Determination of QTLs for earliness in crosses derived from interspecific crosses between Pisum sativum L. and P. fulvum Sibth&Sm

Earliness in crop plants has a crucial role in avoiding drought and heat stress, which are two of the most important challenges in crop production and are predicted to exacarbate in the near future due to global warming. Furthermore, super-early plant cultivar are crucial to meet the future food needs of the growing human population. The study aimed (i) to determine transgressive segregations (progeny with higher and lower values from both parents in transgressive generations), (ii) to select super-early (de novo) progeny from transgressive segregations from F2 to F5, (iii) narrow sense heritability of super-earliness trait (iv) to examine the direct and indirect relationships of important agricultural and morphological traits on earliness with the path coefficient, and (v) to map important agronomic and morphological traits, including earliness, with SSR markers in F4 recombinant inbred lines (RIL), in populations derived from interspecific crosses between garden pea (P. sativum L.) and the most distant relative of pea (P. fulvum Sibth. et Sm.). In the F2 population, the so-called super-early individuals, matured much earlier than the female parent, flowered within 13-17 days after germination and set pods within 18-29 were studied up to the F5 generation. Super-early progeny were found to be earlier by about one month than P. sativum and two months than P. fulvum under short day conditions in the F5 population. In respect to days to flowering and pod setting, super-early progeny had a relatively high level of narrow sense heritability (h2 = 82% and 80%, respectively), indicating that the selections for earliness in segregating populations was effective for improvement of extreme early maturing varieties. In the study, in addition to the de novo super-early progeny, important transgressive segregation were obtained for important agro-morphological traits. A population of 114 RILs obtained through single seed descent from interspecific crosses between P. sativum and P. fulvum was evaluated to identify QTLs for earliness and important agro-morphological traits. A genetic map was constructed with forty-four SSRs markers that are polymorphic between parents were mapped on 7 chromosomes with a total length of 262.6 cM. A total of 14 QTLs on 5 chromosomes were determined for earliness and important agro-morphological traits. For earliness, two QTLs that explained 26% of the phenotypic variance were determined on LG2. The QTL on LG3 explained 16% of the phenotypic variance for plant height was determined, and six QTLs on LG2, LG4, LG5 and LG6 were determined for the number of pods per plant. Addionally, one QTL on LG6 for the number of seeds per pod, one QTL on LG4 for pod length, and 3 QTLs in LG3, LG5 and LG6 for harvest index were also determined. The results indicate that the AA205 and AA372-1 flanking markers for QTLs determined for earliness, and other SSR markers linked to the QTLs for important agro-morphological traits can contribute to future marker-assisted selection studies. Beneficial traits introduced from wild relatives reveal the importance of wild species to meet future challenges of agriculture in expanding the production and securing food supply