Mature Kernels Research Articles

Insights into the Genomic Architecture of Seed and Pod Quality Traits in the U.S. Peanut Mini-Core Diversity Panel.

Traits such as seed weight, shelling percent, percent sound mature kernels, and seed dormancy determines the quality of peanut seed. Few QTL (quantitative trait loci) studies using biparental mapping populations have identified QTL for seed dormancy and seed grade traits. Here, we report a genome-wide association study (GWAS) to detect marker–trait associations for seed germination, dormancy, and seed grading traits in peanut. A total of 120 accessions from the U.S. peanut mini-core collection were evaluated for seed quality traits and genotyped using Axiom SNP (single nucleotide polymorphism) array for peanut. We observed significant variation in seed quality traits in different accessions and different botanical varieties. Through GWAS, we were able to identify multiple regions associated with sound mature kernels, seed weight, shelling percent, seed germination, and dormancy. Some of the genomic regions that were SNP associated with these traits aligned with previously known QTLs. For instance, QTL for seed dormancy has been reported on chromosome A05, and we also found SNP on the same chromosome associated with seed dormancy, explaining around 20% of phenotypic variation. In addition, we found novel genomic regions associated with seed grading, seed germination, and dormancy traits. SNP markers associated with seed quality and dormancy identified here can accelerate the selection process. Further, exploring the function of candidate genes identified in the vicinity of the associated marker will assist in understanding the complex genetic network that governs seed quality.

Reevaluation of calcium source for runner-type peanut (Arachis hypogaea L.)

Calcium supplementation is vital to optimal peanut production. As peanut cultivars and Ca sources change over time, Ca requirement may subsequently change, but few studies have reevaluated effectiveness of different Ca sources using currently produced peanut varieties. To address this issue, field experiments were performed in 12 environments (i.e., site-years) in the southeastern United States with the following treatments: four solid Ca sources, including mined gypsum, flue gas desulfurized (FGD) gypsum, phosphogypsum, and lime and four liquid Ca sources, including CaCl 2 solution, chelated CaCO 3 , CaS 2 O 3 solution, and CaCO 3 suspension. The effectiveness of various Ca sources was evaluated on peanut yield, total sound mature kernels (TSMK), seed Ca, germination, and soil Ca using two runner-type peanut cultivars, Georgia-06G and Georgia Greener. Results indicated that the three evaluated gypsum materials had similar effectiveness, and the mined gypsum was the most effective possibly due to its larger, more crystalline particle size. Lime remains an adequate Ca source for peanut provided that water from rainfall or irrigation does not limit its dissolution. Liquid Ca sources, as stand-alone treatments, were not as effective as solid Ca sources possibly due to their low Ca content and great leaching potential. This study provides helpful information for Ca nutrient management for peanut.

Transcriptomic and Metabolomic Analysis of Wheat Kernels in Response to the Feeding of Orange Wheat Blossom Midges (Sitodiplosis mosellana) in the Field.

The orange wheat blossom midge (Sitodiplosis mosellana Géhin) is an insect pest that feeds on wheat (Triticum aestivum L.). The resistance mechanisms of wheat to S. mosellana infestation are largely unknown. In this study, the wheat varieties LX99 and 6218 were identified as highly resistant and susceptible, respectively, via field investigations conducted over two consecutive years. Morphological and microstructural observations of mature wheat kernels following S. mosellana infestation revealed that the degree of cell structure damage in resistant LX99 grains was less than that in susceptible 6218 grains. Transcriptomic and metabolomic analyses of seeds following S. mosellana feeding showed that the differentially expressed genes and differentially accumulated metabolites from LX99 were mostly enriched in several primary and secondary metabolic pathways, including phenylpropanoid biosynthesis, flavonoid biosynthesis, and phenylalanine biosynthesis. Additionally, phenylpropanoid- and flavonoid-related gene expression was significantly upregulated following S. mosellana infestation in LX99 relative to that in 6218. Some metabolites involved in phenylpropanoid/flavonoid pathways, such as cinnamic acid, coumarin, epigallocatechin, and naringenin, were only induced in infested LX99 kernels. These results suggest that phenylpropanoid/flavonoid pathways play important roles in wheat kernel resistance to S. mosellana attack and provide useful insights for the breeding and utilization of resistant varieties.

