Genome Size and Seed Mass Analyses in Cicer arietinum (Chickpea) and Wild Cicer Species

The genome size of cultivated Cicer arietinum and 12 wild Cicer sp. including seven annual and five perennial species were analyzed using flow cytometry. A significant 2C genome size variation was observed among the Cicer sp. The 2C genome size ranged from 1.00 pg in wild species, Cicer judaicum, to 1.76 pg in cultivated species, C. arietinum. The wild perennial species all had a genome size of ≈1.6 pg. Most if not all of this genome size variation occurred among wild annual species. A significant positive correlation between 2C genome size and seed mass was observed among 12 wild Cicer sp. at α = 0.05. However, artificial selection appears to decrease nucleotype effects in cultivated C. arietinum, which resulted in no correlation between seed mass and genome size at α = 0.05.

Resistance to Phytophthora medicaginis Hansen and Maxwell in wild Cicer species and its use in breeding root rot resistant chickpea (Cicer arietinum L.)

Phytophthora root rot caused by Phytophthora medicaginis is a major disease of chickpea in Australia. Only partial resistance, derived from chickpea, is available in Australian cultivars. Five wild Cicer species were compared with chickpea cv. Jimbour (moderately resistant) in a field experiment. The proportions of accessions with significantly lower (P < 0.05) disease scores, where lower scores equate to higher resistance, were 9/9 for C. echinospermum, 9/21 for C. bijugum, 1/4 for C. judaicum, 1/29 for C. reticulatum, and 0/3 for C. pinnatifidum. The resistance of C. echinospermum (7/7 accessions) but not the other Cicer species was reproduced in a greenhouse test. Nine out of 30 chickpea × C. echinospermum-derived lines were as resistant as the C. echinospermum parents in a separate greenhouse experiment. C. echinospermum appears to be the best of the sources we examined for breeding chickpea cultivars resistant to P. medicaginis.