Genomics assisted breeding: The need and current perspective for rice improvement in India

With the fast increase of human population and reduction in land areas under cultivation, it is essential to breed rice varieties with higher yield potential and tolerance to multiple stresses using modern breeding technologies. Till date, a large number of rice varieties and rice hybrids have been developed in India for different ecologies. However, average rice production in India is 2600 kg/hectare. Since rice is the staple food in India and grown in ~43.86 million hectare, the present production and productivity are not sufficient enough to feed the increasing population. Therefore, it is required to develop high yielding rice varieties to feed the growing population. However, HYVs are usually amenable to various biotic and abiotic stresses for which there is a great yield loss. Besides, there is no significant increase in yield though a number of high yielding rice varieties have been developed through conventional breeding. Thus, higher genetic gain in rice is required to combat the existing situation which is only possible through advanced breeding approaches such as genomic selection, forward breeding, haplotype-based precision breeding along with genomic tools such as Next-Generation Sequencing (NGS) technology. This review addresses the current progress made in advanced genomic-assisted breeding and need of modern breeding technologies for rice improvement.

Validation of Diagnostic Markers for Streak Virus Disease Resistance in Maize

Maize streak virus (MSV) is responsible for streak disease of maize and poses a serious threat to maize production in sub-Saharan Africa. Polygenic resistance to MSV has become an essential requirement in modern maize cultivars to mitigate yield losses. Many single nucleotide polymorphism (SNP) markers linked to putative MSV resistance loci have been identified for use in forward breeding. This study aimed to validate, using the high-throughput kompetitive allele specific PCR (KASP) assay, the diagnostic ability of the three SNP markers linked to the loci for the Msv1 resistance trait in 151 early generations inbred lines with diverse genetic backgrounds, together with nine MSV-resistant elite lines and a susceptible check (cv. Pool-16). The phenotypic responses were determined by MSV inoculation using viruliferous leafhoppers (Cicadulina triangular) under screenhouse conditions. Based on an established MSV disease rating system, the maize lines were categorized into resistant, moderately resistant, susceptible, and highly susceptible. The three SNPs associated with MSV resistance were detected in 133 lines, which were categorized as resistant (54), moderately resistant (76), and susceptible (1). The 18 early generation lines without these SNPs were classified as moderately resistant (10), susceptible (5), and highly susceptible (3). This study confirms the strong association of SNPs with MSV resistance and their usefulness for forward breeding in maize while emphasizing the need to identify additional markers to screen lines for MSV resistance without any ambiguity.