Effect of amylases and storage length on losses, nutritional value, fermentation, and microbiology of silages of corn and sorghum kernels

This study evaluated the effect of two commercial amylases with known activity at low pH and storage length on fermentation profile, microbial diversity, and effective rumen degradation (ERD) of silages of rehydrated kernels of sorghum (RES) or flint corn (REC). Mature kernels were ground through a 1 mm diameter mesh screen with a stationary hammer mill and manually rehydrated to achieve a similar dry matter (DM) concentration (650 g/kg of fresh) for ensiling (4.74 ± 0.30 kg/silo). Treatments were formed using a 2 × 3 × 2 factorial combination of grain type (RES and REC), enzyme [control and amylases AMG (300 AGU/mL) and GAM (138 AGU/mL), both at 0.35 mL/kg of fresh kernels], and storage length (30 and 180 d), with six replicates. The ERD of DM was evaluated in situ with a 2-pool model (A and B fractions) and incubations for 0, 3, 6, 12, 18, and 48 h. The proportional change in ERD mass during silage storage (% of ensiled) was calculated. Lactic acid bacteria (LAB) and spore-forming aerobic bacteria (SAB) were quantified and identified. The loss of DM (6.8 vs. 5.3% of ensiled) and starch (23.9 vs. 13.6% of ensiled) were higher (P < 0.01) for REC than RES. The RES had higher (P < 0.01) DM fraction A (398 vs. 325 g/kg of DM) and ERD (593 vs. 554 g/kg of DM) and lower (P < 0.01) kd of DM fraction B (3.14 vs. 3.33%/h) than REC. Ensiling increased ERD mass of both kernels (+6.8% of ensiled). The RES showed a faster increase (P = 0.04) in ERD mass in response to ensiling than REC. Both amylases and a longer duration of storage reduced (P < 0.01) the starch content and increased (P < 0.01) DM loss. Enzymes induced a faster increase (P < 0.01) in ERD mass relative to control but reduced the gain in ERD mass in extended storage. Longer storage increased (P < 0.01) the ERD content and the pool size of fraction A of both RES and REC. Lactic acid was the primary organic acid in silage, followed by propionic acid. Long storage of sorghum increased (P < 0.01) butyrate and there was no effect of grain type and enzyme on butyrate at 30 days of storage. The RES ensiled for 180 days without enzyme had the highest (P < 0.01) butyrate. The species Levilactobacillus brevis, Lentilactobacillus buchneri, Lactiplantibacillus plantarum, and Pediococcus acidilactici were the most frequent, but in general, amylases reduced numerically their population. The SAB had a greater diversity and lower population than LAB. We concluded that RES was more degradable in the rumen and had a lower loss during storage than REC. The highest ERD mass recovery was observed for long storage without amylase. The amylases seem to be an option only when storage length is short. The LAB population dominated sorghum and corn kernels silage fermentation. Most microorganisms identified were involved in organic acids and alcohol metabolism.

Genetic Variability and G×E Interactions in a Diverse Set of Groundnut Accessions

Background: Knowledge of the genetic diversity for various agronomic traits and their interaction with the environment and subsequent classification of genotypes will be beneficial for identification of divergent and stable sources of agronomic traits. Methods: A set of 96 groundnut germplasm accessions belonging to four botanical groups were evaluated for three years (2017 to 2019) for pod yield and component traits using AMMI analysis and subsequently accessions were classified based Euclidean cluster analysis. Result: Among different botanical groups, Virginia genotypes matured late and possessed high SPAD chlorophyll meter readings (SCMR) and pod yield compared to Spanish types. The component traits of pod maturity like days to flowering (first and 50%) showed low heritability and high genotype × environment interaction (GEI) and significant negatively affected sound mature kernel (SMK) and shelling per centage (SP). The cumulative contribution of environment and GEI component to the total variance was the highest in the expression of SP (67%) followed by days to maturity (54%) and days to 50% flowering (52%). Euclidean distance-based cluster analysis grouped the 96 accessions into five major clusters. Cluster I had accessions with higher pod yield, whereas cluster V contained accessions with low SLA, high SCMR and moderate pod yield. High yielding as well as stable accessions identified based on AMMI stability value (ASV) are NRCG 17332, 10076, 17268, 17197, 17108, 10106, 10089 and 17165. Trait specific as well as stable accessions identified in the present study can be useful donors for groundnut breeding programme.

