, whereas low-viscosity cultivars showed up-regulation of several genes encoding polysaccharide-degrading enzymes.

Expression profile of protein fractions in the developing kernel of normal, Opaque-2 and quality protein maize

Maize protein quality is determined by the composition of its endosperm proteins, which are classified as nutritionally poor zeins (prolamin and prolamin-like) and nutritionally rich non-zeins (albumin, globulin, glutelin-like, and glutelin). Protein quality is considerably higher in opaque-2 mutants due to increased content of non-zeins over zeins. However, the opaque-2 endosperm is soft, which leads to poor agronomic performance and post-harvest infestation. Endosperm modification of opaque-2 had led to the development of Quality Protein Maize (QPM), which has higher protein quality along with hard kernel endosperm. The present study was planned to analyze the expression dynamics of different protein fractions in the endospem of developing maize kernel in normal, opaque-2 and QPM in response to the introgression of endosperm modifiers. Results revealed that albumin and globulin content decreases, whereas, prolamin, prolamin-like, glutelin-like, and glutelin content increases with kernel maturity. It has been observed that opaque-2 mutation affects protein expression at initial stages, whereas, the effect of endosperm modifiers was observed at the intermediate and later stages of kernel development. It has also been noted that prolamin, glutelin, and glutelin-like fractions can be used as quick markers for quality assessment for differentiating QPM varieties, even at the immature stage of kernel development. Overall, the present study implicates the role of different protein fractions in developing and utilizing nutritionally improved maize varieties.

Relationship between Photosynthetic Rate and Stomatal Conductance, Intercellular CO2 Concentration, Transpiration Rate, Vapour Pressure Deficit and Photosynthetically Active Radiation in Sweet Corn (Zea mays)

Sweet corn (Zea mays) is thethird-largest plantation crop in Malaysia. Since it is cultivated mainly for the corncobs, the reproductive and kernel development stages are critical for high yields. Photosynthesis measurement can be used as a major approach to improve photosynthetic efficiency, which can directly affect yield. Additionally, plant nutrient uptake also plays a major role in yield quantity and quality. Conventional fertilisation(chemical and/or organic) may result in excessive fertilizer input, which is detrimental to the environment. We therefore investigated the relationship between photosynthetic rate and stomatal conductance (gs), intercellular CO2concentration (Ci), transpiration rate and vapour pressure deficit based on leaf temperature (VpdL) and photosynthetically active radiation (PAR) during the growth and development stages of sweet corn. The seeds were subjected to the germination test to assess viability and were then planted at a distance of 10 cm both between plantsand rows (replicates). A total of eight subplots (2.2 m long, 60 cm wide, 30 cm high) were prepared in a randomized complete block design (RCBD). Leaf gas exchange measurements were carried out at days 10, 20, 30, 40, 50 and 60 at 9:00 a.m. in the morning and 4:00 p.m. in the evening. Three uniform plants were selected from each replicate and used for measurements throughout the experiment. At day 30, photosynthesis started to decline and was largely unaffected by the set environmental conditions, although stomatal conductance remained high. This can be attributed to the energy diversion from vegetative stages to reproductive stages. Therefore, fertilising practices should be synchronised to match the plant stages for more sustainable and efficient fertilisation and to obtain maximum yield.

Cytokinin activity during early kernel development corresponds positively with yield potential and later stage ABA accumulation in field-grown wheat (Triticum aestivum L.).

Early cytokinin activity and late abscisic acid dynamics during wheat kernel development correspond to cultivars with higher yield potential. Cytokinins represent prime targets for marker development for wheat breeding programs. Two major phytohormone groups, abscisic acid (ABA) and cytokinins (CKs), are of crucial importance for seed development. Wheat (Triticum aestivum L.) yield is, to a high degree, determined during the milk and dough stages of kernel development. Therefore, understanding the hormonal regulation of these early growth stages is fundamental for crop-improvement programs of this important cereal. Here, we profiled ABA and 25 CK metabolites (including active forms, precursors and inactive conjugates) during kernel development in five field-grown wheat cultivars. The levels of ABA and profiles of CK forms varied greatly among the tested cultivars and kernel stages suggesting that several types of CK metabolites are involved in spatiotemporal regulation of kernel development. The seed yield potential was associated with the elevated levels of active CK levels (tZ, cZ). Interestingly, the increased kernel cZ levels were followed by higher ABA production, suggesting there is an interaction between these two phytohormones. Furthermore, we analyzed the expression patterns of representatives of the four main CK metabolic gene families. The unique transcriptional patterns of the IPT (biosynthesis) and ZOG (reversible inactivation) gene family members (GFMs) in the high and low yield cultivars additionally indicate that there is a significant association between CK metabolism and yield potential in wheat. Based on these results, we suggest that both CK metabolites and their associated genes, can serve as important, early markers of yield performance in modern wheat breeding programs.

