Indian Maize Research Articles

Regeneration of Indian maize genotypes (Zea mays L.) from immature embryo culture through callus induction

Callus induction and regeneration ability of five maize genotypes UMI 757, UMI 615, UMI 112, UMI 285 and CO 1 and one promising maize hybrids COH(M) 5 were investigated using 14 days old immature embryos as explants. Callus induction depends on genotype, explants (age and size of explants), medium, type of auxin and their concentration. Explants grown on Murashige and Skoog (MS) medium supplemented with 1.5 mg/l 2, 4 - D (2,4 – dichloro phenoxy acetic acid), 0.3 mg/l kinetin with 30 g/l maltose showed the highest percentage of embryogenic callus induction. Among the six genotypes tested, COH(M) 5 maize hybrids have highest percentage of embryogenic calli. The embryogenic calli incubated on MS medium supplemented with 1.5 mg/l BAP (Benzyl Amino Purine), 0.2 mg/lNAA (Naphthalene Acetic Acid) with 1.0 mg/l kinetin was found to give the highest organogenesis response and regeneration of plantlets.

Diversity in Phytochemical Composition and Antioxidant Capacity of Dent, Flint, and Specialty Corns

ABSTRACTDent, flint, and specialty genotypes of Indian yellow maize were evaluated for phytochemical content and their hydrophilic antioxidant capacity. Solid‐phase extraction coupled with solid–liquid extraction was used to obtain free phenolics and flavonoids from maize samples, reducing the use of excessive solvents and handling time. Bound phenolics were extracted with enhanced acidic hydrolysis to improve extractability. The phenolic contents in Indian maize genotypes ranged from 46 to 79 μmol of ferulic acid equivalents per gram of sample on a dry basis (db). Carotenoids in Indian maize genotypes were found to be equivalent to Chinese yellow maize and ranged from 13 to 24 μg/g of sample (db), whereas tocol content varied greatly in the range of 607–1,238 μg of α‐tocopherol equivalents/g of sample (db). Dent and flint corn did not exhibit differences (P > 0.05) in their phenolic contents, whereas among the specialty genotypes sweet corn contained the highest phenolics but least carotenoids (P < 0.05). Bound extracts appeared to contribute largely to 2,2′‐diphenyl‐1‐picrylhydrazyl free radical scavenging, hydrogen peroxide scavenging, and ferric reducing antioxidant power of maize genotypes. Sweet corn exhibited higher antioxidant capacity (P < 0.05) among all the genotypes. The antioxidant capacities correlated well with the total phenolic contents of the maize genotypes.

Investigating the response of tropical maize (Zea mays L.) cultivars against elevated levels of O3 at two developmental stages.

Tropospheric ozone (O3) concentrations are rising in Indo-Gangetic plains of India, causing potential threat to agricultural productivity. Maize (Zea mays L.) is the third most important staple crop at global level after rice and wheat. Two high yielding cultivars of Indian maize (HQPM1-quality protein maize and DHM117-normal/non quality protein maize) were exposed to two levels of elevated O3 above the ambient level (NFC) viz. NFC + 15 ppb O3 (NFC + 15) and NFC + 30 ppb O3 (NFC + 30) using open top chambers under field conditions. The study was conducted to evaluate the biochemical responses of two cultivars at different developmental stages leading to change in yield responses. Initially at lower O3 dose, photosynthetic pigments showed an increase but reduction at later stage, while higher dose caused a decline at both the stages of sampling. Levels of superoxide radical (O2 (-)) and hydrogen peroxide (H2O2) significantly increased and contributed to lipid peroxidation at elevated O3. Histochemical localization assay of O2 (-) and H2O2 showed that guard cells of stomata and cells around trichomes took deeper stain at elevated O3 reflecting more formation of reactive oxygen species. Secondary metabolites like total phenol, flavonoids and anthocyanin pigments also increased in plants under O3 stress. Enzymatic antioxidants were triggered in both the cultivars due to elevated O3, while induction of non-enzymatic antioxidants was more in HQPM1. Native PAGE analysis also showed that SOD, POX, CAT, APX and GPX were stimulated at elevated O3 concentrations compared to NFC. SDS-PAGE showed reductions of major photosynthetic proteins with higher decrease in DHM117. Principal Component Analysis showed that both the cultivars showed differential response against O3 at two developmental stages. HQPM1 maintained the analogous defense strategy at both the sampling stages while DHM117 showed variable response. Overall metabolic induction of antioxidants related to defense was more in DHM117 than HQPM1. This suggests that DHM117 utilized more assimilates in maintaining the homeostasis against imposed oxidative stress, causing less translocation of assimilates to reproductive parts and thus affecting the final yield. In terms of yield it is suggested that performance of HQPM1 (quality protein maize) was better than the DHM117 (non quality protein maize).

