Genetic improvement of<i>Citrus</i>for disease resistance

Rauf, Saeed; Iqbal, Zafar; Shahzad, Muhammad

doi:10.1080/03235408.2013.783982

Cited by 7 publications

(6 citation statements)

References 37 publications

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“…Despite occasional sterility, successful pseudo-backcrossing occurred for six subsequent generations, allowing for the introgression of the M. rotundifolia gene for powdery mildew resistance, Run1 , while maintaining a high proportion of V. vinifera (Bouquet et al, 2000). In cases of differing ploidy, one solution is the use of protoplast fusion, which has allowed for the creation of somatic hybrids in Citrus with ploidy differences as well as pollen/ovule sterility and abnormal chromosome pairing (Guo and Deng, 2001; Rauf et al, 2013). When fertile hybrids are still not possible and a causal locus has been identified, genome editing provides a viable alternative for introgression of valuable traits from wild germplasm.…”

Section: Genomic Resources and Limitations: Sequencingmentioning

confidence: 99%

Exploiting Wild Relatives for Genomics-assisted Breeding of Perennial Crops

2017

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Perennial crops are vital contributors to global food production and nutrition. However, the breeding of new perennial crops is an expensive and time-consuming process due to the large size and lengthy juvenile phase of many species. Genomics provides a valuable tool for improving the efficiency of breeding by allowing progeny possessing a trait of interest to be selected at the seed or seedling stage through marker-assisted selection (MAS). The benefits of MAS to a breeder are greatest when the targeted species takes a long time to reach maturity and is expensive to grow and maintain. Thus, MAS holds particular promise in perennials since they are often costly and time-consuming to grow to maturity and evaluate. Well-characterized germplasm that breeders can tap into for improving perennials is often limited in genetic diversity. Wild relatives are a largely untapped source of desirable traits including disease resistance, fruit quality, and rootstock characteristics. This review focuses on the use of genomics-assisted breeding in perennials, especially as it relates to the introgression of useful traits from wild relatives. The identification of genetic markers predictive of beneficial phenotypes derived from wild relatives is hampered by genomic tools designed for domesticated species that are often ill-suited for use in wild relatives. There is therefore an urgent need for better genomic resources from wild relatives. A further barrier to exploiting wild diversity through genomics is the phenotyping bottleneck: well-powered genetic mapping requires accurate and cost-effective characterization of large collections of diverse wild germplasm. While genomics will always be used in combination with traditional breeding methods, it is a powerful tool for accelerating the speed and reducing the costs of breeding while harvesting the potential of wild relatives for improving perennial crops.

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Section: Genomic Resources and Limitations: Sequencingmentioning

confidence: 99%

Exploiting Wild Relatives for Genomics-assisted Breeding of Perennial Crops

2017

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“…Major biotic constraint is susceptibility to many diverse pathogens and insects including virus, viroids, fungi, nematodes and bacteria resulting into the manifestation of various diseases such as Citrus Greening Disease (CGD) or Haunglongbing (HLB) disease, bacterial canker, Alternaria brown spot, Dagger nematode, Tristeza, Crinkly leaf, Cachexia, Exocortis etc. Rauf et al, 2013;Harper et al, 2014). Such susceptibility causes huge losses to citrus industry, one of the most important fruit crop industries in the world.…”

Section: Rapd For the Assessment Of Genetic Diversity In Acid Limementioning

confidence: 99%

“…This might be due to various reasons including lack of high yielding varieties, low quality planting materials, lack of use of disease resistant rootstocks, prevalence of various bacterial, fungal and viral diseases, lack of use of advanced crop management practices etc. Development of elite cultivars of acid lime with desirable qualitative and quantitative traits can be achieved via conventional and non-conventional breeding, protoplast fusion, genetic engineering, molecular marker assisted breeding and mutational breeding (Dominquez et al, 2002;Viloria and Grosser, 2005;Rauf et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Genetic Diversity Assessment of Acid Lime (Citrus Aurantifolia Swingle) Landraces of Eastern Nepal Using RAPD Markers