Analysis of preharvest meteorological conditions in relation to concentration of fumonisins in kernels of two genetically different maize hybrids

The effects of meteorological conditions around silking (Si) and physiological maturity (PM) on production of fumonisins (FB=FB1 + FB2) in maize kernels were analyzed. Kernel FB contents were determined on kernel samples collected from an experimental susceptible hybrid (n = 35) and a Bt commercial hybrid (n = 23) planted in several growing seasons/sites from the Argentinean Pampas. Considering the effect of genetic divergence of the two maize hybrids, total kernel FB concentrations (n = 52) binary coded, were predicted appropriately by weather-based logistic regression models but underestimated in some samples severely contaminated with FB. After removing these misclassified cases that registered maximum values of a drought-heat stress index (DI) calculated over 30 days around Si, and weather conditions (assessed by weather interactive components) conducive to infection/production of FB in PM, new logistic models were fitted. These new models improved their predictive ability indices. It was remarkable a model including the discrete genetic variable and the weather variable associated with the simultaneous occurrence of precipitation, temperature between 19.5–33 °C and relative humidity >70%, required for fungal infection in Si. Models that also included weather variables calculated in PM and associated with the kernel drying rate and fungal infection, did not result in better prediction outcomes. Opposite to the general trend, the occurrence of both severe heat-drought stress around Si and favorable weather around PM led to high kernel FB contents. We hypothesize that husk shortening by stress at silking might expose ears, promoting Fusarium verticillioides colonization/FB synthesis in late stages of kernel development and maturity, whenever favorable environmental conditions for both processes prevail.

A proteomic analysis of grain yield-related traits in wheat.

Grain yield, which is mainly contributed by tillering capacity as well as kernel number and weight, is the most important trait to plant breeders and agronomists. Label-free quantitative proteomics was used to analyse yield-contributing organs in wheat. These were leaf sample, tiller initiation, spike initiation, ovary and three successive kernel development stages at 5, 10 and 15 days after anthesis (DAA). We identified 3182 proteins across all samples. The largest number was obtained for spike initiation (1673), while the smallest was kernel sample at 15 DAA (709). Of the 3182 proteins, 296 of them were common to all seven organs. Organ-specific proteins ranged from 148 in ovary to 561 in spike initiation. When relative protein abundances were compared to that of leaf sample, 347 and 519 proteins were identified as differentially abundant in tiller initiation and spike initiation, respectively. When compared with ovary, 81, 35 and 96 proteins were identified as differentially abundant in kernels sampled at 5, 10 and 15 DAA, respectively. Our study indicated that two Argonaute proteins were solely expressed in spike initiation. Of the four expansin proteins detected, three of them were mainly expressed during the first 10 days of kernel development after anthesis. We also detected cell wall invertases and sucrose and starch synthases mainly during the kernel development period. The manipulation of these proteins could lead to increases in tillers, kernels per spike or final grain weight, and is worth exploring in future studies.

Composition analysis of lysine, tryptophan and provitamin-A during different stages of kernel development in biofortified sweet corn

Traditional sweet corn is poor in nutritional quality. Here, a set of biofortified sweet corn hybrids were analyzed for nutritional traits at 20-, 24- and 28- days after pollination (DAP) under three sowing dates. The biofortified hybrids possessed significantly higher lysine (0.34 %), tryptophan (0.08 %), β-carotene (BC: 13.77 μg/g), β-cryptoxanthin (BCX: 11.19 μg/g) and provitamin-A (proA: 19.38 μg/g) over traditional yellow sweet corn (0.21 %, 0.03 %, 1.96 μg/g, 2.32 μg/g and 3.12 μg/g). Sowing time, harvest time and their interactions had significant influence on nutritional traits. Decreasing trend of accumulation for lysine (0.367 %, 0.345 % and 0.315 %), tryptophan (0.086 %, 0.078 % and 0.068 %), BC (15.18 μg/g, 14.00 μg/g and 12.12 μg/g), BCX (12.28 μg/g, 11.48 μg/g and 9.82 μg/g) and proA (21.32 μg/g, 19.74 μg/g and 17.07 μg/g) was observed at 20-, 24- and 28-DAP, respectively. However, mean brix attained the peak at 24-DAP (18.53 %), followed by 20-DAP (17.86 %) and 28-DAP (17.60 %). Considering both nutrition and sweetness, 20-DAP was the best suitable time for harvesting of sweet corn ears. Nutritional traits had higher concentration with delay in sowing time. This is the first report on accumulation of lysine, tryptophan and proA at different stages of kernel development in biofortified sweet corn.

