Cyanogenesis in the Sorghum Genus: From Genotype to Phenotype

Domestication has resulted in a loss of genetic diversity in our major food crops, leading to susceptibility to biotic and abiotic stresses linked with climate change. Crop wild relatives (CWR) may provide a source of novel genes potentially important for re-gaining climate resilience. Sorghum bicolor is an important cereal crop with wild relatives that are endemic to Australia. Sorghum bicolor is cyanogenic, but the cyanogenic status of wild Sorghum species is not well known. In this study, leaves of wild species endemic in Australia are screened for the presence of the cyanogenic glucoside dhurrin. The direct measurement of dhurrin content and the potential for dhurrin-derived HCN release (HCNp) showed that all the tested Australian wild species were essentially phenotypically acyanogenic. The unexpected low dhurrin content may reflect the variable and generally nutrient-poor environments in which they are growing in nature. Genome sequencing of six CWR and PCR amplification of the CYP79A1 gene from additional species showed that a high conservation of key amino acids is required for correct protein function and dhurrin synthesis, pointing to the transcriptional regulation of the cyanogenic phenotype in wild sorghum as previously shown in elite sorghum.

Genetic Diversity and Population Structure of Sorghum [Sorghum Bicolor (L.) Moench] Accessions as Revealed by Single Nucleotide Polymorphism Markers

Ethiopia is the center of origin for sorghum [Sorghum bicolor (L.) Moench], where the distinct agro-ecological zones significantly contributed to the genetic diversity of the crops. A large number of sorghum landrace accessions have been conserved ex situ. Molecular characterization of this diverse germplasm can contribute to its efficient conservation and utilization in the breeding programs. This study aimed to investigate the genetic diversity of Ethiopian sorghum using gene-based single nucleotide polymorphism (SNP) markers. In total, 359 individuals representing 24 landrace accessions were genotyped using 3,001 SNP markers. The SNP markers had moderately high polymorphism information content (PIC = 0.24) and gene diversity (H = 0.29), on average. This study revealed 48 SNP loci that were significantly deviated from Hardy–Weinberg equilibrium with excess heterozygosity and 13 loci presumed to be under selection (P < 0.01). The analysis of molecular variance (AMOVA) determined that 35.5% of the total variation occurred within and 64.5% among the accessions. Similarly, significant differentiations were observed among geographic regions and peduncle shape-based groups. In the latter case, accessions with bent peduncles had higher genetic variation than those with erect peduncles. More alleles that are private were found in the eastern region than in the other regions of the country, suggesting a good in situ conservation status in the east. Cluster, principal coordinates (PCoA), and STRUCTURE analyses revealed distinct accession clusters. Hence, crossbreeding genotypes from different clusters and evaluating their progenies for desirable traits is advantageous. The exceptionally high heterozygosity observed in accession SB4 and SB21 from the western geographic region is an intriguing finding of this study, which merits further investigation.

Potensi Produksi dan Mutu Benih serta Produksi Biomassa Sorghum bicolor Varietas Samurai 2 pada Umur Panen Berbeda sebagai Bahan Pakan

Sorghum bicolor var. Samurai 2 can be used as raw material in silage production for ruminant feed. The problem encountered is the difficulty of obtaining certified seeds for commercial sorghum production. So that is necessary to do this research to investigate potential sorghum seed production and its quality of Sorghum bicolor var. Samurai 2. The study was conducted at University Research Station-Jonggol Animal Education and Research Unit, Bogor Agricultural University. The experimental design used was a randomized block design with 4 treatments and 5 replicates. Five individual plants were taken to measure the variables at each treatment set. The treatments consisted of different harvesting times, namely P95 (harvested 95 days after planting), P100, P105 and P110. The variables observed were dry weight of shelled seeds, seed weight per panicle, weight of panicle stalk, panicle weight, seed production per ha, seed moisture content, seed viability test, and shoot biomass production per ha. The results showed that seed production per ha, panicle dry matter weight, fresh seed moisture content, panicle stalk dry weight was not significantly different. Dry weight of shelled seeds, dry weight of seeds per panicle, panicle dry weight, seed viability, weight of biomass per ha were significantly different (p<0.05). The potential for the production of shelled seeds, dry matter of seeds per panicle was the best in the P105 and P110, the viability of the seeds in the P105 and shoot biomass production per ha in the P105. The potential for shelled seed production (4038 kg ha-1), seed dry weight per panicle (54.87 g panicle-1), seed viability (92.8%) and the best biomass production (55.88 tons ha-1) were in treatment P105. Key words: seed production, shoot biomass, Sorghum bicolor, viability

Respon Pertumbuhan dan Produksi Sorgum (Sorghum bicolor [L.] Moench.) dengan Pemberian Berbagai Dosis Amelioran di Lahan Pasca Tambang Timah

Lahan pasca tambang timah termasuk dalam karakteristik lahan marjinal karena memiliki tingkat kandungan hara yang rendah. Upaya pemanfaatan lahan pasca tambang timah pada pertanian yaitu budidaya tanaman seperti sorgum dengan pemberian berbagai dosis pupuk kotoran ayam dan N,P,K. Tujuan dari penelitian ini adalah mengetahui respon pertumbuhan dan produksi sorgum di lahan pasca tambang timah dengan pemberian berbagai dosis pupuk kotoran ayam dan N,P,K. Penelitian ini menggunakan Rancangan Acak Kelompok Faktorial (RAKF). Faktor pertama adalah dosis pupuk kotoran ayam yang terdiri dari 100 %, 50 % dan 25 % dosis acuan. Faktor kedua adalah dosis pupuk N,P,K yang terdiri dari 100 % dan 50 % dosis acuan. Hasil penelitian menunjukkan pupuk kotoran ayam berpengaruh nyata terhadap parameter jumlah daun. Pupuk N,P,K berpengaruh sangat nyata terhadap parameter tinggi tanaman, diameter batang, bobot berangkasan basah, panjang akar, hasil biji per tanaman dan produktivitas. Pupuk N,P,K berpengaruh nyata terhadap parameter total padatan terlarut. Pengurangan dosis pupuk kotoran ayam dari 100 % ke 50 % menunjukkan hasil berbeda tidak nyata terhadap jumlah daun. Pengurangan dosis pupuk N,P,K menunjukkan hasil berbeda nyata terhadap semua parameter. Perlakuan A1K1 (pupuk kotoran ayam 100 % + pupuk N,P,K 100 %) merupakan kombinasi perlakuan terbaik untuk pertumbuhan dan produksi sorgum di lahan pasca tambang timah.