Molecular diversity and association of simple sequence repeat markers with kernel mass in cultivated groundnut (Arachis hypogaea L.)

Abstract Groundnut yield can be further enhanced by improving pod and kernel size vis-a-vis mass. Marker assisted breeding will be an ideal option for directed improvement of hundred kernel mass. A study was undertaken to detect molecular diversity using 35 SSRs in 12 mutant genotypes, developed through chemical mutagenesis, from an interspecific large kernel size pre-breeding line and to identify markers associated with kernel mass. SSRs yielded an average of 3.57 polymorphic bands per primer. Average polymorphism and PIC were 64.95% and 0.62, respectively. Cluster analysis revealed two main clusters separated at 61% Jaccard's similarity coefficient. Vast of the genotypes were grouped into single cluster, confirming common pedigree of these genotypes. AMOVA among 12 mutant genotypes and their parent detected 15% of total variation associated with kernel mass. K-W ANOVA detected significant association of five SSRs with kernel mass. Among these associated primers, TC3A12 and TC9H09 accounted for 28% and 12% of phenotypic variation due to kernel mass and were associated with major QTLs. Out of these two associated primer, TC3A12 differentiated genotypes with higher kernel mass from genotypes with lower kernel mass by amplifying a band of approximately of 450bp. Thus association of TC3A12 primer with a major QTL of kernel mass was further validated in genotypes with diverse background. The TC3A12 primer discriminated genotypes with higher kernel mass from genotype with lower kernel mass by amplifying the band of 400bp among genotypes with higher kernel mass

Does improved oleic acid content due to marker-assisted introgression of ahFAD2 mutant alleles in peanuts alter its mineral and vitamin composition?

Peanuts (Arachis hypogaea L.) with high oleic acid content have extended shelf life and several health benefits. Oleic, linoleic, and palmitic acid contents in peanuts are regulated by ahFAD2A and ahFAD2B mutant alleles. In the present study, ahFAD2A and ahFAD2B mutant alleles from SunOleic 95R were introgressed into two popular peanut cultivars, GG-7 and TKG19A, followed by markers-assisted selection (MAS) and backcrossing (MABC). A total of 22 MAS and three MABC derived lines were developed with increased oleic acid (78–80%) compared to those of GG 7 (40%) and TKG 19A (50%). Peanut kernel mineral and vitamin composition remained unchanged, while potassium content was altered in high oleic ingression lines. Two introgression lines, HOMS Nos. 37 and 113 had over 10% higher pooled pod yield than respective best check varieties. More than 70% recurrent parent genome recovery was observed in HOMS-37 and HOMS-113 through recombination breeding. However, the absence of recombination in the vicinity of the target locus resulted in its precise introgression along with ample background genome recovery. Selected introgression lines could be released for commercial cultivation based on potential pod yield and oleic acid content

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Not AvailablePeanut bud necrosis disease is one of the major diseases in peanut. Interspecific pre-breeding lines were identified as resistant to bud necrosis disease. Molecular diversity analysis in 115 lines resistant to bud necrosis disease using simple sequence repeat markers revealed wide genetic diversity among lines. Out of 219 bands amplified, 205 were found polymorphic. Polymorphism information content (PIC) value ranged from 0.5 to 0.94, with an average of 0.82. The cluster analysis and PCoA grouped 115 resistant lines and one susceptible cultivar into three major clusters sharing 58% similarity. Susceptible cultivar KRG-1 was distantly related to resistant lines NRCGCS-28 and NRCGCS-86. AMOVA predicted 96% variation within population and 4% among populations. NRCGCS-28 and NRCGCS-86 were found to be moderately resistant and KRG-1 as highly susceptible under artificially challenged inoculation conditions. The incubation period for appearance of disease symptoms were longer in NRCGCS-28 and NRCGCS-86 than KRG-1 under artificially challenged inoculation conditions. Thus, the present study reports additional sources for resistance to peanut bud necrosis disease (PBND).Not Availabl

