Wild Diploid Research Articles

ISOENZYME DIFFERENCES BETWEEN THE WILD DIPLOID AND TETRAPLOID WHEATS

Variability of acid phosphatase (ACP), esterase (EST), and superoxide dismutase (SOD) isoenzymes among 660 accessions of wild diploid wheats Triticum boeoticum (475) and T. urartu (185) and among 35 accessions of wild tetraploid wheats T. araraticum (21) and T. dicoccoides (14) was studied with the use of polyacrylamide gel electrophoresis. The wild diploids are differentiated by the electrophoretic variants of ACP-B, ACP-C, EST-A, EST-B, EST-C, EST-D, and SOD-B. Triticum urartu matches the A genome of wild tetraploid wheats T. araraticum and T. dicoccoides by allozymes of ACP-B, ACP-C and SOD-B, but differs distinctly by the monomorphic allozyme EST-A66. Triticum boeoticum fits the A genome of polyploid wheats by allozymes of EST-A and EST-B, but differs in allozymes of ACP-B and SOD-B. Thus, none of the two contemporary diploid wheats corresponds exactly to the A genome of wild tetraploid wheats by all diagnostic isoenzymes. Triticum boeoticum and T. arararicum share EST-C46 and EST-D71, whereas T. urartu and T. dicoccoides are fixed for silent EST-C0 and share EST-D73, suggesting independent origin of the two tetraploid wheats with a contribution from ancestral forms of both diploids.

Solanum salasianum: New wild tuber-bearing species from Peru

A new wild Peruvian diploid (2n=2x=24) tuber-bearing species ofSolanum, S. salasianum (seriesConicibaccata, Sect.Petota) from the moist montane forest near Monocanca, province Pachitea, department of Huanuco is described and illustrated. It is named in honor of my assistant, agronomist Alberto Salas Lopez.

Solanum bill-hookeri: New wild potato species from Peru

There is presented the original diagnosis ofSolanum bill-hookeri from the series Tuberosa (Sect. Petota), a new wild tuber-bearing diploid (2n=2x=24) species from Peru, named in honor of Dr. William J. Hooker.

The importance of wild potato species resistant to the potato cyst nematode, Globodera pallida, pathotypes P4A and P5A, in potato breeding. II. The crossability of resistant species

Over 2400 pollinations were made to investigate the crossability relationships between cultivated potatoes, and wild diploid species from Series Tuberosa and Circaeifolia, as well as wild polyploid species in Series Tuberosa and Longipedicellata resistant to potato cyst nematode, Globodera pallida pathotypes P4A and P5A. Wild diploids in Series Tuberosa crossed easily with cultivated diploid species, except with Solanum lignicaule where most pollinations failed, and seed set was extremely low (0.2 seeds per pollination or less). It is suggested that this species is 1EBN. S. capsicibaccatum is clearly isolated from Series Tuberosa, but can form hybrids with S. lignicaule, which can act as a bridging species to S. tuberosum haploids. S. gourlayi and S. oplocense can be crossed with both subspecies of S. tuberosum, but S. papita, Series Longipedicellata is reproductively isolated from the tetraploid cultigens. The crossability data are discussed in the light of germplasm utilisation for breeding potato varieties resistant to potato cyst nematode.

Dry Matter Yields and Photosynthetic Rates of Diploid and Hexaploid Triticum Species

The above ground dry matter yields of two wild diploid Triticum species averaged 76 per cent of that of two hexaploid bread wheat varieties in field trials carried out over five years. A cultivated diploid species, T. monococcum, gave similar dry matter yields to the bread wheat varieties but had a longer growth cycle. The flag leaves of wild diploid species had higher rates of photosynthesis than those of the bread wheat varieties both when expressed per unit area of leaf or per unit weight of chlorophyll. Photosynthetic rates of other organs, expressed per unit weight of chlorophyll were also greater for the wild diploids than for hexaploids. For snoots at the stage when their flag leaves were fully expanded, the investment in photosynthetic machinery, as measured by chlorophyll concentration, was less in the two wild diploids than in the hexaploids. This compensated for the high photosynthetic rate of the former, such that the specific growth rates, assessed by carbon-14 fixation per unit shoot dry matter, were similar.