Combined Transcriptome and Lipidomic Analyses of Lipid Biosynthesis in Macadamia ternifolia Nuts.

Macadamia nuts are considered a high-quality oil crop worldwide. To date, the lipid diversity and the genetic factors that mediate storage lipid biosynthesis in Macadamia ternifolia are poorly known. Here, we performed a comprehensive transcriptomic and lipidomic data analysis to understand the mechanism of lipid biosynthesis by using young, medium-aged, and mature fruit kernels. Our lipidomic analysis showed that the M. ternifolia kernel was a rich source of unsaturated fatty acids. Moreover, different species of triacylglycerols, diacylglycerol, ceramides, phosphatidylethanolamine, and phosphatidic acid had altered accumulations during the developmental stages. The transcriptome analysis revealed a large percentage of differently expressed genes during the different stages of macadamia growth. Most of the genes with significant differential expression performed functional activity of oxidoreductase and were enriched in the secondary metabolite pathway. The integration of lipidomic and transcriptomic data allowed for the identification of glycerol-3-phosphate acyltransferase, diacylglycerol kinase, phosphatidylinositols, nonspecific phospholipase C, pyruvate kinase 2, 3-ketoacyl-acyl carrier protein reductase, and linoleate 9S-lipoxygenase as putative candidate genes involved in lipid biosynthesis, storage, and oil quality. Our study found comprehensive datasets of lipidomic and transcriptomic changes in the developing kernel of M. ternifolia. In addition, the identification of candidate genes provides essential prerequisites to understand the molecular mechanism of lipid biosynthesis in the kernel of M. ternifolia.

Trihelix Transcription Factor ZmThx20 Is Required for Kernel Development in Maize

Maize kernels are the harvested portion of the plant and are related to the yield and quality of maize. The endosperm of maize is a large storage organ that constitutes 80–90% of the dry weight of mature kernels. Maize kernels have long been the study of cereal grain development to increase yield. In this study, a natural mutation that causes abnormal kernel development, and displays a shrunken kernel phenotype, was identified and named “shrunken 2008 (sh2008)”. The starch grains in sh2008 are loose and have a less proteinaceous matrix surrounding them. The total storage protein and the major storage protein zeins are ~70% of that in the wild-type control (WT); in particular, the 19 kDa and 22 kDa α-zeins. Map-based cloning revealed that sh2008 encodes a GT-2 trihelix transcription factor, ZmThx20. Using CRISPR/Cas9, two other alleles with mutated ZmThx20 were found to have the same abnormal kernel. Shrunken kernels can be rescued by overexpressing normal ZmThx20. Comparative transcriptome analysis of the kernels from sh2008 and WT showed that the GO terms of translation, ribosome, and nutrient reservoir activity were enriched in the down-regulated genes (sh2008/WT). In short, these changes can lead to defects in endosperm development and storage reserve filling in seeds.

