Beside as precursors of BRs biosynthesis, more and more evidences supported that phytosterols play an important role in plant growth and development. To investigate the effects of phytosterols on the fiber development of upland cotton （Gossypium hirsutum L.） and the molecular base of sterol regulating cotton fiber growth, a homologue of HYDRA1 was cloned from upland cotton （cv. Xuzhou 142） by screening cotton fiber EST database and contigging the candidate ESTs. The GhHYDRA1 encoded a polypeptide of 218 amino acid residues and the deduced amino acid sequences had high homology with the members of HYDRA1 in Populus trichocarpa, Solanum tuberosum, and Arabidopsis thaliana. Moreover, GhHYDRA1 had comparable transmembrane regions to AtHYDRA1 in sequence, length, order, and spacing, except for a C-terminal polylysine cluster. Quantitative real-time RT-PCR analysis revealed that the higher expression levels of GhHYDRA1 gene were detected in 6 to 12 DPA （days post anthesis） fibers, while the lower levels were observed in 0 DPA ovule （with fibers） and 16 to 18 DPA fibers. These results indicated that GhHYDRA1 is the homologue of HYDRA1 gene and plays a crucial role in fiber elongation. Furthermore, auxin and BL up-regulated the expression level of GhHYDRA1 while ABA and KT down-regulated the expression level of GhHYDRA1 in cotton ovule and fiber growth. The result suggested that phytosterols play a role in the interaction of plant hormones.
ZANG Zhen-le HU Ming-yu LI Xian-bi CHEN Kui-jun LIAO Peng XIAO Yue-hua HOU Lei PEI Yanand LUO Ming
Phytosterols play an important role in plant growth and development, including cell division, cell elongation, embryogenesis, cellulose biosynthesis, and cell wall formation. Cotton fiber, which undergoes synchronous cell elongation and a large amount of cellulose synthesis, is an ideal model for the study of plant cell elongation and cell wall biogenesis. The role of phytosterols in fiber growth was investigated by treating the fibers with tfidemorph, a sterol biosynthetic inhibitor. The inhibition of phy- tosterol biosynthesis resulted in an apparent suppression of fiber elongation in vitro or in planta. The determination of phy- tosterol quantity indicated that sitosterol and campesterol were the major phytosterols in cotton fibers; moreover, higher con- centrations of these phytosterols were observed during the period of rapid elongation of fibers. Furthermore, the decrease and increase in campesterol：sitosterol ratio was associated with the increase and decease in speed of elongation, respectively, dur- ing the elongation stage. The increase in the ratio was associated with the transition from cell elongation to secondary cell wall synthesis. In addition, a number of phytosterol biosynthetic genes were down-regulated in the short fibers of ligon lintless-1 mutant, compared to its near-isogenic wild-type TM-1. These results demonstrated that phytosterols play a crucial role in cot- ton fiber development, and particularly in fiber elongation.
Cotton fiber is major materials of the textile industry in the world.Productions of cotton fiber affect our li...
