**2. Conventional breeding**

#### **2.1 Germplasm conservation and plant genetic diversity**

Prebreeding performance as phenotypic and genetic appraisal of germplasm collections are2 key functions of a breeding program to obtain basic information about the genetic relationships1 amongst accessions, inheritance patterns of some important traits and to select lines for subsequent1 crossing cycles [7]. In this regard, the characterization of germplasm banks of legume crops1 worldwide has been crucial for the development of agriculture because they are the reservoirs of1 genetic diversity [8].

The genetic resources of other legume species are also a primary locus of genes associated with biotic and abiotic resistance and agronomic traits of value to breeders. 1 The genetic diversity of legume species has been described, which has been extremely useful for separating major collections of germplasm1 and genetically identifying different sets of parental lines used in breeding cycles/stages [8–11]. The germplasm of major legume species has shown similar values when they were1 analyzed using micro-satellites (SSRs) markers. This is not surprising because most of the legumes are highly self-pollinate with low and very low out-crossing rate values except pigeon pea [12]. Thus, they1 have tended to display low to moderate genetic variability at intra-population and intra-group. However, most of their inherited variability is spread amongst populations or groups of accessions,1 which is very prominent for breeding purposes.

The technology makes it possible to insert genetic material from unusual sources. It is now possible to insert genetic material from species, families and even kingdoms that may not previously have been sources of genetic material for a specific species, and even to insert custom-engineered genes which do not exist in nature. As a result,

#### **Figure 1.**

*Comparing conventional breeding and genetic engineering. https://www.isaaa.org/resources/publications/agric ultural\_biotechnology/download/*

we can create what could be considered synthetic life forms, something that cannot be done through conventional breeding (**Figure 1**).

#### **2.2 Characterization of legumes**

The legume genotypes have showed significant differences on morphological and phenological1 traits such as pod curvature, days to flowering, hypocotyl color, growth habit, number of nodes, number of flower buds and hundred or thousand seed weight, which is significant for legume breeding [13].

They indicated that traditional breeding approaches have been particularly successful in improving monogenic traits, such as color, size, texture, appearance of some traits, although they are less specific and slow when it comes to quantitative traits, which are controlled by many genes. Are strongly influenced by the environment and are influenced by the environment and genetic interactions [14, 15].

### **3. Molecular and advance breeding method**

#### **3.1 Genomics-assisted breeding**

Recent advances in the field of pulsed genomics deserve attention, for example, the discovery of genome-wide genetic markers, high-throughput genotyping and various sequencing platforms, high-density gene linkage1/QTL mapping, and most importantly, whole-genome sequence access. With the genome sequence in hand, there is considerable potential for using whole genome methods for trait mapping1 using correlation studies and selecting desirable genotypes through genomic selection. It is anticipated that GAB will accelerate progress in pulse/legume breeding, leading to rapid expansion of varieties with high yield, high stress tolerance and broad genetic base [16, 17].

#### **3.2 Genetic engineering in legumes**

The consequences that may result in the release of Genetically Modified crops (GM crops) in agriculture are a matter of ongoing debate [18]. However, it is logical to technically evaluate the risks1 of utilizing GM crops relative to their benefits and evaluate them with the conventional methods of1 genetic improvement [19]. The most successful case of public information is glyphosate resistant1 transgenic soybean [20], which has been commercializedc for over 20 years [21], and it is1 undoubtedly the most important genetic modification in soybeans [22].

Genetic engineering opens the door for plant breeders to bring together useful genes from a1 variety in one plant [23]. The development of glyphosate resistant variety utilized the CP4 gene from1 *Agrobacterium* spp., which encodes a glyphosateresistant form of EPSPS, initially introduced in1 soybean [20].

Although gene flow is a legitimate concern of GM soybean [24], trans genes frequently represent gain of function, which might release wild relatives from constraints that limit their fitness1 [25–27]. This was a major breakthrough because no practical resistance to BGMV was known in1 common bean genotypes.

#### **3.3 Modern legume breeding tools**

There are many modern breeding tools are available that can speed up the legume breeding1 programme. The Arabidopsis plant model has allowed the study of metabolic and physiological1 processes during plant growth and in responses to biotic and abiotic stress through genome-wide gene expression analysis [28–30].

In parallel, the major version of the complete common bean genome sequence was recently published [31] and the chickpea genome sequence is also available in "The Cool Season 1 Food Legume Genome Database" [32]. References to legume genomes have also opened the door to feature 1 RNA sequencing approaches to conduct global transcriptomic profiling studies and discover new genes and ESTs [33–35]. Much effort has been made to compare genomes between model plant species and legume crops to correctly translate the information obtained [36].

These traits and their beneficial alleles can be introgressed in breeding lines through conventional1 genetic improvement in an easy manner, however, the application of MAS significantly reduces the1 time taken to select for resistant lines [37–39].

#### *3.3.1 Abiotic stress breeding*

Stress by low and towering temperatures in legumes can harshly affect plant growth, limiting1 yields and restricting the manufacture of certain regions and in specific periods of the season [40, 41]. Most of legume crops are full-grown in arid to semi-arid climate regions in India, and some countries1 in Africa [42–45].

#### *3.3.2 Breeding for biotic stress*

A large wealth of advances in genomic resources of legumes are associated to such as (**1**) Insects1 [46], (2) Fungi [47–50], (4) Bacteria [51, 52], Virus [53, 54] and Nematodes [55] (**Tables 1** and **2**).







#### **Table 1.**

*Central & State released varieties of Pulses in India.*




**Table 2.** *QTL mapping.*

#### **4. Conclusions and prospects**

The importance of legume crops for the agriculture and the environment is considered1 ancestral; however, the invention and the breeding constraints have led to their current lower relative1 significance compared to cereals. Currently, we are witness and significant boost of legume crops-associated research where abundant studies from conventional breeding to advanced genomics, are1 being carried out and published to address and overcome the various constraints faced by the1 production of legumes. Conventional breeding has made significant contributions to legume genetic1 development, especially by developing lines with superior monogenetic traits such as resistance to1 fungi and insects. Considering the accumulation of published information, it is feasible to forecast1 similar achievements for lentil crop in the near future. MAS in legumes have also shaped opportunity1 for the use of pyramiding approaches and the introgression of quantitative traits for resistance of1 certain diseases.

Furthermore, the dominant entry of legumes to the genomics period has endorsed their breeding programs to adopt new biotechnological and bioinformatics tools such as GWAS, which are hopeful in augment the effectiveness and efficiency of modern breeding techniques.

Legume breeding programs may also consider food superiority parameters as important traits to expand materials of high nutritional and commercial value, meeting the needs of both consumers and the food industry.

The application of genetic modification in legumes shows remarkable progress as reflected in the two successful cases discussed in this article. As the effects of GM crops are still well thought out and public acceptance is not well established, editing tools appear to be more appropriate. Scientist must develop the alternative tools of GM crop.

The strong efforts to accelerate and augment legume breeding and their current global production status show great potential to increase their relative importance in the alimentation and the nourishment of the world population. Presently, cereals exceed pulses as well as legumes 6.7 times in harvested area and 6.0 times in production.

This manufacture boost states a precedent and shows actual possibilities of increasing legume crops production to unexpected levels by genetic advances and improved cultivars, linked to advances in farming technology and agronomic practices.

### **Acknowledgements**

Authors highly thank the department of genetics and plant breeding, School of Agriculture, Lovely professional University, Phagwara, Jalandhar Punjab (India) for providing all necessary facilities to write this book chapter.

### **Conflict of interest**

The authors declare no conflict of interest.