Sound Splits as Influenced by Seed Size for Runner and Virginia Market Type Peanut Shelled on a Reciprocating Sheller

The objective of this study was to examine peanut (Arachis hypogaea L.) kernel percent sound splits as a function of sound mature kernel seed size when shelled on a reciprocating sheller. Data were compiled from a total of 139 field experiments conducted in the Virginia-Carolina region and Georgia from 2005 to 2020. Runner and Virginia peanut market types were graded according to United States Department of Agriculture (USDA) standards using standard sheller screens with upper grid sizes corresponding to the red pan from the pre-sizer of 10.3 × 19.1 mm (26/64 × 3/4 ″) and 13.5 × 25.4 mm (34/64 × 1 ″) with minimum bar grid clearances of 8.7 (11/32 ″) and 12.7 mm (1/2 ″), respectively. A subset of runner market type samples was graded using the Virginia sheller screen. Grade data per market type and sheller screen was analyzed separately. Among runner market types shelled with the standard runner-type screen, percent sound splits increased linearly with increasing seed size at the logit rate of 1.16 per sound mature kernel g (p &lt; 0.001). Sound splits for Virginia and runner market types shelled on the standard Virginia-type screen did not significantly vary by kernel size (p = 0.939 and 0.687, respectively). Extra-large kernels (proportion) for Virginia types linearly increased with seed size at 1.91 per sound mature kernel g (logit scale) (p &lt; 0.001). Runner market types sized 75 to 91 g/100 sound mature kernels (605 to 500 seed/lb) were estimated to have a 50% probability of a 2.3 to 4.5% or greater increase in sound splits when shelled with the standard runner-type screen compared to runner-type seed sized 55 g/100 sound mature kernels (820 seed/lb), respectively, equivalent to a potential deduction increase of 1.8 to 4.4 USD /1000 kg. For both Virginia and runner market types, seed weight linearly increased with pod weight at 0.169 and 0.195 g/g (p &lt; 0.001), respectively. Results from this study may be used as a reference to suggest runner-type seed sizes above which larger reciprocating sheller screen utilization in line with USDA grading practices is warranted to reduce mechanically induced sound splits during grading and subsequent economic deduction penalties for corresponding farmer stock peanut.

Registration of ‘AG18’ peanut

Abstract‘AG18’ (Reg. no. CV‐147, PI 698186) is a high‐yielding, high‐grading, high‐oleic fatty acid, runner‐type peanut (Arachis hypogaea L. ssp. hypogaea var. hypogaea) cultivar with good resistance to Sclerotinia blight (caused by Sclerotinia minor Jagger). The cultivar was developed by the Texas A&amp;M AgriLife Research peanut breeding program to provide growers with a higher‐yielding option when compared to the previously released ‘Tamrun OL11’ cultivar. AG18 was tested under the experimental designation of Tx121082 and was released in 2020. It maintains the high percentage of total sound mature kernels that Tamrun OL11 had, as well as the resistance to S. minor. However, it proved to have higher yield potential across environments and years than did Tamrun OL11. Additionally, the seed size of AG18 is smaller than that of Tamrun OL11 and closer to the past industry standard, ‘Florunner’, making it more attractive to manufacturers.

Evaluation and identification of promising advanced breeding lines for quality and yield traits in groundnut (Arachis hypogaea L.)

Kernel size coupled with the nutritional quality will determine the worth of groundnut for direct consumption or export. Focusing on this objective one hundred and fifty advanced breeding lines (ABLs) in both Spanish and Virginia botanical varieties were evaluated with four checks under Augmented Design during Kharif, 2018 at ICAR- Directorate of Groundnut Research, Junagadh, Gujarat. Significant difference was observed for days to 50% flowering, hundred pod weight (g), hundred kernel weight (g), sound mature kernel (%), shelling percent, pod weight per plant (g), and protein percent. Pod yield per plant (g) registered highest estimates of GCV and PCV. High heritability coupled with high genetic advance as per cent of mean was recorded for 100 pod weight (g), 100 kernel weight (g), sound mature kernel percentage and pod yield per plant (g) traits which indicates a significant role of additive gene action for inheritance of these traits which may be exploited through simple selection methods. Eleven genotypes viz., PBS 19013, PBS 19015, PBS 19018, PBS 29079 B, PBS 29082, PBS 29124, PBS 29167, PBS 29196, PBS 29197, PBS 29212 and PBS 29219 had good confectionery quality traits viz., large seed size (HKW: &gt;55 g; KL: &gt;1.5cm and KW: &gt;0.7cm), high protein (&gt;30%), high total soluble sugar (&gt;5 %), moderate oil (42- 48%), uniform pod size and shape, high pod yield per plant (&gt; 10g) and good shelling percentage (&gt;60%). These promising genotypes can directly be released as a variety after testing in multi-location AICRP-G trials or can be used in hybridization programmes as donor parents for improving confectionery qualities in groundnut.

