Search

This study assessed eleven elements in 24 edible-podded peas, including sugar snap pea and snow pea genotypes aiming to identify promising parents for nutraceutical breeding. Elemental concentrations of pods (dry weight basis) were estimated through inductively coupled plasma-optical emission spectroscopy (ICP-OES). The ranges for these elements varied significantly, highlighting the diverse elemental profiles within the edible-podded pea genotypes. All the elements exhibited a high genotypic and phenotypic coefficient of variation along with considerable heritability and hereditary progress. Positive and significant correlations were recorded among all elements, suggesting the potential for simultaneous selection for these traits. Principal component analysis (PCA) revealed that the first two components accounted for 80.56% of the variation. Further, cluster analysis, based on Euclidean distance, grouped the 24 cultivars into two major clusters. Cluster I exhibited higher means for all estimated concentrations compared to Cluster II. Notably, Dwarf Grey Sugar and Arka Sampoorna from the snap pea group and PED-21-5 and Sugar Snappy from the sugar snap pea in Cluster II demonstrated superior elemental concentration in whole pods. The selected edible-podded pea genotypes serve as valuable genetic resources for new cultivar development, particularly in biofortification efforts targeting whole pod nutrient composition. [ABSTRACT FROM AUTHOR]

Drought is a major abiotic stress worldwide limiting chickpea yield drastically. Low heritability and high genotype × environment interactions make the trait-based breeding strategy an unreliable approach. This study was planned to identify the drought-tolerant lines by evaluating yield-based selection indices in a recombinant inbred line (RIL) population derived from an inter-specific cross between drought-tolerant genotype GPF 2 (Cicer arietinum L.) and drought-sensitive accession ILWC 292 (C. reticulatum) at two locations in India (Ludhiana and Faridkot). A total of six yield-based selection indices were calculated and significant variation was observed in the RILs and their parents for yield-based selection indices at both locations. A holistic approach across association analysis and principal component analysis identified drought tolerance index, mean productivity, geometric mean productivity and harmonic mean productivity as key selection indices, which could be used for indirect selection of drought-tolerant lines. Overall, on the basis of these approaches, a total of 15 promising RILs were identified for their use in chickpea breeding programme for developing drought-tolerant cultivars. [ABSTRACT FROM AUTHOR]

Doubled haploid (DH) breeding is a powerful technique to ensure global food security via accelerated crop improvement. DH can be produced in planta by employing haploid inducer stock (HIS). Widely used HIS in maize is known to be governed by ZmPLA, ZmDMP, ZmPLD3, and ZmPOD65 genes. To develop such HIS in rice and wheat, we have identified putative orthologs of these genes using in silico approaches. The OsPLD1; TaPLD1, and OsPOD6; TaPOD8 were identified as putative orthologs of ZmPLD3 and ZmPOD65 in rice and wheat, respectively. Despite being closely related to ZmPLD3, OsPLD1 and TaPLD1 have shown higher anther-specific expression. Similarly, OsPOD6 and TaPOD8 were found closely related to the ZmPOD65 based on both phylogenetic and expression analysis. However, unlike ZmPLD3 and ZmPOD65, two ZmDMP orthologs have been found for each crop. OsDMP1 and OsDMP2 in rice and TaDMP3 and TaDMP13 in wheat have shown similarity to ZmDMP in terms of both sequence and expression pattern. Furthermore, analogs to maize DMP proteins, these genes possess four transmembrane helices making them best suited to be regarded as ZmDMP orthologs. Modifying these predicted orthologous genes by CRISPR/Cas9-based genome editing can produce a highly efficient HIS in both rice and wheat. Besides revealing the genetic mechanism of haploid induction, the development of HIS would advance the genetic improvement of these crops. [ABSTRACT FROM AUTHOR]

