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- Author or Editor: Kate L. Delaporte x
Identifying productive food crops that tolerate moderate soil salinity is critical for global food security. We evaluate the salinity tolerance of Kunzea pomifera (muntries), a traditional Indigenous food plant that grows naturally in coastal regions of southern Australia and thrives on relatively low rainfall. A range of saline irrigation treatments were tested on four genotypes: tap water, 50, 200, 300, and 400 mm NaCl [Maarten’s Favorite (MF)] and up to 200 mm NaCl (MP1, SES2, and CJ1). After a 10-week saline irrigation treatment at 50 mm NaCl, SES2 appeared to have the highest salt tolerance of all genotypes based on no significant change in the number of secondary branches. At 50 mm NaCl, sodium accumulated significantly in roots but not the leaves of three genotypes, suggesting an active shoot exclusion mechanism. At 200 mm NaCl, plant growth decreased, Na+ and Cl− generally accumulated to significantly higher levels in leaves, compared with 50 mm NaCl, whereas potassium (K+) levels were unchanged. At high NaCl (300 and 400 mm), MF showed severe growth retardation with leaf symptoms appearing in week 9. Our results indicate that two genotypes of K. pomifera, SES2 and CJ1, are moderately salt tolerant based on modest reductions in three growth parameters at 50 mm NaCl, compared with MF and MP1. Further evaluation of the natural diversity of this species should reveal a range of diverse mechanisms of salinity tolerance thus providing a new fruit crop for moderately saline soils. Chemical names: NaCl (sodium chloride).
The potential for hybridization among three species of Eucalyptus L'Hér in the Series Macrocarpae, E. macrocarpa Hook (Mottlecah), E. pyriformis Turcz. (pear-fruited mallee), and E. youngiana F. Muell. (large-fruited mallee), was investigated using molecular data generated by randomly amplified polymorphic DNA (RAPD)-polymerase chain reaction (PCR) analysis. Samples of DNA from seedlings derived from controlled pollinations, and from different individuals from each species, were amplified with six different 10-mer primers. The presence or absence of RAPD fragments was used to generate a dendrogram based on genetic similarity, an ordination derived by multidimensional scaling (MDS), and a minimum spanning tree (MST) to show the relative links and dissimilarities between the individuals tested. Two clusters were identified on the unweighted pair-group method arithmetric average dendrogram. The first included all of the E. macrocarpa genotypes and all but one of the E. macrocarpa hybrids. The second included all of the E. youngiana and E. pyriformis genotypes and their hybrids. The MDS ordinations placed the hybrid seedlings between the parent species. From the 30 progeny investigated, 28 were assessed from the molecular data to be hybrids from controlled pollinations. The remaining two seedlings appeared to be derived from self-pollination. The parentage of two mature trees, thought to be natural hybrids involving the three species, was also investigated. One was confirmed as a cross between E. youngiana and E. pyriformis, but the second was less certain because of its low genetic similarity to all other individuals, and may be a hybrid involving species not included in this study.