Genome-wide association study suggests an independent genetic basis of zinc and cadmium concentrations in fresh sweet corn kernels.

Despite being one of the most consumed vegetables in the United States, the elemental profile of sweet corn (Zea mays L.) is limited in its dietary contributions. To address this through genetic improvement, a genome-wide association study was conducted for the concentrations of 15 elements in fresh kernels of a sweet corn association panel. In concordance with mapping results from mature maize kernels, we detected a probable pleiotropic association of zinc and iron concentrations with nicotianamine synthase5 (nas5), which purportedly encodes an enzyme involved in synthesis of the metal chelator nicotianamine. In addition, a pervasive association signal was identified for cadmium concentration within a recombination suppressed region on chromosome 2. The likely causal gene underlying this signal was heavy metal ATPase3 (hma3), whose counterpart in rice, OsHMA3, mediates vacuolar sequestration of cadmium and zinc in roots, whereby regulating zinc homeostasis and cadmium accumulation in grains. In our association panel, hma3 associated with cadmium but not zinc accumulation in fresh kernels. This finding implies that selection for low cadmium will not affect zinc levels in fresh kernels. Although less resolved association signals were detected for boron, nickel, and calcium, all 15 elements were shown to have moderate predictive abilities via whole-genome prediction. Collectively, these results help enhance our genomics-assisted breeding efforts centered on improving the elemental profile of fresh sweet corn kernels.

Registration of ‘FloRun ‘331’ ’ peanut

Abstract‘FloRun ‘331’ ’ (Reg. no. CV‐144, PI 680624) is a high‐oleic, runner market‐type peanut (Arachis hypogaea L. ssp. hypogaea var. hypogaea) cultivar with medium runner seed size developed by the University of Florida, Florida Agricultural Experiment Station, North Florida Research and Education Center, near Marianna, FL. It was tested under the experimental designation UF15302 and was approved for release in 2016. FloRun ‘331’ has a semi‐prostrate growth habit, with a tall and prominent center stem and dark green leaves. The seed testa is tan and the seeds are smaller than seeds of ‘Georgia‐06G’ (68.8 g vs. 76.9 g per 100 seeds, P &lt; .001). FloRun ‘331’ was released based on its pod yield and grading potential, disease resistance, and high oleic oil content. During the 3‐yr period from 2013 to 2015, at three locations, FloRun ‘331’ had higher pod yield (8,101 vs. 7,533 kg ha–1; P = .0088) than ‘Georgia‐06G’, the dominant cultivar in the southeastern United States. The total sound mature kernels grade of FloRun ‘331’ was slightly less than that of Georgia‐06G (77.1 vs. 79.9%, P &lt; .0032. It also has the benefit of high oleic oil chemistry. with oil composed of 79.3% oleic fatty acid versus 61.3% for Georgia‐06G (P &lt; .01). In addition, FloRun ‘331’ has very good tolerance to two major fungal diseases: late leaf spot and white mold. Therefore, it combines excellent agronomic, grade, disease, and oil chemistry traits and should be beneficial to farmers and manufacturers of peanut foods.