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Not AvailableGroundnut yield can be further enhanced by improving pod and kernel size vis-a-vis mass. Marker assisted breeding will be an ideal option for directed improvement of hundred kernel mass. A study was undertaken to detect molecular diversity using 35 SSRs in 12 mutant genotypes, developed through chemical mutagenesis, from an interspecific large kernel size pre-breeding line and to identify markers associated with kernel mass. SSRs yielded an average of 3.57 polymorphic bands per primer. Average polymorphism and PIC were 64.95% and 0.62, respectively. Cluster analysis revealed two main clusters separated at 61% Jaccard’s similarity coefficient. Vast of the genotypes were grouped into single cluster, confirming common pedigree of these enotypes. AMOVA among 12 mutant genotypes and their parent detected 15% of total variation associated with kernel mass. K-W ANOVA detected significant association of five SSRs with kernel mass. Among these associated primers, TC3A12 and TC9H09 accounted for 28% and 12% of phenotypic variation due to kernel mass and were associated with major QTLs. Out of these two associated primer, TC3A12 differentiated genotypes with higher kernel mass from genotypes with lower kernel mass by amplifying a band of approximately of 450bp. Thus association of TC3A12 primer with a major QTL of kernel mass was further validated in genotypes with diverse background. The TC3A12 primer discriminated genotypes with higher kernel mass from genotype with lower kernel mass by amplifying the band of 400bp among genotypes with higher kernel mass.Not Availabl

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Not AvailableMolecular markers are useful tools for assaying genetic variation and provide an efficient means for early and reliable selection of genotypes having resistance to peanut bud necrosis disease (PBND) in peanut breeding programs. Molecular diversity and association of simple sequence repeat (SSR) markers with resistance to PBND was detected in 21 interspecific pre-breeding lines and three cultivars of peanut differing in degree of resistance to PBND. Forty-five primer pairs yielded a total of 531 fragments, of which 337 were polymorphic, with an average of 7.5 polymorphic fragments per primer. Polymorphism ranged from 0 - 100% with an average of 60.2%. Cluster analysis (UPGMA) revealed two main clusters separated at 77% Jaccard’s similarity oefficient based on resistance to PBND. All 14 susceptible lines were grouped into a single cluster, while 11 resistant lines grouped into a separate cluster. AMOVA among 24 lines detected 43% (P < 0.001) of total variation associated with resistance to PBND. Kruskal-Wallis ANOVA detected the significant association of 16 primers with resistance to PBND. Nine out of 16 primers explained more than 10% of phenotypic variation due to resistance to PBND. It appears that these loci are associated with the resistance to PBND in peanut and major QTLs with regression coefficient value (r2) ranging from 10.1% to 77.5%. Of which PM15190, PM188165 and PM201130 loci effectively differentiated most of the resistant lines from the susceptible lines.Not Availabl

Steady expression of high oleic acid in peanut bred by marker-assisted backcrossing for fatty acid desaturase mutant alleles and its effect on seed germination along with other seedling traits.

Peanut (Arachis hypogaea L.) is an important nutrient-rich food legume and valued for its good quality cooking oil. The fatty acid content is the major determinant of the quality of the edible oil. The oils containing higher monounsaturated fatty acid are preferred for improved shelf life and potential health benefits. Therefore, a high oleic/linoleic fatty acid ratio is the target trait in an advanced breeding program. The two mutant alleles, ahFAD2A (on linkage group a09) and ahFAD2B (on linkage group b09) control fatty acid composition for higher oleic/linoleic ratio in peanut. In the present study, marker-assisted backcrossing was employed for the introgression of two FAD2 mutant alleles from SunOleic95R into the chromosome of ICGV06100, a high oil content peanut breeding line. In the marker-assisted backcrossing-introgression lines, a 97% increase in oleic acid, and a 92% reduction in linoleic acid content was observed in comparison to the recurrent parent. Besides, the oleic/linoleic ratio was increased to 25 with respect to the recurrent parent, which was only 1.2. The most significant outcome was the stable expression of oil-content, oleic acid, linoleic acid, and palmitic acid in the marker-assisted backcrossing-introgression lines over the locations. No significant difference was observed between high oleic and normal oleic in peanuts for seedling traits except germination percentage. In addition, marker-assisted backcrossing-introgression lines exhibited higher yield and resistance to foliar fungal diseases, i.e., late leaf spot and rust