Satish Kumar Luthra

Production and characterization of somatic hybrids between Solanum tuberosum L. and S. pinnatisectum Dun.

Interspecific somatic hybrids between the dihaploid Solanum tuberosum and the wild species S. pinnatisectum Dun. were produced via protoplast fusion. Protoplast isolation, electrofusion, culture of post-fusion products and regeneration of calli/shoots were undertaken following optimized protocols. Regenerants were characterized for hybridity, ploidy and resistance to Phytophthora infestans (Mont.) de Bery, causal fungal pathogen of late blight disease. From a total of 126 regenerated macrocalli, 12 somatic hybrids were confirmed by possessing species-specific diagnostic bands of their corresponding parents as revealed by RAPD, SSRs and cytoplasmic-DNA analyses. Tetraploid status of the 12 hybrids was determined using flow cytometry analysis. Intermediate phenotypes for leaf, flower, and tuber characteristics and high male fertility were observed in field-grown hybrid plants. Hybrids were highly resistant to foliage late blight based on field assessment for two seasons. In contrast, moderate level of resistance to foliage blight was observed in hybrids based on the detached leaf assay under laboratory conditions. Overall, somatic hybrids with moderate levels of resistance to foliage blight were identified, and these will be useful for in situ hybridization in potato breeding efforts.

Genomics in Management and Genetic Enhancement of Potato Germplasm

The systematic characterization and utilization of naturally occurring genetic variation in the plant genetic resources have become an important approach in plant genome research and breeding. The development of molecular techniques now allows a more accurate analysis of a large collections of potato germplasm. The rapid progress in high-throughput technology such as next-generation sequencing (NGS) offers an exciting tool for novel gene discovery involved in phenotypic traits expression. In the years to come, genomics, transcriptomics and other ‘omics’ technologies will play a key role in potato improvement. The discovery and high-throughput screening of single nucleotide polymorphism (SNP), the presence/absence of allelic variations in diverse germplasm collections will give a detailed insight into the origin, domestication and available trait-relevant variations in the polyploid crops such as potato. In the process, novel approaches and possibilities for marker/genomics-assisted potato breeding are facilitated. This chapter highlights the use of potato genome sequence in management and the genetic enhancement of the potato through its characterization and identification of novel gene/QTL/allele followed by their applications in potato improvement with agricultural relevance.

Evaluation of Potato Genotypes for Foliar and Tuber Resistance against Phytophthora infestans Causing Late Blight of Potato under Subtropical Plains of India

The oomycete pathogen Phytophthora infestans (Mont.) de Bary, is still an important pathogen of the potato and tomato crops after more than one hundreds seventy years of occurrence of late blight epidemic in Ireland. The late blight is one of the most destructive diseases of potato and results in yield losses up to 95% in epidemic conditions. In India, it cause up to 10-15% yield loss of potato on over all basis (Lal et al., 2016). The yield loss caused by P. infestans, can be minimized using host resistance, chemicals, forecasting, sanitation and even disease escape (Wastie, 1991). Host resistance had always been a better option than the fungicides, since these are expensive, environmentally hazardous and pathogen International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 7 Number 03 (2018) Journal homepage: http://www.ijcmas.com

Evaluation of Interspecific Somatic Hybrids of Potato (Solanum tuberosum) and Wild S. cardiophyllum for Adaptability, Tuber Dry Matter, Keeping Quality and Late Blight Resistance

Interspecific potato somatic hybrids (here after referred as ‘cph-hybrids’) derived earlier through protoplast fusion (Solanum tuberosum + S. cardiophyllum) were used in this study. The genetic potential of cph-hybrids was assessed based on the field performance in the Indian sub-tropical conditions. In general, cph-hybrids exhibited higher plant stand, poor plant vigour and late foliage maturity as compared to the control potato var. Kufri Bahar. Yield performance of cph-hybrids was poor as compared to the control, but produced 3–6 times higher marketable tuber yield than the wild parent (S. cardiophyllum). All cph-hybrids possessed significantly higher tuber dry matter content (≥ 24%) than the parents (20.82%) and var. Kufri Bahar (18.52%), excellent keeping quality and showed high resistance to late blight. Thus, based on this study the promising cph-hybrids viz., Crd 6, Crd 10 and Crd16, can be used as parents in breeding for the improvement of important traits viz., higher tuber dry matter content, better keeping quality and high late blight resistance, along with adaptability under sub-tropical conditions.

Genomics in True Potato Seed (TPS) Technology: Engineering Cloning Through Seeds

Tuber is the main planting material for commercial potato production. Besides, true potato seed (TPS), i.e. true botanical seed is another technology of potato. The TPS-raised crop has several advantages over the tuber-raised crops but due to the certain limitations of the conventional TPS technology, it could not be popularized, as expected the world over. The major drawbacks are non-uniformity of crop and tuber characters, lengthy crop duration, and labour-intensive farming due to seedling raising and transplanting. To address these issues, this chapter highlights a brief overview of the production of hybrid TPS, applying genomics approaches to engineer cloning through apomixis seeds, and offers the prospect of F1 hybrid potato technology.