Registration of ‘Georgia‐Val/HO’ peanut

Abstract‘Georgia‐Val/HO’ (Reg. no. CV‐143, PI 695316) is a new high‐yielding, high‐oleic, large‐podded, large‐seeded, valencia‐type peanut (Arachis hypogaea L. ssp. fastigiata var. fastigiata) cultivar. Georgia‐Val/HO has an atypical semi‐prostrate growth habit and medium maturity, but typical valencia three seed per pod and red testa color. It also has moderate resistance to tomato spotted wilt disease. Georgia‐Val/HO was released by the Georgia Agricultural Experiment Station in 2020 and was developed at the University of Georgia Coastal Plain Experiment Station, Tifton, GA. It was developed from an intersubspecific cross made in 2010 between two Georgia cultivars, ‘Georgia‐11J’ (ssp. hypogaea) and ‘Georgia Valencia’ (ssp. fastigiata). During 4 yr (2016–2019) averaged across two planting dates (April and May), Georgia‐Val/HO had significantly less total disease incidence and higher pod yield, total sound mature kernel (TSMK) grade, and dollar values compared with six other valencia cultivars in Georgia. Georgia‐Val/HO had significantly higher overall performance at both early April and optimum May planting dates. Georgia‐Val/HO combines high yield, TSMK grade, and dollar value with large pods and seed and the high O/L ratio trait for longer shelf life of peanut and peanut products.

Registration of ‘Georgia‐20VHO’ Peanut

Abstract‘Georgia‐20VHO’ (Reg. no. CV‐145, PI 695315) is a new high‐yielding, high‐grading, very high‐oleic (O) to linoleic (L) fatty acid ratio, runner‐type peanut (Arachis hypogaea L. ssp. hypogaea var. hypogaea) cultivar. It also has disease resistance to Tomato spotted wilt virus (TSWV). Georgia‐20VHO was released by the Georgia Agricultural Experiment Station in 2020 and was developed at the University of Georgia Coastal Plain Experiment Station, Tifton, GA. Georgia‐20VHO was developed from a cross made in 2009 between two runner‐type parental lines, GA 072515 and ‘Tifguard’. During 5 yr (2015–2019) and 3 yr (2017–2019) averaged across multilocation tests in Georgia, Georgia‐20VHO had significantly higher percentages of total sound mature kernel grade than ‘Georgia‐09B’ and six other high‐oleic runner cultivars. It also was among the lowest in TSWV and total disease incidence and among the highest in pod yield and dollar values compared with the other high‐oleic runner cultivars in Georgia. Georgia‐20VHO combines high yield, grade, and dollar values with TSWV resistance and very high O/L ratio for longer shelf life of peanut and peanut products.

Fine mapping and candidate gene analysis of maize defective kernel mutant &amp;lt;italic&amp;gt;dek54&amp;lt;/italic&amp;gt;

<p indent=0mm>Maize kernel is closely related to yield and nutritive quality. Study on the function of maize kernel development relative genes provides important basis for the molecular mechanism analysis, yield increasing and nutritive quality improving. B73 pollen was treated with ethyl methylmethanesulfonate (EMS) and a defective maize kernel <italic>defective kernel 54</italic> (<italic>dek54</italic>) was screened. <italic>dek54</italic> had small mature kernel, wrinkled and whitened seed coat phenotype. Genetic analysis indicated that <italic>dek54</italic> is a recessive mutant controlled by a single gene. Paraffin sections showed starchy endosperm cells of <italic>dek54</italic> had irregular shape and dense arrangement at developmental stage. Scanning electron microscopy observation indicated that protein bodies around starch granules in the central region of the <italic>dek54 </italic>mature kernel endosperm were fewer and arranged more loosely compare to wild type. Total protein, zein, amino acids components contents and total nitrogen content of <italic>dek54 </italic>mature kernel were significantly lowered compared with the wild type. <italic>dek54</italic> was located on chromosome 7 within the interval of the physical distance of about 290 kb between markers SSR6 and SSR7. Sequencing revealed that the 351th base G on the 2nd exon of <italic>Zm00001d019294 </italic>gene changed into A, which led to the premature termination of the protein translation. <italic>Zm00001d019294</italic> gene was specifically expressed in immature maize kernel, and has the highest expression in 12 DAP (days after pollination) immature kernel. Targeted mutation was performed using CRISPR/Cas9 system to identify that mutant phenotype was caused by candidate gene <italic>Zm00001d019294</italic>. <italic>Dek54</italic> encoded an MFS (major facilitator superfamily) protein and had high homology with ZmNRT1.5 (nitrate transporter). Besides, Dek54 protein was localized in the plasma membrane of maize protoplasts. The study of <italic>dek54 </italic>laid the foundation for the molecular mechanism analysis of maize kernel development.

