Differences of nitrogen efficiency of oilseed rape (Brassica napus L.) cultivars and their physiological properties were studied in a pot experiment, and the ratio of seed yield with no nitrogen ...supplied to that with normal nitrogen supply was adopted as a nitrogen efficiency coefficient. Results showed that the nitrogen efficiency coefficient determined for eight oilseed rape cultivars varied from 0.37 to 0.69, the ratio of nitrogen uptake amounts per plant, nitrogen transfer velocity from stems and leaves to seeds, and nitrogen physiological efficiency of oilseed rape cultivars under nitrogen stressed condition differed from with normal nitrogen supply. The higher the nitrogen efficiency of a cultivar, the higher the ratio of N uptake in no nitrogen to with N supplied. Under low nitrogen-supplying conditions, high nitrogen efficiency cultivars had longer roots, more lateral roots, higher amounts of reuse of nitrate from stem and leaves, and higher nitrate reductase activities in leaves.
Large amount of N03 --N are accumulated in vacuole, and cannot be timeously reducted, reutilized and transported into cytoplasm. It is the main reason for great N03 --N accumulation in vacuole and ...nitrogen (N) use efficiency cannot be further improved. Transport mechanism of N03 --N across tonoplast is explained in this paper, there are two proton pumps (H+-ATPase and H+-PPase) on tonoplast with absolutely different biology functions and physical characteristic. Mg.ATP and Mg.PPi are the specific substrates of H+-ATPase and H+-PPase respectively, hydrolysis H+ is pumped into vacuole, and contribution to build electrochemical proton gradient between cytoplasm and vacuole. N03 --N transport from vacuole to cytoplasm greatly depends on electrochemical proton gradient, N03 --N transport from cytoplasm to vacuole is mainly achieved by vacuole H+/N03 - antiport system, while symport system (vacuole N03 --N combined with anion) is of benefit for vacuole N03 --N transporting into cytoplasm. N03 --N transported by proton pump of tonoplast is influenced by NR activity in cytoplasm, N03 --N can be continuing assimilation and reduction by NR in cytoplasm, and accelerating vacuole N03 --N transported into cytoplasm. These results will supply references and research forecast for further study on efficiency and practicable methods of N utilization, and improving reuse efficiency of N03 --N in plant tissues.
TT1 gene encodes a WIP domain protein with Zn-finger, which is essential for seed coat development and organ color in
Arabidopsis. The mutation of this gene causes transparent testa. The
BjTT1 gene ...was cloned from
B. juncea using homology-based cloning and rapid-amplification of cDNA ends (RACE) strategy. A modified allele-specific PCR procedure was developed for assaying single nucleotide polymorphisms (SNP) of the
BjTT1 gene. The full length of
BjTT1 sequence was 2197 bp with only one intron. The cDNA sequence of
BjTT1 was 1412 bp in length including 903 bp of open reading frames. This gene encodes a deduced polypeptide of 300 amino acids with a predicted molecular weight of 33.97 kD and an isoelectric point of 6.99. The genomic sequence of
BjTT1 showed 99% and 85% identity with that of
BnTT1 and
AtTT1, respectively. The reverse transcription-polymerase chain reaction (RT-PCR) analysis showed the expressions of
BjTT1 in the seed coats of both black-seeded near-isogenic lines NILA and NILB. Based on sequence comparisons between
BjTT1 genes from parents with different seed coat colors and between the NILB mutant and its wide type parent, nucleotide variations at 8 sites inside the
BjTT1 coding region were detected, but mutations at these sites had no effect on seed coat color. The allele-specific PCR of
BjTT1 could distinguish the yellow-seeded and black-seeded parents.