Evaluation of maize (Zea mays) inbred lines for tolerance to low temperature stress under field conditions

In northern India, cold spell is experienced at early vegetative stage. Tolerance to cold in inbred lines is important to ensure seed production in rabi season. Sixty-six inbred lines of Indian maize program were evaluated for their tolerance to low temperature stress under field conditions. Maize (Zea mays L.) inbred lines of Bajaura Centre (BJIM 2780, BJIM 08-100, BJIM 10-1 and BJIM 10-35) and Almora Centre (V 366, V 384, V 351, V 382 and V 378) performed better with minimum leaf yellowing and good plant growth under the cold stress. Inbreds lines BJIM 10- 35, BJIM 10-43, BJIM 10-37, V 364, V 404, V 390, LM 14 and BML 6 exhibited high reduction in yellowing of leaves coupled with fast growth recovery. Expression of yellowing of leaves and plant growth showed significant negative correlation. Yellowing of leaves and recovery of plant growth due to cold spell were important parameters for cold tolerance at early vegetative stage in maize.

Differential effect of immature embryo's age and genotypes on embryogenic type II callus production and whole plant regeneration in tropical maize inbred lines (Zea maysL.)

The study was undertaken to elucidate the effect of genotypes and age of immature embryo on callus induction, embryogenic type II calli production and regeneration from immature maize embryos. The immature embryos were excised from a selfed ear of ten elite Indian maize inbred lines on 6, 12 and 18 days after pollination. The mean callus induction, embryogenic type II calli production, and regeneration was highest across all the genotypes in 12 days old immature embryos and were 44.25, 26.12, and 11.20 per cent respectively. The significant differences were observed with respect to callus induction, embryogenic type II calli production and regeneration capacity between genotypes. The highest regeneration capacity was observed by immature embryo at 12 days after pollination (DAP) of genotype HKI1105 and CM300.

An efficient and rapid regeneration via multiple shoot induction from mature seed derived embryogenic and organogenic callus of Indian maize (Zea mays L.)

An efficient method for in vitro micro propagation and genetic transformation of plants are crucial for both basic and applied research. Maize is one of the most important cereal crops around the world. Regeneration from immature embryo is hampered due to its unavailability round the year. On the contrary mature embryo especially tropical maize is recalcitrant toward tissue culture. Here we report a highly efficient regeneration (90%) system for maize by using 2 different approaches i.e., embryogenic and organogenic callus cultures. Seeds were germinated on MS medium supplemented with 5 mg/l 2,4-D and 3 mg/l BAP. Nodal regions of 2 wks old seedlings were longitudinally split upon isolation and subsequently placed on callus initiation medium. The maximum frequency of embryogenic callus formation (90%) was obtained on MS medium supplemented with 2 mg/l 2,4-D and 1 mg/l BAP in the dark conditions. The compact granular organogenic callus formation (85% frequency) was obtained on MS medium supplemented with 2.5 mg/l 2,4-D and 1.5 mg/l BAP at light conditions. MS medium supplemented with 2 mg/l BAP, 1 mg/l Kinetin and 0.5 mg/l NAA promoted the highest frequency of shoot induction. The highest frequency of root formation was observed when shoots were grown on MS medium. The regenerated plants were successfully hardened in earthen pots after adequate acclimatization. The important advantage of this improved method is shortening of regeneration time by providing an efficient and rapid regeneration tool for obtaining more stable transformants from mature seeds of Indian tropical maize cultivar (HQPM-1).

