ESTs analysis in maize developing kernels exposed to single and combined water and heat stresses

Molecular and metabolic response of plants to a combination of two abiotic stresses is unique and cannot be directly extrapolated from the response of plants to each of the stresses individually. cDNA macroarray has become a useful tool to analyze expression profiles and compare the similarities and differences of various expression patterns. A macroarray of approximately 2,500 maize (Zea mays 1,.) cDNAs was used for transcriptome profiling in response to single and simultaneous application of water and high temperature stress of maize developing kernels at 15 days after pollination. All stress treatments (water stress-WS, heat stress-HS and their combined application-CS) induced changes in expression of 106 transcripts with 54 up-regulated and 52 down-regulated. There were 11 up-regulated and 15 down-regulated transcripts in common for all three stresses. Although these common transcripts showed existence of a mutual mechanism in stress response, the 23 transcripts induced only in CS indicate that plants responded in a different manner when exposed to simultaneous effects of both stresses. A glimpse of functions regulated under WS, HS and CS is provided, and also the common and different responses between individual and simultaneous stresses

DNA and biochemical analysis of a potential opaque2 maize population

Maize has low nutritional value because it is poor in essential amino acids lysine and tryptophan, but different mutations have been identified that increase their content. Two high lysine/tryptophan populations from Maize Research Institute genebank (IP1 and IP2) were identified in a previous research. In both populations, analysis with umc1066 opaque2 specific marker detected a recessive (o2), a dominant (O2) and an unknown allele (UA). However, IP2 lacked homozygous recessive o2o2 genotypes. The aim of the present research was to determine by DNA and biochemical analysis if UA allele was a recessive allele and/or if high tryptophan content was due to the o2 or some other mutation. Tree more opaque accessions with different mutations - IP3o5, IP4o14 and IP5floury (no data on type of mutation) were used in biochemical analysis for comparison with IP1 and IP2. Kernels were divided into two samples - with hard and with soft kernels. The UA allele sequencing revealed that it was a dominant allele with four GCCAGA repeats. SSR analysis showed presence of o2 in IP1 in both hard and soft kernels. Decrease in 22 kDa, 19 kDa and 27 kDa zeins in soft kernels was observed only in IP1 and IP2. Tryptophan content was high in soft kernels of IP1 (0.081) and IP2 (0.085), and in both hard and soft kernels of -IP3o5 (0.083 and 0.085, respectively). It can be concluded that IP1 is an o2 mutant and that IP2 carries a high tryptophan mutation other than o2, o5, o14 or floury

Identification of chromosome regions determining kernel high oil content in maize (Zea mays L.) Synthetic populations

Chromosome regions determining kernel high oil content were identified by RFLP analysis of individual plants from C0 and C9 selection cycles of two maize synthetic populations -DS7u and YuSSSu. Identification of chromosome regions was done with informative RFLP markers (that were identified with BSA earlier) using a single plant approach - analysis of individual plants. This analysis revealed the number of plants carrying alleles that endured frequency alterations during selection process. Statistical analysis (χ2 test) revealed chromosome regions that comprise putative QTLs affecting expression of kernel high oil content of analyzed maize populations. Four regions on chromosomes 1, 6, 7 and 8 were identified in both DS7u and YuSSSu populations. Additional four regions on chromosome 4, 9 and 10 were detected only in DS7u population

Maize genebank collections as potentially valuable breeding material

Vancetovic J., S. Mladenovic Drinic, M.Babic, D. Ignjatovic Micic and V.Andelkovic (2010): Maize genebank collections as potentially valuable breeding material. - Genetika, Vol. 42, No. 1, 9 - 21. Characterization and evaluation of the genetic resources provide breeders with valuable information on an effective utilization of the genetic resources in breeding programs. In this paper we present the results of different research programs aimed at identification of superior genotypes among MRI gene bank accessions, regarding stress tolerance (drought and herbicides), better nutritional quality (phosphorus) and specific traits (cytoplasmic male sterility - CMS). Fifty-two genotypes were identified as a potential source for drought tolerance. Considering herbicide tolerance only genotypes with resistance to the Pivot were found. Within 100 sources of CMS in the collection S cytoplasm was identified as the predominant type. Phytate analysis of 60 maize populations identified three groups of populations with low (8), intermediate (25) and high (27) phytate content. The results of these researches, which are a part of pre-breeding activities, will be included in MRI breeding programs, with the aim of developing new genotypes with improved traits important in commercial maize breeding and seed production

