Asian Solanaceous & Cucurbits Round Table 2020 - 2021

Even though COVID-19 has restricted our activities, APSA is determined as always to facilitate its members in the best way possible. Under the hood of APSA R&D Advisory Group, the Asian Solanaceous and Cucurbits Roundtable (ASCRT) will be arranged as a series of 'Expert Talk on Crop Improvement Webinars'. APSA invites experts from the vegetable breeding sector to talk on the recent problems and potential solutions in vegetables breeding. There will be one webinar every 2 months.

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ASCRT - SESSION 1
December 16, 2020
2:00pm - 4:00 pm (ICT)

"Breeding for Heat Stress Management"

Dr. Kartikeya Srivastava

Biography
Dr Kartikeya Srivastava, Professor in Department of Genetics & Plant Breeding Institute of Agricultural Sciences, Banaras Hindu University, Varanasi India, He worked at various capacities in corporate sectors viz. Tata Energy Research Institute, NewDelhi, Indo American Hybrid Seeds India Pvt Ltd, Bangalore, Namdhari Seeds Pvt Ltd, Bangalore, He worked on vegetable breeding & seed production, Strategic research planning & management. Worked on development of cauliflower and cabbage hybrids for Indian and overseas. Developed synthetic variety of Brassica napus viz. INDAM Canola-1, cauliflower hybrid NS-120 and mustard variety HUJM10-6 (recommended for release in U.P. State). His area of interest is breeding for abiotic stress tolerance in vegetables and oilseeds. Development of molecular markers system and mapping populations for breeding stress tolerance in vegetables. While working with Banaras Hindu University, He worked on University Grant Commission, a Major Research Project entitled “Genetic improvement for high temperature stress tolerance in tomato”, standardized the methodology of screening genotypes for heat stress in vegetable and identified tomato genotypes & hybrids tolerant to high temperature tolerance. Dr Srivastava has published more than 77 research papers, popular article, book chapters, manuals in the research area and honored by various societies and national bodies.

Abstract

Heat set tomatoes breeding approaches and perspectives
Heat stress due to increased temperature is an agricultural problem in many areas in the world. Transitory or constantly high temperatures cause an array of morpho-anatomical, physiological and biochemical changes in plants, which affect plant growth and development and may lead to a drastic reduction in economic yield. Several physiological activities such as, photosynthesis, assimilate translocation, cellular membrane organization, and reproductive activities like pollen viability, pollen germination, fruit set, etc are greatly affected which results in reduced yield and quality of tomato. These parameters can be used for screening the tomato genotypes for stress tolerance. Hybrids have better ability to perform under stress condition, if parental lines have stress tolerance, as these exploits both non-additive and additive gene action.  The experiment was carried out to assess heat tolerance in Banaras Hindu University, Varanasi and to screen out the tolerant tomato genotypes for further improvement and heterotic hybrid development for high temperature stress conditions. The crosses NDTVR-60 × H-88-74-1 and Pusa Sadabahar × H-88-74-1 expressed better fruit yield/plant under high temperature regime. The crosses NDTVR-60 × FLA7171 and PS-1× FLA7171 recorded the least reduction of 36.10 and 36.91% for fruit yield /plant, respectively under stress.  In one of our study, we observed crucial role of pollen starch and soluble sugar content on fruit set in tomato under heat stress. A major effect of heat stress on pollen development is a decrease in starch concentration before anthesis, which results in a decreased soluble sugar concentration in the mature pollen grains at anthesis. These events possibly contribute to the decreased pollen viability, pollen germination, and ability to fruit set in tomato. Two tomato genotypes (Pusa Sadabahar and NDTVR-60) could be a valuable source of heat-tolerant germplasm for tomato breeding programs. QTL-mapping for heat stress tolerance, marker as well as genomic assisted selection and bioinformatic tools can be used for precision accelerated tomato breeding for the trait concerned.  

Dr. Derek W. Barchenger

Biography
Dr. Derek Barchenger is the Pepper Breeder at the World Vegetable Center, Taiwan. He holds a Ph.D. in New Mexico State University. Derek has extensive experience in international agriculture and food security.

Research –Development of pepper varieties in diverse genetic backgrounds combining resistance to multiple diseases and stresses for diverse markets.

• Resistance to the major viral, bacterial, and fungal diseases facing smallholder farmers
• Tolerance to high temperature, flooding and drought
• Improved quality and nutritional value of pepper
• Diverse cytoplasmic male sterile and genic male sterile lines to enable hybrid cultivar development in underdeveloped countries

Abstract

Heat stress tolerance of tomato and pepper
Harnessing crop tolerance to elevated temperatures is essential for sustaining vegetable production in tropical areas and will become even more important under climate change. Pollen is the most heat susceptible stage in many crop species and without viable pollen, fruit set of tomato, chili and sweet pepper and other fruiting vegetables is reduced or completely impeded. While both are susceptible to high temperatures, sweet pepper is generally more sensitive than chili pepper. Selection for heat tolerant plants can be done by monitoring fruit set, but this method does not discriminate between pollen and flower traits. Furthermore, it requires measuring fruit set over an extended time and is sensitive to variations in temperature that could permit an otherwise heat sensitive plant to set fruit. For crops like tomato and pepper, pollen viability alone does not sufficiently inform about the capacity of pollen to fertilize female germ cells. Instead pollen germination data are required to estimate heat tolerance of pepper pollen. In vitro pollen germination may be affected by genotype specific differences in compatibility with germination media. Like the pollen viability test, this method is laborious and has very low throughput, limiting its usefulness in breeding. Therefore, WorldVeg has recently started to characterize WorldVeg pepper and tomato heat tolerant sources and breeding lines for pollen number and pollen activity using impedance flow cytometry. IFC is an efficient, label-free and reliable technique to analyze pollen activity in a species-independent manner in high throughput mode. Active pollen is defined as viable pollen that will likely germinate. Preliminary results indicate that the average pollen number per flower is associated with tolerance to high temperature stress, although these results need to be confirmed. The overall objective of this project is to strengthen heat stress tolerance breeding by identifying new sources of heat stress tolerance for pepper and tomato. Emphasis will be given to high fruit set under elevated temperatures. Information on pollen number, pollen activity and yield under heat stress is used to select heat tolerant tomato and pepper lines for multilocation trials. In addition, high performing heat tolerant tomato recombinant inbred lines will be selected from four biparental mapping populations for the trials. For both crops, 20-30 diverse heat tolerant sources will be distributed to participating companies and evaluated by them for fruit set and other heat related traits in dry and humid heat stress environments in South and Southeast Asia with temperature up to 42°C during the day and a maximum of 27°C during the night using a common protocol. A training workshop for involved staff will be conducted to harmonize the evaluation. The sites should have low leaf curl virus infection pressure to avoid confounding effects. If there is demand, segregating populations can be produced from selected materials for mapping heat stress tolerance traits in a third project year.