5 research outputs found
Not Available
Not AvailableVitamin A deficiency (VAD) is a global health problem. Maize
naturally accumulates carotenoids including β-carotene, a
major source of vitamin A. Thirty-seven Indian maize
genotypes were screened for total carotenoids and β-
carotene content. A positive significant association of
kernel colour was observed with total carotenoid but not
for β-carotene. The level of β-carotene among the selected
37 genotypes was low (0.14 to 4.63µg/g) as compared to
total carotenoids (15.94 to 66.46 µg/g) thus necessitates
the introduction and deployment of lines with high β-
carotene. Hence, 54 inbred lines developed under the
HarvestPlus programme were screened with functional
markers of lcyE and crtRB1 genes of the carotenoid
biosynthetic pathway. Three genotypes (HP704-13, HP704-
22, and HP704-23) amplified most of the favorable alleles
for both these genes. However, due to long Anthesis Silking
Interval (ASI) and poor adaptation HP704-13 and HP704-23
could not be maintained. Under normal storage condition
genotype, HP704-22 recorded 7.32 µg/g of β-carotene which
can be used as a donor for provitamin-A or to diversify the
Indian germplasm.Not Availabl
Not Available
Not AvailableLarge scale germplasm screening for Chilo partellus resistance in maize is solely based on visual scoring of damage by leaf injury rating (LIR), where the accuracy in judging a genotype comes by experience of the person, who logically integrate certain symptoms such as levels of growth retardation. Since the pest spends more than half of its larval period damaging the stalk, a quantitative phenotyping method that gives weightage to stalk resistance is required. To explore the traits governing stalk resistance, stalk infestation behaviour of C. partellus was studied first. It was found that first instar C. partellus larva is exclusive whorl feeder, second instar is the transition stage which disperse to infest stalk, and third instar onwards are exclusive stalk borers. To access the stalk, larva tends to penetrate the second above ground internode (seventh internode of maize plant) of V6-10 stage maize. Thus, penetration resistance (PR) of seventh internode was hypothesized to be the characteristic resistance trait. Twenty elite maize breeding lines were evaluated for PR of rind (RPR) and pith (PPR) of seventh internode in V6-7, V8-9 and V10-11 stage plants by TA + Di Texture Analyzer. Significant negative correlation of LIR with RPR of all plant stages and with PPR of V6-7 stage plants suggests the ability of seventh internode to resist larval penetration would confer tolerance to C. partellus. The trait was also found a strong predictor of antibiosis, by affecting the biology and behaviour of C. partellus larva. Thus, PR of seventh internode is proposed to be the trait for phenotyping stalk resistance to C. partellus in maize, whose deployment could lead to selection of genotypes which are resistant to stalk lodging also.Not Availabl
Not Available
Not AvailablePhytic acid (PA) is one of the important anti-nutritional factors which affect the
bioavailability of micronutrients like iron, zinc. Maize being one of the important
food and feed crop requires serious attentions to reduce its PA; majority of total
phosphorous is stored in this form which makes it unavailable to monogastric animals.
The phosphorus thus stored in the form of PA phosphate contributes to water
pollution because it is excreted as such. PA being strong chelating agent also forms
phytate salts with cation mineral elements like iron, zinc, calcium etc., thus affects the bioavailability of micronutrient mineral elements. Thus causes micronutrient mineral
deficiency in humans and phosphorous deficiency in animals. In the present study
efforts have been made to introgress gene (lpa2) determining lowPA has been
transferred from low-phytate mutant line lpa2 into an elite inbreds LM14 and LM17
through marker-assisted backcross breeding (MABB). The BC2F2 near-isogenic lines
(NILs) have been developed through introgression of lpa2 gene. Out of 118 BC2F2
plants of LM 17 × LPA2 family, 26 were homozygous positive for lpa2 gene and 65
were heterozygous; the remaining plant were negative (27 plants). Similarly, in LM
19 × LPA2 cross, out of 127 BC2F2 plants 24 were homozygous for lpa2and 70 plants
were heterozygous. The remaining plants were (33) were negative for the lpa2 gene.
The molecular marker, umc2230 was used as linked marker to select lpa2 gene.
