Effect of the combination of biological, chemical control and agronomic technique in integrated management pea root rot and its productivity.

Root rot of pea caused by Fusarium spp. is one of the important diseases of pea (Pisum sativum L.). The causal fungus of the disease isolated from naturally infected pea plants was identified as Fusarium solani f. sp. pisi (Jones). Evaluation of four bio agents and nine fungicides was done in vitro against Fusarium solani. Trichoderma harzianum was the most effective bio agent in inhibiting the mycelial growth of F. solani by (82.62%). Carbendazim 50 WP was the most effective fungicide in inhibiting the mycelial growth of F. solani by (91.06%). Carbendazim at the rate of 0.1% and T. harzianum at concentration of 109 cfu when used as seed treatment under field conditions were evaluated along with three planting techniques v.i.z, raised beds, ridges and flat beds. It was found that Carbendazim at the rate of 0.1% when given as seed treatment in raised beds exhibited the lowest disease incidence (10.97%), intensity (2.89%) and the maximum pod yield (89.63 q ha-1) as compared to control.

DNA marker based diversity across rice genotypes and advanced breeding lines bred for temperate regions of North-West India.

BACKGROUND: Characterization and evaluation of plant genetic resources play an important role for their utilization in the crop improvement programmes. METHODS AND RESULTS: This study involves the agro-morphological and cooking quality besides, molecular characterization of 51 genotypes/advance breeding lines of rice from Kashmir Himalayas. Significant variability was observed for all agro-morphological and cooking quality traits among all the studied genotypes. Cluster analysis using UPGMA method divided the genotypes into two major clusters having 15 and 36 genotypes. Thirty eight genotypes screened using 24 SSR markers detected 48 alleles with 2.0 alleles for each locus with average polymorphism information content (PIC) of 0.37. High polymorphism information content (PIC) values was observed for the primers RM263 (0.67), RM159 (0.59) and RM333 (0.50). Furthermore, out of 38 SSR markers screened on 192 temperate rice germpalsm lines, R4M17 accurately differentiated indica and temperate japonica genotypes amplifying 220 bp and 169 bp, respectively. Accordingly, 15 genotypes were reported as indica and 28 temperate japonica in addition to 149 genotypes as intermediate types. CONCLUSION: The information on marker-based diversity and performance based on cooking quality and agronomic traits helped to select the most divergent lines for crossing. Also the analysis was useful to classify the temperate germplasm into indica and temperate japonica. The classification could be helpful to devise a strategy for inter-sub species hybridization to breed for improved rice varieties.

Mapping of quantitative trait loci for scab resistance in apple (Malus × domestica) variety, Shireen.

BACKGROUND: Scab caused by Venturia inaequalis (Cke.) Wint. is the most important fungal disease of apple. Fungicide application is a widely practiced method of disease control. However, the use of chemicals is costintensive, tedious, and ecologically unsafe. The development of genetic resistance and the breeding of resistant cultivars is the most reliable and safest option. One such source of scab resistance happens to be the variety 'Shireen', released from SKUAST-Kashmir. However, to date, the nature of resistance and its genetic control have not been characterized. Objective This research aimed to elucidate the genetic basis of scab resistance in Shireen. METHODS: Genetic mapping of quantitative trait loci (QTL) for resistance to apple scab disease was performed using an F1 cross developed between the susceptible cultivar 'StarKrimson' and the resistant cultivar 'Shireen'. The population was evaluated for two consecutive years. Further, six candidate genes were analyzed via quantitative real-time PCR, to determine their expression level in response to the pathogen infestation. RESULTS: Genotyping and disease phenotyping of populations led us to identify two quantitative trait loci (QTLs), namely qRVI.SS-LG2.2019 and qRVI.SS-LG8.2019 on chromosomes 2 and 8 with LOD-values of 7.67 and 4.99 respectively, and six potential CDGs for the polygenic resistance in 'Shireen'. The genomic region corresponding to the mapped QTLs in LG 2 and LG 8 of 'Shireen' was examined for candidate genes possibly related to scab resistance using in silico analysis. CONCLUSION: The QTLs mapped in the genetic background of Shireen are the novel QTLs and may be transferred to desirable genetic backgrounds and provide opportunities for isolation and cloning of genes apart from their utility to achieve durable resistance to scab.

Improved protocol for efficacious in vitro androgenesis and development of doubled haploids in temperate japonica rice.