The root-knot nematodes (RKN) (Meloidogyne graminicola) are a devastating threat to rice worldwide. The cultivated germplasm is either susceptible or moderately resistant to rice RKN. Therefore, there is a need to identify resistance sources against M. graminicola as an eco-friendly management strategy. The present study evaluated the host response of Oryza sativa genotypes comprising basmati, non-basmati improved varieties, their advanced breeding lines (83) and Oryza glaberrima accessions (42) against M. graminicola in the nematode-infested plot for two consecutive years. All O. sativa genotypes exhibited susceptible responses, while O. glaberrima accessions showed variable levels of resistance. Three of the O. glaberrima accessions (IRGC102196, IRGC102538 and IRGC102557) were highly resistant. M. graminicola significantly affected plant growth parameters in susceptible genotypes compared to resistant O. glaberrima accessions. The results were supported by histopathological studies that showed apparent giant cell formation in PR121 while penetration and development of M. graminicola juveniles were low in the O. glaberrima acc. IRGC102196. In silico analysis indicated that none of the reported nematode resistance genes from different crops had homology with the rice genome. The two anti-nematode genes (Oryzacystatin-I and Oryzacystatin-II) from O. sativa japonica revealed homology with O. sativa cv. PR121 and O. glaberrima acc. IRGC102206. Comparative analysis of these genes between PR121 and O. glaberrima acc. IRGC102206 resulted in the identification of SNPs/InDels that could be associated with nematode resistance. The identified SNPs/InDels could be validated, and further molecular studies are needed to provide insights into the resistance mechanism against rice RKN. [ABSTRACT FROM AUTHOR]

Sheath blight of rice caused by Rhizoctonia solani Kuhn [teleomorph: Thanatephorus cucumeris (Frank) Donk] is a significant threat to rice cultivation, accounting for up to 50% yield losses. The present investigation demonstrates the early pathogenesis events and R. solani pre‐ and post‐penetration activities on moderately resistant (MR) and highly susceptible (HS) lines under field conditions. A pure culture of R. solani isolate (R1965) was inoculated inside the sheath at the maximum tillering stage for different time intervals (24, 48, 72 and 96 hpi). R. solani exhibited more profuse, dense, closely contact around surface grooves, lobate appressoria‐like structures and greater microsclerotia development on the HS line compared to the MR one. Using fluorescent, optical, and scanning electron microscopy, it was noticed for the first time that R. solani could intercept sheath papillae and employ them for attachment or penetration in two ways: (a) direct penetration by lobate or runner hyphae, appressorium and infection cushion and (b) indirect stomatal penetration. Assays using in vivo plant inoculation showed that disease lesion length was higher in the HS line than the MR line. Intraxylary hyphal colonization could be seen using microtomy to understand the cellular spatial dynamics of xylem colonization by R. solani. The penetration mechanism along with penetration hyphae of the R. solani inside HS rice lines describe in this paper for the first time using optical ultrastructure. These results supported for better understanding of host–pathogen interaction, penetration mechanism and colonization of R. solani in rice. [ABSTRACT FROM AUTHOR]

Rice is a high-silica (SiO2·nH2O) accumulator. Silicon (Si) is designated as a beneficial element associated with multiple positive effects on crops. However, the presence of high silica content is detrimental to rice straw management, hampering its use as animal feed and as raw material in multiple industries. Rice straw management is a serious concern in north-western India, and it is eventually burned in situ by farmers, contributing to air pollution. A practical solution could lie in reducing the silica content in rice while also attaining sound plant growth. A set of 258 Oryza nivara accessions along with 25 cultivated varieties of Oryza sativa was used to assess the variation in straw silica content using the molybdenum blue colorimetry method. A large continuous variation was observed for straw silica content in O. nivara accessions, ranging from 5.08% to 16%, while it varied from 6.18% to 15.81% in the cultivated varieties. The O. nivara accessions containing 43%-54% lower straw silica content than the currently prominent cultivated varieties in the region were identified. A set of 22,528 high-quality single nucleotide polymorphisms (SNPs) among 258 O. nivara accessions was used for estimating population structure and genomewide association studies (GWAS). A weak population structure with 59% admixtures was identified among O. nivara accessions. Further, multi-locus GWAS revealed the presence of 14 marker-trait associations (MTAs) for straw silica content, with six of them co-localizing with previously reported quantitative trait loci (QTL). Twelve out of 14 MTAs showed statistically significant allelic differences. Thorough candidate gene analyses revealed the presence of promising candidate genes, including those encoding the ATPbinding cassette (ABC) transporter, Casparian thickening, multi-drug and toxin extrusion (MATE) protein, F-box, and MYB-transcription factors. Besides, ortho-QTLs among rice and maize genomes were identified, which could open ways for further genetic analysis of this trait. The findings of the study could aid in further understanding and characterizing genes for Si transport and regulation in the plant body. The donors carrying the alleles for lower straw silica content can be used in further marker-assisted breeding programs to develop rice varieties with lower silica content and higher yield potential. [ABSTRACT FROM AUTHOR]

