High grain quality accessions within a maize drought tolerant core collection

Grain oil content is negatively correlated with starch content in maize in general. In this study, 282 and 263 recombinant inbred lines (RIL) developed from two crosses between one high-oil maize inbred and two normal dent maize inbreds were evaluated for grain starch content and its correlation with oil content under four environments. Single-trait QTL for starch content in single-population and joint-population analysis, and multiple-trait QTL for both starch and oil content were detected, and compared with the result obtained in the two related F2∶3 populations. Totally, 20 single-population QTL for grain starch content were detected. No QTL was simultaneously detected across all ten cases. QTL at bins 5.03 and 9.03 were all detected in both populations and in 4 and 5 cases, respectively. Only 2 of the 16 joint-population QTL had significant effects in both populations. Three single-population QTL and 8 joint-population QTL at bins 1.03, 1.04–1.05, 3.05, 8.04–8.05, 9.03, and 9.05 could be considered as fine-mapped. Common QTL across F2∶3 and RIL generations were observed at bins 5.04, 8.04 and 8.05 in population 1 (Pop.1), and at bin 5.03 in population 2 (Pop.2). QTL at bins 3.02–3.03, 3.05, 8.04–8.05 and 9.03 should be focused in high-starch maize breeding. In multiple-trait QTL analysis, 17 starch-oil QTL were detected, 10 in Pop.1 and 7 in Pop.2. And 22 single-trait QTL failed to show significance in multiple-trait analysis, 13 QTL for starch content and 9 QTL for oil content. However, QTL at bins 1.03, 6.03–6.04 and 8.03–8.04 might increase grain starch content and/or grain oil content without reduction in another trait. Further research should be conducted to validate the effect of these QTL in the simultaneous improvement of grain starch and oil content in maize.

IntroductionMaize is a crucial source of nutrition, and the quality traits such as starch content, oil content, and lysine content are essential for meeting the demands of modern agricultural development. Understanding the genetic basis of these quality traits significantly contributes to improving maize yield and optimizing end-use quality. While previous studies have explored the genetic basis of these traits, further investigation into the quantitative trait loci (QTL) responsible for variations in starch content, oil content, and lysine content still requires additional attention.MethodsDouble haploid (DH) populations were developed via a nested association mapping (NAM) design. Phenotypic data for starch, oil, and lysine content were collected using near-infrared spectroscopy and analyzed via ANOVA. Genotyping employed a 3K SNP panel, and genetic maps were constructed using QTL IciMapping. QTL analysis integrated single linkage mapping (SLM) and NAM approaches, with candidate genes identified via maizeGDB annotation and transcriptome data.ResultsThe broad-sense heritability of the populations with a range of 63.98-80.72% indicated the majority of starch content, oil content and lysine content variations were largely controlled by genetic factors. The genetic maps were constructed and a total of 47 QTLs were identified. The phenotypic variation explained (PVE) of the three traits is in a range of 2.60-17.24% which suggested that the genetic component of starch content, oil content and lysine content was controlled by many small effect QTLs. Five genes encoding key enzymes in regulation of starch, oil and lysine synthesis and metabolism located within QTLs were proposed as candidate genes in this study.DiscussionThe information presented herein will establish a foundation for the investigation of candidate genes that regulate quality traits in maize kernels. These QTLs will prove beneficial for marker-assisted selection and gene pyramiding in breeding programs aimed at developing high-quality maize varieties.

An improvement in the quality of maize grain by increasing the level of components responsible for its biological value is possibleby using genetic means. However, a change in the genotype, together with improving the nutrient properties of the grain, also has someadverse consequences connected with a fall in yield and in resistance to diseases.Field experiments were conducted during three years (2003, 2004and 2005) to evaluate environmental effects on grain yield andquality responses of maize hybrids. Twenty one hybrids of various maturity groups (FAO 150-400) were planted to achieve an optimum(60-70 000 plants per hectare) plant populations and grown under the medium-N (80 kg N ha-1) fertilization. Environmental conditionssignificantly affected maize hybrid responses for grain yield, starch, oil and protein contents, and consequently, starch, oil and proteinyields per hectare. Hybrids of flint type, which have a short vegetation period, had high protein and oil content but the yield averageswere low due to the slower rate of starch incorporation. Hybrids of the dent type have a longer growing season and more intensecarbohydrate accumulation, but low protein and oil contents. In wet years there was a higher rate of starch accumulation, while dryyears are favorable for protein and oil accumulation. Positive correlation existed between starch content and grain yield and 1000-weight as well as between oil content and volumetric weight among tested hybrids. Negatively correlation existed between grain oil andstarch content as well as between oil content and grain yield and 1000-weight. Thus, end-users that require high quality maize may needto provide incentives to growers to off set the negative correlation of grain yield with oil and protein content.

