RESUMEN
Yellow mosaic disease (YMD) is one of the major devastating constraints to soybean production in Pakistan. In the present study, we report the identification of resistant soybean germplasm and a novel mutation linked with disease susceptibility. Diverse soybean germplasm were screened to identify YMD-resistant lines under natural field conditions during 2016-2020. The severity of YMD was recorded based on symptoms and was grouped according to the disease rating scale, which ranges from 0 to 5, and named as highly resistant (HR), moderately resistant (MR), resistant (R), susceptible (S), moderately susceptible (MS), and highly susceptible (HS), respectively. A HR plant named "NBG-SG Soybean" was identified, which showed stable resistance for 5 years (2016-2020) at the experimental field of the National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan, a location that is a hot spot area for virus infection. HS soybean germplasm were also identified as NBG-47 (PI628963), NBG-117 (PI548655), SPS-C1 (PI553045), SPS-C9 (PI639187), and cv. NARC-2021. The YMD adversely affected the yield and a significant difference was found in the potential yield of NBG-SG-soybean (3.46 ± 0.13a t/ha) with HS soybean germplasm NARC-2021 (0.44 ± 0.01c t/ha) and NBG-117 (1.12 ± 0.01d t/ha), respectively. The YMD incidence was also measured each year (2016-2020) and data showed a significant difference in the percent disease incidence in the year 2016 and 2018 and a decrease after 2019 when resistant lines were planted. The resistance in NBG-SG soybean was further confirmed by testing for an already known mutation (SNP at 149th position) for YMD in the Glyma.18G025100 gene of soybean. The susceptible soybean germplasm in the field was found positive for the said mutation. Moreover, an ortholog of the CYR-1 viral resistance gene from black gram was identified in soybean as Glyma.13G194500, which has a novel deletion (28bp/90bp) in the 5`UTR of susceptible germplasm. The characterized soybean lines from this study will assist in starting soybean breeding programs for YMD resistance. This is the first study regarding screening and molecular analysis of soybean germplasm for YMD resistance.
RESUMEN
Soybean is considered one of the important crops among legumes. Due to high nutritional contents in seed (proteins, sugars, oil, fatty acids, and amino acids), soybean is used globally for food, feed, and fuel. The primary consumption of soybean is vegetable oil and feed for chickens and livestock. Apart from this, soybean benefits soil fertility by fixing atmospheric nitrogen through root nodular bacteria. While conventional breeding is practiced for soybean improvement, with the advent of new biotechnological methods scientists have also engineered soybean to improve different traits (herbicide, insect, and disease resistance) to fulfill consumer requirements and to meet the global food deficiency. Genetic engineering (GE) techniques such as transgenesis and gene silencing help to minimize the risks and increase the adaptability of soybean. Recently, new plant breeding technologies (NPBTs) emerged such as zinc-finger nucleases, transcription activator-like effector nucleases, and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR/Cas9), which paved the way for enhanced genetic modification of soybean. These NPBTs have the potential to improve soybean via gene functional characterization precision genome engineering for trait improvement. Importantly, these NPBTs address the ethical and public acceptance issues related to genetic modifications and transgenesis in soybean. In the present review, we summarized the improvement of soybean through GE and NPBTs. The valuable traits that have been improved through GE for different constraints have been discussed. Moreover, the traits that have been improved through NPBTs and potential targets for soybean improvements via NPBTs and solutions for ethical and public acceptance are also presented.