Whereas the sequence-tagged molecular markers (STMS), were chosen to select
segregants with the highest genome recovery. The recurrent parent genome (RPG) varies
between 79-89 and 82-93 per cent in BC2F2 individuals derived from LM 17 × LPA2
and LM 19 × LPA2 respectively. The agronomic performance of selected NILs of
BC2F3 and the respective recurrent parents has shown that the NILs are comparable
with respective recurrent parents for days to flowering and almost all the yield
component traits like number of ear length, ear girth, kernel rows, kernels per row,
test weight etc. and also biochemical analysis for lowPA is underway. The NILs
developed would be used to reconstitute the original hybrids.Not Availabl
Not Available
Not AvailableMaize (Zea mays L.) is grown on nearly 190 million ha in about 165 countries with
total production yielding approximately 39% of total grain production. In India maize
is third most important cereal crop after rice and wheat and accounts for around 10%
of total food grain production. Maize contributes 25 to 35 per cent of total calories of
the diets in several African, Asian and Latin American countries. Thus it is a valuable
source of food and feed worldwide. Further enhancement of nutritional value through
micronutrients like provitamin A in maize through biofortification could play an vital
role in reducing the micronutrient malnutrition, the major challenge to ensure
nutritional security in developing countries. Biofortification is the process by which
the nutrient density of food crops is increased through conventional plant
breeding and/or improved agronomic practices and/or modern biotechnology without
sacrificing any characteristic that is preferred by consumers or most importantly to
farmers. In the present study, gene encoding β-carotene hydroxylase 1 (crtRB1)
alleles associated with higher β-carotene concentrations was introgressed into elite
inbred line LM 17 and 19 using marker-assisted backcross breeding (MABB). The
donor for crtRB1 gene was CIMMYT5 inbred line. For foreground selection crtRB1
gene-based simple sequence repeat (SSR) markers were successfully used in
foreground selection. Presently introgressed lines are in BC2F2 generation. In LM17 ×
CIMMYT5 cross, out of 90 plants, 31 plants were homozygous, 42 plants were
heterozygous while 17 plants were negative and in LM19 × CIMMYT5 cross out of
167 plants, 54 plants were homozygous, 87 plants were heterozygous while 26 plants
were negative. The plants carrying gene of interest, were screened with SSR markers
and recovery of recurrent parent genome (RPG) in background selection ranged
between 82.40 - 93.70% for the LM17 × CIMMYT5 and 84.7091.30% for LM19 ×
CIMMYT5. The newly developed provitamin A near siogenic lines (NILs)
developed in both the crosses are comparable with their recurrent parents for
agronomic performance for different traits like days of anthesis, ear diameter, ear
height, ear length, kernels per row and kernels rows, however the biochemical
analysis is being carried out.Not Availabl
Not Available
Not AvailableProtein malnutrition is one of the challenges to ensure nutritional security of the
global poor masses especially in rural population of the developing world. Cereals
are deficient in some of essential amino acids like lysine and tryptophan. The
deficiency leads to one of the protein deficiency disorder like kwashiorkor. Therefore
the challenge is to deliver nutritious, safe and affordable food to reduce the impact of
nutritional deficiency. Quality protein maize (QPM), contain double the amount of
lysine and tryptophan as compared to normal maize is one of the intervention could
play vital role to reduce amino acid deficiency. In this context, several efforts have
been made to enhance the lysine and tryptophan levels through marker assisted
introgression of o2 gene into elite inbred lies of maize. In the present study, opaque2
gene along with phenotypic selection for kernel modification was incorporated using
marker assisted backcross breeding (MABB) program into normal inbred line i.e. LM19. This is the parental line of popular single cross hybrids PMH6 in India. HKI
163 was the donor for opaque2 allele. opaque2 genebased simple sequence repeat
(SSR) markers were successfully used for introgression of opaque2 allele. BC2F2
population derived from marker identified BC2F1 individuals were subjected to
foreground selection. 86 BC2F2 plants derived from LM19 × HKI 163 cross were
screened for o2 gene linked molecular marker. The result showed that 50 plants were
heterozygous, 18 plants were homozygous while 15 plants were negative for o2 allele.
The o2 carrying homozygous plants were subjected to background selection using
sequence tagged microsatellites (STMS) to accelerate the recovery of recurrent parent
genome (RPG). The background selection has revealed that the RPG varied from 79
87 % in BC2F2 generation derived from LM19 × HKI 163 cross. The newly developed
near isogenic lines (NILs) from the hard endosperm kernels were evaluated for
desirable agronomic and biochemical traits in replicated trials and the best lines were
chosen to represent the QPM version of LM19. The agronomic performance of the
selected BC2F2 population for LM19 × HKI 163 inbreds showed comparable
performance with LM17 in days of anthesis, days of silking and yield and yield
component traits.Not Availabl