A study in twenty four genotypes of Brassica juncea under nitrogen (N) fertilization (80 kg ha−1 N (N80)) showed genotypic variation in oil content. Regression analysis showed oil content to be highly dependent on the availability of seed nitrogen. There was an inverse relationship between oil content and seed meal protein under N treatment in few genotypes only, while others showed opposite effect. This may be due to the distribution of more carbon towards starch synthesis in some genotypes as oil and starch content are negatively correlated (r = − 0.298). The increase in biomass under N80 showed the influence of N on the rate of photosynthesis. N application also influenced total soluble sugar content with a reduction of 8.2–79.8% within the genotypes. This was proportional to the change in biomass, which in turn reflects in the variation of starch, protein and oil content. Based on our observations using the SAS software the twenty four genotypes were clustered into two categories, cluster I showed increased in oil content and cluster II showed decrease in oil content.

به‌منظور ارزیابی اثر تنش آب، محلول‌پاشی روی و مقادیر مختلف اسید‌سالیسیلیک بر درصد روغن و پروتئین دانه هم‌چنین ارتباط آن‌ها با عملکرد روغن و پروتئین سویا، آزمایشی به‌صورت اسپلیت‌فاکتوریل در قالب طرح بلوک‌های کامل تصادفی با چهار تکرار در باغ کشاورزی استان لرستان در سال 1392 اجرا شد. عامل‌های آزمایشی شامل تیمار‌های آبیاری در دو سطح (60 و120‌میلی‌متر تبخیر از تشتک تبخیر کلاس A) به‌عنوان عامل اصلی و عامل فرعی حاصل از ترکیب محلول‌پاشی عنصر روی (عدم مصرف، مصرف) و هورمون اسید‌سالیسیلیک در سه غلظت صفر، 5/0، یک میلی‌مولار در نظر گرفته شدند. نتایج نشان داد که صفات مورد‌بررسی، تحت تأثیر تیمارهای آزمایشی قرار گرفتند به‌طوری‌که تغییرات به‌وجود آمده در کیفیت و عملکرد دانه در کرت‌های تنش دیده مشهودتر بود. عملکرد دانه با عملکرد روغن و پروتئین همبستگی معنی‌دار و قوی داشت. اثرات متقابل سه گانه، تأثیر معنی‌داری بر میزان روغن و پروتئین دانه داشته است. با افزایش غلظت اسید‌سالیسیلیک میزان روغن و پروتئین دانه کاهش یافت. افزایش اسید‌سالیسیلیک و مصرف روی با افزایش میزان تبخیر سبب افزایش عملکرد دانه، روغن و پروتئین شد. محلول‌پاشی روی و 5/0‌میلی‌مولار اسید‌سالیسیلیک سبب افزایش درصد روغن و پروتئین دانه گردید. در مجموع، با کاربرد روی و اسید‌سالیسیلیک کاهش عملکرد در اثر تنش جبران شده و کیفیت دانه را افزایش دادند.

High-oil maize (Zea mays L.) has special value in animal feed and human food. Two hundred and eight-four and 265 F2:3 families developed from two crosses between one high-oil maize inbred and two normal dent maize inbreds were evaluated for grain oil and starch contents under two environments. Using composite interval mapping, 1–6 QTL for each trait were detected under each environment and in combined analysis in both populations. Only one common QTL across two environments in each population and across two populations were found for starch content. Among the detected QTL, nine digenic interactions with small effects were identified. Comparison of single-trait QTL and the results of multiple-trait QTL mapping showed that oil content might be complicatedly correlated with starch content. Although single-trait QTL with the same parental effects for both traits and oil-starch QTL were all detected at the same genetic bin 6.04 as the cloned high-oil QTL (qHO6) with no unfavorable effects on grain weight, our results did reflect the difficulty to realize simultaneous improvement on grain oil and starch contents. Of course, these results should be validated in further experiments under more environments using RILs, NILs and other permanent populations.

