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  • Author or Editor: R. Kaur x
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Thirty maize genotypes were characterized for their nutritional, antinutritional and nutraceutical traits for identification of elite germplasm rich in beneficial characteristics. Starch, proteins, lipids, tryptophan, lysine, β-carotene, condensed tannins, protease inhibitor, phytic acid, total phenols, flavonols, o-dihydroxy phenols and DPPH radical scavenging activity were determined in grains of all the genotypes. Correlation coefficient among the various parameters showed that lysine, total phenols, flavonols and o-dihydroxy phenols were negatively correlated with phytic acid content of the genotypes. This showed that the nutritional and the nutraceutical potency of genotypes, rich in lysine and phenolic compounds, is further propounded by a reduction of phytic acid content in them. On the basis of various constituents, the genotypes were divided into three groups. Group-A genotypes had high to moderate levels of both nutritional and nutraceutical traits. Group-B included those genotypes that exhibited high to moderate levels of either nutritional or nutraceutical traits. Group-C was constituted of genotypes that had lower levels of both nutritional and nutraceutical traits. Agglomerative hierarchical clustering showed that the D subcluster of MC-2 was chiefly comprised of genotypes that had high to moderate levels of both nutritional and nutraceutical traits. It may be concluded that CML134, CML266, TOO14601, LM11, CML264, CML321, SE563, LM10, LM18, LM14 and CML32 were nutritionally rich nutraceutical genotypes having low antinutrient potency.

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Drought and high temperature are especially considered as key stress factors with high potential impact on crop yield. The aim of this study was to investigate the effect of short periods of high temperature, drought and their combination at different growth stages of plant under controlled conditions. The effects of high temperature and drought on grain yield were additive. However, high temperature increased the degree of water stress and the combined effects of drought and high temperature were much more severe than those of each individual treatment. High temperature and drought applied at post- anthesis shortened duration of maturation, grain filling duration and reduced grain yield, mean grain weight, grain number and thousand-grain weight.

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ADP-glucose pyrophosphorylase (AGPase) activity in the developing grains of two contrasting wheat cultivars WH730 (thermo-tolerant) and UP2565 (thermo-sensitive) was determined in relation to their allosteric effectors and grain growth. The developing grains (35 days after anthesis) were excised from the middle portion of spikes of wheat genotypes subjected to high temperature, drought and their combination at booting, post-anthesis and booting+post-anthesis. The impact of stress treatments was studied by measuring starch content and yield attributes in relation to AGPase activity. AGPase, a key enzyme for starch synthesis, is allosterically activated by 3-phosphoglyceric acid (3-PGA) and inhibited by inorganic phosphate (Pi). Sensitivity of AGPase towards individual and combined high temperature and drought has not been adequately investigated, therefore the present study analyzed AGPase activity, its sensitivity to allosteric effectors under influence of high temperature, drought in order to elucidate the relationship of AGPase with starch accumulation and grain growth. Significant difference in behavior of the enzyme and its allosteric effectors were observed between the two cultivars under high temperature and/or drought. AGPase activity was substantially decreased by high temperature, drought and was found to be positively correlated with the 3-PGA, starch accumulation and yield attributes, while negatively correlated with Pi content. The results showed that effects of high temperature and drought were additive and more severe at booting+post-anthesis stage. Such studies might help in understanding the control mechanisms associated with the pathway of starch biosynthesis and thus provide chemical means to manipulate starch content vis-à-vis grain yield under heat and drought stress.

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Maize cultivars (4 composites, 14 inbreds and 7 hybrids) cultivated in Punjab were characterized using a set of 70 Simple Sequence Repeat (SSR) markers with a total of 199 alleles. Out of these, 67 markers produced polymorphic profiles, 3 were monomorphic. Eight SSR primers detected eight unique alleles in three genotypes. These unique SSR alleles provide an opportunity for unambiguous differentiation of the respective genotypes. SSR profiles were analyzed by using computer softwares NTSYS-pc and DARwin 5.0. Both of them classified the genotypes in four distinct groups.

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Drought and high temperature are two major factors limiting crop production. The two stresses occur together in many regions of the world but they usually are investigated separately. Irrespective of the genotype, growth or treatment conditions, grain growth was severely reduced when wheat plants were exposed to high temperature, drought and combination of both the stresses during endosperm cell division. The extent of thermal as well as drought induced disruption of grain development, however was dependent on genotype. This structural data support the hypothesis that high temperature and drought during endosperm cell division reduces grain sink potential and subsequently mature grain mass, mainly by disrupting cell divisions in peripheral and central endosperm and thus reducing endosperm length and breadth to a considerable extent. The interaction of high temperature and drought stresses resulted in stronger reduction of pericarp thickness and endosperm size than either stress alone.

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Cereal Research Communications
Authors: B. Kumar, K.S. Hooda, R. Gogoi, V. Kumar, S. Kumar, A. Abhishek, P. Bhati, J.C. Sekhar, K.R. Yathish, V. Singh, A. Das, G. Mukri, E. Varghese, H. Kaur, V. Malik and O.P. Yadav

Maydis leaf blight (MLB), a serious foliar fungal disease of maize, may cause up to 40% losses in yield. The present studies were undertaken to identify the stable sources of MLB resistance, its inheritance study, and testing of MLB resistance linked markers from diverse background in the Indian adapted tropical maize genotypes. A set of 112 inbred lines were screened under artificially created epiphytotics conditions at three hotspot locations. Analysis across multi-locations revealed significant effects of genotypes and environments, and non-significant effects due to genotypes × environment interaction on disease incidence. A total of 25 inbred lines with stable resistance were identified across multi-locations. Inheritance of resistance was studied in six F1s and two F2s of resistant and susceptible parents. The null hypothesis of segregation of resistance and susceptible for mono and digenic ratios in two F2 populations was rejected by Chi-square test. The non-significant differences among the reciprocal crosses depicted the complete control of nuclear genome for MLB resistance. Partial dominance in F1s and normal distribution pattern in F2s of resistant and susceptible parents suggested polygenic nature of MLB resistance. Correlation studies in F2 populations exhibited significant negative correlation between disease score and days to flowering. Five simple sequence repeats (SSRs) markers, found associated to MLB resistance in different studies were unable to differentiate amongst MLB resistance and susceptible parents in our study. This emphasizes the need of fine mapping for MLB resistance in Indian germplasm. The identified stable sources of resistance and information on inheritance study can be used further in strengthening of resistance breeding against MLB.

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