Symbiotic effectiveness of acid-tolerant Bradyrhizobium strains with soybean in low pH soil

Eight acid tolerant strains of Bradyrhizobium isolated from soybean plants grown on acid soils in Madhya Pradesh, India, were examined for their ability to survive in soil and YEMB at low pH levels. All the tested isolates survived in acidic (pH 4 -6) conditions and their survival capacity was higher in soilthan in nutrient medium at same levels of low pH. Variation among different strains showed that there is potential to improve strain performance under stress conditions. Further, symbiotic effectiveness of these strains was determined under the polyhouse conditions in sterilized soil (pH 4.5). Highest and lowest symbiotic characters, dry matter production and nitrogen improvement per plant were observed in PSR001 and NSR008 inoculated plants, respectively. All the examined isolates showed considerablevariability in their symbiotic performance. The strain found to be more tolerant to stress were more effective N2 fixers in symbiosis with soybean in acid-soil condition

VARIATION IN SYMBIOTIC PERFORMANCE OF BRADYRHIZOBIUM JAPONICUM STRAINS AND SOYBEAN CULTIVARS UNDER FIELD CONDITIONS

In this study the symbiotic interactive effect of different Bradyrhizobium japonicum strains with six soybean cultivars were evaluated under fi eld conditions. The rhizobial strains ASR011, USDA123 and CB1809 respectively showed hostcultivar specifi city with JS335, Lee and Bragg. B. japonicum ASR011 recorded the highest nodulation and nitrogenase activity with all the studied cultivars. Generally, plants inoculated with strain ASR011 produced higher plant dry matter accumulation and seed yield over all other cultivars. On the basis of analysis of correlation coeffi cients, it was found that plant dry matter accumulation emerged as best criterion for selection of most effective legume-Rhizobium associations for given physical and biological conditions

Low cost high throughput image based root phenotyping pipeline for evaluation of sugarcane root system architecture under drought stress

Root System Architecture (RSA) plays an important role in the agronomic performance of a crop. Incorporation of these root traits in breeding program is hampered by the complexity in accessing the roots and its phenotyping. Lack of high throughput root phenotyping platforms for sugarcane is one of the major constraints in sugarcane root studies. In the present study an attempt was made to develop high throughput sugarcane root phenotyping pipeline comprising of a low cost plant cultivation platform and customized root image acquisition platform and image analyses using already available automated software. PVC tube system of specified dimension were used for plant growth and customized optical correction tank were used for imaging RSA. The acquired root images were fed into automated software GIAroots and about twenty quantitative root phenotype data were extracted and analysed. The working of the whole pipeline from plant growth to image analyses is demonstrated through comparative root phenotyping under drought using five genotypes of sugarcane wild relative Erianthus arundinaceus and three commercial sugarcane varieties.The relationships between the different root variables and genotypes in PCA biplots indicated high correlation among the different root traits. The study shows the low cost high throughput image based root phenotyping pipeline can be used to extract quantifiable root traits and analysed within a short span of time

Prospecting in Western Ghats of Karnataka for indigenous Bacillus thuringiensis isolates harbouring novel crystal toxin genes for sugarcane pest management

Prospecting for potential novel Bacillus thuringiensis with new holotype crystal toxins was carried out in the Western ghats hill range of Karnataka state, India. From the soil samples collected three Bt isolates SBIKWG 12, SBIKWG 24 and SBIKWG 70 were isolated. Of these while the two isolates, namely SBIKWG 12 and SBIKWG 24 produced bipyramidal crystal toxins, the third isolate produced spherical crystal. PCR screening of the isolates revealed the presence of lepidopteran and coleopteran active cry genes. Partial sequences obtained from these isolates revealed the presence of multiple crystal toxin genes. BlastX analysis of the partial gene sequences indicated the potential for the occurrence of new holotype crystal toxin genes in SBIKWG 24 and SBIKWG 70

Studies on association of coefficient of coancestry with progeny performance in sugarcane

The utilization of superior parental lines and identification of superior families enhance the genetic gain in sugarcane. To identify the superior parental lines and superior progenies, 1889 progenies derived from twenty crosses involving genetically diverse historical parents were evaluated for juice quality and yield attributing traits.The historical parental lines were selected based on coefficient of coancestry from the tropical and subtropical parents maintained at National Hybridization Garden. Based on progeny performance, families of Co 99006 × CoSe 92423 and Co 86032 × 85R186 were found superior for number of millable canes, , Co 86032 × 85R186 and Co 8371 × CoT 8201 for cane thickness and CoSe 95422 × Co 775 and Co 8371 × CoV 92102 for sucrose content. Parental lines such as Co 86002, Co 99006 and CoLk 98184, Co 775, 85R186 and BO 130 were identified for HR Brix; Co 419 and Co 89010, CoS 510, CoV 92102 and CoSe 92423 for cane thickness; and CoLk 94184, BO 91 and BO 32 for number of millable canes. The estimates of coefficient of coancestry was negatively correlated with HR Brix and cane thickness suggesting that parental cross combination with lesser value of coefficient of coancestry or inbreeding coefficient resulted in produce the heterotic progenies. This study based on the historic parental lines selected based on the coefficient of coancestry and inference limited to only to this experimental material. The evaluation of families derived from the population parental cross combination and parental lines in replication family block design permits the estimation of BLUP based breeding values and helpful in selection of superior parental lines and superior progenies