A wide range of variation was observed in a diverse set of 178 pigeonpea germplasm lines for all the studied traits. The GCV and PCV estimates were the highest for seed yield/plot (35.48% and 36.12%) followed by pods/plant (31.57% and 32.58%). The little difference between PCV and GCV indicated their control largely by genetic factors. Seed yield/plot (96.46%), pods/plant (93.89%) and plant height (92.14%) recorded high heritability estimates. The high heritability coupled with high genetic advance recorded for seed yield/plot, pods/plant and primary & secondary branches/plant indicated the predominance of additive gene action controlling these traits and phenotypic selection would be effective. Skewness and kurtosis indicated the governance of primary branches and seed yield by complementary gene interaction with less number of dominant genes. Association studies identified primary & secondary branches/plant, pods/plant and seeds/pod as important yield components and due weightage should be given to these during selection for yield improvement. [ABSTRACT FROM AUTHOR]

Background: Pigeonpea has remarkable contribution in flourishing the Indian agricultural economy but over the decades, its productivity has remained stagnant. Presence of genetic diversity in breeding population is the key to develop high yielding varieties. Therefore the current study was aimed to explore genetic divergence among pigeonpea genotypes. Methods: A set of 178 pigeonpea germplasm lines were evaluated in randomized block design to assess the genetic divergence and clustering pattern of pigeonpea genotypes. Observations on various yield component traits were recorded. For the estimation of the Fe and Zn content ICP-OES (Perkin Elmer USA) was used. Mahalanobis D² analysis was carried out to assess the genetic divergence. Result: Wide range of genetic diversity was revealed among lines for eleven traits studied. Mahalanobis D² analysis grouped all the genotypes into eleven non-overlapping clusters. The inter cluster D² values indicated that cluster IV and XI (21046.45) were the most diverse and cluster V and cluster VII (60.67) were the less diverse. Out of the eleven characters studied days to maturity, plant height and yield per plot contributed 93.32 per cent of the total divergence. Based on mean performances, cluster XI and cluster II were found to be beneficial for early flowering and early maturity genotypes, cluster V and cluster VII for number of pods per plant and yield per plot, respectively. The highest mean value for grain iron and zinc content was recorded in cluster III rendering simultaneous improvement for these traits. Therefore, trait-wise selection of diverse parents from different clusters would be desirable and beneficial. [ABSTRACT FROM AUTHOR]

Mukaku Kishu (‘MK’), a small sized mandarin, is an important source of seedlessness in citrus breeding. Identification and mapping the gene(s) governing ‘MK’ seedlessness will expedite seedless cultivar development. In this study, two ‘MK’-derived mapping populations- LB8-9 Sugar Belle® (‘SB’) × ‘MK’ (N=97) and Daisy (‘D’) × ‘MK’ (N=68) were genotyped using an Axiom_Citrus56 Array encompassing 58,433 SNP probe sets, and population specific male and female parent linkage maps were constructed. The parental maps of each population were integrated to produce sub-composite maps, which were further merged to develop a consensus linkage map. All the parental maps (except ‘MK_D’) had nine major linkage groups, and contained 930 (‘SB’), 810 (‘MK_SB’), 776 (‘D’) and 707 (‘MK_D’) SNPs. The linkage maps displayed 96.9 (‘MK_D’) to 98.5% (‘SB’) chromosomal synteny with the reference Clementine genome. The consensus map was comprised of 2588 markers including a phenotypic seedless (Fs)-locus and spanned a genetic distance of 1406.84 cM, with an average marker distance of 0.54 cM, which is substantially lower than the reference Clementine map. For the phenotypic Fs-locus, the distribution of seedy and seedless progenies in both ‘SB’ × ‘MK’ (55:42, χ2 = 1.74) and ‘D’ × ‘MK’ populations (33:35, χ2 = 0.06) followed a test cross pattern. The Fs-locus mapped on chromosome 5 with SNP marker ‘AX-160417325’ at 7.4 cM in ‘MK_SB’ map and between two SNP markers ‘AX-160536283’ and ‘AX-160906995’ at a distance of 2.4 and 4.9 cM, respectively in ‘MK_D’ map. The SNPs ‘AX-160417325’ and ‘AX-160536283’ correctly predicted seedlessness of 25-91.9% progenies in this study. Based on the alignment of flanking SNP markers to the Clementine reference genome, the candidate gene for seedlessness hovered in a ~ 6.0 Mb region between 3.97 Mb (AX-160906995) to 10.00 Mb (AX-160536283). This region has 131 genes of which 13 genes (belonging to seven gene families) reportedly express in seed coat or developing embryo. The findings of the study will prove helpful in directing future research for fine mapping this region and eventually underpinning the exact causative gene governing seedlessness in ‘MK’. [ABSTRACT FROM AUTHOR]