拟南芥的
TT1基因(编码含有WIP结构域的锌指蛋白)对种皮的发育和颜色的形成具有重要的调控作用。本研究利用同源克隆和RACE技术分离了芥菜型油菜
TT1基因, 在芥菜型油菜黄黑籽材料的种皮中进行转录水平的分析, 比较了黑籽油菜与黄籽油菜基因序列的差异, 并采用等位基因特异(allele-specific) PCR技术对可能存在的单核苷酸多态位点进行验证。结果表明, 芥菜型油菜
TT1基因的DNA序列全长为2 197 bp, 包含1个内含子, 与甘蓝型油菜
TT1-1基因的DNA序列的相似性为99%, 与拟南芥的
TT1基因DNA序列的相似性为85%; 推导的TT1蛋白序列为300 氨基酸残基, 理论分子量为33.97 kD, 等电点为6.99;
TT1在所有材料的种皮中均检测到表达; 比较紫叶芥、四川黄籽、NILA和NILB的
TT1基因序列, 共发现8个核苷酸变异位点, 均在基因的外显子区域, 其中紫叶芥和NILA的序列相同, 四川黄籽和黒籽近等基因系NILB的序列相同。与紫叶芥相比, 黒籽近等基因系NILB有8个核苷酸差异, 但种皮颜色与紫叶芥一样, 均为黑色,
TT1基因这些位点的突变并不影响芥菜型油菜种皮的颜色。通过等位特异PCR可以区分来自四川黄籽与紫叶芥的
TT1基因。
FAD2 gene is essential for converting oleic acid to linoleic acid in plant seeds. From Xiangyou 15, a cultivar of
Brassica napus, 56
FAD2 DNA clones and 47
FAD2 cDNA clones were obtained including 6 ...new copies of
FAD2, which were designated
FAD2P1 to
FAD2P6. These new
FAD2 copies ranged from 1141 bp to 1157 bp in length and contained no introns in their open reading frames. They had 96.1% homology in nucleotide sequence and shared more than 87.0% of nucleotides identity to the published
FAD2 gene (AY577313). The deduced amino acid sequences of the 6
FAD2 copies presented 1–12 stop codons within the coding regions, which prevented from coding functional proteins. These copies were transferred into
Saccharomyces cerevisiae through vector pYES2.0, and the expression products showed no functions to synthesize 16:2 and 18:2 fatty acids. These results indicate that they are pseudogenes of
FAD2.
以甘蓝型油菜湘油15为材料, 采用PCR方法克隆并分析了56个
FAD2基因克隆和47个
FAD2基因cDNA克隆, 从中发现6个新的
FAD2拷贝。它们与公布的甘蓝型油菜
FAD2基因(AY577313)具有87.0%以上的同源性, 没有内含子, 在开放阅读框中存在1∼12个终止密码子, 其中有2个拷贝具有转录功能。将这6个
FAD2拷贝在酿酒酵母中进行体内表达实验, 通过气相色谱检测脂肪酸组成证明其不具备油酸脱氢酶功能, 与对照相比, 也没有改变酵母体内脂肪酸组成。由此推测这6个
FAD2拷贝为假基因。
Dihydroflavonol 4-reductase (
DFR) gene is a key gene of proanthocyanidins biosynthesis pathway in seed coat of Arabidopsis
thaliana. The mutation of this gene brings about a transparent testa. To ...study molecular mechanism of seed coat color in
Brassica, DFR gene was cloned from
B. juncea using homology-based clone strategy. The cloned gene 1,612 bp in length contains 5 introns. The complementary DNA (cDNA) consists of 1,214 bp and has a 1,158 bp open reading frame encoding a deduced polypeptide of 385 amino acids with a predicted molecular weight of 42,886 Da and an estimated isoelectric point of 5.54. RT-PCR analysis showed that
DFR was expressed in leaves, embryos, and seed coats of Purple-Leaf Mustard and 2 black-seeded near-isogenic lines developed from backcross breeding using Sichuan Yellow as a recurrent parent. Gene
DFR was expressed only in the leaves and embryos of Sichuan Yellow, but not in seed coats. No expression of
DFR blocked the biosynthesis of anthocyanidins and proanthocyanidins in the yellow seed coat, and seeds appeared yellow because of transparent testa. Gene
DFR is essential in the formation of seed coat color in
B. juncea. This study provided a foundation for understanding the molecular mechanism of seed coat color and developing novel yellow-seeded rapeseed germplasm through antisense expression or RNAi suppression of
DFR gene in black-seeded cultivars using a seed- or seed-coat-specific promoter.
In the present study, we characterized the transcriptional regulatory region (KF038144) controlling the expression of a constitutive FAD2 in Brassica napus. There are multiple FAD2 gene copies in B. ...napus genome. The FAD2 gene characterized and analyzed in the study is located on chromosome A5 and was designated as BnFAD2A5-1. BnFAD2A5-1 harbors an intron (1192bp) within its 5′-untranslated region (5′-UTR). This intron demonstrated promoter activity. Deletion analysis of the BnFAD2A5-1 promoter and intron through the β-glucuronidase (GUS) reporter system revealed that the −220 to −1bp is the minimum promoter region, while −220 to −110bp and +34 to +285bp are two important regions conferring high-levels of transcription. BnFAD2 transcripts were induced by light, low temperature, and abscisic acid (ABA). These observations demonstrated that not only the promoter but also the intron are involved in controlling the expression of the BnFAD2A5-1 gene. The intron-mediated regulation is an essential aspect of the gene expression regulation.
•A transcriptional regulatory region controlling the expression of a FAD2 in Brassica napus was characterized.•BnFAD2A5-1 harbors an intron within its 5'-UTR. This intron demonstrated promoter activity.•Deletion analysis of the BnFAD2A5-1 promoter and intron revealed that the –220 to –1bp is the minimum promoter region, while –220 to –110bp and +34 to +285bp are two important regions conferring high-levels of transcription.•BnFAD2A5-1 transcripts can be induced by light, low temperature, and abscisic acid (ABA).