Identification and analysis of the FAD gene family in walnuts (Juglans regia L.) based on transcriptome data

BackgroundWalnut kernels contain a large amount of unsaturated fatty acids, such as linoleic acid and linolenic acid, which are essential fatty acids for humans and have important effects on growth and health. The main function of fatty acid desaturase (FAD), which is widely distributed in organisms, is to remove hydrogen from carbon chains in the biosynthesis of unsaturated fatty acids to generate C=C bonds.ResultsBy performing a series of bioinformatics analysis, 24 members of the JrFAD gene family were identified from the genome database of walnut, and then compared with the homologous genes from Arabidopsis. Phylogenetic analysis showed that JrFADs were classified into four subfamilies: the SAD desaturase subfamily, Δ7/Δ9 desaturase subfamily, Δ12/ω-3 desaturase subfamily and “front-end” desaturase subfamily. Meanwhile, the expression of fatty acid synthesis genes in walnut kernels at different developmental stages was analysed by transcriptome sequencing, with expression of JrFAD3-1, which encodes an enzyme involved in linolenic acid synthesis, being particularly prominent. The relative expression level of JrFAD3-1 changed dramatically with the kernel development stages and exhibited a Bell-Shaped Curve. A significant positive correlation was observed between the expression of JrFAD3-1 during 70–100 DAF (Days after flowering) and the content of alpha-linolenic acid during 100–130 DAF, with a correlation coefficient of 0.991. Additionally, JrFAD3-1 was proved closely related to homologous genes in Betula pendula and Corylus heterophylla, indicating that the conserved structure of FADs is consistent with classical plant taxonomy.ConclusionTwenty-four members JrFADs in walnut were identified and classified into four subfamilies. JrFAD3-1 may play significant roles in the biosynthesis of polyunsaturated fatty acids in walnut.

Effect of sulphur on yield and biochemical constituents in groundnut (Arachis hypogaea L.) grown on Vertic Ustropept of Tamilnadu

A pot culture experiment was conducted with groundnut (CO 7) in a sulphurdeficient (7.19 mg kg-1) Inceptisol (Vertic Ustropept) at the Radioisotope(Tracer) Laboratory, Department of Soil Science and Agricultural Chemistry,Tamil Nadu Agricultural University, Coimbatore during October 2016 toJanuary 2017. The treatment structure comprised five levels of sulphur(0, 20, 40, 60, and 80 kg ha-1) along with the recommended fertilizer dose.The variation in yield and the changes in starch, sugars, cysteine, methionine,protein, and oil content with kernel development as influenced by thesulphur application were studied. The yield attributes viz., number of podspot-1, pod and kernel yield pot-1 and shelling percentage, were remarkablyinfluenced due to the application of sulphur up to 60 kg ha-1, which wascomparable with S @ 40 kg ha-1 and had an adverse effect with S @ 80 kgha-1. In all the stages of sampling (30 DAS, 15 DOP (75 DAS), 30 DOP (90DAS) and at harvest stage), starch, total sugars, reducing and non-reducingsugars of groundnut were found to decrease with increasing S levels withcontrol recording the highest value and S @ 60 kg ha-1 recording the lowestvalue. During crop growth, protein content and sulphur-containing aminoacids viz., cysteine, and methionine showed an increasing trend up to 60kg S ha-1 application and recorded comparable values with S @ 40 kg ha-1.Similarly, oil content in the kernel steadily increased with stages of kerneldevelopment. The highest oil content at all stages of kernel developmentwas recorded at 60 kg S ha-1.

Temporal profiling of essential amino acids in developing maize kernel of normal, opaque-2 and QPM germplasm.