Chickpea yield is severely affected by drought stress, which is a complex quantitative trait regulated by multiple small-effect genes. Identifying genomic regions associated with drought tolerance component traits may increase our understanding of drought tolerance mechanisms and assist in the development of drought-tolerant varieties. Here, a total of 187 F8 recombinant inbred lines (RILs) developed from an interspecific cross between drought-tolerant genotype GPF 2 (Cicer arietinum) and droughtsensitive accession ILWC 292 (C. reticulatum) were evaluated to identify quantitative trait loci (QTLs) associated with drought tolerance component traits. A total of 21 traits, including 12 morpho-physiological traits and nine rootrelated traits, were studied under rainfed and irrigated conditions. Composite interval mapping identified 31 QTLs at Ludhiana and 23 QTLs at Faridkot locations for morphological and physiological traits, and seven QTLs were identified for root-related traits. QTL analysis identified eight consensus QTLs for six traits and five QTL clusters containing QTLs for multiple traits on linkage groups CaLG04 and CaLG06. The identified major QTLs and genomic regions associated with drought tolerance component traits can be introgressed into elite cultivars using genomics-assisted breeding to enhance drought tolerance in chickpea. [ABSTRACT FROM AUTHOR]

The hull-less pumpkin (Cucurbita pepo) seed does not require de-hulling before use for human consumption, as a result highly preferred by the oil, nut, and baking industries. In hull-less seeds, a single recessive gene is responsible for the absence of outer thick seed coat layers; however, the genomic region and gene(s) controlling the trait are unclear to date. In this study, four crosses attempted to derive F2 and backcross populations confirmed the single recessive gene inheritance of hull-less seed trait in populations adapted to the sub-tropical climate. The candidate genomic region for hull-less seed trait was identified through the BSA-QTLseq approach using bulks of F2: 3 progenies from a cross of HP111 (hulled) and HLP36 (hull-less). A novel genomic region on chromosome 12 ranging from 1.80 to 3.86Mb was associated with the hull-less seed trait. The re-sequencing data identified a total of 396 SNPs within this region and eight were successfully converted into polymorphic KASP assays. The genotyping of segregating F2 (n = 160) with polymorphic KASP assays resulted in a 40.3cM partial linkage map and identified Cp_3430407 (10cM) and Cp_3498687 (16.1cM) as flanking markers for hull-less locus (Cphl-1). These flankingmarkers correspond to the 68.28 kb region in the reference genome, and the marker, Cp_3430407 successfully predicted the genotype in 93.33% of the C. pepo hull-less germplasm lines, thus can be used for marker-assisted selection in parents polymorphic for the hull-less seed trait. The Cphl-1-linked genomic region (2.06Mb) encompasses a total of 182 genes, including secondary cell wall and lignin biosynthesis-related transcriptional factors viz., "NAC" (Cp4.1LG12g04350) and "MYB" (Cp4.1LG12g03120). These genes were differentially expressed in the seeds of hulled and hull-less genotypes, and therefore could be the potential candidate genes governing the hull-less seed trait in pumpkin. [ABSTRACT FROM AUTHOR]

Root-knot nematode (Meloidogyne graminicola) is one of the emerging threats to rice production worldwide that causes substantial yield reductions. There is a progressive shift of the cropping system from traditional transplanting to direct-seeded water-saving rice production that favored the development of M. graminicola. Scouting and deploying new resistance genes is an economical approach to managing the root-knot nematodes. Here, we report that the inheritance of root-knot nematode resistance in Oryza glaberrima acc. IRGC102206 is governed by a single dominant gene. Traditional mapping coupled with BSA-seq is used to map nematode resistance gene(s) using the BC1F1 population derived from a cross of O. sativa cv. PR121 (S) and O. glaberrima acc. IRGC102206 (R). One major novel genomic region spanning a 3.0-Mb interval on chromosome 6 and two minor QTLs on chromosomes 2 and 4 are the potential genomic regions associated with rice root-knot nematode resistance. Within the QTL regions, 19 putative candidate genes contain 81 non-synonymous variants. The detected major candidate region could be fine mapped to accelerate marker-assisted breeding for root-knot nematode resistance in rice. [ABSTRACT FROM AUTHOR]

