Utilizing a pair of primers that specifically targeted the BMP 15 gene’s coding region, the gene was amplified successfully in a polymerase chain reaction (PCR). Data points to a DNA fragment size of 350 bp as the amplification fragment. The results of electrophoresis in Fig 1 showed that the primers used are specific to the BMP 15 gene, with only one DNA band formed for all samples.
Genotype frequency and allele frequency of BMP15 gene fragment
The BMP 15 is one of the reproductive genes that regulate ovarian folliculogenesis, which is vital for cattle production since it impacts breeding profitability
(Belli and Shimasaki, 2018;
DOcchio et al., 2020;
Tang et al., 2019). Since the importance of the BMP 15 gene, the biological roles of BMP 15 in Ongole cattle must be investigated, as mutations in small ruminants have been linked to high ovulation rates and fertility
(Ghoreishi et al., 2019; Heath et al., 2017; Pourali et al., 2020). BMP 15 supplementations during in vitro fertilization in mouse group increased oocyte quality and blastocyst rate significantly
(Velasquez et al., 2019). The BMP 15 gene’s DNA sequence was amplified using the PCR technique, with the PCR result being 350 bp in length (Fig 1). Another obtained amplicon of the BMP 15 gene based on the NCBI information has a length of 1185 bp, which is possibly caused by breed difference with the accession number (NM_001031752) for
Bos taurus BMP 15 Gene mRNA. Six polymorphic SNPs were discovered during the sequencing of the BMP 15 gene in SO cattle. They were SNP c.57 G>A, SNP c.120 C>T, SNP c.338 G>T, SNP c.360 C> A, SNP c.361 G>T and SNP c.365 A>T.
The SNPs in this study were polymorphic, with an allele frequency less than 0.99 or greater than 0.01. As a result, it is possible to conclude that the BMP 15 gene in Sumba SO cattle is polymorphic. When a change in the DNA sequence happens in a population at a rate of 1% or greater, it is called a polymorphism
(Brookes, 1999). The greatest allele frequency was identified in SNP c.120 C > T (0.95) and SNP c.361 G>T (0.95) (Table 1). It suggests that this BMP 15 polymorphism may have spontaneously developed with a neutral or advantageous impact because of the increased prevalence in the population.
Previous studies have reported that polymorphism of the BMP 15 gene with a high ovulation rate that causes high litter size in Anglo-Nubian goats
(Abdel-Rahman et al., 2013), Batang goats
(Hidayat, 2008) and white goats
(Ran et al., 2010). In Olkusha sheep, a single mutation of the BMP 15 gene was responsible for high prolificacy resulting in a high ovulation rate and litter size with excellent maternal abilities, which are valuable in sheep breeding
(Smołucha et al., 2020). It is also shown that mutations in heterozygous ewes affect fecundity by increasing the ovulation rate, while homozygous ewes are infertile due to the blockage of follicle development
(Zhang et al., 2009).
The BMP 15 gene, however, was not correlated with the efficacy of artificial insemination in polymorphic Peranakan Ongole (PO) cattle from Pasuruan in East Java
(Damayanti et al., 2013). It was also reported that some heterozygous
Bos taurus breeds in Luxi, Qinchuan, Nanyang, Jinnan and Bohai Black cattle were found to be polymorphic, but fecundity was not increased in these individuals’ cattle
(Zhang et al., 2009). The result of this finding implies that six mutations of the BMP 15 gene could provide opportunities as a molecular marker for improving reproductive performance in SO cattle breeding, although the observation of BMP 15 gene polymorphism could be connected to the particular type of animals. More study is needed to determine whether this mutation affects the phenotype of Ongole cattle.
Heterozygosis of BMP 15 gene and hardy-weinberg equilibrium
According to the findings, the observed heterozygosis (Ho) was lower than the expected heterozygosis (He). Based on the result, the value of Ho is less than He, which may imply an active selection process and a high likelihood of inbreeding in this SO population. Furthermore, it suggests that the difference between the Ho and the He might be utilized to detect a genetic imbalance in the observed SO cattle. This might imply that there has previously been selection action and that there is no random mating
(Kuralkar et al., 2016; Surekha et al., 2018). All of the SNPs in SO cattle (Table 2) have Ho values below 0.5, indicating limited diversity, as reported by
Vissers et al., (2003). Adaptation efforts by SO cattle to the severe climatic circumstances on Sumba Island are thought to have resulted in the mutation seen in SO cattle as it is stated by
(Gaina et al., 2022; Vani et al., 2022). Heterozygosis values are a method of gauging a population’s genetic diversity that can inform a selection program’s choices
(Marson et al., 2005).
A molecular selection marker in cattle is essential for evaluating genetic diversity. Following the. criteria of
(Botstein et al., 1980), the polymorphic informative content (PIC) value was reached from low (0.02) to moderate-high (0.45 and 0.47). The SNPs with moderate-high PIC values were c.360 C>A and c.365 A>T. In addition to the heterozygosity value, the PIC value can not only be used to determine genetic markers but can also be used to determine the presence and absence of polymorphic alleles. Thus, based on this finding, the BMP 15 gene showed polymorphism, which could be potentially used in molecular selection for the breeding program. Further research in a bigger population is necessary to corroborate those findings, though, as SNPs identified on the BMP 15 gene’s entire genomic structure may have a greater impact on production in SO cattle.
Although
Godara et al., (2012) stated that BMP 15 gene is not a major gene that affects fecundity in Marwari Goats like in Some of the Chinese native cattle
(Zhang et al., 2009), this gene was discovered to be a major gene that affected the prolificacy of Jining Grey goats and other ruminants. Several mutations in this gene have been linked to prolificacy and fertility in ruminants, both small and large ruminants
(Niu et al., 2021; S.
Bibinu et al., 2016). With a p-value close to the significant level (
p =0.08), the detected SNP on BMP15 (BMP15-1: G > A) demonstrated an association with the litter size with some BMP 15 mutations have previously been shown to influence litter size and ovulation rate in small ruminants
(El Halawany et al., 2018). This finding implies that BMP 15 gene might have a beneficial effect on fertility traits in SO cattle like in other small ruminants as it was polymorphic. However, further investigation is required to determine whether this mutation exists and whether it affects phenotype in the SO cattle. Moreover, the findings of this study also add support to the idea that variations in BMP15 function among species may be responsible for phenotypic differences between them.