Introgression of Shoot Fly (Atherigona soccata L. Moench) Resistance QTLs into Elite Post-rainy Season Sorghum Varieties Using Marker Assisted Backcrossing (MABC)

Shoot fly (Atherigona soccata L. Moench) is a serious pest in sorghum production. Management of shoot fly using insecticides is expensive and environmentally un-safe. Developing host–plant resistance is the best method to manage shoot fly infestation. Number of component traits contribute for imparting shoot fly resistance in sorghum and molecular markers have been reported which were closely linked to QTLs controlling these component traits. In this study, three QTLs associated with shoot fly resistance were introgressed into elite cultivars Parbhani Moti (= SPV1411) and ICSB29004 using marker assisted backcrossing (MABC). Crosses were made between recurrent parents and the QTL donors viz., J2658, J2614, and J2714. The F1s after confirmation for QTL presence were backcrossed to recurrent parents and the resultant lines after two backcrosses were selfed thrice for advancement. The foreground selection was carried out in F1 and BCnF1 generations with 22 polymorphic markers. Forty-three evenly distributed simple sequence repeat markers in the sorghum genome were used in background selection to identify plants with higher recurrent parent genome recovery. By using two backcrosses and four rounds of selfing, six BC2F4 progenies were selected for ICSB29004 × J2658, five BC2F4 progenies were selected for ICSB29004 × J2714 and six BC2F4 progenies were selected for Parbhani Moti × J2614 crosses. Phenotyping of these lines led to the identification of two resistant lines for each QTL region present on chromosome SBI-01, SBI-07 and SBI-10 in ICSB 29004 and Parbhani Moti. All the introgression lines (ILs) showed better shoot fly resistance than the recurrent parents and their agronomic performance was the same or better than the recurrent parents. Further, the ILs had medium plant height, desirable maturity with high yield potential which makes them better candidates for commercialization. In the present study, MABC has successfully improved the shoot fly resistance in sorghum without a yield penalty. This is the first report on the use of MABC for improving shoot fly resistance in post-rainy season sorghum

Variations in structure and saccharification efficiency of biomass of different sorghum varieties subjected to aqueous ammonia and glycerol pretreatments

Sorghum biomass is a potential feedstock for lignocellulosic bioethanol production. The selection of suitable sorghum variety is essential to obtain high ethanol yield. In this paper we screened sorghum varieties belonging to sweet sorghum, post rainy sorghum, and hybrid sorghum. These varieties were screened based on their agronomic traits, amenability to pretreatment methods, and enzymatic digestibility. The sorghum biomass was pretreated using glycerol (60 %) at 190 ̊C for 60 min and aqueous ammonia (15 %) at 120 ̊C for 60 min. The digestibility of the pretreated biomass was determined using commercial cellulase (Cellic CTec2) at 10U/g loading, and the structural changes in the pretreated biomass were analyzed by spectroscopy and scanning electron microscopy. Sweet sorghum varieties showed significant variations in phenotypic traits such as fresh stalk yield, dry fodder yield, and juice yield. The cellulose digestibility among the sorghum varieties after the pretreatment also differed significantly. The cellulose digestibility levels of glycerol range from 64 % to 89 % and ammonia pretreated sorghum from 63 % to 81 %. The total sugar yields varied from 227 mg/g to 356 mg/g and 209 mg/g to 313 mg/g for sorghum pretreated with ammonia and glycerol, respectively. Although the delignification of sorghum varieties was higher (31%–65%) after ammonia pretreatment than glycerol pretreatment, the cellulose digestibility was higher for the glycerol pretreated biomass. These results indicated that effect of delignification on cellulose digestibility is trivial. This study explores factors affecting pretreatment and cellulose digestibility of sorghum varieties for maximum sugar yield in the cellulosic ethanol process

Comparison of shoot fly resistance qtls in sorghum introgression lines using snp genotyping