Comparison of the Performance of Best Linear Unbiased Estimation and Best Linear Unbiased Prediction of Genotype Effects from Zoned Indian Maize Data

ABSTRACTThe maize (Zea mays L.) growing area in India is divided into five zones for cultivar testing. During triannual testing of genotypes in official trials within the All‐India Coordinated Maize Improvement Program (AICMIP), a large number of entries is rejected each year. Therefore, only a low number of entries is carried forward to the advanced stage of testing. The subdivision of the breeding sites into zones results in limited data per zone. Hence, the question arises how to select the best genotypes per zone and how information can be borrowed across zones to improve the accuracy of selection within zones. We compared the performance of best linear unbiased prediction (BLUP) using the correlation of genetic effects between zones with best linear unbiased estimation (BLUE) based on data per zone. In both cases, data were analyzed using a mixed model. We used simulations to calculate correlations between the true simulated values and the predicted genotype values obtained by BLUE and BLUP using the same models. The data structure and the variance components used in simulations were based on the analysis of 40 triannual series of four different maize maturity groups. Best linear unbiased prediction outperformed BLUE in 38 out of 40 series and on average across all series. An advantage of BLUP was observed for varying genetic correlations between zones. We conclude that the use of BLUP enhanced the estimation accuracy in zoned AICMIP maize testing trials and can be recommended for future use in these trials.

English

  Five elite Indian maize inbreds namely; HKI1105, HKI1105, HKI335, CM300 and LM5 were evaluated for callus induction and regeneration. Immature embryos obtained 14 days after pollination were used as explants. Genotype, medium, type of auxin and their concentrations influenced callus induction. N6 medium supplemented with different concentration of 2,4-D (1, 2 and 3 mg/l) and Dicamba (1, 2 and 3 mg/l) were used for callus induction. N6 supplemented with 2 mg/l of 2,4-D has shown highest percentage of embryogenic callus induction. Among the five genotypes tested, CM300 gave highest percentage of embryogenic calli. CM300 and LM5 both have shown higher regeneration percentage of 12.22%.    Key words: Maize, in-vitro culture and regeneration.

Maize-Poultry Value Chains in India: Implications for Research and Development

Rapid growth of the poultry industry in India has caused an increased demand for maize (Zea mays L.). Poultry feed contains 60–65% of maize and approximately 50% of India's annual maize harvest of 19 million tons is used for poultry feed. This article reports on a qualitative study of maize-poultry value chains. It identifies bottlenecks in the value chains and highlights some of the impediments to the uptake of quality-protein maize (QPM; maize with elevated levels of the essential amino acids lysine and tryptophan), which is being heavily promoted by Indian maize breeders. Further research is needed to produce QPM varieties that outperform normal maize varieties and to work more closely with the poultry industry so that QPM value chains become more demand than supply-driven.

Callus induction and whole plant regeneration in elite Indian maize (Zea mays L.) inbreds

Callus induction and regeneration ability of five elite maize inbred lines, CM 111, CM 117, CM 124, CM 125 and CM 300 were investigated using 14-day-old immature embryos as explants. Genotype, medium, source of auxin and their concentrations influenced induction of callus. Explants grown on Murashige and Skoog (MS) medium supplemented with 2,4-dichlorophenoxyacetic acid at 1 mg l−1 showed the highest frequency of callusing. Among all the media tested, explants grown on N6 medium gave the highest frequency of organogenic callus. Moreover, N6 supplemented with Dicamba promoted higher callus response in terms of both frequency of induction as well as quality, compared to N6 medium with 2,4-D. N6 supplemented with 2 mg l−1 Dicamba induced the highest frequency of organogenic callus. Among the five genotypes tested, CM 124, CM 125, and CM 300 gave the best callus. Explants of both CM 124 and CM 300 incubated on MS medium supplemented with 1 mg l−1 benzyladenine and 0.5 mg l−1 indole acetic acid promoted the highest frequency of shoot induction. Though CM 124 induced higher percentage of shoot formation than CM 300, the mean number of developed shoots per explant was higher for CM 300. The highest frequency of root formation was observed when shoots were grown on MS medium supplemented with 2 mg l−1 naphathalene acetic acid. Percentage of regenerated plants ranged from 54 to 66.