Variability and molecular diversity of wild sugarcane germplasm collected from low temperature regions Lohit and Changlang of Arunachal Pradesh

159-168Saccharum spontaneum L. is a perennial grass representing the most genetically diversified species in Saccharum genus. It has the potential to withstand severe biotic/abiotic stresses and frequently used as donor of stress tolerant genes in sugarcane improvement program through gene introgression. In this study, the phenotypic variation and molecular diversity of forty nine S. spontaneum accessions collected from Lohit and Changlang regions of Arunachal Pradesh, North Eastern India were investigated for morphometric traits and polymorphic STMS marker. The phenotypic coefficient of variation showed ample variability for the traits viz., plant height (27.19%), stalk diameter (28.21%), single cane weight (48.97%), internode number (22.60%) and internode length (29.15%). Further, twenty nine sequence-tagged microsatellite site (STMS) markers generated 495 bands with an average of 14.06 polymorphic bands. The accessions specific bands in respect to specific marker combinations were identified. The Jaccard’s similarity coefficients among these accessions ranged from 0.42 to 0.78 with an average of 0.58 and clustering using unweighted pair group method of arithmetic-average (UPGMA) showed two major clusters with subclusters. Similarly polulation structure analysis based Bayesian approach grouped the individuals into two subpopulations, with alpha value of 0.112. The study shows that S. spontaneum accessions collected from Arunachal Pradesh is highly diverse, most of them will be harbouring the genes for cold tolerance and biomass. The set of markers which produced specific bands for the specific accessions identified in the study will help in identification of the particular accessions. The accessions studied are potential source for cold tolerance and high biomass, the results obtained in the present study will definitely help in planning and utilising them in sugarcane improvement programme

Complete Genome of the Xanthomonas euvesicatoria Specific Bacteriophage K Phi 1, Its Survival and Potential in Control of Pepper Bacterial Spot

Xanthomonas euvesicatoria phage K Phi 1, a member of Myoviridae family, was isolated from the rhizosphere of pepper plants showing symptoms of bacterial spot. The phage strain expressed antibacterial activity to all X. euvesicatoria strains tested and did not lyse other Xanthomonas spp., nor other less related bacterial species. The genome of K Phi D1 is double-stranded DNA of 46.077 bp including 66 open reading frames and an average GC content of 62.9%, representing the first complete genome sequence published for a phage infecting xanthomonads associated with pepper or tomato. The highest genome similarity was observed between phage K Phi 1 and the Xanthomonas oryzae pv. oryzae specific phage OP2. On the other hand, when compared with other members of the genus Bcep78virus, the genome similarity was lower. Forty-four (67%) predicted K Phi 1 proteins shared homology with Xanthomonas phage OP2, while 20 genes (30%) were unique to K Phi 1. Phage K Phi 1, which is chloroform resistant and stable in different media and in the pH range 5-11, showed a high titer storage ability for at least 2 years at +4 degrees C. Copper-hydroxide and copper-oxychloride reduced phage activity proportionally to the used concentrations and the exposure time. UV light was detrimental to the phage strain, but skim milk plus sucrose formulation extended its survival in vitro. The phages survived for at least 7 days on the surface of pepper leaves in the greenhouse, showing the ability to persist on the plant tissue without the presence of the host bacterium. Results of three repeated experiments showed that foliar applications of the unformulated K Phi 1 phage suspension effectively controlled pepper bacterial spot compared to the standard treatment and the untreated control. The integration of the phage K Phi 1 and copper-hydroxide treatments resulted in an increased efficacy compared to the copper-hydroxide alone

Whole genome analysis and functional characterization of a novel Bacillus thuringiensis (Bt 62) isolate against sugarcane white grub Holotrichia serrata (F)

In this study, we report the whole genome assembly of Bt 62, a novel isolate harbouring cry8 holotype gene identified by us earlier. Sequencing was carried out using a combination of Illumina NextSeq 500 and Oxford Nanopore sequencing Technologies (ONT). The final assembled genome was 6.13 Mb comprising a circular chromosome and four plasmids. The bioassay studies against Holotrichia serrata (F.) (Coleoptera: Scarabaeidae), a polyphagous pest infesting sugarcane and other crops, indicated significant toxicity to first instar grubs over untreated larvae achieving a highest mean mortality of 91.11% for various doses tested. In vitro proteolytic assay and histopathological studies of the midgut of infected white grubs revealed proteolytic processing of the protoxin and extensive degeneration of larval midgut epithelial cells. The results demonstrate that this novel isolate could be used as a biopesticide or its crystal toxin genes could be expressed in sugarcane and other crops for resistance against H. serrata