以棉花细胞质雄性不育系、保持系、恢复系及杂种F1的花瓣、花药、柱头、蜜腺、苞叶和叶片为材料，测定和比较了各材料的总糖、蔗糖和果糖含量，观察和分析了三系杂交棉制种田中蜜蜂造访的数量与制种产量性状的相关性。试验结果表明：不育系的花瓣、苞叶、蜜腺可溶性总糖和蔗糖含量比可育的恢复系、保持系和F1的含量高，并达到显著或极显著水平，而果糖含量差异不明显。其中，不育系花器蔗糖含量是影响蜜蜂造访制种田蜂群量和不育系结铃率的关键因素；选育花器含糖量高的不育系，有利于提高制种田中的蜜蜂数量，增加不育系的结铃率，以及降低其不孕子率，提高制种产量。

A novel method for the genetic transformation of cotton pollen by means of vacuum infiltration and Agrobacterium-mediated transformation is reported. The acsA and genes, which are involved in cellulose synthesis in Acetobacter xylinum, were transferred into pollen grains of brown cotton with the aim of improving its fiber quality by incorporating useful prokaryotic features into the colored cotton plants. Transformation was carried out in cotton pollen-germinating medium, and transformation was mediated by vector pCAMBIA1301, which contains a reporter gene β-glucuronidase (GUS), a selectable marker gene, hpt, for hygromycin resistance and the genes of interest, acsA and acsB. The integration and expression of acsA, acsB and GUS in the genome of transgenic plants were analyzed with Southern blot hybridization, PCR, histochemical GUS assay and Northern blot hybridization. We found that following pollination on the cotton stigma transformed pollen retained its capability of double-fertilization and that normal cotton seeds were produced in the cotton ovary. Of 1,039 seeds from 312 bolls pollinated with transformed pollen grains, 17 were able to germinate and grow into seedlings for more than 3 weeks in a nutrient medium containing 50mg/l hygromycin; eight of these were transgenic plants integrated with acsA and acsB, yielding a 0.77% transformation rate. Fiber strength and length from the most positive transformants was 15% greater than those of the control (non-transformed), a significant difference, as was cellulose content between the transformed and control plants. Our study suggests that transformation through vacuum infiltration and Agrobacterium mediated transformation can be an efficient way to introduce foreign genes into the cotton pollen grain and that cotton fiber quality can be improved with the incorporation of the prokaryotic genes acsA and acsB.

Lintless mutant is a super-short fiber mutant in upland cotton only 4-8mm in fiber length and also named Ligon cotton controlled by one dominant gene Li1. Fiber ultrastructure of the mutant (Li1) and its wild type (li1) in situ and in vitro was observed under an electron microscope to understand its cytological characteristics during the fiber cell elongation. The results showed that the mutant fiber in situ had thinner cytoplasm, more small vacuoles, less mitochondria, Golgi apparatus and endoplasmic reticula, and there were more starch granules which were free or packed in the amyloplast beside the cell wall than that of wild type. It was indicated that scarcity of functional organelles and disability of transformation from starch to sugar might be associated with the fact that the mutant fiber cell was aborted too early to elongate into normal length. Mutant ovule in some media containing GA3 could produce a kind of huge callus that grew faster than normal ovules. The callus was covered with many white, loose, and semitransparent fiber-like cells that apt to get off from ovule. These fiber-like cells were multicellular fibers generated by cell division and had black dots just like pigment glands in the stem and leaf of cotton. There were lots of micro-tubes beside cytoplasm membrane of the multicellular fiber, which were thought to be primary preparation for second wall deposition of multicellular fiber. It was indicated that GA3 might induce the expression of gene(s) that kept inactive in the field condition and then stimulate the original fiber cell in vitro to undergo division again.

以棉花等基因系超短纤维突变体（Ligon Li1）及其野生型（Ligon li1）为材料，用胚珠离体培养方法，研究IAA（生长素）和GA3（赤霉酸）与纤维细胞伸长的关系。研究表明：（1）在含单激素IAA或GA3培养基内，离体诱导突变体胚珠产生的纤维长度分别约为1.86mm和2.1mm，比在对照（不含激素）培养基内的纤维长度分别显著增长86%和110%，表明外源激素IAA或GA3对突变体纤维伸长能力的缺损有补偿作用。（2）在同时含有IAA和GA3两种激素的培养基中，突变体和野生型胚珠产生的纤维长度分别为3.41mm和7.23mm，是它们在田间自然条件下纤维长度的76%和24.3%，均显著高于只含一种激素培养基内的纤维长度，这表明IAA与GA3间在诱导纤维伸长上有协同作用，而且，这种作用对突变体的作用大于野生型高达3.1倍，即：在一定程度上能解除突变体纤维伸长受到的阻碍。（3）突变体胚珠在含GA3和IAA培养基内经培养21d后，胚珠IAA和GA3平均含量，虽稍高于对照培养基内野生型胚珠的含量，但明显小于GA3和IAA培养基内野生型胚珠的平均含量，而且其纤维长度也显著小于野生型的纤维长度。说明在离体培养条件下，突变体的纤维伸长比野生型需更高的胚珠GA3和IAA水平，但由于突变体在遗传上的缺损，外源GA3和IAA尚不能完全解除突变体胚珠纤维伸长受到的限制。这可能与突变体胚珠利用外源激素能力不及野生型胚珠有关。

A fiberless seed mutant (fl) was identified in a commercial cotton (Gossypium hirsutum L.) variety Xu-Zhou 142 (FL). This phenotype is associated with lack of fiber cell initiation in the outer integument of the ovule, as was characterized by analysis of genes related to fiber differentiation and development. Two genes, fl-E6 and FL-E6, were cloned from fl-integument cells and FL-fiber or integument cells, respectively. Compared with FL-E6, fl-E6 showed a dramatic change in nucleotide sequence: (1). FL-E6 contained a tandem repetitive sequence in which GGCTCA (Gly-Ser) is repeated five times between the 82nd and the 93rd codon from the first ATG codon, while in fl-E6 the same sequence is repeated four times;(2). The fl-E6 gene encodes a polypeptide of 241 amino acids but lacks two codons between the 90th and 93rd codon and three between the 171st and 174th relative to FL-E6;(3). There are also 12 nucleotide substitutions which would result in 7 amino acid differences between fl-E6 and FL-E6. Analysis of RT-PCR and Northern Blot showed that expression of the fl-E6 gene is suppressed in the fl-integument cells, but highly expressed in FL-fiber cells. The difference between fl-E6 and FL-E6 may be associated with lower expression of fl-E6 in the fl-integument cells. Searches of protein databases with the FL-E6 gene sequence showed similarity to the protein backbones of two arabinogalactan-proteins (AGPs), one from the filtrate of suspension-cultured cells of Pyrus communis (AGPPc2) and the other from Nicotiana alata (AGPNa2). Although the function of the FL-E6 protein in differentiation and development of cotton fiber cells is not known, the data indicate that the mutation of fl-E6 gene from FL-E6 gene may inhibit the fiber cell initiation from epidermal cells of the outer integument of the ovule.