Shoot fly is a major pest in sorghum that causes significant annual yield loss. Use of pesticide to control this pest is an expensive and environmentally unsafe approach. Present study investigated the host plant resistance mechanism to develop shoot fly resistance (SFR) lines through transfer of shoot fly resistance QTLs (glossiness, trichome density, ovipositional non-preference) using SSR marker assisted backcrossing. Genomic regions for SFR showed four QTLs on SBI 01, SBI 07, SBI 05 and SBI 10 contributing up to 11.5%, 18.3%, 14% and 14.7% phenotypic variation. But QTLs on SBI 05 and SBI 10 for glossiness and trichome density are the major QTLs for which 10 SNPs have been designed. In earlier studies, three QTL regions associated with shoot fly resistance were successfully introgressed into elite cultivar SPV 1411 (Parbhani Moti) and a B line ICSB29004 using donors viz. J2658 (SBI01), J2614 (SBI10), and J2714 (SBI07) (which are derivatives of BTx 623). Phenotyping of introgression lines (ILs) led to the identification of resistant lines for each QTL region present on chromosome SBI-01, SBI-07 and SBI-10. Hence, in this study we have analysed the above developed ILs using single-nucleotide polymorphism (SNP) markers tightly linked to shoot fly resistant QTLs. The results showed that introgression lines with QTL present on chromosome SBI-10 were segregating for favorable alleles for leaf glossiness and for trichome density in homozygous condition. Other introgression lines with QTLs on chromosome SBI-01 and SBI-07 for component traits - oviposition non-preference, seedling vigor are segregated for glossiness trait also thus showing the transfer of non-targeted region, which in this case proved beneficial for SFR. This study showed that these SNPs can be used to analyze introgression lines and can be used as genomic markers for early generation selection of shoot fly resistance lines

Heterosis and Combining ability studies for improving grain Fe and Zn concentration and agronomic traits in Sorghum [Sorghum bicolor (L.) Moench]

Objective: Sorghum is a staple food for more than 300 million people in more than 30 counties. It is a rich source of micronutrients. Biofortifying sorghum with enhanced grain Fe and Zn is a major breeding objective. The present study was aimed at formulating suitable breeding program by studying gene action, heterosis and combining ability for improving grain Fe and Zn concentration in sorghum. Materials & Methods: This study was conducted in Line × Tester mating design involving seven parents. Twelve hybrids were developed by mating three lines with four testers. The combining ability of the crosses indicated predominance of dominance variance than additive variance for the agronomic traits such as days to 50 % flowering, grain yield, grain Fe and Zn concentration except for plant height and 100 seeds weight. Main Findings: Higher magnitude of SCA than GCA variance for grain iron and zinc concentration indicated the importance of non-additive gene action in these nutritional traits improvement. Hybrids showed heterosis for agronomic traits and for grain Fe concentration and limited heterosis for grain Zn. Most of the traits showed significant positive heterosis over mid parent value indicating the predominance of dominant gene action except the trait -100 seeds weight. Significant positive midparent heterosis for grain iron (Fe) indicated that there would be an opportunity to exploit heterosis in improving for grain Iron. But for Zn concentration, there is limited possibility for exploitation of heterosis. This study suggested that simple selection will improve plant height and 100-seed weight in sorghum but heterosis breeding is more useful for improving grain yield. While both parents need to be improved for improving grain Zn concentration there is good scope for exploiting heterosis for improving grain Fe concentration in sorghum. Conclusion & Recommendations: We released first biofortified sorghum variety ‘Parbhani Shakti’ (45 ppm Fe and 32 ppm Zn) with higher yield (4 tha-1), higher protein (11.9%) and low phytates content (4.1 mg/100 g) and released in 2018. Biofortified sorghums complements the on-going approaches for combating dietary induced micronutrient malnutrition

Doubling grain Fe and Zn concentration in sorghum to combat the micronutrient malnutrition in sorghum eating populations

