棉花4个栽培种纤维初始发育的比较研究

Comparative Studies on Fiber Initiation Development of Four Cultivated Cotton Species

利用扫描电镜技术,对棉花4个栽培种陆地棉(泗棉3号)、海岛棉(海7124)、亚洲棉(定远小花)以及非洲棉(A1-50)开花前后的胚珠进行比较观察,并探讨延迟授粉对各棉种纤维初始发育的影响。结果表明,在南京大田气候条件下,除亚洲棉外其他3个棉种均在开花前1d出现纤维细胞突起。在开花当天和开花后1d,所有棉种的纤维突起(或伸长)密度均在珠柄顶部的脊突处最大,合点端和胚珠中部其次,珠孔附近最小。除陆地棉外,其他棉种在开花后1d的纤维伸长密度均低于开花当天的纤维突起密度。说明随着棉胚珠体积的膨大,其他3个棉种胚珠表面的纤维细胞"稀释"程度大于陆地棉。在棉纤维初始发育阶段,纤维密度不仅受气象因子如温度的影响,而且与授粉时柱头的生活力密切相关;延迟授粉对纤维初始发育的影响以非洲棉较大,海岛棉较小,亚洲棉和陆地棉最小。本研究为理解棉纤维的分化和发育机理,探讨4个栽培棉种纤维发育的亲缘关系,及人工授粉棉纤维的杂种优势利用提供了一定的理论依据。

Cotton is a fine natural fiber, an important textile, and a major industrial resource, accounting for nearly half of the world＇s natural fiber consumption. Understanding the growth and development of cotton fibers is thus of global importance. Cotton fiber development is divided into four overlapping stages： fiber initiation, fiber elongation, secondary wall thickening, and maturation. The development of fiber initiation might include these aspects such as fiber cells differentiation, fiber protrusion, and initial elongation. At present, many studies on cotton fiber differentiation and development have been documented, but most of them are focused on Cossypium hirsutum, and the reports of comparative studies on fiber development among cotton species axe ever less. Here we observed the ovules before and after anthesis of four cultivated cotton species including Gossypium hirsutum ev. Simian 3, Gossypium barbadense ev. Hai 7124, Gossypium arboreum ev. Dingyuan xiaohua, and C, ossypium herbaceum ev. A1-50 by utilizing SEM （scanning electron microscope）, and explored the influence of delay pollination on fiber initiation development of each cultivar. The results showed that under the climate conditions in the field at Nanjing, fiber cells protruded on the ovular surface in all cultivars except G. arboreum at 1 day before anthesis. At 0 and 1 day post-anthesis （DPA）, fiber protrusion （or elongation） density of all materials was the highest at the funicular crest, higher at the chalazal cap and the middle part of ovule, and the least near the mieropyle; moreover except upland cotton eultivar Simian 3, fiber density of the other three eultivars was lower at 1 DPA than that at 0 DPA, suggesting that with the expanding of the cotton ovular volume , the fiber ＂diluting＂ degree on the ovular surfaces was greater in G. barbadense , G. arboreum, and G. herbaceum than in G. hirsutum. During cotton fiber initial stage, fiber density not only was affected by weather factors such as tempemtme but also related to the viability of stigma. Delay pollination exerted relatively significant influence on fiber initiation development of G. herbaceum, relatively less influence on G. barbadense, and the least influence on G. hirsutum and G. arboreum. Our studies might provide some theoretical references on understanding the mechanism of cotton fiber differentiation and growth, and exploring the phylogeuetic relationships of fiber development of four cultivated cottons, as well as utilizing the heterosis of cotton fiber through artificial pollination.