摘要
【目的】研究自花结实枣的柱头可授性、授粉受精及早期胚胎发育进程,为研究早期胚胎败育机制和克服枣树落花落果提供参考与依据。【方法】以迎秋红枣品种为材料,定位观察单花开花动态,显微观察柱头不同发育时期的花粉萌发情况、授粉受精及早期胚胎发育进程。【结果】迎秋红枣花为日开型,单花开放时间较短,约为26 h;最佳可授期为花瓣展平期至雄蕊展平期,持续4.5 h;授粉后8 h花粉管沿花柱道继续生长,并有少量花粉管生长到花柱的1/3处,36 h多数花粉粒进入花柱的2/3处,授粉后48 h,到达花柱基部;授粉后2 d花粉管经珠孔进入珠心释放2个精细胞,一个精细胞与胚囊次生核融合,形成初生胚乳核;授粉后3 d,另一个精细胞与卵细胞融合形成合子,授粉后5 d,合子开始第一次分裂,形成两个细胞。接着继续分裂,形成六细胞原胚。但授粉后6 d,可见珠被开始萎缩、原胚发育停滞的现象。授粉后12 d,发育成球形胚。【结论】揭示了迎秋红枣的柱头形态变化、授粉受精及早期胚胎发育过程,在授粉后6 d珠被萎缩引起了枣的早期败育。这种自花结实的迎秋红枣早期胚胎败育可能与落花落果现象有关。
【Objective】Fruit set in Chinese Jujube(Zizyphus jujuba Mill.)is usually only about 1%of the total number of flowers because of serious flower and fruit drop.Moreover,severe embryo abortion makes it difficult to obtain seedlings and select new varieties to meet the market demand.The fruit of Chinese jujube has various origins,from parthenocarpy,closed pollination or open pollination,and the fruit set can be improved by providing appropriate pollinizer trees.The complexity and diversity of the fruit-bearing and fertility characteristics make Chinese jujube breeding very difficult.Therefore,it is necessary to study the reproductive characteristics of Chinese Jujube in order to improve the breeding efficiency and overcome the problems of severe flower and fruit drop and early embryo abortion.At present,most of studies focus on different artificial hybrids,while there are few studies on the different fruiting characteristics of Chinese Jujube.Embryo observation of cultivars with parthenocarpy and char-acteristics of pollen tube growth of self-incompatible cultivars were previously reported.Yingqiuhong is an early-maturing table Jujube variety,which has self-fruiting characteristics and serious problem of flower and fruit drop.This study provides reference for overcoming the problems of severe flower and fruit drop and early embryo abortion in Chinese Jujube.【Methods】The flowering dynamics of Ying-qiuhong jujube were observed in the field,and pollen germination,pollination,fertilization,early em-bryonic development and stigma changes were observed microscopically.【Results】The results showed that the Yingqiuhong jujube flower was a day-blooming type,and mucilage was observed on the stigma surface during opening period,indicating that Yingqiuhong is a wet-stigma jujube.The shape of the style changed as the flowering progressed,so were the nectar volume(increased first and then de-creased)and honey plate color(from yellow to light yellow,and finally white).The opening time for a single flower was relatively short(lasting about 26 h).The best pollination period was from petal expan-sion to stamen extension stage,which lasted only 4.5 h.Especially in the stamen extension stage,a large amount of secretion covered the stigma surface,which provided substrate for pollen germination.Intensive pollen germination was observed,and the germination rate was higher than that in the petal ex-pansion stage.The stigma had the strongest adhesion to pollen and the strongest pollination ability dur-ing petal expansion period and stamen spreading period,and a small amount of pollen germinated in stigma 2 h after pollination.The pollen tubes continued to grow along the stylopodium 8 h after pollina-tion and a few pollen tubes grew to 1/3 of the style,while most pollen tubes grew to 2/3 of the style 36 h after pollination,and reached the base of the style 48 h after pollination.No callosal block was ob-served at the end of the style.The pollen tube stopped growing when it reached the synergids and re-leased sperms in the area between the egg and the central cell.The released spermatids moved to the egg cell and the central cell,and the polar nuclei in the center of the embryo sac began to fuse to form secondary nuclei.One sperm cell fused with the secondary nucleus of the embryo sac to form the prima-ry endosperm nucleus 2 d after pollination.The other sperm cell fused with the egg cell to form the zy-gote 3 d after pollination;the zygote began its first division 5 d after pollination,which was transverse and formed two cells,and the basal cell was near the micropyle and the apical cell was at the distal mi-cropyle.The basal cell divided laterally to form a three-cell proembryo,and the apical cell of the three cells divided longitudinally to form two unequal cells,then a six-cell proembryo.However,on the 6th day after pollination,the integument began to atrophy and the development of proembryo stopped.The ovary became yellow,stopped expansion,and then fell off.The normal developing ovules showed obvi-ous expansion and growth.The proembryo developed into globular embryo 12 d after pollination.【Con-clusion】Stigma morphological changes,pollination,fertilization and early embryogenesis development of Yingqiuhong Chinese jujube were revealed,and the dehiscence of integuments caused the early abor-tion of Jujube on the 6th day after pollination.The abortion of the early embryo of Yingqiuhong jujube may be related to the severe flower and fruit drop.
作者
任海燕
李登科
王永康
赵爱玲
薛晓芳
苏万龙
石美娟
刘丽
李毅
REN Haiyan;LI Dengke;WANG Yongkang;ZHAO Ailing;XUE Xiaofang;SU Wanlong;SHI Mei-juan;LIU Li;LI Yi(Institute of Pomology,Shanxi Agricultural University/Shanxi Provincial Key Laboratory of Genetic Improvement and Use of Pomology,Taigu 030815,Shanxi,China)
出处
《果树学报》
CAS
CSCD
北大核心
2022年第4期602-609,共8页
Journal of Fruit Science
基金
山西省自然科学研究面上基金(202103021224147)
农业农村部种质资源保护专项(111721301354052002)
科技部平台专项(NHGRC2020-NH12-1)
山西省农业科学院科研创新团队培育专项(YGC2019TD04)
现代农业产业技术体系专项(CARS-30-1-07,CARS-30-ZZ-22)。
关键词
枣
自花结实
授粉受精
早期胚胎发育
Ziziphus jujuba
Parthenocarpy
Pollination and fertilization
Early embryo development