Any rice variety to be released for cultivation to farmers should have acceptable grain quality, besides being high yielding. Black pin-point damage appears as small black spot on the milled rice grains which reduces the yield of milled rice and directly reflects on consumer acceptability. The black pin-point damage beyond the permissible limit set by Food Safety and Standards Authority of India (FSSAI) regulations, resulted in withdrawal of a very high yielding variety, PAU 201 released by Punjab Agricultural University in 2008. The damage has been later seen in high yielding rice genotypes PR 125 and PR 126 at Punjab Agricultural University, Ludhiana. Both PR 125 and PR 126 are the introductions from International Rice Research Institute (IRRI), Philippines, of which PR 126 was released for commercial cultivation having advantages of high yield, short duration with minimal black pin-point damage intensity. To understand the genetics of this trait, the black pin-point damage intensity was studied in F3 seeds of crosses PR 121 x PR 125. The percentage intensity of damage was 0.61 g ± 0.06 damaged grains with range of 0.32-1.1 g in twenty different samples. The percentage intensity of damage was 2.48 ± 0.22 with the range of 1.28-4.44 in PR125 and 2.03 ± 0.05 with a range of 0.5-5.1 in 256 F3 individuals. The black pin-point damage followed continuous distribution showing quantitative inheritance of trait. The anatomical evaluation of damaged grains using scanning electron microscopy (SEM) showed the malformation of starch granules at cellular level. The starch granules of damaged grains at the site of damage were loosely packed as compared to the normal grains. However, no sign of pathological infestation was observed at the site of damage on the grains. The analysis of transverse section of the point of damage demonstrated that the black pin-point was embedded inside the grain. These observations indicate that black pin-point might be due to loose packing of starch granules at the site of damage and deformities in the genes involved in starch packing could be the possible reason for development of this trait. [ABSTRACT FROM AUTHOR]

Being a model crop as well as a staple food crop, rice possesses a conspicuous position in plant sciences. Doubled haploid (DH) breeding in rice offers multiple advantages over conventional methods via accelerating the process of pure lines development. For ages, several methods have been devised for haploid production in rice. In vitro‐based methods have demonstrated their potential in DH production, but these methods are further impeded by stringent requirements and restricted to few species. Further, unlike maize, the in vivo DH breeding technology is still impractical in rice. Recent findings of the key molecular players behind the haploid induction (HI) trait in maize and rice have shown their potential in rice improvement programmes. In this review, we have discussed different strategies of HI in rice particularly focusing on recent progress made for developing haploid inducer stock (HIS) by employing both conventional and modern approaches. It also focuses on future implications of HIS so that it can be incorporated in the pipeline of modernized rice breeding. [ABSTRACT FROM AUTHOR]

Heat stress during reproductive stages has been leading to significant yield losses in chickpea (Cicer arietinum L.). With an aim of identifying the genomic regions or QTLs responsible for heat tolerance, 187 F8 recombinant inbred lines (RILs) derived from the cross GPF 2 (heat tolerant) × ILWC 292 (heat sensitive) were evaluated under late-sown irrigated (January-May) and timely-sown irrigated environments (November-April) at Ludhiana and Faridkot in Punjab, India for 13 heat tolerance related traits. The pooled ANOVA for both locations for the traits namely days to germination (DG), days to flowering initiation (DFI), days to 50% flowering (DFF), days to 100% flowering (DHF), plant height (PH), pods per plant (NPP), biomass (BIO), grain yield (YLD), 100-seed weight (HSW), harvest index (HI), membrane permeability index (MPI), relative leaf water content (RLWC) and pollen viability (PV)) showed a highly significant difference in RILs. The phenotyping data coupled with the genetic map comprising of 1365 ddRAD-Seq based SNP markers were used for identifying the QTLs for heat tolerance. Composite interval mapping provided a total of 28 and 23 QTLs, respectively at Ludhiana and Faridkot locations. Of these, 13 consensus QTLs for DG, DFI, DFF, DHF, PH, YLD, and MPI have been identified at both locations. Four QTL clusters containing QTLs for multiple traits were identified on the same genomic region at both locations. Stable QTLs for days to flowering can be one of the major factors for providing heat tolerance as early flowering has an advantage of more seed setting due to a comparatively longer reproductive period. Identified QTLs can be used in genomics-assisted breeding to develop heat stress-tolerant high yielding chickpea cultivars. [ABSTRACT FROM AUTHOR]