Genetic Diversity of Early Maturing Indian Maize (Zea mays L) Inbred Lines Revealed by SSR Markers

A set of 16 popular inbred lines, (8 released and 8 experimental) were analyzed using 24 Simple Sequence Repeats (SSR) markers. In total 71 SSR alleles were identified with a mean of 2.96 alleles per locus. The study revealed 28 rare alleles among the total, out of which 9 were unique to some of the inbred lines. The average Polymorphism Information Content (PIC) and Discrimination Rate (DR) were 0.39 and 0.61, respectively. Genetic similarity expressed as Jaccard’s coefficient varied from 0.23–0.68 with an average of 0.41. Five clusters were obtained by using Unweighted Paired Group Method using Arithmetic Averages (UPGMA). The pattern of grouping did not match well with available pedigree information, which may be attributed to inadequate pedigree information. Inbred lines used in present study revealed heterozygosity ranges from 8.3–33.3% and were clearly distinguished with a minimum set of three markers with high PIC and DR. However, fingerprints obtained using 13 markers with high DR revealed a probability of identical match by chance at 4.06×10−8. In this study we found SSR as a good tool for characterization of maize genotypes along with morphological markers.

A PCR-Based Assay for the Detection and Differentiation of Potential Fumonisin-Producing Fusarium verticillioides Isolated from Indian Maize Kernels

One hundred and three Fusarium isolates from maize samples collected from different districts of Karnataka state, India, were analyzed with genus-specific, species-specific, and potential fumonisin specific oligonucleotide primers. One set of genus-specific primers ITS F and ITS R based on a highly conserved ITS region of the genus Fusarium were used to differentiate Fusarium species from closely related genera. All the Fusarium species tested scored positive with the ITS pair of primers. Detection and identification of Fusarium verticillioides species was done by using a newly designed reverse primer VERT-R (5′- CGA CTC ACG GCC AGG AAA CC −3′) based on an intergenic spacer sequence (IGS) combined with an already designed forward primer VERTF-1 (5′-GCG GGA ATT CAA AAG TGG CC -3′) published previously. Out of 103 Fusarium species tested, 83 isolates of F. verticillioides scored positive for VERTF-1/ VERT-R species-specific pair of primers. Further to discriminate potential fumonisin-producing and nonproducing strains of F. verticillioides, the VERTF-1/VERTF-2 set of primers [VERTF-1 (5′-GCG GGA ATT CAA AAG TGG CC -3′) and VERTF-2 (5′-GAG GGC GCG AAA CGG ATC GG -3′)] were used. 64 isolates of F. verticillioides scored positive for VERTF-1/ VERTF-2 pair of primers. In total, three primers, one forward primer VERTF-1 and two reverse primers VERT-R and VERTF-2, were used for the confirmation of F. verticillioides up to the species level and the second pair of primers were used to confirm the potential for fumonisin production. The developed PCR assay should provide a powerful tool for the detection and differentiation of potential fumonisin-producing F. verticillioides strains in a population.

Effect of 2,4-D and inoculation with Azorhizobium caulinodans on maize

Research over the last few years has shown that inoculation with nitrogen-fixing bacteria of the genus Azorhizobium presents an alternative for (or supplement to) chemical fertilization, mainly due to the capability of the bacteria to produce plant growth- promoting hormones. The Azorhizobium caulinodans strain ORS 571 in combination with 2,4-D was able to colonize the root interior of an Indian maize cultivar. After transplanting to pots, it was noticed that nodulated and Azorhizobium -treated plants showed higher chlorophyll content in the leaf and enhanced nitrate reductase activity, leading to higher yield as compared to the control plants (non-nodulated). A plant growth-promoting effect was clearly visible in all inoculated plants examined. nodulated plants treated with Azorhizobium had higher physiological activities as compared to plants treated only with Azorhizobium . Azorhizobium therefore creates potentially better symbiosis in the form of para -nodules and promotes a higher level of nitrogen fixation, leading to better growth and plant development, with reduced requirements for chemical fertilizers.

