Marker-Assisted Selection (MAS) {with two real-world case studies}

A short description of Marker-Assisted Selection (MAS), accompanied by two real-world case studies.

1. ASSIGNMENT 1
APPLICATIONS OF GENETICS IN AGRICULTURE
SUBMITTED BY: AKASH RANA (23/BT/06)

2. MARKER ASSISTED
SELECTION
NAME: AKASH RANA
ROLL NO: 23/BT/06
SUBJECT: GENETICS (BT-205)

3. INDEX
1) Introduction to Marker-Assisted Selection (MAS)
2) Procedure of Marker-Assisted Selection (MAS)
4) Pros & Cons of Marker Assisted Selection
5) CASE-STUDY I (MAS IN WHEAT MPROVEMENT)
6) CASE-STUDY II (MAS IN RICE IMPROVEMENT)
7) References

4. INTRODUCTION TO MARKER-ASSISTED SELECTION (MAS)
Marker-assisted selection or Marker-aided selection (MAS) is an indirect
selection process where a trait of interest is selected based on a marker
(morphological, biochemical, or DNA/RNA variation) linked to a trait of
interest (e.g., productivity, disease, resistance, abiotic stress tolerance and
quality), rather than on the trait itself.
PRINCIPLE
Marker-assisted selection involves selecting individuals based on their
marker pattern (genotype) rather than their observable traits (phenotype).

5. PROCEDURE OF MARKER-ASSISTED SELECTION (MAS)
Marker-assisted is done to retain a specific characteristic through plant
breeding mostly.
Steps:
i) Identifying the specific genes using molecular or genetic markers, which
are themselves a sequence of nucleic acids that make up a segment of DNA.
The markers are located near the DNA sequence of the desired gene and the
transmission of features takes place through the laws of inheritance.
ii) Since the markers and the genes are close together on the same
chromosome, desired features are transmitted with each generation of
plants that is produced.
iii) This process helps in plant breeding to ensure high-quality and disease-
resistant features are retained in the variety produced.

6. Figure: Procedure of
Marker-assisted
Selection

7. PROS & CONS OF MARKER ASSISTED SELECTION
Pros:
i) MAS can be used for all 3 groups of crops plants, viz. self-pollinated, cross-
pollinated and asexually-propagate species.
ii) Molecular markers possess a very high degree of accuracy.
iii) MAS permits rapid crop improvement. MAS permits identification of
recessive alleles even in heterozygous condition, and thus speeds up the crop
improvement work.
Cons:
i) DNA markers require expensive equipment and reagents.
ii) MAS sometimes involves use of radioactive isotopes for labelling DNA,
which are extremely hazardous to human health.

8. CASE-STUDY I (MAS IN WHEAT MPROVEMENT)
MAS has been used to introduce the Fhb1 gene into good-quality wheat
lines by researchers International Maize and Wheat Improvement Center
(CIMMYT). By the addition of this gene the good-quality wheat lines have
been further made resistant to Fursarium Head Blight.
Another example of the use of MAS in case of improvement of wheat crop
would be the introduction of Pm21, a gene for powdery mildew resistance.
Markers were used to track down the Pm21 gene during breeding, resulting
in new powdery mildew resistant lines.

9. CASE-STUDY II (MAS IN RICE IMRPOVEMENT)
MAS has been used to confirm a previous hypothesis that the presence of
certain alleles in two genes on the Chromosome 12 and Chromosome 7
were one of the major factors in granting rice crop partial resistance to the
Rice Yellow Mottle Virus (RYMV).
Research was undertaken using MAS to transfer the resistant pair of alleles
from Japonica variety, Azucena, into a susceptible indica variety IR64.
MAS led to a very successful transfer of genes to the recipient genome and
the confirmation of the aforementioned hypothesis - opening up new
opportunities for the development of tools and technologies to make good-
quality rice varieties immune to Rice Yellow Mottle Virus (RYMV).

10. REFERENCES
1) Singh, B. D., & Singh, A. K. (2015). Marker-assisted plant breeding: principles
and practices.
2)Song, L., Wang, R., Yang, X., Zhang, A., & Liu, D. (2023). Molecular markers
and their applications in marker-assisted selection (MAS) in bread wheat
(Triticum aestivum L.). Agriculture, 13(3), 642.
3)Rana, M. M., Takamatsu, T., Baslam, M., Kaneko, K., Itoh, K., Harada, N., ... &
Mitsui, T. (2019). Salt tolerance improvement in rice through efficient SNP
marker-assisted selection coupled with speed-breeding. International
journal of molecular sciences, 20(10), 2585.

11. THANK YOU