Munankarmi

Shrestha²,

Rana

et al. 2014

Int J Appl Sci Biotechnol

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Acid lime (Citrus aurantifolia Swingle) is an important commercial fruit crop, cultivated from terai to high hill landscapes of Nepal. However, production and productivity is very low due to various reasons including infestations by various diseases and pests, lack of diseases and pests resistant and high yielding varieties. In this context, determination of genetic variation at molecular level is fundamental to citrus breeders for the development of elite cultivars with desirable traits. In the present study, Random Amplified Polymorphic DNA (RAPD) marker technique has been employed to assess genetic diversity in 60 acid lime landraces representing different agro-ecological zones of eastern Nepal. Nine selected arbitrary primers generated 79 RAPD fragments of which 75 were polymorphic (94.94%). Phenogram was constructed by NTSYS-PC ver. 2.21i using UPGMA cluster analysis based on Jaccard's similarity coefficient to deduce overall genetic diversity and relationships of the acidlime genotypes under study. Sixty acid lime landraces formed seven clusters and similarity value ranged from 38% to 98% with an average of 72%. Genetic variation at different agro-ecological zones was assessed using Popgene ver. 1.32 and found 47% to 69.6% polymorphism. Shannon's index and Nei's gene diversity showed highest level of acid lime diversity in Terai zone (PPB, 69.62%; H, 0.213; I, 0.325) followed by mid-hill zone (PPB, 67.09%; H, 0.208; I, 0.317). The results obtained will be useful to citrus breeders for elite cultivar development. The RAPD-PCR technique is found to be the rapid and effective tool for genetic diversity assessment in acid lime landraces of Nepal.

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“…Considering these scenarios, elite acid lime varieties with desirable qualities—such as nematode resistance, resistance to disease, juice content, higher yield, stress tolerance, etc.—hold great promise. Development of such cultivars with desirable qualities can be achieved via breeding programs (conventional and non-conventional) viz., molecular marker-assisted breeding, protoplast fusion, mutation breeding, and genetic engineering [ 16 , 17 , 18 ]. Therefore, the study of genetic diversity at the molecular level would furnish valuable information regarding the diversity in the gene pool, which could be harnessed for a breeding and cultivar development program as well as for the conservation of acid lime germplasm in Nepal.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the Genetic Diversity of Acid Lime (Citrus aurantifolia (Christm.) Swingle) Cultivars of Eastern Nepal Using Inter-Simple Sequence Repeat Markers

Munankarmi

Rana

Bhattarai

et al. 2018

Plants

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Acid lime (Citrus aurantifolia (Christm.) Swingle) is an important fruit crop, which has high commercial value and is cultivated in 60 out of the 77 districts representing all geographical landscapes of Nepal. A lack of improved high-yielding varieties, infestation with various diseases, and pests, as well as poor management practices might have contributed to its extremely reduced productivity, which necessitates a reliable understanding of genetic diversity in existing cultivars. Hereby, we aim to characterize the genetic diversity of acid lime cultivars cultivated at three different agro-ecological gradients of eastern Nepal, employing PCR-based inter-simple sequence repeat (ISSR) markers. Altogether, 21 polymorphic ISSR markers were used to assess the genetic diversity in 60 acid lime cultivars sampled from different geographical locations. Analysis of binary data matrix was performed on the basis of bands obtained, and principal coordinate analysis and phenogram construction were performed using different computer algorithms. ISSR profiling yielded 234 amplicons, of which 87.18% were polymorphic. The number of amplified fragments ranged from 7–18, with amplicon size ranging from ca. 250–3200 bp. The Numerical Taxonomy and Multivariate System (NTSYS)-based cluster analysis using the unweighted pair group method of arithmetic averages (UPGMA) algorithm and Dice similarity coefficient separated 60 cultivars into two major and three minor clusters. Genetic diversity analysis using Popgene ver. 1.32 revealed the highest percentage of polymorphic bands (PPB), Nei’s genetic diversity (H), and Shannon’s information index (I) for the Terai zone (PPB = 69.66%; H = 0.215; I = 0.325), and the lowest of all three for the high hill zone (PPB = 55.13%; H = 0.173; I = 0.262). Thus, our data indicate that the ISSR marker has been successfully employed for evaluating the genetic diversity of Nepalese acid lime cultivars and has furnished valuable information on intrinsic genetic diversity and the relationship between cultivars that might be useful in acid lime breeding and conservation programs in Nepal.

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Genetic improvement ofCitrusfor disease resistance

Cited by 7 publications

References 37 publications

Exploiting Wild Relatives for Genomics-assisted Breeding of Perennial Crops

Exploiting Wild Relatives for Genomics-assisted Breeding of Perennial Crops

Genetic Diversity Assessment of Acid Lime (Citrus Aurantifolia Swingle) Landraces of Eastern Nepal Using RAPD Markers

Characterization of the Genetic Diversity of Acid Lime (Citrus aurantifolia (Christm.) Swingle) Cultivars of Eastern Nepal Using Inter-Simple Sequence Repeat Markers

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