Integrisan pristup u poboljšanju tolerantnosti kukuruza na sušu

Drought is one of the most serious a biotic factors limiting crop production worldwide. Prediction of climate change increases the need of better adaptation and breeding for improved drought tolerance in crops. Maize is one of the most sensitive crops to drought, despite of the fact that it is a C4 plant, with high photosynthetic rate and relatively low transpiration rate. In Serbia drought severely decreased maize grain yield, particularly in the last decade. A major task for breeders is to create drought tolerant maize that will successfully cope with negative consequences of global warming are facing scientists today. Enhancing the tolerance of maize has been elusive in terms of conventional plant breeding. Interdisciplinary approaches tried to understand and dissect the mechanism of drought tolerance, but with limited success. Modern genomics and genetics, together with advances in phenotyping and knowledge in physiology and breeding are expected to reveal genes and pathways that confer drought tolerance.Suša je jedan od najznačajnijih abiotičkih faktora koji ograničava biljnu proizvodnju širom sveta. Projekcije klimatskih promena povećavaju potrebu za boljom adaptacijom useva i oplemenjivanjem na poboljšanu tolerantnost prema suši. Kukuruz je jedan od najosetljivijih useva na sušu, uprkos činjenici da je C4 biljka, sa visokom brzinom fotosinteze i relativno niskom brzinom transpiracije. U Srbiji, suša značajno utiče na smanjenje prinos zrna kod kukuruza, posebno u poslednjoj deceniji. Zbog toga je glavni zadatak oplemenjivača stvaranje kukuruza tolerantnog na sušu koji će se uspešno nositi sa negativnim posledicama globalnog zagrevanja. Dalje poboljšanje tolerantnosti na sušu kod kukuruza je postalo vrlo ograničeno metodama konvencionalnog oplemenjivanja. Interdisciplinarnim pristupom se pokušava bolje proučiti i raščlaniti mehanizam tolerantnosti na sušu, ali je uspeh dosta limitiran. Od moderne genomike i genetike, zajedno sa dostignućima u fenotipskoj oceni, kao i saznanjima iz fiziologije i oplemenjivanja se očekuje da otkriju gene i procese koji su uključeni u tolerantnost na sušu

Simulating of Top-Cross system for enhancement of antioxidants in maize grain

Blue maize (Zea mays L.) is grown for its high content of antioxidants. Conversion of yellow and white to blue maize is time consuming because several genes affect blue color. After each backcross selfing is needed for color to be expressed. In order to overcome the problem of time and effort needed for conversion to blue kernel color, we have set a pilot experiment simulating a Top-cross system for increasing antioxidants in maize grain. The idea is to alternately sow six rows of sterile standard quality hybrid and two rows of blue maize in commercial production. Five commercial ZP hybrids were crossed with a blue pop-corn population. Xenia effect caused by cross-pollination produced blue grain on all hybrids in the same year. Chemical analyses of the grains of five selfed original hybrids, five cross-pollinated hybrids and selfed blue popcorn pollinator were performed. Cross-fertilization with blue popcorn had different impact on antioxidant capacity and phytonutrients, increasing them significantly in some but not all crosspollinated hybrids. Popcorn blue pollinator had higher values for all the analyzed traits than either selfed or crosspollinated hybrids. Selfed vs. pollinated hybrids showed significant difference for total antioxidant capacity (p lt 0.1), total phenolics and total yellow pigments (p lt 0.01), with the increase of total phenolics and decrease of total yellow pigments in pollinated ones. Total flavonoids showed a little non-significant decrease in pollinated hybrids, while total anthocyanins were not detected in selfed yellow hybrids. Blue maize obtained this way has shown good potential for growing high quality phytonutrient genotypes

