Molecular characterization of sweet potato(Ipomoea batatas[L.]Lam)germplasms for desirable traits by using simple sequence repeats markers

Every breeding program that aims to create new and improved cultivars with desired traits mostly relies on information related to genetic diversity.Therefore,molecular characterization of germplasms is important to obtain target cultivars with desirable traits.Sweet potato[Ipomoea batatas(L.)Lam]is widely considered the world’s most important crop,with great diversity in morphological and phenotypic traits.The genetic diversity of 20 sweet potato germplasms originating from Bangladesh,CIP,Philippines,Taiwan,and Malaysia were compared,which was accomplished by genetic diversity analysis by exploring 20 microsatellite DNA markers for germplasm characterization and utilization.This information was effective in differentiating or clustering the sweet potato genotypes.A total of 64 alleles were generated using the 20 primers throughout the 20 germplasm samples,with locus IBS97 having the highest number of alleles(5),whereas locus IbU33 had the fewest alleles(2).The alleles varied in size from 105(IbU31)to 213 base pairs(IBS34).The Polymorphism Information Content(PIC)values for the loci IbL46 and IBS97 varied from 0.445 to 0.730.IBS97 has the highest number of effective alleles(3.704),compared to an average of 2.520.The average Shannon’s diversity index(H)was 1.003,ranging from 0.673 in IbU3 to 1.432 in IBS97.The value of gene flow(Nm)varied between 0.000 and 0.005,with an average of 0.003,whereas genetic differentiation(FST-values)ranged between 0.901 and 1.000.The sweet potato germplasm included in this study had a broad genetic base.SP1 vs.SP9 and SP12 vs.SP18 germplasm pairings had the greatest genetic distance(GD=0.965),while SP1 vs.SP2 germplasm couples had the least genetic diversity(GD=0.093).Twenty genotypes were classified into two groups in the UPGMA dendrogram,with 16 genotypes classified as group“A”and the remaining four genotypes,SP10,SP18,SP19,and SP20,classified as group“B.”According to cluster analysis,the anticipated heterozygosity(gene diversity)of Nei(1973)was 0.591 on average.In summary,SSR markers successfully evaluated the genetic relationships among the sweet potato accessions used and generated a high level of polymorphism.The results of the present study will be useful for the management of germplasm,improvement of the current breeding strategies,and the release of new cultivars as varieties.

Screening and evaluation of chilli(Capsicum annuum L.)genotypes for waterlogging tolerance at seedling stage

Waterlogging is an illustrious abiotic stress and the constrictions it enforces on plant roots have negative effects on growth and development.This study was undertaken to investigate waterlogging stress tolerant potential in chilli(Capsicum annum L.)genotypes through evaluating morphological,physiological,biochemical and anatomical parameters.Thirty-five days old seedlings of 10 chilli genotypes were exposed to waterlogging stress maintaining water height 3–5 cm over the soil surface artificially for three days.This duration(36–38 DAE)was termed as waterlogging period,and subsequent withdrawal of waterlogging condition(39–45 DAE)was regarded as a recovery phase.Based on their survival performance,two tolerant genotypes viz.,SRC-517 and BARI morich-2 and two susceptible genotypes viz.,AHM-206 and RI-1(6)were selected for studying stress tolerance mechanism.Under waterlogging,however,both genotypes(tolerant and susceptible)exhibited reduced root shoot length,dry weight ratio,petiole weight and leaf area,and noticeable reduction regarding these parameters was observed in susceptible genotypes.Moreover,tolerant genotypes displayed a higher recovery than susceptible genotypes after removal of waterlogging stress.Lower reduction of leaf area and photosynthetic pigments as well as higher reduction of relative water content(RWC)were noticed in susceptible genotypes.Higher accumulation of proline and total antioxidant capacity(TAC)during waterlogging condition in tolerant genotypes suggested lower oxidative damage.Although both genotypes lost total soluble sugar(TSS)relative to control at waterlogging stress,better performance was recorded in tolerant genotypes.During the period after the removal of extra water,a similar genotypic response in terms of TSS gain was seen.Undoubtedly,under flooding conditions,the development of aerenchyma cells in tolerant genotypes is a means of tolerance mechanism for long-term survival.Thus,the morpho-physiological and biochemical changes help to understand the tolerance mechanism in chilli under waterlogging stress.