MAS in Backcross and Heterosis Breeding

Introduction

In the field of plant breeding, it is often necessary to combine desirable traits from two or more different varieties of plants. One way to achieve this is through the use of backcross breeding and heterosis breeding.

Backcross breeding involves crossing a hybrid plant with one of its parents in order to transfer desirable traits from the parent to the hybrid.

Heterosis breeding involves crossing two genetically distinct plants to create a hybrid that has improved traits compared to both parents. One of the key tools used in both backcross and heterosis breeding is the marker-assisted selection (MAS) technique.

The given article elucidates how MAS is used in backcross and heterosis breeding.

What is Marker-Assisted Selection (MAS)?

Marker-assisted selection (MAS) is a technique used in plant breeding to identify and select for specific genes or traits. It involves using molecular markers, which are DNA sequences that are associated with specific traits or genes of interest.

By analysing the molecular markers, breeders can determine which plants have the desired genes or traits and select them for further breeding.

MAS can be used in different stages of plant breeding, including the selection of parental lines, the creation of hybrids, and the selection of superior progeny.

The use of MAS in plant breeding has several advantages, including increased efficiency and accuracy of selection, reduced time and cost of breeding, and the ability to select for traits that are difficult or impossible to observe directly.

MAS in Backcross Breeding

Backcross breeding involves crossing a hybrid plant with one of its parents in order to transfer desirable traits from the parent to the hybrid.

The objective of backcross breeding is to create a hybrid that has the desirable traits of the parent while retaining the desirable traits of the hybrid.

MAS can be used in backcross breeding to identify and select specific genes or traits that are present in the parent but not in the hybrid.

The first step in backcross breeding is to identify the desired trait or gene that is present in the parent but not in the hybrid.

This can be done using various methods, such as phenotypic selection or the use of molecular markers.

Once the desirable trait or gene has been identified, molecular markers can be used to select plants that have the desired trait or gene.

For example, suppose a breeder wants to transfer a disease-resistance gene from a wild variety of tomatoes to a commercial variety of tomatoes. The breeder can use MAS to identify molecular markers that are linked to the disease-resistance gene in the wild variety. The breeder can then use these markers to select plants that have the desired gene from the wild variety while retaining the desirable traits of the commercial variety.

MAS in Heterosis Breeding

Heterosis breeding involves crossing two genetically distinct plants to create a hybrid that has improved traits compared to both parents.

The objective of heterosis breeding is to create a hybrid that has increased yield, improved quality, and better adaptability to different environments.

MAS can be used in heterosis breeding to identify and select specific genes or traits that are present in the parent but not in the hybrid.

The first step in heterosis breeding is to identify the desired trait or gene that is present in one parent but not in the other parent. This can be done using various methods, such as phenotypic selection or the use of molecular markers.

Once the desirable trait or gene has been identified, molecular markers can be used to select plants that have the desired trait or gene.

For example, suppose a breeder wants to create a hybrid corn plant that has increased yield and resistance to pests. The breeder can use MAS to identify molecular markers that are linked to the genes that control yield and pest resistance in the two parent plants. The breeder can then use these markers to select plants that have the desired genes from both parents while minimizing the negative traits.

Benefits of MAS in Backcross and Heterosis Breeding

The use of MAS in backcross and heterosis breeding offers several benefits. Some of the key benefits are discussed below −

Increased Efficiency and Accuracy of Selection

The use of MAS allows breeders to identify and select specific genes or traits with a high degree of accuracy. This can significantly reduce the time and cost of breeding by eliminating the need for phenotypic selection, which can be time-consuming and costly.

Reduced Time and Cost of Breeding

The use of MAS can significantly reduce the time and cost of breeding by allowing breeders to select plants with the desired genes or traits in a shorter period of time. This can also reduce the number of generations required to create a desired hybrid or variety.

Selection of Traits that are Difficult or Impossible to Observe Directly

MAS allows breeders to select traits that are difficult or impossible to observe directly. For example, disease resistance traits are difficult to observe directly, but molecular markers can be used to select plants that have the desired disease resistance genes.

Improvement of Complex Traits

MAS can be used to select complex traits that are controlled by multiple genes. This is particularly useful in heterosis breeding, where the objective is to create a hybrid that has improved traits compared to both parents.

Challenges of MAS in Backcross and Heterosis Breeding

Despite the many benefits of MAS in backcross and heterosis breeding, there are also some challenges that need to be addressed. Some of the key challenges are discussed below −

Limited Availability of Molecular Markers

The use of MAS requires the availability of molecular markers that are linked to the genes or traits of interest. In some cases, the availability of molecular markers may be limited, which can limit the effectiveness of MAS.

Complexity of Trait Inheritance

In some cases, the inheritance of traits may be complex, which can make it difficult to identify and select for specific genes or traits using MAS. This is particularly true for traits that are controlled by multiple genes.

Need for Validation

The use of MAS requires validation of the molecular markers to ensure that they are linked to the genes or traits of interest. This validation process can be time-consuming and costly, particularly when dealing with complex traits.

Conclusion

In conclusion, marker-assisted selection (MAS) is a powerful tool in plant breeding that can be used to identify and select for specific genes or traits in backcross and heterosis breeding.

MAS offers several benefits, including increased efficiency and accuracy of selection, reduced time and cost of breeding, and the ability to select for traits that are difficult or impossible to observe directly.

However, there are also some challenges associated with the use of MAS, such as the limited availability of molecular markers, the complexity of trait inheritance, and the need for validation. Despite these challenges, MAS remains an important tool in plant breeding that can help breeders create new and improved varieties of plants.