A dissection of the genetic regulation of protein, oil and starch contents in maize (Zea mays L.) kernels will enhance high-quality breeding. The objective of the present research was to detect the quantitative trait loci (QTL) controlling protein, oil, starch and lysine contents in maize kernels and to dissect their inheritable relationships and basis. A population of 498 recombinant inbred lines derived from a biparental cross of two elite inbred lines were grown in six environments. All individuals were genotyped with 151 pairs of simple sequence repeat markers to construct a genetic linkage map. Using composite interval mapping, we detected total 25, 13, 31 and 15 QTLs for protein, oil, starch and lysine contents, respectively, in six environments. 32 QTLs at bins 2.03–2.04, 2.05–2.07, 5.05–5.07, 6.01–6.04, 8.03–8.05 and 10.03–10.05 were stably expressed across multiple environments. Co-localizations of QTLs for the four traits were found on chromosomes 1, 2, 5, 6, 8, and 10. Part of the co-localized QTLs, the direction of QTL effects coincided with the sign of their phenotypic correlations, which likely indicates the presence of pleiotropic QTL or tight linkage among them. Additionally, seven pairs of QTLs with significant additive × additive epistatic interaction effects were identified based on single-environment QTL analysis. The results obtained from the present investigation may hold great promise for further studies of improving kernel quality in maize.

干旱胁迫对青藏高原6种植物生理指标的影响

Abiotic factors, such as drought, can significantly impact the vegetative growth and productivity of maize. To investigate the effects of the combined foliar application of zinc (Zn) and iron (Fe) nanoparticles with the recommended nitrogen dose (RND) on maize production and grain chemical composition under different water regimes, two field experiments were conducted in El-Ayyat city, Giza, Egypt, during the summer seasons of 2022 and 2023. This study utilized a split-split-plot experimental design with three replications. The main plots were designated to different water regimes (100, 80, 60, and 40% of estimated evapotranspiration), while the sub-plots were randomly distributed with Zn and Fe nanoparticle concentrations (0, 100, and 200 mg/L). The sub-sub-plots were randomly allocated to three maize cultivars (SC-P3062, SC-32D99, and SC-P3433). The results revealed that exposure to drought conditions resulted in a significant decline in the yield and yield-related attributes across all maize cultivars examined. Grain yield decreased by 10–50% under drought conditions. However, the foliar application of Zn and Fe nanoparticles was found to significantly improve grain yield, protein content, oil content, starch content, crude fiber, ash, and macro- and micronutrient concentrations in the maize cultivars under control and drought stress conditions. The foliar application of Zn and Fe nanoparticles at a concentration of 200 mg/L to the SC-P3433 maize cultivar led to the greatest grain yield per hectare, reaching 11,749 and 11,657 kg under the irrigation regimes with 100 and 80% total evapotranspiration, respectively. According to the assessment using the relative drought index, the SC-P3062 maize cultivar demonstrated tolerance (T) to water stress conditions. In conclusion, the foliar application of Zn and Fe nanoparticles (100–200 mg/L) effectively mitigated the negative effects of drought stress on maize plants. This approach can be recommended for farmers in arid and semi-arid regions to maintain and improve maize yield and grain quality under water-deficit conditions.