Girdling Effects on Fruit Maturity, Kernel Quality, and Nutritional Value of Walnuts (Juglans regia L.) alongside the Effects on Leaf Physiological Characteristics

Girdling, based on the accumulation of photosynthetic products above the girdling zone, is a common technique applied to tree species to increase the yield and fruit quality. The aim of this study was to investigate the girdling effects on photosynthesis and soluble sugars (Sols) of leaves in fruiting shoots and, for the first time, on quality variables of ‘Franquette’ walnuts harvested at two harvests, early and late, 43 and 84 d after treatment, respectively. Girdling was conducted on a part of four-year old branches at the onset of kernel growth. At late harvest, coinciding with commercial harvest, girdling advanced the mature fruit percentage, kernel weight, and oil content, whereas decreased kernel moisture and slightly affected the color brightness, although kernels remained with an extra light color. Advanced maturation increased linoleic acid and polyunsaturated fatty acid (PUFA) fraction in oil, whereas it decreased palmitic acid and the saturated fatty acid (SFA) fraction in oil, kernel total antioxidants, and Sols (sucrose, glucose, fructose) in kernels and leaves and leaf photosynthesis (Pn), whereas girdling had no effect on these variables. Oil rancidity remained stable throughout the experiment. Development of callus was observed on tree wounds 84 d after treatment. Conclusively, girdling enhanced the fruit maturation, resulting in higher uniformity of maturity and increased oil yield with no quality deterioration or apparent tree damage.

Maize kernel development.

Maize (Zea mays) is a leading cereal crop in the world. The maize kernel is the storage organ and the harvest portion of this crop and is closely related to its yield and quality. The development of maize kernel is initiated by the double fertilization event, leading to the formation of a diploid embryo and a triploid endosperm. The embryo and endosperm are then undergone independent developmental programs, resulting in a mature maize kernel which is comprised of a persistent endosperm, a large embryo, and a maternal pericarp. Due to the well-characterized morphogenesis and powerful genetics, maize kernel has long been an excellent model for the study of cereal kernel development. In recent years, with the release of the maize reference genome and the development of new genomic technologies, there has been an explosive expansion of new knowledge for maize kernel development. In this review, we overviewed recent progress in the study of maize kernel development, with an emphasis on genetic mapping of kernel traits, transcriptome analysis during kernel development, functional gene cloning of kernel mutants, and genetic engineering of kernel traits.

Yield and Economic Response of Peanut (Arachis hypogaea L.) Cultivars to Prohexadione Calcium in Large-Plot Trials in Georgia

ABSTRACT Prohexadione calcium, a plant growth regulator, has been used on virginia market type peanut cultivars for many years to manage excessive vine growth and improve digging efficiency. Prohexadione calcium has not been widely used on runner market type cultivars due to their slower growth habit and sporadic yield response at the labeled rate until recent research showed lower use rates of prohexadione calcium provided similar vine control and enhanced yield response. Large plot experiments were conducted in Colquitt county at the Darrell Williams Research Farm on the Sun Belt Ag Expo to quantify yield and market grade quality and economics of using prohexadione calcium at 105 g a.i./ha on six runner type cultivars. Prohexadione calcium was applied twice during the growing season. The first application was made when 50% or greater of lateral vines from adjacent rows were touching. A second application of each treatment was applied 14d after the first application. The runner type cultivars were Georgia-06G, Georgia-12Y, Georgia-13M, Georgia-14N, TUFRunnerTM-297, and TUFRunnerTM-511. Similar large-plot experiments were conducted on farms in Baker and Early counties evaluating yield and economic response of prohexadione calcium on Georgia-06G. A non-treated control was used in all experiments. Prohexadione calcium increased pod yield in all experiments ranging from 450 to 650 kg/ha compared to the non-treated control with response similar across cultivars. Prohexadione calcium reduced the dollar value per metric ton (DVMT) as a result of lowering total sound mature kernel (%TSMK) percentages up to 3 points. The higher yields obtained for the prohexadione calcium-treated peanut provided higher gross dollar value return/ha (GDR) in all experiments and higher gross dollar value return/ha above treatment cost (GDRAT) in the on-farm trials. Therefore, prohexadione calcium at 105 g/ha applied twice on runner market type peanut is warranted to improve yield and financial return when excessive vine growth is a concern.