Diffusion technology as a tool for characterizing and enhancing germination of maize (Zeα mαys. L) genotypes

Diffusion technology employed earlier for characterizing seed genotypes and the theory of water diffusivity recently developed has now been further extended and tested for enhancing germination of two promising maize (Zea mays. L) genotypes viz. BH-660 and Pop-902 x 903. The values of the seed constant obtained clearly showed that the two maize genotypes were genetically different, not only from one another but also from the four Indian maize genotypes, viz. Paras, Parkash, Parbhat and Kesri. The water diffusivities at 25 °C were found to be 0.0651 x 10 -5 cm 2 s -1 and 0.0556 x 10 -5 cm 2 s -1 , respectively indicating that the diffusion rate of water in BH-660 was 1.2 times greater than that in Pop-902 x 903, and that it absorbed nearly 11.1% more water than the latter genotype. Field trials results showed an increase of 8% and 2% in seed germination when the seeds of the two genotypes were sown after these were subjected to water diffusion at 25 °C and steady-state conditions obtained in the laboratory. These studies distinctly demonstrated that the critical moisture content, biochemical and physiological activities attained under the steady-state conditions during water diffusion bore a direct relation with critical time for seed germination, defined earlier and experimentally tested for selected seed genotypes of different crops. The technology so developed can be fruitfully exploited with seeds of other maize genotypes, as well as crops.

Simple sequence repeat polymorphism in Quality Protein Maize (QPM) lines

A set of 23 Quality Protein Maize (QPM) lines, including 13 lines developed in India and 10 lines at CIMMYT (International Maize and Wheat Improvement Center), Mexico, was analyzed using microsatellite or simple sequence repeat (SSR) markers. Polymorphic profiles for 36 SSR loci have aided in differentiating the QPM inbred lines. The study resulted in identification of SSR markers, such as bnlg439, phi037, bnlg125, dupssr34 andbnlg105, with high polymorphism information content in the selected QPM genotypes. Detection of 30 unique/rare SSR alleles could contribute to effective differentiation of 14 of the 23 QPM inbreds. An opaque2-specific microsatellite marker, phi057, also facilitated differentiation of opaque2-carrying QPM inbreds from the non-opaque genotypes. Analysis using SSR markers indicated high levels of heterozygosity in majority of the Indian QPM lines and in one CIMMYT QPM inbred, CML188. Cluster analysis using SSR data, followed by canonical discriminant analysis, clearly distinguished the Indian QPM inbreds from those developed at CIMMYT. The cluster patterns were largely in congruence with the available pedigree information of the QPM inbreds studied. The study demonstrates the effectiveness of SSR markers in QPM genotype discrimination and analysis of genetic relationships, and could potentially contribute towards effective utilization of the elite QPM germplasm in Indian maize breeding programmes.

RELATIONSHIP BETWEEN DEBRANNING, ASH DISTRIBUTION PATTERN, AND CONDUCTIVITY IN MAIZE

Two Indian flint maize cultivars were evaluated for ash distribution pattern using a McGill No. 2 miller. Both the maize cultivars was debranned for 20, 40, 60, 80, 100 and 120 s and determined for percent bran removed, ash content and conductivity. The regression equations were computed to determine the relationship between bran removed versus debranning duration, ash content versus debranning duration and ash content versus conductivity. The maize cultivars differ significantly with respect to percentage loss of ash content at various debranning stages. Parbhat cultivars showed lower loss of ash as compared to Megha under similar stages of debranning. The quadratic regression model for the relationship between ash content and conductivity of solubles extracted from maize grain debranned for different intervals had a high coefficient of determination (0.959 0.979). This indicated that the computed models can be used to determine percent bran removed from debranning duration and ash content from the conductivity.