Identification of unconditional and conditional QTL for oil, protein and starch content in maize

Field experiments were conducted during summer 2008-09 (Y1) and 2009-10 (Y2) at the Agronomy Research Farm of The University of Agriculture Peshawar-Pakistan to investigate the impact of different N-fertilizer sources [urea, calcium ammonium nitrate (CAN) and ammonium sulphate (AS)] and their levels (50, 100, 150 and 200 kg ha-1) on phenology, seed weight and composition (seed protein, oil and starch content) of maize (Zea mays L.) genotypes “Local cultivars (Azam and Jalal) vs. hybrid maize (Pioneer-3025)”. The results revealed that the rest (all the experimental plots applied with N) had delayed phonological development and had produced heavy grains with higher protein, oil and starch contents over control (N not applied). In both years, the maturity was delayed, seed weight and seed protein content increased with the application of two higher N rates (150 and 200 kg ha-1) as compared with the two lower N rates (50 and 100 kg ha-1). Applications of N in the form of ammonium sulphate enhanced maturity and decreased seed weight but increased seed oil content over urea and calcium ammonium nitrate. The maize hybrid (P-3025) with delayed maturity produced heavy seeds and higher seed protein and oil contents as compared to the two local cultivars (Azam and Jalal). The hybrid (P-3025) was considered the more efficient maize genotype that responded very well to different sources and rates of N than the local maize cultivars.

BackgroundAbiotic stresses due to environmental factors could adversely affect the growth and development of crops. Among the abiotic stresses, drought and heat stress are two critical threats to crop growth and sustainable agriculture worldwide. Considering global climate change, incidence of combined drought and heat stress is likely to increase. The aim of this study was to shed light on plant growth performance and leaf physiology of three tomatoes cultivars (‘Arvento’, ‘LA1994’ and ‘LA2093’) under control, drought, heat and combined stress.ResultsShoot fresh and dry weight, leaf area and relative water content of all cultivars significantly decreased under drought and combined stress as compared to control. The net photosynthesis and starch content were significantly lower under drought and combined stress than control in the three cultivars. Stomata and pore length of the three cultivars significantly decreased under drought and combined stress as compared to control. The tomato ‘Arvento’ was more affected by heat stress than ‘LA1994’ and ‘LA2093’ due to significant decreases in shoot dry weight, chlorophyll a and carotenoid content, starch content and NPQ (non-photochemical quenching) only in ‘Arvento’ under heat treatment. By comparison, the two heat-tolerant tomatoes were more affected by drought stress compared to ‘Arvento’ as shown by small stomatal and pore area, decreased sucrose content, ΦPSII (quantum yield of photosystem II), ETR (electron transport rate) and qL (fraction of open PSII centers) in ‘LA1994’ and ‘LA2093’. The three cultivars showed similar response when subjected to the combination of drought and heat stress as shown by most physiological parameters, even though only ‘LA1994’ and ‘LA2093’ showed decreased Fv/Fm (maximum potential quantum efficiency of photosystem II), ΦPSII, ETR and qL under combined stress.ConclusionsThe cultivars differing in heat sensitivity did not show difference in the combined stress sensitivity, indicating that selection for tomatoes with combined stress tolerance might not be correlated with the single stress tolerance. In this study, drought stress had a predominant effect on tomato over heat stress, which explained why simultaneous application of heat and drought revealed similar physiological responses to the drought stress. These results will uncover the difference and linkage between the physiological response of tomatoes to drought, heat and combined stress and be important for the selection and breeding of tolerant tomato cultivars under single and combine stress.

