Assessment of genetic diversity and species relationships in eggplant (Solanum melongena L.) using STMS markers

Ninety six accessions including 92 of Solanum melongena and four related non-tuberous species (Solanum insanum, S. incanum, S. integrifolium and S. sysimbriifolium) were taken for the assessment of genetic diversity using 23 STMS primers. Eleven of the 23 primers tested showed polymorphism. The number of alleles per primer ranged from three to six with an average of 4.4. S. melongena had maximum average similarity with its closely related species, S. insanum (0.67) and minimum average similarity with the wild species, S. sysimbriifolium (0.50). The two weedy species S. incanum and S. integrifolium showed more average similarity value of 0.62 and 0.61, respectively with the cultivated S. melongena. S. insanum. S. incanum and S. integrifolium were relatively similar to each other with similarity index value of 0.61 (between S. insanum and S. incanum), 0.63 (between S. insanum and S. integrifolium) and 0.62 (between S. incanum and S. integrifolium). In contrast S. sysimbriifolium was most divergent with the similarity value of 0.49, 0.47 and 0.51 with S. insanum, S. incanum and S. integrifolium, respectively. The closely related species S. insanum and S. incanum, which clustered along with S. melongena accessions, being crossable with cultivated species, constitute important sources of genes that can be introgressed by backcross breeding. Molecular markers can be employed to identify the hybrids and also to monitor introgression of the useful genes.     

Genetic diversity of ash gourd [Benincasa hispida (Thunb.) Cogn.] inbred lines based on RAPD and ISSR markers and their hybrid performance

Ten inbred lines of ash gourd [Benincasa hispida (Thunb.) Cogn.] were crossed to produce 45 F₁ hybrids (without reciprocal) which were evaluated along with the parents for 20 growth- and yield-related traits, in a replicated field trial. High level of heterosis was observed among the hybrids for most of the traits examined, including yield. These inbred lines were analysed by using 42 RAPD primers those produced 282 DNA marker bands. A total of 130 RAPD markers were obtained with a mean of 3.1 per primer, which in combination discriminated all the inbreds from each other. Pair-wise genetic distance measurements ranged from 0.07 to 0.31, suggesting a wide genetic diversity for these inbreds. These inberds were also analysed with five ISSR primers of which four were informative. Twenty-six ISSR marker bands were generated of which 11 were polymorphic with an average of 2.80 per primers. The percentage of polymorphic bands produced were higher in ISSR markers (>80%) than generated through RAPD markers (46%). Although the results indicated significant positive correlations of genetic distance with hybrid performance and heterosis, the RAPD based genetic distance measures and use of limited ISSR markers in this present study could not effectively predict hybrid performance in this crop. The genetic variation among ash gourd inbred lines examined, herein, defined a marker array (combined ISSR and RAPD) for the development of a standard reference for further genetic analyses, and the selection of potential parents for predicting hybrid performance and heterosis.     

Revealing Genetic Relationship and Prospecting of Novel Donors Among Upland Rice Genotypes Using qDTY-Linked SSR Markers

A total of 17 simple sequence repeat (SSR) markers linked to QTLs (qDTYs) governing grain yield under reproductive stage (RS) drought stress were used to assess the genetic relationship and prospecting new donors for qDTYs among 32 popular upland rice genotypes. These SSR markers generated a total of 36 alleles with an average allele count of 2.1 per locus. Polymorphic information content value of the markers ranged from 0.376 to 0.662 with an average value of 0.484. The expected heterozyogosity ranged from 0.381 to 0.632. STRUCTURE analysis divided the 32 genotypes into three sub-populations. Subsequent phenotyping revealed that all the tolerant genotypes were grouped into one sub-population, whereas the moderately tolerant and susceptible genotypes were grouped into separate sub-populations. Phylogenetic tree constructed by the unweighted neighbour-joining method also divided the genotypes into three clusters. The grouping pattern of genotypes into the clusters was similar to that into the STRUCTURE analysis, on the basis of drought tolerance level. The average value of genetic dissimilarity coefficient among the genotypes was observed to be 0.486. Furthermore, by combining genotyping data with phenotyping data, 16 new donors for 6 qDTYs were identified.     

Soil fertility and yield-limiting nutrients in oil palm plantations of north-eastern state Mizoram of India

A survey was conducted for assessment of soil fertility status, leaf nutrient concentration and finding yield-limiting nutrients of oil palm (Elaeis guineensis Jacq.) plantations in Mizoram state situated in the northeastern part of India. Soil pH, electrical conductivity (EC), organic carbon (OC), available potassium (K), available phosphorus (P) (Bray's-P), exchangeable calcium (Ca) (Exch. Ca) and magnesium (Mg) (Exch. Mg), available sulfur (S) (CaCl₂-S), and hot-water-soluble boron (B) (HWB) content in surface (0–20 cm depth) and subsurface (20–40 cm depth) soil layers varied widely. Diagnosis and Recommendation Integrated System (DRIS) norms were established for different nutrient expressions, and DRIS indices were computed. As per DRIS indices, the order of requirement of nutrients was found to be B > K > Mg > P > nitrogen (N). Optimum leaf nutrient ranges as per DRIS norms varied from 1.91% to 2.95%, 0.46% to 0.65%, 0.63% to 1.00%, 0.48% to 0.88%, and 9.41 to 31.0 mg kg^?1 for N, P, K, Mg, and B, respectively. On the basis of DRIS-derived optimum ranges, 32%, 9%, 27%, 12%, and 12% leaf samples had less than optimum concentration of N, P, K, Mg, and B, respectively. The optimum ranges developed could be used as a guide for routine diagnostic and advisory purpose for efficient fertilizer application.     

