文献类型： 外文期刊

作者： Shen, Qiong ¹ ; Wu, Liyang ³ ; Zhao, Xinghua ⁴ ; Li, Yaling ¹ ;

作者机构： 1.Shanxi Agr Univ, Coll Hort, Taigu 030801, Peoples R China

2.Shanxi Acad Agr Sci, Inst Vegetables, Taiyuan 030031, Shanxi, Peoples R China

3.Nanjing Normal Univ, Coll Life Sci, Nanjing 210023, Jiangsu, Peoples R China

4.Agr Biotechnol Res Ctr Shanxi Prov, Taiyuan 030031, Shanxi, Peoples R China

关键词： Cucurbita moschata; Hull-less; Seed coat development; Seed coat; Seed testa; Lignin biosynthesis

期刊名称：SCIENTIA HORTICULTURAE （ 影响因子：3.463； 五年影响因子：3.672 ）

ISSN： 0304-4238

年卷期： 2019 年 245 卷

页码：

收录情况： SCI

摘要： The hull-less seed (thin-coated seeds) Cucurbita moschata is an excellent material for the food and seed oil industry; however, there are very few studies on this important trait. Here, using a scanning electronic microscope, we investigated the anatomical structure of the seed testa in two C. moschata inbred lines with hulled and hull-less seeds. We found that the seed coat of hulled seeds possessed a typical five-layer structure including, from the outside to inside, the epidermis (E), hypodermis (H), sclerenchyma (S), aerenchyma (A) and the chlorenchyma (C). During seed development, significant differences were observed in the seed testa between hulled and hull-less seeds. In the seed coat of hulled seeds, with seed development, there was increasing lignification in the S and H layers which was lacking in that of hull-less seeds. Instead, in the seed coat of hull-less seeds, after 15 days post anthesis(DPA), the five layers exhibited successive degradation, and were devoid of vascular bundle and lipid droplets. The lignin content in the testa of hull-less seeds also showed continued decrease over time, but continued to increase in that of hulled seeds, which was 0.22 mg/g and 64.22 mg/g at 50 DPA for the former and latter, respectively, suggesting lignin plays a critical role in the formation of seed testa. We examined the activities of four enzymes that are important for lignin biosynthesis and found that, consistent with the declined lignin content, there were also decreased activities in the seed coat for the phenylalanine ammonia lyase (PAL), 4-coumaric acid coenzyme A ligase (4CL), cinnamate-4-hydroxylase (C4H), and cinnamyl alcohol dehydrogenase (CAD). We conclude that degeneration or absence of the typical seed testa structure in hull-less seeds of C. moschata is due to reduced activity of key enzymes in the lignin biosynthesis pathway.