Maize, an important cereal crop, has apoor quality of endosperm protein due to the deficiency of essential amino acids, especially lysine and tryptophan. Discovery of mutants such as opaque-2 led to the development of nutritionally improved maize with a higher concentration of lysine and tryptophan. However, the pleiotropic effects associated with opaque-2 mutants necessitated the development of nutritionally improved hard kernel genotype, the present-day quality protein maize (QPM). The aim of present study was to analyze and compare the temporal profile of lysine and tryptophan in the developing maize kernel of normal, opaque-2 and QPM lines. A declining trend in protein along with tryptophan and lysine content was observed with increasing kernel maturity in the experimental genotypes. However, opaque-2 retained the maximum concentration of lysine (3.43) and tryptophan (1.09) at maturity as compared to QPM (lysine-3.05, tryptophan-0.99) and normal (lysine-1.99, tryptophan-0.45) lines. Opaque-2 mutation affects protein quality but has no effect on protein quantity. All maize types are nutritionally rich at early stages of kernel development indicating that early harvest for cattle feed would ensure a higher intake of lysine and tryptophan. Two promising lines (CML44 and HKI 1105) can be used for breeding high value corn for cattle feed or human food in order to fill the protein inadequacy gap. Variation in lysine and tryptophan content within QPM lines revealed that differential expression of endosperm modifiers with varying genetic background significantly affects nutritional quality, indicating that identification of alleles affecting amino acid composition can further facilitate QPM breeding program.

KNMAIZE–A Model to Investigate the Dynamics of Kernel Set in Maize

Core Ideas The dynamics of kernel set in maize was modeled at the individual kernel level.Kernels survived when enough assimilate was available to meet their needs.The model captures the dynamics of ear size, plant growth rate, and kernel growth. The adjustment of kernels plant−1 to the assimilate supply is an important component of the yield production process in maize (Zea mays L.). A simulation model (KNMAIZE) was developed to better understand this process at the individual kernel level. Kernel survival was determined by comparing the assimilate supply (calculated from solar radiation) partitioned to reproductive growth during the initial stages of kernel development with the kernel assimilate requirement (based on published kernel growth curves) on a daily basis. When model parameters were optimized by maintaining the ratio of the sink (total kernel growth rate) and the source (total assimilate supply) equal to 1.0 during the linear phase of kernel growth, the model accurately mimicked the effect of plant growth rate, individual kernel growth rate, and ear size on kernels plant−1. The model also mimicked the plant density‐kernels m−2 relationship. Short‐term (3 or 5 d) variation in plant growth rate influenced kernels plant−1 11 to 15 d after the beginning of kernel growth. Modeling kernel number at the individual kernel level makes it possible to capture important aspects of the dynamics of kernel set that will lead to better predictions of kernel number and a clearer understanding of the elements of maize productivity in the field.

Characterization of phytohormone and transcriptome reprogramming profiles during maize early kernel development

BackgroundDuring maize early kernel development, the dramatic transcriptional reprogramming determines the rate of developmental progression, and phytohormone plays critical role in these important processes. To investigate the phytohormone levels and transcriptome reprogramming profiles during maize early kernel development, two maize inbreds with similar genetic background but different mature kernel sizes (ILa and ILb) were used.ResultsThe levels of indole-3-acetic acid (IAA) were increased continuously in maize kernels from 5 days after pollination (DAP) to 10 DAP. ILa had smaller mature kernels than ILb, and ILa kernels had significantly lower IAA levels and significantly higher SA levels than ILb at 10 DAP. The different phytohormone profiles correlated with different transcriptional reprogramming in the two kernels. The global transcriptomes in ILa and ILb kernels were strikingly different at 5 DAP, and their differences peaked at 8 DAP. Functional analysis showed that the biggest transcriptome difference between the two kernels is those response to biotic and abiotic stresses. Further analyses indicated that the start of dramatic transcriptional reprogramming and the onset of significantly enriched functional categories, especially the “plant hormone signal transduction” and “starch and sucrose metabolism”, was earlier in ILa than in ILb, whereas more significant enrichment of those functional categories occurred at later stage of kernel development in ILb.ConclusionsThese results indicate that later onset of the significantly enriched functional categories, coincide with their stronger activities at a later developmental stage and higher IAA level, are necessary for young kernels to undergo longer mitotic activity and finally develop a larger kernel size. The different onset times and complex interactions of the important functional categories, especially phytohormone signal, and carbohydrate metabolism, form the most important molecular regulators mediating maize early kernel development.