Hu Mingyu Tan Kunling Xiao Zhongyi Chen Kuijun Liao Peng Luo Ming (Key Laboratory of Biotechnology and Crop Quality Improvement,Ministry of Agriculture
Cotton(Gossypium hirsutum L.) is the leading fiber crop and one of the mainstays of the economy in the world.Cotton fibers,as the main product of cotton plants,are unicellular,linear
LUO Ming,XIAO Zhong-yi,TAN Kun-ling,HU Ming-yu,LIAO Peng(Key Laboratory of Biotechnology and Crop Quality Improvement,Ministry of Agriculture
As one of the longest cells characterized in plant kingdom,cotton fibers were regarded as an ideal material for studying plant cell growth and development.In recent years,several reports revealed
HU Ming-yu,LUO Ming,TAN Kun-ling,XIAO Zhong-yi,PEI Yan(Key Laboratory of Biotechnology and Crop Quality Improvement,Ministry of Agriculture,Biotechnology Research Center,Southwest University,Chongqing 400716,China)
Vacuolar H^+-ATPase was regarded as a key enzyme promoting the fiber cell elongation in cotton (Gossypium hirsuturm L.) through regulating turgor-driven pressure involved in polarity expansion of single cell fiber. The DET3, a V-ATPase subunit C, plays an important role in assembling subunits and regulating the enzyme activity, and is involved in Brassinosteroid-induced cell elongation. To analyze the function of GhDET3 on the elongation of cotton fibers, seven candidates of ESTs were screened and contigged for a 5'-upstream sequence, and the 3'-RACE technique was used to clone the 3'-downstream sequence for the full length of GhDET3 gene. The full length of the target clone was 1,340 bp, including a 10 bp 5'-UTR, an ORF of 1,134 bp, and a 196 bp 3'-UTR. This cDNA sequence encoded a polypepide of 377 amino acid residues with a predicted molecular mass of 43 kDa and a basic isoelectric point of 5.58. Furthermore, a length of 3,410 bp sequence from genomic DNA of GhDET3 was also cloned by PCR. The deduced amino acid sequence had a high homology with DET3 from Arabidopsis, rice, and maize. Quantitative real-time PCR (qRT-PCR) analysis showed that the GhDET3 expression pattern was ubiquitous in all the tissues and organs detected. The result also revealed that the accumulation of GhDET3 mRNA reached the highest profile at the fiber elongation stage in 12 DPA (days post anthesis) fibers, compared with the lowest level at the fiber initiation stage in 0 DPA ovules (with fibers). The transcript accumulation in fibers and ovules shared the similar variation tendency. In addition, in vitro ovule culture experiment demonstrated that exogenous 24-EBL treatment to 4 DPA ovules (with fibers) was capable of increasing the expression level of GhDET3, and the mRNA accumulation of GhDET3 increased in transgenic FBP7::GhDET2 cotton fibers in vivo. These results indicate that GhDET3 gene plays a crucial role in cotton fiber elongation.
Zhongyi XiaoKunling TanMingyu HuPeng LiaoKuijun ChenMing Luo
Brassinosteroids （BRs） are an important class of plant steroidal hormones that are essential in a wide variety of physiological processes. Two kinds of intermediates, sitosterol and campesterol, play a crucial role in cell elongation, cellulose biosynthesis, and accumulation. To illuminate the effects of sitosterol and campesterol on the development of cotton （Gossypiurn hirsuturm L.） fibers through screening cotton fiber EST database and contigging the candidate ESTs, two key genes GhSMT2-1 and GhSMT2-2 controlling the sitosterol biosynthesis were cloned from developing fibers of upland cotton cv. Xuzhou 142. The full length of GhSMT2-1 was 1,151 bp, including an 8 bp 5＇-untranslated region （UTR）, a 1,086 bp open reading frame （ORF）, and a 57 bp 3＇-UTR. GhSMT2-1 gene encoded a polypeptide of 361 amino acid residues with a predicted molecular mass of 40 kDa. The full length of GhSMT2-2 was 1,166 bp, including an 18 bp 5＇-UTR, a 1,086 bp ORF, and a 62 bp 3＇-UTR. GhSMT2-2 gene encoded a polypeptide of 361 amino acid residues with a predicted molecular mass of 40 kDa. The two deduced amino acid sequences had high homology with the SMT2 from Arabidopsis thaliana and Nicotiana tabacurn. Furthermore, the typical conserved structures characterized by the sterol C-24 methyltransferase, such as region I （LDVGCGVGGPMRAI）, region II （IEATCHAP）, and region III （YEWGWGQSFHF）, were present in both deduced proteins. Southern blotting analysis indicated that GhSMT2-1 or GhSMT2-2 was a single copy in upland cotton genome. Quantitative real-time RT-PCR analysis revealed that the highest expression levels of both genes were detected in 10 DPA （day post anthesis） fibers, while the lowest levels were observed in cotyledon and leaves. The expression level of GhSMT2-1 was 10 times higher than that of GhSMT2-2 in all the organs and tissues detected. These results indicate that the homologue of sterol C-24 methyltransferase gene was cloned from upland cotton and both GhSMT2 genes play a crucial rol
Ming Luo,Kunling Tan,Zhongyi Xiao,Mingyu Hu,Peng Liao,Kuijun Chen Key Laboratory of Biotechnology and Crop Quality Improvement,Ministry of Agriculture
