**2.3 Biochemical markers**

Biochemical markers have been among the most widely used markers for assessing variations among and within crop species before the advent of molecular/ DNA markers. The alternative forms of protein (isozymes) exhibit specific banding patterns on gel electrophoresis, owing to variations in charge- based protein mobility. Isozymes are the products of different alleles, their position can be mapped on to chromosomes and hence are used to map other genes. Protein/isozyme analysis is still among the simple, rapid and cheap methods and fits well in the projects where low level of genetic diversity estimation is desired. Though protein markers are more reliable than morphological markers, their expression is plant growth stage dependent and is readily influenced by the environment [3, 4].

7.Functional molecular markers (FMM): The term "Functional markers" was proposed by Andersen and Lübberstedt [9] for DNA markers that arise from

variations in the desired phenotypic traits. Hence, these are more reliable and

Each marker system has its own benefits and disadvantages and variations exist

The word sorghum originated from "*Syricum*" in Latin, meaning "Grain of Syria*"* [10]. Sorghum (*Sorghum bicolor*) belongs to class *Liliopsida*, family *Graminea*, genus *Sorghum Moench* and has five groups named as: *Hetrosorghum*, *Chaetosorghum*, *Spitosorghum*, *Parasorghum* and *Eusorghum*. It is an ancient grain that has been cultivated for thousands of years. It originated mainly from Sudanese and Ethiopian

About 100 countries grow sorghum worldwide (**Figure 1**). USA is the top sorghum producer with five countries viz.; Nigeria, Ethiopia, Mexico, India and China follow in the order of production (**Figure 2**). The countries of Japan, Mexico, and Philippines are the major importers of North American sorghum, while China is the

In Pakistan, sorghum is grown for fodder and forage of livestock. It is grown as kharif fodder in irrigated and rain fed areas of Punjab and Sindh provinces. Production of sorghum (*Sorghum bicolor*) in Pakistan is 1.45 million metric tons in 2020 (www.indexmundi.com). Sorghum is the second largest fodder crop after berseem (Pakistan Bureau of Statistics, 2016). Scarce record exists on use and adoption of

sequence polymorphism among functional genes that are linked with

informative than all previous PCR- based markers.

**3.1 Sorghum origin**

grasslands more than 6000 years ago.

*DOI: http://dx.doi.org/10.5772/intechopen.95026*

world's largest sorghum importer.

**3.3 Sorghum in Pakistan**

**Figure 1.**

**105**

*Country-wise production of sorghum in the world.*

**3.2 Global sorghum distribution and production**

on the basis of development cost, efficiency and reproducibility.

*Exploring Plant Genetic Variations with Morphometric and Molecular Markers*

**3. Need for genetic diversity assessment of sorghum germplasm**
