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  • Author or Editor: Zhi Li x
  • Journal of the American Society for Horticultural Science x
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Seashore paspalum (Paspalum vaginatum) is an important warm-season turfgrass distributed in tropical and coastal areas. It has excellent resistance to abiotic stresses, such as salinity, drought, and low temperature. However, the research on genetic diversity of local P. vaginatum collections from China is limited. In this study, the genetic diversity among 58 P. vaginatum accessions from four different provinces in China and four cultivars were assessed using simple sequence repeat (SSR) markers. The results indicated that a total of 45 alleles were detected by 19 polymorphic markers, with a range of 2 to 4 and an average of 2.4 alleles per marker. The genetic similarity coefficients between each pair of the 58 P. vaginatum accessions and four cultivars ranged from 0.51 to 1.00, with an average of 0.77. The range of variation of Shannon diversity index of each SSR marker was 0.047 to 1.075, with an average of 0.486. The polymorphic information content of each SSR marker varies from 0.016 to 0.577, with an average of 0.249. The results of cluster analysis and principal component analysis (PCA) showed that 58 P. vaginatum accessions and four cultivars were divided into four groups. These results provide the theoretical basis for the genetic diversity assessments and molecular marker–assisted breeding of P. vaginatum species.

Open Access

To select resistant germplasm resources and understand the growth and physiological responses of kiwifruit (Actinidia sp.) to drought stress, five species, Actinidia macrosperma (Acma), Actinidia longicarpa (Aclo), Actinidia deliciosa (Acde), Actinidia hemsleyana (Ache), and Actinidia valvata (Acva), were assessed under tissue culture conditions. Rootless seedlings of five species were cultured in a medium containing polyethylene glycol [PEG (formula weight 8000)] to induce drought stress (0%, 5%, 10%, 15%, and 20%). After a 30-day culture, three growth indices [fresh weight (FW), plant height (PLH), and leaf number (LN)] and six physiological indices were determined, and the drought damage index (DDI) was determined. The DDIs of five species increased, and three growth indices decreased with increasing PEG concentrations. The following changes were observed under 20% PEG treatment conditions: superoxide dismutase (SOD) activities increased significantly in Acma, Aclo, and Ache specimens; peroxidase (POX) activities remained stable in Acde, Ache, and Acva specimens; and catalase (CAT) activities increased sharply in Acma and Acva. Furthermore, the results indicated that soluble sugar (SS) content increased slightly in Acma, Aclo, Acde, and Ache but it decreased in Acva specimens. Proline (PRO) content increased significantly in Acma and Acva, and malondialdehyde (MDA) contents tended to increase under drought stress in all five species. Principal component analysis (PCA) results indicated that the order of drought tolerance in the five genotypes examined in this study under tissue culture conditions was as follows: Acma > Acva > Acde > Aclo > Ache. Therefore, we concluded that Acma and Acva are more resilient germplasm resources that represent promising kiwifruit-breeding materials. Furthermore, tolerance to drought stress in these species should be further investigated under orchard conditions.

Free access