The gene-for-gene relationship of host–pathogen interaction explained by H. H. Flor in mid of the 20th century set a milestone in understanding the biochemical and genetic basis of plant diseases and several components involved in plant–pathogen interactions. It highlighted the importance of accomplishing differential sets and understanding the pathogen population structure, it further led to the identification and cloning of several resistance (R) genes in plants. These R genes have been deployed and altered for fighting against diseases in a large number of crops using various conventional approaches and biotechnological tools. Identification of R genes and their corresponding Avr genes in many cases played a significant role in understanding of R-Avr gene interactions. Rapid cloning of R genes and editing of susceptible R genes are the other avenues that have broadened the horizon of utilizing R genes in crop improvement programmes. Further, combining R genes with quantitative disease resistance genes has paved the way to develop durable resistance in cultivars. The recent advances in genetics, genomics, bioinformatics and other OMICS tools are now providing greater prospects for deeper understanding of host–pathogen interaction. [ABSTRACT FROM AUTHOR]

Ascochyta blight (AB) and botrytis grey mould (BGM) are the most devastating fungal diseases of chickpea worldwide. The wild relative of chickpea, C. reticulatum acc. ILWC 292 was found resistant to BGM whereas, GPF2 (Cicer arietinum L.) is resistant to AB. A total of 187 F8 Recombinant Inbred Lines (RILs) developed from an inter-specific cross of GPF2 × C. reticulatum acc. ILWC 292 were used to identify quantitative trait loci (QTLs) responsible for resistance to AB and BGM. RILs along with parents were evaluated under artificial epiphytotic field/laboratory conditions for two years. Highly significant differences (P < 0.001) were observed for reaction to both pathogens in both years. Parents and RILs were genotyped-bysequencing to identify genome wide single nucleotide polymorphism (SNPs). A total of 1365 filtered and parental polymorphic SNPs were used for linkage map construction, of which, 673 SNPs were arranged on eight linkage groups. Composite interval mapping revealed three QTLs for AB and four QTLs for BGM resistance. Out of which, two QTLs for AB and three QTLs for BGM were consistent in both years. These QTLs can be targeted for further fine mapping for deployment of resistance to AB and BGM in elite chickpea cultivars using marker-assisted-selection. [ABSTRACT FROM AUTHOR]

Introgression Lines (ILs) carrying alien genomic segments in the homozygous state may or may not be able to contribute positively to the phenotype on account of replacement of cultivated genome segment, however, the genetic elite in heterozygous condition can be attributed to the presence of both recipient and donor genome complements. Therefore, overdominance or pseudo‐overdominance effect at the heterozygous loci is anticipated. Set of 318 ILs, carrying several genomic segments from "A" genome donor wild species, were used for developing test hybrids with CMS line PMS17A. Of these, three hybrids observed significant yield advantage (>25%) over recurrent parents and checks. Parental ILs of these hybrids viz., IL326, IL901 and IL951 carried 5.62%, 2.52% introgression from Oryza rufipogon and 6.71% from Oryza nivara, respectively. These ILs were also crossed with their recurrent parent to develop introgression line hybrids (ILHs) to observe the contribution of the alien segment(s), in the homozygous and heterozygous state. The traits studied have higher mean value when genomic segments from wild species were in the heterozygous state as compared to the homozygous state. [ABSTRACT FROM AUTHOR]

