Cicer turcicum: A New Cicer Species and Its Potential to Improve Chickpea

Abstract

Genetic resources of the genus Cicer L. are not only limited when compared to other important food legumes and major cereal crops but also, they include several endemic species with endangered status based on the criteria of the International Union for Conservation of Nature. The chief threats to endemic and endangered Cicer species are over-grazing and habitat change in their natural environments driven by climate changes. During a collection mission in east and south-east Anatolia (Turkey), a new Cicer species was discovered, proposed here as C. turcicum Toker, Berger & Gokturk. Here, we describe the morphological characteristics, images, and ecology of the species, and present preliminary evidence of its potential utility for chickpea improvement. C. turcicum is an annual species, endemic to southeast Anatolia and to date has only been located in a single population distant from any other known annual Cicer species. It belongs to section Cicer M. Pop. of the subgenus Pseudononis M. Pop. of the genus Cicer L. (Fabaceae) and on the basis of internal transcribed spacer (ITS) sequence similarity appears to be a sister species of C. reticulatum Ladiz. and C. echinospermum P.H. Davis, both of which are inter-fertile with domestic chickpea (C. arietinum L.). With the addition of C. turcicum, the genus Cicer now comprises 10 annual and 36 perennial species. As a preliminary evaluation of its potential for chickpea improvement two accessions of C. turcicum were field screened for reproductive heat tolerance and seeds were tested for bruchid resistance alongside a representative group of wild and domestic annual Cicer species. C. turcicum expressed the highest heat tolerance and similar bruchid resistance as C. judaicum Boiss. and C. pinnatifidum Juab. & Spach, neither of which are in the primary genepool of domestic chickpea. Given that C. arietinum and C. reticulatum returned the lowest and the second lowest tolerance and resistance scores, C. turcicum may hold much potential for chickpea improvement if its close relatedness supports interspecific hybridization with the cultigen. Crossing experiments are currently underway to explore this question.

Keywords: Cicer; bruchid resistance; genetic resources; heat tolerance; new species.

FIGURE 1

West Asian Cicer survey (2013–18) routes and waypoints (a), collection sites classified by species (b), and close-up of the sole C. turcicum collection site at Yedipinar collection site, Sivrice district, Elazig province, Turkey. (Image from Google maps, Map data @2021, Australia) (c).

FIGURE 2

C. turcicum in situ at Yedipinar collection site, Sivrice district, Elazig province, Turkey on 12th June 2015. Specimen is both flowering and podding, with some mature pods.

FIGURE 3

Indicative C. turcicum growing season temperature (A), precipitation and sun hours (B) based on long term monthly data (1981–2010) from the Elazig airport weather station (892 m asl), located 24.1 km from the Yedipinar collection site (1,548 m asl) at lower elevation (892 vs. 1,548 m). C. turcicum germinates in October, flowers in April/May and matures in June/July based on field observations and phenology data from common garden evaluation (see Figure 6).

FIGURE 4

Leaves of C. pinnatifidum, C. turcicum and C. judaicum (a, left to right). Single leaflet at the base of leaves of C. turcicum (red arrow). Stipules of C. judaicum, C. pinnatifidum, and C. turcicum (b, left to right). Seeds of C. reticulatum, C. echinospermum, and C. turcicum (c, left to right). Seeds of C. judaicum, C. pinnatifidum, and C. turcicum (d, left to right). Shoots of C. pinnatifidum, C. judaicum, and C. turcicum (e, left to right).

FIGURE 5

Phylogenetic tree from the maximum parsimony analysis based on the sequence of ITS region in Cicer taxa.

FIGURE 6

C. turcicum phenology (flowering, podding, maturity) compared to related annual wild and domestic Cicer species. Data is from Mediterranean cool-season common garden screenhouse comparisons at Akdeniz University, (a) 2018/19, (b) 2019/20. Color-coded vertical lines represent accession least significant differences (LSD P < 0.05) for flowering (2.6–2.7 days), podding (2.4–2.7 days) and maturity (1.9–2.4 days). Abbreviations: C. arie, C. arietinum; C. turc, C. turcicum; C. pin, C. pinnatifidum; C. jud, C. judaicum; C. ret, C. reticulatum.

FIGURE 7

C. turcicum pod set percentage (A,B) under high reproductive phase temperatures (C,D) compared to related annual wild and domestic Cicer species. Data is from Mediterranean cool-season common garden screenhouse comparisons at Akdeniz University, (A,C) 2018/19, (B,D) 2019/20. Error bars represent accession least significant differences (LSD P < 0.05). Reproductive phase lengths (flowering to maturity) are shown individually for each species (B). Abbreviations: C. arie, C. arietinum; C. turc, C. turcicum; C. pin, C. pinnatifidum; C. jud, C. judaicum; C. ret, C. reticulatum.

FIGURE 8

Bruchid resistance in wild compared to domestic Cicer species in terms of seed damage (A), number of holes (B), weight loss (C), and number of eggs (D), from a no-choice feeding test at Akdeniz University. Letters represent accession group membership from Duncan multiple range test, different letters indicate significant difference (P < 0.05).