Induction, identification and genetics analysis of tetraploid Actinidia chinensis

Abstract

Actinidia chinensis is a commercially important fruit, and tetraploid breeding of A. chinensis is of great significance for economic benefit. In order to obtain elite tetraploid cultivars, tetraploid plants were induced by colchicine treatment with leaves of diploid A. chinensis ‘SWFU03’. The results showed that the best treatment was dipping leaves 30 h in 60 mg l−1 colchicine solutions, with induction rate reaching 26%. Four methods, including external morphology comparison, stomatal guard cell observation, chromosome number observation and flow cytometry analysis were used to identify the tetraploid of A. chinensis. Using the induction system and flow cytometry analysis methods, 187 tetraploid plants were identified. Three randomly selected tetraploid plants and their starting diploid plants were further subjected to transcriptome analysis, real-time quantitative polymerase chain reaction (RT-qPCR) and methylation-sensitive amplification polymorphism (MSAP) analysis. The transcriptome analysis results showed that there were a total of 2230 differentially expressed genes (DEG) between the diploid and tetraploid plants, of which 660 were downregulated and 1570 upregulated. The DEGs were mainly the genes involved in growth and development, stress resistance and antibacterial ability in plants. RT-qPCR results showed that the gene expression levels of the growth and stress resistance of tetraploid plants were higher than those of diploid ones at the transcriptome level. MSAP analysis of DNA methylation results showed that tetraploid plants had lower methylation ratio than diploid ones. The present results were valuable to further explore the epigenetics of diploid and tetraploid kiwifruit plants.

Transcriptome analysis of diploid and triploid Populus tomentosa

“…Photosynthesis includes a series of complex reactions in which carbon fixation is a central link in the regulation of photosynthesis ( Feng et al., 2006 ). We compared the data of carbon fixation pathways in previous photosynthetic organism kiwifruit ( Li et al, 2019 ) and selected the up-regulated malate dehydrogenase ( MDH ) for the RT-qPCR validation, and the expression levels of MDH gene were up-regulated in triploid P. tomentosa plants, compared to the diploid ones. With the possible exception of the stomatal dimension, the response to polyploidy can be very variable and complex.…”

“…Using the EF1a as an internal reference gene, and using the gene sequences of the transcriptome, the primers were designed using Primer primer 5 ( Lalitha, 2000 ), as listed in Table 1 . The RT-qPCR processes were described according to Li et al (2019) on a Bio-Rad CFX96TM Real-time PCR Detection System (Bio-Rad, California, USA), with a final volume of 25.0 μl, containing 2.5 units of Taq DNA polymerase, 0.4 mM deoxyribonucleotides (dNTPs), 20 μl of ddH 2 O, 1 μl of cDNA, and 500 nM of each primer. Each sample was carried out in triplicate for the RT-qPCR reactions.…”

“…RNA interference and dosage compensation in a polyploid cell often leads to epigenetic changes as it alters the gene expression levels ( Osborn et al, 2003 ; Soltis, Soltis & Tate, 2004 ). Many studies have found significant differences between the expression levels of genes in diploid and polyploid plants ( Osborn et al, 2003 ; Gutierrez-Gonzalez & Garvin, 2017 ; Li et al, 2019 ). Polyploid plants often exhibit commercially beneficial qualities, e.g., increased vigour, improved product quality, enlarged organs, enhanced tolerance to both biotic and abiotic stresses and increased heterozygosity and heterosis, in contrast to their diploid relatives ( Sattler, Carvalho & Clarindo, 2016 ; Liu & Sun, 2019 ).…”

“…Polyploid plants often exhibit commercially beneficial qualities, e.g., increased vigour, improved product quality, enlarged organs, enhanced tolerance to both biotic and abiotic stresses and increased heterozygosity and heterosis, in contrast to their diploid relatives ( Sattler, Carvalho & Clarindo, 2016 ; Liu & Sun, 2019 ). Polyploidy often results in downregulated fertility because the expression of fertility-related genes is lower than that of compared to their diploid relatives ( Li et al, 2019 ). Developing polyploidy in plants has been the focus of many plant breeders for some time ( Huang, Li & Cong, 1990 ; Bancroft et al, 2011 ; Rambani, Page & Udall, 2014 ; Li et al, 2019 ; Shenton et al, 2020 ).…”

“…Polyploidy often results in downregulated fertility because the expression of fertility-related genes is lower than that of compared to their diploid relatives ( Li et al, 2019 ). Developing polyploidy in plants has been the focus of many plant breeders for some time ( Huang, Li & Cong, 1990 ; Bancroft et al, 2011 ; Rambani, Page & Udall, 2014 ; Li et al, 2019 ; Shenton et al, 2020 ).…”