Time course of physiological,biochemical,and gene expression changes under short-term salt stress in Brassica juncea L.

Salinity-imposed limitations on plant growth are manifested through osmotic and ionic imbalances. However, because salinity-induced responses vary considerably among crop plants, monitoring of such responses at an early stage has relevance. In this study,physiological(seed germination, seed vigor index, root length, shoot length, fresh weight,dry weight) and biochemical attributes(osmoprotectants, K^+/Na^+ ratio) were analyzed for a time-course assessment of salt responses in Indian mustard(Brassica juncea L.) with an emphasis on early monitoring. The results showed strong correlations for total soluble sugars at germination phase(24 h), proline content in the seedling establishment phase(48 h) and various physiological parameters including seed vigor index(R^2= 0.901), shoot length(R^2= 0.982), and fresh weight(R^2= 0.980) at 72 h(adaptation under stress). In addition, transcriptional changes were observed under NaCl treatment for key genes belonging to the family of selective ion transporters(NHX, HKT) and abscisic acid synthesis(AAO-3). The status of mitochondrial respiration was also examined as a probe for salinity tolerance at an early stage. The results suggested that although all the analyzed parameters showed correlations(negative or positive) with salt stress magnitude, their critical response times differed, with most of the studied biochemical, physiological, or molecular markers providing valuable information only after radicle emergence, whereas mitochondrial respiration via alternative oxidase was useful for the early detection of salt responses.

Genotypic variation for seed protein and mineral content among post-rainy season-grown sorghum genotypes

Sorghum is an important staple food crop of Asian and African countries.As a poor man s crop",it provides dietary starch,protein,and some vitamins and minerals.Minerals are important for various physiological functions in the human body.As a major staple crop of central and southern Indian provinces,sorghum landraces are a source of supplementary micronutrients.Concentrations of micronutrients and protein and yield parameters were studied using 112 local landraces and varieties.Univariate analysis revealed wide variation for iron(1.10-9.54 mg 100 g^(-1)),zinc(1.12-7.58 mg 100 g^(-1)),protein(3.50-12.60%),and grain yield(2.50-76.50 g) among the landraces.High estimates of genetic/phenotypic coefficient of variation,and genetic advances over the mean were identified for landraces and varieties.High heritabilities were also identified for yield and mineral content.Correlation estimates among the genotypes indicated that grain yield was positively correlated with copper and protein with copper and zinc.Cluster analysis based on Euclidean distance resolved all of the genotypes into three major clusters.The wide range of values with high heritability estimates may favor the use of these landraces in recombination breeding to improve nutritional quality in sorghum.

Genetic variation for seed phosphorus and yield traits in Indian sorghum landraces and varieties

Phytic acid is the major storage form of phosphorus in cereals. It binds with nutritionally important metals and affects mineral bioavailability. The present study analyzed phytic acid, inorganic phosphorus(IP) content, seed weight, and grain yield in 98 sorghum landraces and varieties grown in two environments to evaluate genotypic and environmental effects and to determine trait stability. Genotypic effects and genotype × interaction were significant for phytic acid concentration and yield components. A promising landrace, Malkhed-1, had the lowest phytic acid(0.015 mg g-1)concentration, with a higher yield(70.02 g plant-1), than the check variety M-35-1 in both environments. Similarly, among the varieties, Phule Maulee showed the lowest phytic acid(0.07 mg g-1) and a higher grain yield of 53.15 g plant-1in both environments. Phytic acid and IP were negatively correlated(r =- 0.34), whereas grain yield and seed weight were positively correlated(r = 0.20). Cluster analysis based on seed phosphorus traits and yield components identified five and six clusters, respectively. Genotypes containing low phytic acid with high yield identified in this study would be helpful for increasing the bioavailability of mineral nutrients.

Construction of Genetic Linkage Map of Bread Wheat (Triticum aestivum L.) Using an Intervarietal Cross and QTL Map for Spike Related Traits

Most often a genetic linkage map is prepared using populations obtained from two highly diverse genotypes. However, the markers from such a map may not be useful in a breeding program as these markers may not

Genetic variation for phytic acid content in mungbean(Vigna radiata L. Wilczek)

Mungbean(Vigna radiata L. Wilczek) is a short-duration legume crop cultivated for seeds that are rich in protein and carbohydrates. Mungbeans contain phytic acid(PA), an anti-nutritional factor that is the main storage form of organic phosphorus in seeds. It is a strong inhibitor against the absorption of nutrients including iron, zinc, calcium and magnesium in monogastric animals. Genotypes with low phytic acid(lpa) in seed may show increased assimilation of nutrients and be useful in breeding lpa cultivars. The present study was conducted to identify lpa sources, genetic variation, heritability, and association with seed coat color, inorganic phosphorus(IP), and seed size in 102 mungbean genotypes including released varieties, land races, mutants, and wild species grown in two seasons: summer 2011 and rabi 2012. PA and IP in dry seeds were estimated by modified colorimetric method and Chen's modified method,respectively. PA, IP, and 100-seed weight differed significantly in the two seasons. PA content in102 genotypes ranged from 5.74 to 18.98 mg g-1and 5.85 to 20.02 mg g-1in summer 2011 and rabi 2012, respectively. High heritability was found for PA(0.87 and 0.86) and seed size(0.82 and0.83) but low heritability for IP(0.61 and 0.60). A negative correlation was found between PA and seed size(r =-0.183 and-0.267). Yellow and green seed coat genotypes contained significantly less PA than black seed coat genotypes. Cluster analysis revealed the distinctness of wild species, land races and cultivated varieties on the basis of PA content. The genotypes YBSM(6.001 mg g-1) and JL-781(6.179 mg g-1) showed lowest PA. These lpa sources can be used to develop high-yielding mungbean cultivars with low phytic acid.

Rpivnt1 provides resistance through the mediation of a light responsive guardee in potato

The disease triangle describes the interrelationship among pathogen,host,and environment towards disease prevalence in the field.The mechanistic role of environment on NLR-mediated resistance was not known until now.Recently,a comprehensive work revealed that light controls late blight disease reaction in potato caused by the lrish famine pathogen.A specific R gene Rpivnt1 in potato showed dichotomous behavior in disease reaction due to the light-responsive alternate promoter selection of another host gene glycerate 3 kinase(GLYK)during its transcription.The full-length GLYK protein traps the pathogen effector AVRvnt1 into a recognition event which is later sensed by Rpivnt1 in the presence of light.In dark,the truncated GLYK protein devoid of its chloroplastic transit peptide could not able to recognize AVRvnt1 and thus resistance get compromised.A possible model for this event is proposed here for ease in understanding.