Studies on the Morphologic Characteristics and Economic Traits of Different Ploidy Materials of Ramie

Different ploidy ramie materials were studied via microscopic observation on stem sections and macerated fiber cells. Morphologic differences between different ploidy plants were analyzed. Average bark area percentages in ramie stem transection of haploids, tetraploids, diploids and triploids were 28. 91, 27. 05, 26. 97 and 24.77% respectively. Average percentages of fiber layer area of diploids, haploids, tetraploids and triploids were 16.80, 16. 58, 15.52 and 13.78% respectively. Average fiber cell diameter and cell wall thickness were increased along with the increase of the ploidy of the plants. Average fiber length of diploids, triploids and haploids were 8. 49, 7. 96 and 6. 93 cm respectively. Average L/B (length/breadth) of diploids, triploids and haploids were 2 470. 7, 2 390. 6 and 1 616.3 respectively. Average breadths of fiber of haploids, diploids and triploids were 29. 30, 33. 87 and 49. 20μm respectively. However, there were relatively large variations in the above characteristics among the ramie materials of the same ploidy levels. Field performance of different ploidy plants was also investigated. As the chromosome ploidy increasing, there was a tendency of declining in shoot number per plant and increasing in stem diameter. Average shoots per plant of haploids, diploids, triploids and tetraploids were 5.83, 5.30, 3.77 and 3. 65 whereas their average stem diameters were 0.66, 0. 67, 0. 74 and 0. 76 cm respectively. Triploids were the tallest, while haploids were the shortest. Triploids had strong growth vigour, diploids and tetraploids had moderate growth vigour, while haploids appeared to be lack of growth vigour. Cold stress tolerance of tetraploids were the strongest, diploid had the moderate tolerance, while haploids and triploids were the least tolerant to cold stress. Both haploids and triploids were sterile.

Screening the Best Material for Ploidy Identification of Sugarcane-related Genera

[Objectives] Flow cytometry is widely used to identify plant chromosome ploidy because of its simplicity, rapidity and accuracy. Chromosome ploidy identification is an important part of sugarcane ploidy breeding and application research. It is particularly important to find out the best detection part for ploidy identification in sugarcane. [Methods] The cell suspensions of sugarcane stem tips and leaves were prepared by blade chopping method. The cell suspensions were detected by flow cytometry. The best position for ploidy identification was determined by comparing the cell suspension prepared from stem tips and cell suspension prepared from leaves. [Results] The results showed that the cell suspension dissociated from stem tips was more clear than that from leaf cell suspension;the proportion of non-adherent cells in the suspension prepared from stem tips was larger than that from the leaf cell suspension;the main peak of the stem tip cell suspension was single and the number of cells was more than that of the stem tip cell suspension by flow cytometry. Using the known ploidy ‘Badilar’ as the internal reference, the ploidy of cyathomi 87-16 was detected to be 8.37. [Conclusions] Sugarcane shoot tips are an ideal material for ploidy identification. This study provides a theoretical basis for selecting the best detection site for ploidy identification of sugarcane.

Changes in Root Hydraulic Conductivity During Wheat Evolution

Abstract: A better understanding of the mechanisms of water uptake by plant roots should be vital for improving drought resistance and water use efficiency (WUE). In the present study, we have demonstrated correlations between root system hydraulic conductivity and root characteristics during evolution using six wheat evolution genotypes (solution culture) with different ploidy chromosome sets (Triticum boeoticum Bioss., T. monococcum L.: 2n=2x=14; T. dicoccides Koern., T. dicoccon (Schrank) Schuebl.: 2n = 4x = 28; T. vulgare Vill., T. aestivum L. cv. Xiaoyan No. 6: 2n = 6x = 42). The experimental results showed that significant correlations were found between root system hydraulic conductivity and root characteristics of the materials with the increase in ploidy chromosomes (2x→6x) during wheat evolution. Hydraulic conductivity of the wheat root system at the whole-plant level was increased with chromosome ploidy during evolution, which was positively correlated with hydraulic conductivity of single roots, whole plant biomass, root average diameter, and root growth (length, area), whereas the root/shoot ratio had an inverse correlation with the hydraulic conductivity of root system with increasing chromosome ploidy during wheat evolution. Therefore, it is concluded that that the water uptake ability of wheat roots was strengthened from wild to modern cultivated species during evolution, which will provide scientific evidence for genetic breeding to improve the WUE of wheat by genetic engineering.