AUTHOR=Bollam Srikanth , Romana Kirandeep Kaur , Rayaprolu Laavanya , Vemula Anilkumar , Das Roma Rani , Rathore Abhishek , Gandham Prasad , Chander Girish , Deshpande Santosh P. , Gupta Rajeev 

TITLE=Nitrogen Use Efficiency in Sorghum: Exploring Native Variability for Traits Under Variable N-Regimes

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.643192

DOI=10.3389/fpls.2021.643192

ISSN=1664-462X

ABSTRACT=Exploration and exploitation of natural genetic variability for improved Nitrogen Use Efficiency (NUE) in Sorghum is one of the primary goals in the modern crop improvement programs. The integrated strategies include high-throughput phenotyping, new generation sequencing-based genotyping technologies, and apriori selected candidate gene studies that help understand the detailed physiological and molecular mechanisms underpinning this complex trait. A set of sixty diverse sorghum genotypes were evaluated for different leaf, growth, panicle, and biological yield traits along with NUE traits in the field (under three N regimes) for two seasons. Significant variations for different yield and related traits under 0% and 50% N confirmed the availability of native genetic variability in sorghum under low N regimes. Sorghum genotypes with distinct genetic background had interestingly similar NUE associated traits. The Genotyping-By-Sequencing based SNPs (>89K) used to study the population structure, and phylogenetic groupings identified three distinct groups. The information on grain N and stalk N content of the individuals overlaid on the phylogenetic groups indicated randomness in the distribution for adaptation under variable N regimes. This study identified promising sorghum genotypes with consistent performance under varying environments, with buffer capacity for yield under low N conditions. We also report better performing genotypes for varied production use - grain, stover, and dual-purpose sorghum having differential adaptation response to NUE traits. Expression profiling of NUE associated genes in shoot and root tissues of contrasting lines (PVK801 and HDW703) grown in varying N conditions revealed interesting outcomes. Root tissues of contrasting lines exhibited differential expression profiles for transporter genes (SbAMT and SbNRT); primary assimilatory and assimilatory genes (SbGS, SbGOGAT[NADH], SbGOGAT[Fd], and SbNiR[NADH]3); and amino acid biosynthesis associated gene (SbGDH). Identification and expression profiling of contrasting sorghum genotypes in varying N dosages will provide new information to understand the response of NUE genes towards adaptation to the differential N regimes in sorghum. High NUE genotypes identified from this study could be potential candidates for in-depth molecular analysis and contribute towards the development of N efficient sorghum cultivars.