Drought stress is seriously affecting maize production. To investigate the influence of calcium (Ca) foliar application on maize production and chemical composition of grains under drought stress, two experiments were carried out at Cairo University Research Station, Giza, Egypt, during the summer seasons of 2018 and 2019. The experimental design was split-split plot design with a completely randomized blocks arrangement with three replications. Water regimes were assigned to the main plots [100 (control), 75, and 50% of estimated evapotranspiration]. Calcium levels (zero and 50 mg/L) were assigned to the sub plots. Maize cultivars (SC-P3444, Sammaz-35 and EVDT) were assigned to the sub-sub plots. Three maize cultivars were sprayed with Ca solution concentration (50 mg/L) under normal and drought conditions. The control treatment (0 mg/L) was sprayed with an equal amount of distilled water for comparison. Results indicated a significant decrease in total yield and grain characteristics [protein, ash, total sugars, nitrogen (N), phosphorus (P), potassium (K), and iron (Fe) contents] as a response of drought. Calcium foliar application significantly increased maize yield, protein, ash, carbohydrates, starch, total sugars, and ionic contents of grains, except for manganese (Mn), under all irrigation levels. Based on the drought tolerance index (DTI), only cultivar SC-P3444 showed drought tolerance while cultivars Sammaz-35 and EVDT were sensitive to drought stress. Foliar application of Ca on SC-P3444 cultivar achieved the highest grain yield per hectare (8061 kg) under the water regime of 100% of the total evapotranspiration, followed by Sammaz-35 (7570 kg), and EVDT (7191 kg) cultivars. At the water regime of 75% of estimated evapotranspiration (75% irrigation), Ca foliar application increased grain yield by 16, 13 and 14% in SC-P3444, Sammaz-35, and EVDT, respectively. At the water regime of 50% of the estimated evapotranspiration (50% irrigation), Ca foliar application increased grain yield by 17, 16, and 13% in SC-P3444, Sammaz-35, and EVDT, respectively. In brief, Ca had a clear impact on productivity and grain quality with important implications for maize yield under normal and water stress conditions. Our findings demonstrate that foliar application of Ca enabled drought stressed maize plants to survive better under stress. The most water stress tolerant cultivar was SC-P3444 followed by Sammaz-35 and EVDT under drought stress.

Corn (Zea Mays L.) is the main crop in the United States and starch is the most important product derived from corn kernels. Use of corn by the processing industry has steadily increased and hybrids with high grain yield and higher starch, protein, or oil content are available to growers. However, utilization of exotic germplasm in maize breeding programs does not represent more than 3% of the genetic base currently in use to produce corn hybrids grown in the United States. In addition to yield trial evaluations to determine the agronomic performance of new corn cultivars, it is necessary to determine the physical, compositional, and milling characteristics that could provide added value for processing and increase the usefulness of new inbred lines and hybrids. The present study was conducted to determine whether Corn Belt lines introgressed with exotic materials from Argentina, Chile, Uruguay, Cuba, and Florida have appropriate wet-milling characteristics. Ten lines from the Germplasm Enhancement of Maize project with different starch content yields, three commercial inbred lines, and two public inbred lines (B73 and Mo17) were analyzed using both Near-Infrared Transmitance (NIT) and a 100-g wet-milling procedure. Statistical differences (P<0.05) were found for yield of the wet-milled fractions (starch, fiber, gluten, and germ). AR227 and CU562, two lines of exotic origin, had similar or better starch yield and starch recovery than B73 and the other adapted inbred lines, which indicates that these lines can potentially be used to improve the proportion of extractable starch present in the kernels of their hybrids. Residual protein levels in the starch and gluten fractions were in the range of 0.26-0.32% and 3845%, respectively. The starch yield of exotic corn lines from wet milling correlated positively with starch content and was negatively correlated with protein content of the corn kernels. Oil content in the germ varied from 50 to 60%. Our results indicate that the use of exotic germplasm to improve the wet-milling characteristics in a corn breeding program may enhance genetic diversity available for breeding.

The present study was carried out at the Maize Researches Department in General Commission for Science agriculture Research (G-C-S-A-R) Damascus, Syria. This study aimed at estimating the potence ratio and phenotypic correlations and path analysis coefficient analysis for protein, oil, and starch content in grain, grain yield per plant and 100-kernel weight. Twenty eight single cross hybrids were produced using a half diallel cross in 2008 cropping season and consequently evaluated during 2009 cropping season. Potence ratio results indicated that partial and over-dominance gene effects played a major role in inheritance of protein, oil, and starch content in grain while, over-dominance gene effects were the most dominant in the inheritance grain yield per plant and 100-kernel weight. Positive and high significantly correlations were observed between protein and oil content in grain (0.366) and between grain yield and100-kernel weight (0.386). Potence ratio estimates indicating partial and over-dominance towards the higher starch, oil, protein, for 100 grain yield per plant over-dominance gene effects played a major role in inheritance of this trait. Path analysis results showed the contribution of oil content in grain, 100-kernel weight and grain yield per plant for protein content in grain variation account 15.55%, and the relative important of oil content in grain reach to 13.40%. So, it can be considered as selection criteria which may lead to improve protein content in maize grain.