Perspective and application of molecular markers linked to the cytoplasm types and male‐fertility restorer locus in onion (Allium cepa)

Abstract

Onion (Allium cepa L.; 2n = 16) belongs to the family alliaceae, and order asparagales; and the Allium is the monocot's largest genus, comprised of 920 species (Govaerts et al., 2005(Govaerts et al., -2014. Among them, onion (A. cepa L.), garlic (A. sativum L.), bunching onion (A. fistulasum L.), leek (A. porrum L.) and chives (A. schenoprosum L.) are widely being in cultivation. Among alliums, the onion has the largest economic potential, with 70% share value, followed by garlic (25%) (FAOSTAT, 2016), the consumption of onions has been steadily increasing over the world, most likely due to the nutritional benefits (Manjunathagowda et al., 2019); presence of an unique dietary flavonoids source and quercetin compounds (Slimestad et al., 2007); and medicinal therapeutic values such as lacrimatic, anti-cancer, antibiotic and anti-cholesterol activity (Grifths et al., 2002; Perez-Gregorio et al., 2010).In the world, onion acreage of 4.96 million hectare (mha) with production of 93.17 million tonnes (mt), the world's biggest onion growers are China (23.91 mt) and India (19.42 mt) (FAOSTAT, 2016).But the productivity of major onion-producing countries, China (22 tonnes per hectare (t/ha)) and India (16.18 t/ha), is low compared to Netherlands (49.70 t/ha) (National Horticultural Board, 2017), the United States (56.40 t/ha), Iran (37.95 t/ha) and Egypt (36.71 t/ha) (National Horticultural Board, 2018). This could be because of the largest onion-growing nations (China and India) have been largely covered by open-pollinated varieties, which produce poor yields per unit area and are influenced by seasonal short-day environmental conditions, as compared to countries that have adopted F 1 hybrids using the male sterility trait

Deciphering genetic diversity phylogeny and assembly of Allium species through micro satellite markers on nuclear DNA

“…The molecular markers employed for identifying variety, disclose differences in genetic makeup, phylogenetic relationships, and genotype classification with the greatest precision [ 5 , 7 , [37] , [38] , [39] , [40] ]. Despite of commercial importance of cultivated alliums, it is witnessing minimal research on genetic revolution paradigm of alliums.…”

“…The genus Allium contain numerous ancient cultivated plant species [ 4 ]. The genus Allium is the largest among monocots, with over 1000 species adaptable to diverse climatic conditions worldwide [ 5 ]. Allium has a variety of economically important crop and decorative species, including bulb onion ( A ll i um cepa ), garlic ( Allium sativum ), chives ( Allium schoenoprasum ), Chinese chives ( Allium tuberosum ), rakkyo ( Allium chinense ), bunching onion ( Allium fistulosum ) and leek ( Allium porrum ).…”

“…Onions are in high demand because of the world's rapidly rising population [ 7 ]. Onions are difficult to breed due to their biennial life cycle, high frequencies of inbreeding, and cross-pollination [ 5 , 12 ]. The distinct features that aid in resistance and tolerance to various stresses challenges are found in wild and semi-domesticated Allium species [ 1 ].…”

Newly Developed Restorer Lines of Sorghum [Sorghum bicolor (L.) Moench] Resistant to Greenbug

“…The allele-specific molecular markers developed based on the SNPs in the candidate gene sequences, as well as the SSR markers closely linked to the Rf2 gene, can be used for controlling F 1 seed hybridity, determining the purity of R-lines, and for the analysis of populations and isolating homozygous plants from them. There are numerous examples of developing the diagnostic molecular markers for fertility restorer genes in sunflower [17], pepper [18], onion [19], rapeseed [20], and other crops [21]. Currently, several SSR markers have been developed which are intensively used for the identification of the Rf2 gene in sorghum collection and breeding material [22,23].…”

Current insights and advances into plant male sterility: new precision breeding technology based on genome editing applications

“…This condition can be overcome by nuclear genes that are functional in dominant conditions (Jindal et al, 2019); they are defined as restorers of fertility (Rf) and can suppress or downregulate the CMS genes and revert male sterility (Schnable and Wise, 1998;Ning et al, 2020). In contrast, genic male sterility (GMS), also reported as nuclear male sterility (NMS), or two-lines breeding system, is generally controlled by single nuclear genes, mostly by recessive alleles (ms) (Colombo and Galmarini, 2017;Manjunathagowda, 2021).…”