Acid Citrus Fruit Improvement via Interploid Hybridization Using Allotetraploid Somatic Hybrid and Autotetraploid Breeding Parents
Acid Citrus Fruit Improvement via Interploid Hybridization Using Allotetraploid Somatic Hybrid and Autotetraploid Breeding Parents
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DOI:
10.21273/jashs.130.3.392
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发表时间:
2005-05
影响因子:
1.9
通讯作者:
Z. Viloria;J. Grosser
中科院分区:
文献类型:
--
作者:
Z. Viloria;J. Grosser
Interploid hybridization was conducted using ʻKeyʼ lime (Citrus aurantifolia (Cristm.) Swing.), ʻLakelandʼ limequat hybrid (C. aurantifolia × Fortunella japonica (Thumb.) Swing.), Palestine sweet lime (C. limettioides Tan.), ʻEtrogʼ citron (C. medica L.), and seven lemon (C. limon (L.) Burm. F.) varieties as female progenitors and fi ve allo- tetraploid somatic hybrids {ʻHamlinʼ sweet orange (C. sinensis (L.) Osbeck) × ʻFemminelloʼ lemon (C. limon)); ʻKeyʼ lime × ʻValenciaʼ sweet orange (C. sinensis); ʻValenciaʼ sweet orange × rough lemon (C. jambhiri Lush); Milam lemon (purported C. jambhiri hybrid) × ʻFemminelloʼ lemon (C. limon); and ʻValenciaʼ sweet orange × ʻFemminelloʼ lemon} and two autotetraploids (ʻGiant Keyʼ lime (C. aurantifolia) and ʻFemminelloʼ lemon) as pollen progenitors. A few tetraploid × diploid crosses were also performed. Thirty-fi ve parental cross combinations were accomplished in 2000, 2001, and 2002. The breeding targets were seedlessness, cold-tolerance, and disease resistance. Triploid hybrids were recovered through embryo culture. Generation of triploid citrus hybrids was affected by several factors including sexual compatibility, cross direction, embryo developmental stage, pollen viability, as well as horticultural practices and climatic conditions. Effi ciency of triploid hybrid production was higher in diploid × tetraploid crosses than the reciprocal. Many more triploid hybrids were generated from lemon seed progenitors compared to the other acid citrus fruit progenitors. ʻTodo el Anoʼ, ʻLisbonʼ, and ʻLimonero Fino 49ʼ showed the highest sexual compatibility. Embryo germination rate and normal plant recovery were also higher in lemons as compared to the other seed progenitors. Low winter temperatures might have affected the hybrid production effi ciency from tropical acid fruit progenitors. A total of 650 hybrids (mostly triploid) were transferred to soil. The novel genetic combinations of these progenies should be valuable for the genetic improvement of acid citrus fruit (lemons and limes). Commercial acid citrus fruits are primarily represented by lemon and acid limes in world production. Lemon was identifi ed as a hybrid of sour orange (Citrus aurantium L.) and citron (C. medica) through chloroplast and nuclear genome analysis (Gulsen and Roose, 2001). Citrus aurantifolia is considered a true acid lime, with small, spherical, and seedy fruit. The most common variety is ʻMexicanʼ lime (also known as ʻWest Indianʼ or ʻKeyʼ lime). Molecular analysis suggested that citron and C. micrantha Wester. were its progenitors (Nicolosi et al., 2000). Citrus latifolia Tan. is also an acid lime, with larger spherical, seedless fruit. It is a triploid hybrid of unknown origin. ʻTahitiʼ or ʻPersianʼ lime is the most commercially grown variety. ʻBearssʼ was initially considered a variety of ʻTahitiʼ lime, but it did not differ suffi ciently from ʻTahitiʼ lime to be considered a new variety. Both lemon and limes require different climatic conditions for optimal production. Lemon is more adapted to subtropical conditions with low-humidity atmosphere; even so, most of the growing lemon areas are periodically exposed to freezes. Limes are tropical species that are generally grown in warm and humid areas of the subtropics. Marketing of fresh acid citrus fruit estab- lishes fruit color difference to facilitate the identifi cation of the two groups—yellow for lemon and green for limes. The worldwide acid citrus fruit industry requires new varieties not only to satisfy a fresh market that demands high quality seed- less fruit with high acid content and the manufacturing industry that calls for high-quality juice and oil but also to develop other horticultural traits to minimize the more threatening citrus diseases such as asiatic citrus canker (Xanthomonas axonopodis pv. citri (Hasse) Vauterin et al.), mal secco fungus (Phoma tracheiphila (Petri) Kantsch. & Gik.) citrus tristeza virus, and witchesʼ broom disease of lime (Phytoplasma aurantifolia Zreik et al.) Further- more, since lemon and lime are cold sensitive, improving cold hardiness is another important objective. In Florida, in addition