Significant progress has been made as researchers successfully developed three times the seedless Nagpur Mandarin (Citrus reticulata blanco) through endosperm Rescue’s innovative technology. Nagpur Mandarin, also known as Nagpur Santra, is highly lit across India with flavor and bright colors. Traditionally, this fruit contains many seeds, which may be a deterrent to consumers and limit its processing potential. By creating varieties without species, researchers aim to meet consumer preferences and open up new markets. This breakthrough not only represents a technological milestone, but also has a huge economic commitment to promote the citrus industry by increasing the acceptance of Nagpur Mandarin both domestically and internationally.
The research team led by Dr. Vijayakumarinarukulla is composed of Yogesh Lahane, Shashi Pandey, Krutika Fiske, Priya Uge and Kartikikawale of the ICAR-CERTRAL CITRUS Institute in Nagpur, India. Their work was published in peer-reviewed agricultural journals.
The process of innovation begins with selecting a high-yield tree in Nagpur Mandarin from the CCRI experimental farm. During the flowering season, thousands of flowers were marked and immature fruit was harvested in the months after marijuana. The endosperm of these fruits was removed and cultivated in a controlled laboratory environment. The researchers tried various medium preparations to induce primary callus and promote embryogenesis.
The maximum response and survival rate induced by primary callus was achieved using medium containing malt extract, casein hydrolyzed salt (CH) and 2,4-dichlorophenoxyacetic acid. The transition from callus to green embryonic form occurs when the culture is transferred to a medium containing MT, CH, CH, adenine sulfate, and benzyl adenine (BA). This combination leads to the highest percentage of co-leaf embryos.
Subsequent stages involve in vitro buds and root regeneration of embryos. The highest response to bud differentiation was observed in MT medium supplemented with adenine sulfate, gaberellic Acid (GA3) and BA. The developed triploid buds were micro-transplanted onto a five-month-old thick lemon rhizome and then transferred to the field.
The confirmed triploid plants were planted on site on the CCRI experimental farm, showing encouraging results. “Our study shows that the successful regeneration of stable triploids from hybrid endosperm occurs through somatic embryos, a pioneering achievement of the Indian citrus triple sports species.”
Initial evaluation trials showed that the fruits of these triploid trees were commercially seedless, which made them very desirable for local consumption and international exports. The dark green leaves and other morphological characteristics of triploid plants further confirm their unique characteristics compared to diploids.
A breakthrough in developing seedless Nagpur Mandarin can stimulate the citrus industry by reducing the limitations brought about by high seed content. It also opens up new avenues for the use of similar biotechnical methods to reproduce other seedless citrus species.
Dr. Vijayakumari and her research team plan to continue their work by optimizing the process and exploring the commercial viability of seedless Mandarin. This innovation not only has the potential to increase profitability of farmers, processing industries, but also improves the competitiveness of Indian Mandarin in the global market.
Journal reference
Narukulla, V., Lahane, Y., Pandey, S., Fiske, K., Uge, P., Kawale, K. , & Ziogas, V. (2023). Triploid seedless Nagpur Mandarin (Citrus net blue) was developed through endosperm rescue. Agronomics, 13 (2814). doi: https://doi.org/10.3390/gronomy13112814
About the author
(Madam) Vijayakumari Narukulla She received her PhD from IARI from New Delhi in 1990. She is an alumnus of Angrau, Hyderabad and Iari, New Delhi, and joined the CCRI scientist in 1991. A significant contribution to citrus improvement programs has been made to the citrus improvement program through clonal selection and hygiene, introduction and isolation of exotic germplasms, and citrus improvement areas of microorganisms. She also studied mutation breeding, hybridization and salinity screening.
She helped develop research facilities, namely, tissue culture laboratory for the whole foot, molecular marker laboratory, 13 green houses, fields and protected foundation blocks, etc., located in CCRI in Nagpur. She has successfully standardized (i) “in vitro firing tip transplant (STG)”, (ii) dual transplant, and (iii) microbuds on molecular markers. The STG-based scheme is being successfully used in CCRI for “massive production and supply of disease-based Nagpur Mandarin”. Until March 2024, about 5.51 million buds were provided to farmers/nurses from all over the country and generated revenue of Rs 293 crore. During the 2014-23 years, 10 Moores signed a technology transfer for large-scale breeding stocks. This technology is adopted in all citrus growing regions in India. 23 citrus exotic varieties were cleaned and the citrus gene library was expanded. She is one of the authors who obtained the “Diagnosis and Diagnosis Based on DNA” patent in 2022. Micro booking technology promotes shortening of the citrus nursery stage and saves costs and time. Currently, she is working on polyploid manipulation of fertility. Participated in international conferences in Türkiye in 2022 and Italy in 2023
Mrs. Vijayakumari is the winner of the Harbhajan Singh Ph.D. Award and 1991 Gold Medal. She won the prestigious ICAR Award. DESHMUKH Outstanding Female Scientist Award in Punjab Province “2011”. Shri’s winner. Giridhari Lal Chadhdha commemorative gold medal, from the National Academy of Horticulture Sciences, New Delhi. Delhi, July 16, 2023.
