Molecular mechanisms underlying virescent mutation in Cotton

Agrima Bhatt, Rajasthan University

Cotton or scientifically known as Gossypiuma hirsutum is a typical perennial plant, developed for commercial cultivation by farmers all over the world as an annual crop. In textile industries, cotton is a crucial fiber. A majority of the world, today uses cotton in everyday life, whether it’s for washing face on soft cotton cloth or a good night’s sleep on a cotton sheet.

Cotton has a variety of uses in everyone’s daily life, from clothing like the manufacturing of good old denim to our shoelaces to industrial applications such as livestock feed, medicinal value, oils, and paper. Such variety of applications has led to an increase in its crop production yield reaching its maximum at over 23 million tones making it a leading cash crop in the U.S alone. With such great significance of plant crop, scientists are always trying to develop different methods to produce high-quality cotton breeds. Studying the underlying mechanisms in virescent mutation will provide a big boost to science and may help assist in the molecular breeding process.

Virescent mutation – A big concern to scientists

Virescence is defined as the abnormal green pigmentation in plant parts like shoots, flowers, etc. A virescent mutation is the yellowing of leaves in the early stages of plant development and later becoming green on maturation due to the disproportion of photosynthetic pigments in leaves. 

These mutations are genetically quite stable and are found in different varieties of plants such as cotton, rice, cucumber, etc. This mutant expression is regulated by a pair of recessive genes thus making the plant with it an ideal experimentation material for scientists to develop and manipulate. Scientists can research and develop hybrids by crossing the mutant plant with the wild type to study the gene expression for chlorophyll synthesis which is later responsible for plant development and their property of photosynthesis.

Sumian 22 is one such strain of cotton which yields high-quality fiber and provides disease resistance capacity to the plant. In this study, a wild type of Sumian 22 and a virescent mutant of the same were crossed for the F1 progeny. F1 progeny was again self-pollinated and the resulting F2 progeny was screened and tested by RT-PCR (reverse transcriptase-polymerase chain reaction) to identify responsible genes for chlorophyll synthesis and any existing mutation present.

Result and Conclusion

By cross-breeding of the two plant strains, a resultant ratio of 3:1 (green and yellow-leaved plants) demonstrated that the virescent mutation in Sumian 22 is recessive. With technologies such as BSA-seq technology (Bulked segregant analysis (BSA), coupled with Next-generation sequencing) candidate genomic region was separated, and RT-qPCR was utilized to resolve gene transcription levels.

With the help of genome sequencing, regulatory mechanisms of the gene ABC transporter I family member 1 (ABCI1) transcription was further explored since it was reported to be involved in chlorophyll synthesis in Arabidopsis. Scientists were able to demonstrate experimentally the low amounts of Mg-proto IX and Pchld due to their suppression during synthesis thus showing conclusive evidence in support of the mechanism of ABCI1 under the virescent mutation in Sumian 22.

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References:

1. Gao, J., Shi, Y., Wang, W., Wang, Y.-H., Yang, H., Shi, Q.-H., Chen, J.-P., Sun, Y.-R., & Cai, L.-W. (2021). Genome sequencing identified novel mechanisms underlying virescent mutation in upland cotton Gossypiuma hirsutum. BMC Genomics, 22(1). https://doi.org/10.1186/s12864-021-07810-z

About Author:

Agrima Bhatt is an undergraduate student studying BSc. Biotechnology in Jaipur. She is a science and research enthusiast who also loves to write articles and short snippets.

Some of her published articles at BioXone are:

1. https://bioxone.in/news/worldnews/multi-angle-projection-microscope-a-novel-imaging-technique/
2. https://bioxone.in/news/worldnews/scientists-develop-novel-cholera-vaccine-from-rice-grains/
3. https://bioxone.in/news/worldnews/ai-predicts-the-relation-between-viruses-and-mammals/
4. https://bioxone.in/news/worldnews/molecular-diagnostic-test-for-covid-testing-under-30-minutes/

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