DH (Doubled haploid) is the immortal mapping population and an outcome of single meiotic cycle, contributed from male partner. An improved procedure was developed for high frequency androgenesis in japonica genotypes, K-332 and GS-88 and their F1s. A total of 207 fertile, green, di-haploid plants were generated from K-332 × GS-88 hybrids using the improved anther culture protocol. The investigation was carried out to evaluate callus induction potential and regeneration response for the genotypes and the derived F1s on N6 media and modified N6 media (N6M). Whereas, N6 failed to induce callusing, agarose solidified N6M media supplemented with 4% maltose, growth regulators; NAA (2 mg/l), 2, 4-D (0.5 mg/l), Kinetin (0.5 mg/l), and silver nitrate induced high calli percentage of 27.6% in F1s, 9.5% and 6.7% in GS-88 and K-332 respectively. Murashige and Skoog (MS) media supplemented with 3% sucrose, and the hormonal combination BAP (2 mg/l), Kinetin (1 mg/l) and NAA (1 mg/l) induced high green shoot regeneration rates (0-60.0%). The effect of cold pre-treatment at 4°C and the stage of anther collection and their interaction was studied. The effect of cold pre-treatment (CP) of collected boots at 4°C (for CP2: 2, CP4: 4, CP6: 6 and CP8: 8 days) at different stages of panicle emergence (BES4-6: 4-6, BES7-10: 7-10, BES11-13: 11-13, BES>13: more than 13 inches was worked out in relation to the effect on response of calli induction, albino regeneration, green plant regeneration and number of shoots/green calli. CP referred to the number of days for which the collected boots were incubated before they were inoculated. BES was the length (inches) between flag leaf and penultimate leaf at the time of boot collection. We concluded that CP6 and BES7-10 showed better response to callus proliferation and regeneration of plantlets across genotypes. The appropriate pre-treatment, stage of anther collection and favourable media composition resulted in high calli induction and green plant regeneration rates in recalcitrant japonica genotypes. The modified N6 media resulted into efficient callus induction and is expected to be useful for studies which aim at rapid generation of mapping populations for genetic studies.

Tweaking genome-editing approaches for virus interference in crop plants.

Plant viruses infect various economically important crops and cause a serious threat to agriculture. As of now, conventional strategies employed are inadequate to circumvent the proliferation of rapidly evolving plant viruses. In this regard, recent advancement in genome-editing approach looks promising to produce plants resistant to DNA/RNA virus infections. Clustered regularly interspaced palindromic repeats (CRISPR) system has been emerged as a promising genome-editing tool that has received special interest because of its ease, competence and reproducibility. Recent studies have demonstrated that CRISPR/Cas9 system has great potential to confer plant immunity by either directly targeting or cleaving the viral genome in both RNA and DNA viruses. Similarly, the approach can be used for targeting the host susceptibility genes more particularly in case of RNA viruses. In the present review, different approaches and strategies being used to improve plant resistance against devastating viruses are discussed in view of recent advances in CRISPR systems. This review also describes the major pitfalls of CRISPR/Cas9 system that utilizes highly efficient and novel platforms to engineer interference to single and multiple plant RNA viruses.

Harnessing Genome Editing Techniques to Engineer Disease Resistance in Plants.

Modern genome editing (GE) techniques, which include clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (CRISPR/Cas9) system, transcription activator-like effector nucleases (TALENs), zinc-finger nucleases (ZFNs) and LAGLIDADG homing endonucleases (meganucleases), have so far been used for engineering disease resistance in crops. The use of GE technologies has grown very rapidly in recent years with numerous examples of targeted mutagenesis in crop plants, including gene knockouts, knockdowns, modifications, and the repression and activation of target genes. CRISPR/Cas9 supersedes all other GE techniques including TALENs and ZFNs for editing genes owing to its unprecedented efficiency, relative simplicity and low risk of off-target effects. Broad-spectrum disease resistance has been engineered in crops by GE of either specific host-susceptibility genes (S gene approach), or cleaving DNA of phytopathogens (bacteria, virus or fungi) to inhibit their proliferation. This review focuses on different GE techniques that can potentially be used to boost molecular immunity and resistance against different phytopathogens in crops, ultimately leading to the development of promising disease-resistant crop varieties.

Host-Pathogen Interaction in Fusarium oxysporum Infections: Where Do We Stand?

Fusarium oxysporum, a ubiquitous soilborne pathogen, causes devastating vascular wilt in more than 100 plant species and ranks 5th among the top 10 fungal plant pathogens. It has emerged as a human pathogen, too, causing infections in immune-compromised patients. Therefore, it is important to gain insight into the molecular processes involved in the pathogenesis of this transkingdom pathogen. A complex network comprising interconnected and overlapping signal pathways-mitogen-activated protein kinase signaling pathways, Ras proteins, G-protein signaling components and their downstream pathways, components of the velvet (LaeA/VeA/VelB) complex, and cAMP pathways-is involved in perceiving the host. This network regulates the expression of various pathogenicity genes. However, plants have evolved an elaborate protection system to combat this attack. They, too, possess intricate mechanisms at the molecular level which, once triggered by pathogen attack, transduce signals to activate defense response. This review focuses on understanding and presenting a wholistic picture of the molecular mechanisms of F. oxysporum-host interactions in plant immunity.