Yield and Zinc,Copper, Manganese and Iron Concentration in Maize (Zea mays L.) Grown on Vertisol as Influenced by Zinc Application from Various Zinc Fertilizers

Zinc (Zn) deficiency in soils and field crops is widespread across the world, including India, resulting in severe reduction in yield. Hence, soil application of Zn fertilizers is recommended for ameliorating Zn deficiency in soil and for obtaining higher crop yield and better crop quality. Zinc sulfate is commonly used Zn fertilizer in India because of its solubility and less cost. However, good quality and adequate quantity of zinc sulfate is not available in the market round the year for farmers' use. Field experiments were therefore conducted during rainy season of 2010 and 2011 at research farm of Indian Institute of Soil Science, Bhopal, India to assess the influence of Zn application through zinc sulfate monohydrate (33% Zn), zinc polyphosphate (21% Zn) and Zn ethylenediaminetetraacetate (EDTA) (12% Zn) on yield and micronutrient concentration and uptake by maize (Zea mays L.). In both the years, grain and vegetative tissue (stover) yield of maize increased significantly with successive application of Zn up to 1 kg ha^?1 added through zinc sulfate monohydrate and zinc polyphosphate. Addition of 2.5 kg Zn ha^?1 did not increase yield further but resulted in highest stover Zn concentration. Zinc, copper (Cu), manganese (Mn), and iron (Fe) concentration in maize grain varied from 22.2 to 27.6, 1.6 to 2.5, 3.5 to 4.7 and 19.9 to 24.5 mg kg^?1 respectively in both the years. Maize stover had 25.9 to 36.2, 7.9 to 9.8, 36.7 to 44.9 and 174 to 212 mg kg^?1 Zn, Cu, Mn, and Fe, respectively. Zinc application did not influence Cu, Mn and Fe concentration in both grain and stover of maize. Transfer coefficients (TCs) of micronutrients varied from 0.72 to 0.95, 0.18 to 0.30, 0.08 to 0.13 and 0.10 to 0.15 for Zn, Cu, Mn, and Fe respectively. Total Zn uptake significantly increased with Zn application from 0.5 to 2.5 kg ha^?1 supplied through zinc sulfate monohydrate and zinc polyphosphate. Recovery efficiency of Zn declined with increased Zn rates.     

Cytomorphology of <Emphasis Type="Italic">Gentiana kurroo</Emphasis>: an important endangered bitter plant of temperate Himalaya

Gentiana kurroo, a potent bitter drug plant of Indian subcon- tinent, is under threat due to over exploitation and destruction of natural habitat. We studied the morphophenology and chromosomes of G. kur- roo on both wild and field grown plants, which is very important for proper identification, conservation and domestication. Results reveal that G. kurroo is a perennial herb, and its shoot is represented by flowering branches only. Stem is modified to rhizome. The older rhizomes split into four parts at collar region appearing to fuse together at the ends and is an important diagnostic feature for crude raw materials. Two types of leaves i.e. radical leaves at the base of the plant and cauline leaves on flowering shoot are present. Flowering occurs during September to Octo- ber with 1-9 inflorescences per plant. Inflorescence is terminal monoca- sial cysome type. Flowers are protrandus. Anthesis starts around 7.30 am and continued till 10.0 am. Ovary is bicarpillary syncarpous unilocular. Fruit is Capsule and takes 18 20 days to mature after fertilization. Seeds are very small elliptical and 1 000 seeds weigh to 0.1275 g. Chromoso- mal studies made by usual squash method reveals the species is a ge- nomic allotetraploid with n = 13. The anaphase-I segregation was normal and in none of the cells at Anaphase-I or Telophase-I could any abnor- mality like laggards, bridges, micronuclei etc. be observed.     

Genetic Dissection of Grain Size Traits Through Genome-Wide Association Study Based on Genic Markers in Rice

Grain size plays a significant role in rice, starting from affecting yield to consumer preference, which is the driving force for deep investigation and improvement of grain size characters. Quantitative inheritance makes these traits complex to breed on account of several alleles contributing to the complete trait expression. We employed genome-wide association study in an association panel of 88 rice genotypes using 142 new candidate gene based SSR (cgSSR) markers, derived from yield-related candidate genes, with the efficient mixed-model association coupled mixed linear model for dissecting complete genetic control of grain size traits. A total of 10 significant associations were identified for four grain size-related characters (grain weight, grain length, grain width, and length-width ratio). Among the identified associations, seven marker trait associations explain more than 10% of the phenotypic variation, indicating major putative QTLs for respective traits. The allelic variations at genes OsBC1L4, SHO1 and OsD2 showed association between 1000-grain weight and grain width, 1000-grain weight and grain length, and grain width and length-width ratio, respectively. The cgSSR markers, associated with corresponding traits, can be utilized for direct allelic selection, while other significantly associated cgSSRs may be utilized for allelic accumulation in the breeding programs or grain size improvement. The new cgSSR markers associated with grain size related characters have a significant impact on practical plant breeding to increase the number of causative alleles for these traits through marker aided rice breeding programs.     

Effects of high temperature on spikelet sterility in rice (Oryza sativa L.): association between molecular markers and allelic phenotypic effect in field condition

Genetic Resources and Crop Evolution - Rice varieties are generally bred for higher yield but may possess genomic regions conferring tolerance to abiotic stresses. Climate change driven heat stress...