Eng Wee Hiang, Ho Wei Seng, Ling Kwong Hung
Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia.
Sarawak Timber Association, Kuching, Sarawak, Malaysia.
PeerJ. 2021 Oct 27;9:e12399. doi: 10.7717/peerj.12399. eCollection 2021.
Polyploidization has played a crucial role in plant breeding and crop improvement. However, studies on the polyploidization of tropical tree species are still very scarce in this region. This paper described the induction and identification of polyploid plants of by colchicine treatment. belongs to the Rubiaceae family is a natural tetraploid plant with 44 chromosomes (2 = 4 = 44). Nodal segments were treated with colchicine (0.1%, 0.3% and 0.5%) for 24 h and 48 h before transferring to shoot regeneration medium. Flow cytometry (FCM) and chromosome count were employed to determine the ploidy level and chromosome number of the regenerants, respectively. Of 180 colchicine-treated nodal segments, 39, 14 and 22 were tetraploids, mixoploids and octoploids, respectively. The highest percentage of polyploidization (20% octoploids; 6.7% mixoploids) was observed after treated with 0.3% colchicine for 48 h. The DNA content of tetraploid (4C) and octoploid (8C) was 2.59 ± 0.09 pg and 5.35 ± 0.24 pg, respectively. Mixoploid plants are made up of mixed tetraploid and octoploid cells. Chromosome count confirmed that tetraploid cell has 44 chromosomes and colchicine-induced octoploid cell has 88 chromosomes. Both octoploids and mixoploids grew slower than tetraploids under conditions. Morphological characterizations showed that mixoploid and octoploid leaves had thicker leaf blades, thicker midrib, bigger stomata size, lower stomata density, higher SPAD value and smaller pith layer than tetraploids. This indicates that polyploidization has changed and resulted in traits that are predicted to increase photosynthetic capacity of . These novel polyploid plants could be valuable resources for advanced breeding programs to produce improved clones for planted forest development.
多倍体化在植物育种和作物改良中发挥了关键作用。然而，该地区对热带树种多倍体化的研究仍然非常匮乏。本文描述了通过秋水仙碱处理诱导和鉴定多倍体植物的过程。[植物名称]属于茜草科，是一种天然四倍体植物，有44条染色体（2n = 4x = 44）。在转移到芽再生培养基之前，将茎段用秋水仙碱（0.1%、0.3%和0.5%）处理24小时和48小时。分别采用流式细胞术（FCM）和染色体计数来确定再生植株的倍性水平和染色体数目。在180个经秋水仙碱处理的茎段中，分别有39个、14个和22个是四倍体、混倍体和八倍体。在用0.3%秋水仙碱处理48小时后，观察到最高的多倍体化百分比（20%八倍体；6.7%混倍体）。四倍体（4C）和八倍体（8C）的DNA含量分别为2.59±0.09皮克和5.35±0.24皮克。混倍体植物由四倍体和八倍体细胞混合组成。染色体计数证实四倍体细胞有44条染色体，秋水仙碱诱导的八倍体细胞有88条染色体。在[具体条件]下，八倍体和混倍体的生长都比四倍体慢。形态学特征表明，混倍体和八倍体的叶片比四倍体叶片更厚、中脉更粗、气孔尺寸更大、气孔密度更低、SPAD值更高且髓层更小。这表明多倍体化已经改变并导致了预计会增加[植物名称]光合能力的性状。这些新的多倍体植物可能是高级[植物名称]育种计划的宝贵资源，用于为人工林发展培育改良的无性系。