Key message: A BPH-resistant locus designated as Bph34 identified in Oryza nivara acc. IRGC104646 on long arm of chromosome 4 using high-resolution mapping with 50 K SNP chip. BPH resistance contributed by locus showed dominant inheritance in F2 and F3. The Bph34 locus is 91 kb in size and contains 11 candidate genes. In addition to SNP markers, SSR markers, RM16994 and RM17007 co-segregated with the BPH resistance. These two SSR markers can facilitate marker-assisted transfer of the Bph34 locus into elite rice cultivars in all labs.Abstract: Brown planthopper (BPH, Nilaparvata lugen Stål) is one of the most destructive insects of rice (Oryza sativa L.) causing significant yield losses annually. Exploiting host plant resistance to BPH and incorporating resistant genes in susceptible commercial cultivars is economical and environmentally friendly approach to manage this pest. Here, we report high-resolution mapping of a novel genetic locus for resistance to BPH, designated as Bph34 on long arm of rice chromosome 4. The locus was mapped using an interspecific F2 population derived from a cross between susceptible indica cultivar PR122 and BPH-resistant wild species, O. nivara acc. IRGC104646. Inheritance studies performed using F2 and F2:3 populations revealed the presence of single dominant gene. Construction of high-density linkage map using 50 K SNP chip (OsSNPnks) followed by QTL mapping identified single major locus at 28.8 LOD score between SNP markers, AX-95952039 and AX-95921548. The major locus contributing resistance to BPH designated as Bph34 and explained 68.3% of total phenotypic variance. The Bph34 locus is 91 Kb in size on Nipponbare reference genome-IRGSP-1.0 and contains 11 candidate genes. In addition to associated SNP markers, two SSR markers, RM16994 and RM17007, also co-segregated with the Bph34 which can be used efficiently for markers assisted transfer into elite rice cultivars across the labs. [ABSTRACT FROM AUTHOR]

The article offers information on the different types of Lattice designs, analysis using SAS software, and their method of construction. The lattice designs is mentioned including the grouping of block such that each group of block constitutes one complete replication of treatments. The square lattice designs is also cited in which every pair of treatments occurs together once in the same incomplete block.

Considering the potentials of wild rice (Oryza spp.), as well as the need to enhance the yield potential of rice and to increase rice production to meet increasing demands, 1780 backcross inbred lines (BILs) were generated by crossing 70 accessions of six "AA" genome species: Oryza glaberrima Steud., Oryza barthii A. Chev., Oryza nivara Sharma & Shastry, Oryza rufpogon Griff., Oryza longistaminata A. Chev. & Roehr., and Oryza glumaepatula Steud. with two elite cultivars of Oryza sativa L. The wild species accessions were selected based on variation at the DNA markers and agromorphological traits. The BILs were generated by backcrossing F1s twice (thrice in some cases) to recipient parents, followed by continuous selfing and selection for the yield and yield component traits. The set of 1780 BC2F5 to BC2F10 BILs were evaluated in an augmented design over 3 yr. Based on ANOVA in augmented design, 108 agronomically superior BILs were selected and evaluated in randomized complete block design. Of the 108 BILs evaluated, 15 BILs showed >10% yield superiority over the recurrent parent, with spikelet per panicle and thousand-grain weight as most significant traits contributing to yield increase. Based on the contribution of donor accessions for the improvement of yield component traits, six accessions of O. glaberrima, one of O. barthii, two of O. nivara, two of O. rufpogon, and one each of O. longistaminata and O. glumaepatula were identified as potential donors that could be used more rigorously in transferring genes to cultivated rice. The BILs generated in the present study represents a reservoir of novel genetic variation. [ABSTRACT FROM AUTHOR]

PAU 201, a high yielding variety of rice released by Punjab Agricultural University in 2007, was withdrawn from cultivation in the year 2010 mainly due to its red coloured pericarp. It also became susceptible to a new pathotype (PbXo-8) of bacterial blight (BB) pathogen. To improve these specific defects, PAU 201 was mutagenized with ethyl methane sulphonate in different concentrations of 0.6, 0.8 and 1.0% in water (v/v). A total of 841 M1 single panicles were harvested and advanced to M4 generation following selfing and selection for white pericarp colour in each generation. A set of promising 68 M4 progenies was also screened for BB resistance and one putative mutant possessing white pericarp colour as well as BB resistance (designated as RYT 3207) was identified. On further evaluation, RYT 3207 was found to be resistant to all the ten pathotypes of BB pathogen prevalent in the Punjab state and it yielded at par with the PAU 201 in multi-location trials during 2011 to 2013. Molecular marker analysis showed presence of xa13 locus in RYT 3207. The acquired resistance to all the ten pathotypes in RYT 3207, compared to nine pathotypes in PAU 201, could be due to modified function of xa13 gene. The new genotype RYT 3207 is a mutagenized version of the high yielding rice cultivar PAU 201 possessing white pericarp and enhanced resistance to bacterial blight. [ABSTRACT FROM AUTHOR]