Isozyme characterisation of Indian maize inbreds

The need for precise characterisation of crop materials has assumed importance in any established sui generis system for effective protection of plant varieties. Considering this requirement, 37 Indian maize inbreds were analysed for allozyme variations. Seven enzyme systems comprising 16 isozyme loci were analysed using starch gel electrophoresis. The allelic variants were designated using the well-characterised maize inbred Mo 17 as a standard. A total of 29 alleles were scored at the 16-isozyme loci studied. Malate dehydrogenase (Mdh), acid phosphatase (Acp), phosphoglucoisomerase (Pgi), 6-phosphogluconate dehydrogenase (Pad) and isocitrate dehydrogenase (Idh) were the most informative isozyme systems for characterisation of the maize inbreds. These enzyme systems were also useful in detecting and quantifying the extent of `off-types' in each seed lot analysed. The percent off-types (inclusive of the admixtures and segregates) were as high as 47 to 50 percent in seed lots of a few of the inbreds. The results of the study were also useful in studying genetic diversity among the inbreds. An UPGMA based cluster analysis of the allozyme data revealed presence of only moderate genetic diversity among the Indian maize inbreds. This is of significance in crop yield stability as these inbreds have been used extensively in the production of F1 hybrids occupying large area under maize cultivation in India.

Isozyme Diversity in Indian Primitive Maize Landraces

Polymorphism for peroxidase, esterase and acid phosphatase Isozymes in pollen grains of major Indian maize land races known as ‘Sikkim primitives’ were studied and compared with primitive races of maize of Mexican origin and five species of teosinte, Coix lacryma-jobi, Chionachne koenigii and Sorghum bicolor. The isozyme patterns and the resulting dendrograms revealed similarities in primitive Indian maize landraces from Northeastern Himalayan region and Nal-Tel an ancient indigenous race of Mexico. Further, the Asiatic taxa of Maydeae, C. lacryma-jobi and Ch. koenigii differed widely from each other and also from the Zea spp. Presence of greater diversity among the Indian maize collections was also evident from the present analysis.

Natural Occurrence of Fumonisin B1 and Its Co-occurrence with Aflatoxin B1 in Indian Sorghum, Maize, and Poultry Feeds

A total of 138 samples consisting of 19 rain-affected sorghum, 25 rain-affected maize, 35 normal maize, 44 normal sorghum, and 14 poultry feed samples collected from six different places were analyzed for fumonisin B1 and aflatoxin B1. All the rain-affected sorghum and maize samples were contaminated with fumonisin B1 in the range 0.07−8 and 0.04−65 mg/kg, respectively. On the other hand 26 normal maize samples and 2 normal sorghum samples were contaminated with fumonisin B1 at levels ranging from 0.01 to 5 and 0.15 to 0.51 mg/kg. Fumonisin B1 contamination in the poultry feed samples ranged from 0.02 to 0.26 mg/kg. All of the rain-affected samples and poultry feed samples were contaminated with aflatoxin B1. 20% of normal sorghum and 89% of normal maize samples also contained aflatoxin B1 in the range of 5−125 and 0.38−109 μg/kg, respectively. This study reports for the first time the natural co-occurrence of fumonisin B1 and aflatoxin B1 in Indian maize and poultry feeds. Keywords: Fumonisin B1; aflatox...

Nuclear disintegration in chicken peritoneal macrophages exposed to fumonisin B1 from Indian maize.

The effects of fumonisin B1 (FB1) on the morphology of chicken peritoneal macrophages were studied. It was found that FB1-exposure caused nuclear disintegrations in peritoneal macrophages. The number of macrophages experiencing nuclear disintegration increased with the rise in the dose of FB1 from 6 to 18 micrograms ml-1. The finding implies that dietary intake of FB1 may damage the macrophages in consumers rendering the latter susceptible to infection.