Effect of inorganic and bio-fertilizers on yield attributes, yield and economic of summer groundnut Arachis hypogaea L.

A field experiment entitled, “Effect of inorganic and bio-fertilizers on yield attributes, yield and economic of summer groundnut (Arachis hypogaea L.)” was conducted at PG Research Farm, Agronomy Section, R.C.S.M. College of Agriculture, Kolhapur during summer, 2019. The experiment was laid out in factorial randomized block design (FRBD) with three replications and nine treatment combinations of three inorganic fertilizer levels viz., F1-75% RDF (18.75:37.5:0 kg ha-1), F2-100% RDF (25:50:0 kg ha-1), F3-125% RDF (31.25:62.5:0 kg ha-1) and three bio-fertilizers levels viz., B1- Control, B2- Rhizobium spp. + PSB (Lignite based), B3- Rhizobium spp. + PSB (Liquid based). The application of 100% of RDF ha-1 was at par with 125% of RDF ha-1 significantly over 75% RDF ha-1 in respect of recording higher value of yield attributes and yield viz., number of pods plant-1, weight of pods plant-1 (g), dry pod yield (q ha-1), dry haulm yield (q ha-1), biological yield (q ha-1), shelling (%), weight of 100 kernels (g), sound mature kernel (%) and harvest index (%). The dual seed inoculation of Rhizobium spp. + PSB (Lignite based) as well as Rhizobium spp. + PSB (Liquid based) in respect of recording higher value of yield attributes and yield viz., number of pods plant-1, weight of pods plant-1 (g), pod yield (q ha-1), dry haulm yield (q ha-1), biological yield (q ha-1), shelling (%), weight of 100 kernels (g), sound mature kernel (%) and harvest index (%). The gross monetary returns and net monetary returns were higher due to application of 125% of RDF ha-1 which was at par with 100% of RDF ha-1 and dual seed inoculation of Rhizobium spp. + PSB (Lignite based) significantly higher over control and at par with dual seed inoculation of Rhizobium spp. + PSB (Liquid based).

The B3 domain-containing transcription factor ZmABI19 coordinates expression of key factors required for maize seed development and grain filling.

Grain filling in maize (Zea mays) is regulated by a group of spatiotemporally synchronized transcription factors (TFs), but the factors that coordinate their expression remain unknown. We used the promoter of the grain filling-specific TF gene Opaque2 (O2) to screen upstream regulatory factors and identified a B3 domain TF, ZmABI19, that directly binds to the O2 promoter for transactivation. zmabi19 mutants displayed developmental defects in the endosperm and embryo, and mature kernels were opaque and reduced in size. The accumulation of zeins, starch and lipids dramatically decreased in zmabi19 mutants. RNA sequencing revealed an alteration of the nutrient reservoir activity and starch and sucrose metabolism in zmabi19 endosperms, and plant phytohormone signal transduction and lipid metabolism in zmabi19 embryos. Chromatin immunoprecipitation followed by sequencing coupled with differential expression analysis identified 106 high-confidence direct ZmABI19 targets. ZmABI19 directly regulates multiple key grain filling TFs including O2, Prolamine-box binding factor 1, ZmbZIP22, NAC130, and Opaque11 in the endosperm and Viviparous1 in the embryo. A number of phytohormone-related genes were also bound and regulated by ZmABI19. Our results demonstrate that ZmABI19 functions as a grain filling initiation regulator. ZmABI19 roles in coupling early endosperm and embryo development are also discussed.