Hooghvorst Isidre, Torrico Oscar, Hooghvorst Serge, Nogués Salvador
Departament de Biologia Evolutiva, Ecologia i Ciencies Ambientals, Secció de Fisiologia Vegetal, Universitat de Barcelona, Barcelona, Spain.
ROCALBA S.A., Girona, Spain.
Front Plant Sci. 2020 Apr 3;11:378. doi: 10.3389/fpls.2020.00378. eCollection 2020.
Doubled haploids in cucurbit species are produced through parthenogenesis via pollination with irradiated pollen for further use as parental lines for hybrid F1 production. In this study, seven genotypes of melon "Piel de Sapo" were appraised for agronomic traits and pathogen resistances to evaluate its commercial value and used as donor plant material for the parthenogenetic process. Then, parthenogenetic capacity of melon "Piel de Sapo" germplasm was evaluated and optimized. Several steps of the parthenogenetic process were assessed in this study such as melon fruit set after pollination with irradiated pollen, haploid embryo obtention, germination and growth of parthenogenetic embryos and plantlets, and chromosome doubling with colchicine or oryzalin and fruit set of doubled haploid lines. Parthenogenetic efficiencies of "Piel de Sapo" genotypes showed a high genotypic dependency during the whole process. Three different methods were assayed for parthenogenetic embryo detection: one-by-one, X-ray and liquid medium. X-ray radiography of seeds was four times faster than one-by-one method and jeopardized eight times less parthenogenetic embryo obtention than liquid medium. One third of melon fruits set after pollination with irradiated pollen contained at least one parthenogenetic embryo. The 50.94% of the embryos rescued did not develop into plantlets because failed to germinate or plantlet died at the first stages of development because of deleterious gene combination in haploid homozygosity. The distribution of the ploidy-level of the 26 parthenogenetic plantlets obtained was: 73.08% haploid, 23.08% spontaneous doubled haploid and 3.84% mixoploid. Two chromosome doubling methods, with colchicine or oryzalin, were compared with a third colchicine method. immersion of apical meristems in a colchicine solution for 2 h showed the highest results of plant survival, 57.33%, and chromosome doubling, 9.30% mixoploids and 20.93% doubled haploids. Fruit set and seed recovery of doubled haploids lines was achieved. In this study, doubled haploid lines were produced from seven donor genotypes of melon "Piel de Sapo," however, further improvements are need in order to increase the parthenogenetic efficiency.
通过用辐照花粉授粉诱导孤雌生殖来产生葫芦科作物的双单倍体，以供进一步用作杂交F1代生产的亲本系。在本研究中，对7种甜瓜“皮尔德萨波”基因型进行了农艺性状和病原菌抗性评估，以评价其商业价值，并用作孤雌生殖过程的供体植物材料。然后，对甜瓜“皮尔德萨波”种质的孤雌生殖能力进行了评估和优化。本研究评估了孤雌生殖过程的几个步骤，如用辐照花粉授粉后甜瓜坐果、单倍体胚胎的获得、孤雌生殖胚胎和植株的萌发与生长，以及用秋水仙素或氨磺乐灵进行染色体加倍和双单倍体系的坐果情况。“皮尔德萨波”基因型的孤雌生殖效率在整个过程中表现出高度的基因型依赖性。采用三种不同方法检测孤雌生殖胚胎：逐个检测、X射线检测和液体培养基检测。种子的X射线成像比逐个检测方法快四倍，且孤雌生殖胚胎获得受损率比液体培养基检测低八倍。用辐照花粉授粉后，三分之一的甜瓜果实至少含有一个孤雌生殖胚胎。50.94%的获救胚胎未能发育成植株，原因是未能萌发或在发育初期由于单倍体纯合中的有害基因组合导致植株死亡而死亡。所获得的26株孤雌生殖植株的倍性水平分布为：73.08%为单倍体，23.08%为自发双单倍体，3.84%为混倍体。将两种用秋水仙素或氨磺乐灵进行染色体加倍的方法与第三种秋水仙素方法进行了比较。将顶端分生组织浸入秋水仙素溶液中2小时，植株存活率最高，为57.33%，染色体加倍率为9.30%混倍体和20.93%双单倍体。实现了双单倍体系的坐果和种子回收。在本研究中，从7种甜瓜“皮尔德萨波”供体基因型中产生了双单倍体系，然而，为了提高孤雌生殖效率，还需要进一步改进。