Dietary induced micronutrient malnutrition (MNM) is one of the greatest global challenges of our times and India has largest number of malnourished people globally. Sorghum is among the major staples and a cheapest sources of micronutrients therefore, biofortification of sorghum is of high priority. From screening of more than 4000 accessions and breeding lines we identified promising donors for Fe and Zn and established the genetic control. Fe and Zn are quantitatively inherited. While grain Zn in predominantly under additive gene control, non-additive gene actions also has role in controlling grain Fe. To develop hybrids with high Fe and Zn both parents should have high Fe and Zn. We demonstrated the prediction of F1 hybrid performance based on mid-parental value for Fe and Zn. Both Fe and Zn are positively correlated (r=0.6 to 0.8) and simultaneous improvement for Fe and Zn is feasible. Using RIL population sorghum genetic map was constructed with 2,088 markers (1148 DArTs, 927 DArTSeqs and 13 SSRs) covering 1355.52 cM with an average marker interval of 0.6cM. Forty-seven QTLs (individual) and 7 QTLs (across) environments with small maineffect and 21 co-localized QTLs for Fe and Zn were identified

Identification of QTLs and candidate genes for high grain Fe and Zn concentration in sorghum [Sorghum bicolor (L.)Moench]

Sorghum is a major food crop in the semi-arid tropics of Africa and Asia. Enhancing the grain iron (Fe) and zinc (Zn) concentration in sorghum using genetic approaches would help alleviate micronutrient malnutrition in millions of poor people consuming sorghum as a staple food. To localize genomic regions associated with grain Fe and Zn, a sorghum F6 recombinant inbred line (RIL) population (342 lines derived from cross 296B PVK 801) was phenotyped in six environments, and genotyped with simple sequence repeat (SSR), DArT (Diversity Array Technology) and DArTSeq (Diversity Array Technology) markers. Highly significant genotype environment interactions were observed for both micronutrients. Grain Fe showed greater variation than Zn. A sorghum genetic map was constructed with 2088 markers (1148 DArTs, 927 DArTSeqs and 13 SSRs) covering 1355.52 cM with an average marker interval of 0.6 cM. Eleven QTLs (individual) and 3 QTLs (across) environments for Fe and Zn were identified. We identified putative candidate genes from the QTL interval of qfe7.1, qzn7.1, and qzn7.2 (across environments) located on SBI-07 involved in Fe and Zn metabolism. These were CYP71B34, and ZFP 8 (ZINC FINGER PROTEIN 8). After validation, the linked markers identified in this study can help in developing high grain Fe and Zn sorghum cultivars in sorghum improvement programs globally

Genome‑wide association study and expression of candidate genes for Fe and Zn concentration in sorghum grains

Sorghum germplasm showed grain Fe and Zn genetic variability, but a few varieties were biofortified with these minerals. This work contributes to narrowing this gap. Fe and Zn concentrations along with 55,068 high-quality GBS SNP data from 140 sorghum accessions were used in this study. Both micronutrients exhibited good variability with respective ranges of 22.09–52.55 ppm and 17.92–43.16 ppm. Significant marker-trait associations were identified on chromosomes 1, 3, and 5. Two major effect SNPs (S01_72265728 and S05_58213541) explained 35% and 32% of Fe and Zn phenotypic variance, respectively. The SNP S01_72265728 was identified in the cytochrome P450 gene and showed a positive effect on Fe accumulation in the kernel, while S05_58213541 was intergenic near Sobic.005G134800 (zinc-binding ribosomal protein) and showed negative effect on Zn. Tissue-specific in silico expression analysis resulted in higher levels of Sobic.003G350800 gene product in several tissues such as leaf, root, flower, panicle, and stem. Sobic.005G188300 and Sobic.001G463800 were expressed moderately at grain maturity and anthesis in leaf, root, panicle, and seed tissues. The candidate genes expressed in leaves, stems, and grains will be targeted to improve grain and stover quality. The haplotypes identified will be useful in forward genetics breeding

The epidemiology and clinical manifestation of neurological melioidosis: A series of 19 cases from Southwest India over 10 years

No abstract availabl