DNA and biochemical analysis of a potential opaque2 maize population

Maize has low nutritional value because it is poor in essential amino acids lysine and tryptophan, but different mutations have been identified that increase their content. Two high lysine/tryptophan populations from Maize Research Institute genebank (IP1 and IP2) were identified in a previous research. In both populations, analysis with umc1066 opaque2 specific marker detected a recessive (o2), a dominant (O2) and an unknown allele (UA). However, IP2 lacked homozygous recessive o2o2 genotypes. The aim of the present research was to determine by DNA and biochemical analysis if UA allele was a recessive allele and/or if high tryptophan content was due to the o2 or some other mutation. Tree more opaque accessions with different mutations - IP3o5, IP4o14 and IP5floury (no data on type of mutation) were used in biochemical analysis for comparison with IP1 and IP2. Kernels were divided into two samples - with hard and with soft kernels. The UA allele sequencing revealed that it was a dominant allele with four GCCAGA repeats. SSR analysis showed presence of o2 in IP1 in both hard and soft kernels. Decrease in 22 kDa, 19 kDa and 27 kDa zeins in soft kernels was observed only in IP1 and IP2. Tryptophan content was high in soft kernels of IP1 (0.081) and IP2 (0.085), and in both hard and soft kernels of -IP3o5 (0.083 and 0.085, respectively). It can be concluded that IP1 is an o2 mutant and that IP2 carries a high tryptophan mutation other than o2, o5, o14 or floury

Identifikacija lokusa za kvantitativna svojstva kod kukuruza u uslovima suše - prinos i morfološka svojstva

Drought is one of the most important factors contributing to crop yield loss. In order to develop maize varieties with drought tolerance, it is necessary to explore the genetic basis. Mapping quantitative trait loci (QTL) that control the yield and associate agronomic traits is one way of understanding drought genetics. QTLs associated with grain yield (GY), leaf width (LW3, LW4) plant height (PH), ear height (EH), leaf number (NL), tassel branch number (TBN) and tassel length (TL) were studied with composite interval mapping. A total of 43 QTLs were detected, distributed on all chromosomes, except chromosome 9. Phenotypic variability determined for the identified QTLs for all the traits was in the range from 20.99 to 87.24%. Mapping analysis identified genomic regions associated with two traits in a manner that was consistent with phenotypic correlation among traits, supporting either pleiotropy or tight linkage among QTLs.Suša je jedan od najznačajnijih faktora koji utiče na smanjenje prinosa. Mapiranje lokusa za kvantitativna svojstva (QTL) koja kontrolišu prinos i vezane agronomske osobine daju uvid u genetičku osnovu odgovora biljke na stres suše i omogućavaju stvaranje tolerantnih genotipova. Lokusi za kvantitativna svojstva vezani za prinos, širinu lista, visinu biljke, visinu biljke do klipa, broj listova, broj grana metlice i dužinu metlice identifikovani su primenom composite interval mapping metode. Detektovano je ukupno 43 QTL-a, na svim izuzev na 9 hromozomu. Fenotipska varijabilnost za ova svojstva bila je u opsegu od 20.99 to 87.24%. Identifikovani su genomski regioni vezani za dva ili više svojstva, i istovremeno je kod njih detektovana visoka fenotipska korelacija, što ukazuje na postojanje plejotropnih ili epistatičkih interakcija između QTL-ova

Effects of adapted quality protein maize on broiler performance

Quality protein maize (QPM) has high contents of essential amino acids lysine and tryptophan. The substitution of standard maize (SM) with QPM in feeds can be profitable due to improved livestock performance and decreased costly dietary lysine supplementation and protein ingredients. Herein, effects of QPM adapted to temperate climate on broiler performance were tested. Feeding experiment was performed on control (fed with SM) and treatment (fed with QPM) broilers. Each feeding trial of 42 days duration was carried out in three phases - starter (1-14), grower (15-35) and finisher (36-42). Diets for each growth phase was formulated based on the biochemical analysis of maize kernels. At the end of each growth phase, feed intake (FI), body weight gain (BWG), average daily gain (ADG) and feed conversion ratio (FCR) were calculated. In the first experiment, SM was completely replaced with QPM in treatment group diets. The results indicated better FCR in the treatment group for grower (1.51:1.56) and finisher (1.56:1.61) phases. In the second experiment QPM was increased and soybean component decreased by 3%. This time, FCR improvement was even better but in all three phases – 1.16:1.33 for starters, 1.28:1.36 for growers and 1.30:1.46 for finishers. These results indicate significant financial reduction in feed as the price of soybean is usually two to four times higher than the price of maize. Overall, it can be concluded that using adapted QPM in broiler diets can be profitable for both feed industry and broiler producers